10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

(Mark One)

x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2016

OR

oTRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from              to             

Commission File Number	Registrants; State of Incorporation; Addresses; and Telephone Number	IRS Employer Identification No.
1-8962	PINNACLE WEST CAPITAL CORPORATION (An Arizona corporation) 400 North Fifth Street, P.O. Box 53999 Phoenix, Arizona 85072-3999 (602) 250-1000	86-0512431
1-4473	ARIZONA PUBLIC SERVICE COMPANY (An Arizona corporation) 400 North Fifth Street, P.O. Box 53999 Phoenix, Arizona 85072-3999 (602) 250-1000	86-0011170

Securities registered pursuant to Section 12(b) of the Act:

	Title Of Each Class	Name Of Each Exchange On Which Registered
PINNACLE WEST CAPITAL CORPORATION	Common Stock, No Par Value	New York Stock Exchange
ARIZONA PUBLIC SERVICE COMPANY	None	None

Securities registered pursuant to Section 12(g) of the Act:

ARIZONA PUBLIC SERVICE COMPANY             Common Stock, Par Value $2.50 per share

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act

PINNACLE WEST CAPITAL CORPORATION	Yes x  No o
ARIZONA PUBLIC SERVICE COMPANY	Yes x  No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

PINNACLE WEST CAPITAL CORPORATION	Yes o  No x
ARIZONA PUBLIC SERVICE COMPANY	Yes o  No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

PINNACLE WEST CAPITAL CORPORATION	Yes x  No o
ARIZONA PUBLIC SERVICE COMPANY	Yes x  No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

PINNACLE WEST CAPITAL CORPORATION	Yes x  No o
ARIZONA PUBLIC SERVICE COMPANY	Yes x  No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or in any amendment to this Form 10-K.x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company.  See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.  (Check one):

PINNACLE WEST CAPITAL CORPORATION
Large accelerated filer x	Accelerated filer o
Non-accelerated filer o	Smaller reporting company o
(Do not check if a smaller reporting company)

ARIZONA PUBLIC SERVICE COMPANY
Large accelerated filer o	Accelerated filer o
Non-accelerated filer x	Smaller reporting company o
(Do not check if a smaller reporting company)

Indicate by check mark whether each registrant is a shell company (as defined in Rule 12b-2 of the Act).  Yes o  No x

State the aggregate market value of the voting and non-voting common equity held by non-affiliates, computed by reference to the price at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day of each registrant’s most recently completed second fiscal quarter:

PINNACLE WEST CAPITAL CORPORATION	$8,961,361,256 as of June 30, 2016
ARIZONA PUBLIC SERVICE COMPANY	$0 as of June 30, 2016

The number of shares outstanding of each registrant’s common stock as of February 17, 2017

PINNACLE WEST CAPITAL CORPORATION	111,340,169 shares
ARIZONA PUBLIC SERVICE COMPANY	Common Stock, $2.50 par value, 71,264,947 shares. Pinnacle West Capital Corporation is the sole holder of Arizona Public Service Company’s Common Stock.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of Pinnacle West Capital Corporation’s definitive Proxy Statement relating to its Annual Meeting of Shareholders to be held on May 17, 2017 are incorporated by reference into Part III hereof.

Arizona Public Service Company meets the conditions set forth in General Instruction I(1)(a) and (b) of Form 10-K and is therefore filing this form with the reduced disclosure format allowed under that General Instruction.

TABLE OF CONTENTS

		Page
GLOSSARY OF NAMES AND TECHNICAL TERMS		ii
FORWARD-LOOKING STATEMENTS		2
PART I		3
Item 1.	Business	3
Item 1A.	Risk Factors	29
Item 1B.	Unresolved Staff Comments	41
Item 2.	Properties	42
Item 3.	Legal Proceedings	45
Item 4.	Mine Safety Disclosures	45
Executive Officers of Pinnacle West		46
PART II		47
Item 5.	Market for Registrants’ Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	47
Item 6.	Selected Financial Data	48
Item 7.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	50
Item 7A.	Quantitative and Qualitative Disclosures About Market Risk	77
Item 8.	Financial Statements and Supplementary Data	78
	Pinnacle West Financial Statements	82
	APS Financial Statements	91
	Combined Notes to Consolidated Financial Statements	97
Item 9.	Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	175
Item 9A.	Controls and Procedures	175
Item 9B.	Other Information	176
PART III		176
Item 10.	Directors, Executive Officers and Corporate Governance of Pinnacle West	176
Item 11.	Executive Compensation	176
Item 12.	Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	176
Item 13.	Certain Relationships and Related Transactions, and Director Independence	176
Item 14.	Principal Accountant Fees and Services	177
PART IV		178
Item 15.	Exhibits and Financial Statement Schedules	178
SIGNATURES		198

This combined Form 10-K is separately filed by Pinnacle West and APS.  Each registrant is filing on its own behalf all of the information contained in this Form 10-K that relates to such registrant and, where required, its subsidiaries.  Except as stated in the preceding sentence, neither registrant is filing any information that does not relate to such registrant, and therefore makes no representation as to any such information.  The information required with respect to each company is set forth within the applicable items.  Item 8 of this report includes Consolidated Financial Statements of Pinnacle West and Consolidated Financial Statements of APS.  Item 8 also includes Combined Notes to Consolidated Financial Statements.

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GLOSSARY OF NAMES AND TECHNICAL TERMS

4CA	4C Acquisition, LLC, a wholly-owned subsidiary of Pinnacle West
ac	Alternating Current
ACC	Arizona Corporation Commission
ADEQ	Arizona Department of Environmental Quality
AFUDC	Allowance for Funds Used During Construction
ANPP	Arizona Nuclear Power Project, also known as Palo Verde
APS	Arizona Public Service Company, a subsidiary of the Company
ARO	Asset retirement obligations
ASU	Accounting Standards Update
BART	Best available retrofit technology
Base Fuel Rate	The portion of APS’s retail base rates attributable to fuel and purchased power costs
BCE	Bright Canyon Energy Corporation, a subsidiary of the Company
BHP Billiton	BHP Billiton New Mexico Coal, Inc.
BNCC	BHP Navajo Coal Company
CAISO	California Independent System Operator
CCR	Coal combustion residuals
Cholla	Cholla Power Plant
dc	Direct Current
distributed energy systems	Small-scale renewable energy technologies that are located on customers’ properties, such as rooftop solar systems
DOE	United States Department of Energy
DOI	United States Department of the Interior
DOJ	United States Department of Justice
DSM	Demand side management
DSMAC	Demand side management adjustment charge
EES	Energy Efficiency Standard
El Dorado	El Dorado Investment Company, a subsidiary of the Company
El Paso	El Paso Electric Company
EPA	United States Environmental Protection Agency
FERC	United States Federal Energy Regulatory Commission
Four Corners	Four Corners Power Plant
GWh	Gigawatt-hour, one billion watts per hour
kV	Kilovolt, one thousand volts
kWh	Kilowatt-hour, one thousand watts per hour
LFCR	Lost Fixed Cost Recovery Mechanism
MMBtu	One million British Thermal Units
MW	Megawatt, one million watts
MWh	Megawatt-hour, one million watts per hour
Native Load	Retail and wholesale sales supplied under traditional cost-based rate regulation
Navajo Plant	Navajo Generating Station
NERC	North American Electric Reliability Corporation
NRC	United States Nuclear Regulatory Commission
NTEC	Navajo Transitional Energy Company, LLC
OCI	Other comprehensive income
OSM	Office of Surface Mining Reclamation and Enforcement
Palo Verde	Palo Verde Nuclear Generating Station or PVNGS
Pinnacle West	Pinnacle West Capital Corporation (any use of the words “Company,” “we,” and “our” refer to Pinnacle West)
PSA	Power supply adjustor approved by the ACC to provide for recovery or refund of variations in actual fuel and purchased power costs compared with the Base Fuel Rate
RES	Arizona Renewable Energy Standard and Tariff
Salt River Project or SRP	Salt River Project Agricultural Improvement and Power District
SCE	Southern California Edison Company
TCA	Transmission cost adjustor
VIE	Variable interest entity

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FORWARD-LOOKING STATEMENTS

This document contains forward-looking statements based on current expectations.  These forward-looking statements are often identified by words such as “estimate,” “predict,” “may,” “believe,” “plan,” “expect,” “require,” “intend,” “assume,” “project” and similar words.  Because actual results may differ materially from expectations, we caution readers not to place undue reliance on these statements.  A number of factors could cause future results to differ materially from historical results, or from outcomes currently expected or sought by Pinnacle West or APS.  In addition to the Risk Factors described in Item 1A and in Item 7 — “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” these factors include, but are not limited to:

• our ability to manage capital expenditures and operations and maintenance costs while maintaining reliability and customer service levels;

• variations in demand for electricity, including those due to weather, seasonality, the general economy, customer and sales growth (or decline), and the effects of energy conservation measures and distributed generation;

• power plant and transmission system performance and outages;

• competition in retail and wholesale power markets;

• regulatory and judicial decisions, developments and proceedings;

• new legislation, ballot initiatives and regulation, including those relating to environmental requirements, regulatory policy, nuclear plant operations and potential deregulation of retail electric markets;

• fuel and water supply availability;

• our ability to achieve timely and adequate rate recovery of our costs, including returns on and of debt and equity capital investment;

• our ability to meet renewable energy and energy efficiency mandates and recover related costs;

• risks inherent in the operation of nuclear facilities, including spent fuel disposal uncertainty;

• current and future economic conditions in Arizona, including in real estate markets;

• the development of new technologies which may affect electric sales or delivery;

• the cost of debt and equity capital and the ability to access capital markets when required;

• environmental, economic and other concerns surrounding coal-fired generation, including regulation of greenhouse gas emissions;

• volatile fuel and purchased power costs;

• the investment performance of the assets of our nuclear decommissioning trust, pension, and other postretirement benefit plans and the resulting impact on future funding requirements;

• the liquidity of wholesale power markets and the use of derivative contracts in our business;

• potential shortfalls in insurance coverage;

• new accounting requirements or new interpretations of existing requirements;

• generation, transmission and distribution facility and system conditions and operating costs;

• the ability to meet the anticipated future need for additional generation and associated transmission facilities in our region;

• the willingness or ability of our counterparties, power plant participants and power plant land owners to meet contractual or other obligations or extend the rights for continued power plant operations; and

• restrictions on dividends or other provisions in our credit agreements and ACC orders.

These and other factors are discussed in the Risk Factors described in Item 1A of this report, which readers should review carefully before placing any reliance on our financial statements or disclosures.  Neither Pinnacle West nor APS assumes any obligation to update these statements, even if our internal estimates change, except as required by law.

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PART I

ITEM 1.  BUSINESS

Pinnacle West

 Pinnacle West is a holding company that conducts business through its subsidiaries.  We derive essentially all of our revenues and earnings from our wholly-owned subsidiary, APS.  APS is a vertically-integrated electric utility that provides either retail or wholesale electric service to most of the State of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona.

Pinnacle West’s other subsidiaries are El Dorado, BCE and 4CA.  Additional information related to these subsidiaries is provided later in this report.

Our reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electric service to Native Load customers) and related activities, and includes electricity generation, transmission and distribution.

BUSINESS OF ARIZONA PUBLIC SERVICE COMPANY

APS currently provides electric service to approximately 1.2 million customers.  We own or lease 6,236 MW of regulated generation capacity and we hold a mix of both long-term and short-term purchased power agreements for additional capacity, including a variety of agreements for the purchase of renewable energy.  During 2016, no single purchaser or user of energy accounted for more than 1.1% of our electric revenues.

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The following map shows APS’s retail service territory, including the locations of its generating facilities and principal transmission lines.

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Energy Sources and Resource Planning

 To serve its customers, APS obtains power through its various generation stations and through purchased power agreements.  Resource planning is an important function necessary to meet Arizona’s future energy needs.  APS’s sources of energy by type used to supply energy to Native Load customers during 2016 were as follows:

Generation Facilities

APS has ownership interests in or leases the coal, nuclear, gas, oil and solar generating facilities described below.  For additional information regarding these facilities, see Item 2.

Coal-Fueled Generating Facilities

Four Corners — Four Corners is located in the northwestern corner of New Mexico, and was originally a 5-unit coal-fired power plant.  APS owns 100% of Units 1, 2 and 3, which were retired as of December 30, 2013. APS operates the plant and owns 63% of Four Corners Units 4 and 5 following the acquisition of SCE’s interest in Units 4 and 5 described below.  APS has a total entitlement from Four Corners of 970 MW. Additionally, 4CA, a wholly-owned subsidiary of Pinnacle West, owns 7% of Units 4 and 5 following its acquisition of El Paso's interest in these units described below.

On December 30, 2013, APS purchased SCE’s 48% interest in each of Units 4 and 5 of Four Corners. The final purchase price for the interest was approximately $182 million. In connection with APS’s prior retail

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rate case with the ACC, the ACC reserved the right to review the prudence of the Four Corners transaction for cost recovery purposes upon the closing of the transaction. On December 23, 2014, the ACC approved rate adjustments related to APS’s acquisition of SCE’s interest in Four Corners resulting in a revenue increase of $57.1 million on an annual basis. On February 23, 2015, the ACC decision approving the rate adjustments was appealed. APS has intervened and is actively participating in the proceeding. The Arizona Court of Appeals suspended the appeal pending the Arizona Supreme Court's decision in the System Improvement Benefits ("SIB") matter discussed in Note 3. On August 8, 2016, the Arizona Supreme Court issued its opinion in the SIB matter, and the Arizona Court of Appeals has now ordered supplemental briefing on how that SIB decision should affect the challenge to the Four Corners rate adjustment. We cannot predict when or how this matter will be resolved.

Concurrently with the closing of the SCE transaction, BHP Billiton, the parent company of BNCC, the coal supplier and operator of the mine that serves Four Corners, transferred its ownership of BNCC to NTEC, a company formed by the Navajo Nation to own the mine and develop other energy projects. BHP Billiton was retained by NTEC under contract as the mine manager and operator through 2016. Also occurring concurrently with the closing, the Four Corners’ co-owners executed a long-term agreement for the supply of coal to Four Corners from July 2016 through 2031 (the "2016 Coal Supply Agreement"). El Paso, a 7% owner in Units 4 and 5 of Four Corners, did not sign the 2016 Coal Supply Agreement. Under the 2016 Coal Supply Agreement, APS agreed to assume the 7% shortfall obligation. On February 17, 2015, APS and El Paso entered into an asset purchase agreement providing for the purchase by APS, or an affiliate of APS, of El Paso’s 7% interest in each of Units 4 and 5 of Four Corners. 4CA purchased the El Paso interest on July 6, 2016. The purchase price was immaterial in amount, and 4CA assumed El Paso's reclamation and decommissioning obligations associated with the 7% interest.

NTEC has the option to purchase the 7% interest within a certain timeframe pursuant to an option granted to NTEC. On December 29, 2015, NTEC provided notice of its intent to exercise the option. The 2016 Coal Supply Agreement contains alternate pricing terms for the 7% shortfall obligations in the event NTEC does not purchase the interest.

APS, on behalf of the Four Corners participants, negotiated amendments to an existing facility lease with the Navajo Nation, which extends the Four Corners leasehold interest from 2016 to 2041.  The Navajo Nation approved these amendments in March 2011.  The effectiveness of the amendments also required the approval of the DOI, as did a related federal rights-of-way grant.  A federal environmental review was undertaken as part of the DOI review process, and culminated in the issuance by DOI of a record of decision on July 17, 2015 justifying the agency action extending the life of the plant and the adjacent mine.  

On April 20, 2016, several environmental groups filed a lawsuit against OSM and other federal agencies in the District of Arizona in connection with their issuance of the approvals that extended the life of Four Corners and the adjacent mine.  The lawsuit alleges that these federal agencies violated both the Endangered Species Act ("ESA") and the National Environmental Policy Act ("NEPA") in providing the federal approvals necessary to extend operations at Four Corners and the adjacent Navajo Mine past July 6, 2016.  APS filed a motion to intervene in the proceedings, which was granted on August 3, 2016. Briefing on the merits of this litigation is expected to extend through May 2017. On September 15, 2016, NTEC, the company that owns the adjacent mine, filed a motion to intervene for the purpose of dismissing the lawsuit based on NTEC's tribal sovereign immunity. Because the court has placed a stay on all litigation deadlines pending its decision regarding NTEC's motion to dismiss, the schedule for briefing and the anticipated timeline for completion of this litigation will likely be extended. We cannot predict the outcome of this matter or its potential effect on Four Corners.

Cholla — Cholla was originally a 4-unit coal-fired power plant, which is located in northeastern Arizona.  APS operates the plant and owns 100% of Cholla Units 1, 2 and 3.  PacifiCorp owns Cholla Unit 4,

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and APS operates that unit for PacifiCorp.  On September 11, 2014, APS announced that it would close its 260 MW Unit 2 at Cholla and cease burning coal at Units 1 and 3 by the mid-2020s if EPA approves a compromise proposal offered by APS to meet required environmental and emissions standards and rules. On April 14, 2015, the ACC approved APS's plan to retire Unit 2, without expressing any view on the future recoverability of APS's remaining investment in the Unit. (See Note 3 for details related to the resulting regulatory asset and Note 10 for details of the proposal.) APS believes that the environmental benefits of this proposal are greater in the long-term than the benefits that would have resulted from adding the emissions control equipment. APS closed Unit 2 on October 1, 2015. Following the closure of Unit 2, APS has a total entitlement from Cholla of 387 MW. 

On January 13, 2017, EPA approved a final rule incorporating APS's compromise approach. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

APS purchases all of Cholla’s coal requirements from a coal supplier, an affiliate of Peabody Energy Corporation, that mines all of the coal under long-term leases of coal reserves with the federal and state governments and private landholders.  On April 13, 2016, Peabody Energy Corporation and certain affiliated entities filed a petition for relief under chapter 11 of the Bankruptcy Code in the United States Bankruptcy Court for the Eastern District of Missouri.  Under the Coal Supply Agreement, dated December 21, 2005, Peabody supplied coal to APS and PacifiCorp (collectively, the “Buyers”) for use at Cholla.  APS believes that the Coal Supply Agreement terminated automatically on April 13, 2016 as a result of Peabody's bankruptcy filing. The Buyers filed a motion requesting that the Bankruptcy Court enter an order determining that the Buyers are authorized to enforce the termination provisions in the Coal Supply Agreement. 

On May 13, 2016, Peabody filed a complaint against the Buyers in the bankruptcy court in which Peabody alleged that the Buyers breached the Coal Supply Agreement. On January 27, 2017, the bankruptcy court approved a settlement between the parties, and on February 6, 2017 the parties executed an amendment to the Coal Supply Agreement that allows for continuation of the agreement with modified terms and conditions acceptable to the parties.

APS has a long-term coal transportation by rail contract that expires in 2017.

Navajo Generating Station — The Navajo Plant is a 3-unit coal-fired power plant located in northern Arizona.  Salt River Project operates the plant and APS owns a 14% interest in Navajo Units 1, 2 and 3.  APS has a total entitlement from the Navajo Plant of 315 MW.  The Navajo Plant’s coal requirements are purchased from a supplier with long-term leases from the Navajo Nation and the Hopi Tribe.  The Navajo Plant is under contract with its coal supplier through 2019, with extension rights through 2026.  The Navajo Plant site is leased from the Navajo Nation and is also subject to an easement from the federal government.  The current lease expires in 2019.

On February 13, 2017, the co-owners of the Navajo Plant voted not to pursue continued operation of the plant beyond December 2019, the expiration of the current lease term, and to pursue a new lease or lease extension with the Navajo Nation that would allow decommissioning activities to begin after December 2019 instead of later this year. Various stakeholders including regulators, tribal representatives and others interested in the continued operation of the plant intend to meet to determine if an alternate solution can be reached that would permit continued operation of the plant beyond 2019. We cannot predict whether any alternate solutions will be found that would be acceptable to all of the stakeholders and feasible to implement. APS is currently

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recovering depreciation and a return on the net book value of its interest in the Navajo Plant. APS will seek continued recovery in rates for the book value of its remaining investment in the plant ($108 million as of December 31, 2016) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and which may be material. We cannot predict whether APS would obtain such recovery.

On February 14, 2017, the ACC opened a docket titled "ACC Investigation Concerning the Future of the Navajo Generating Station" with the stated goal of engaging stakeholders and negotiating a sustainable pathway for the Navajo Plant to continue operating in some form after December 2019. APS cannot predict the outcome of this proceeding.

These coal-fueled plants face uncertainties, including those related to existing and potential legislation and regulation, that could significantly impact their economics and operations.  See “Environmental Matters” below and “Management’s Discussion and Analysis of Financial Condition and Results of Operations — Overview and Capital Expenditures” in Item 7 for developments impacting these coal-fueled facilities.  See Note 10 for information regarding APS’s coal mine reclamation obligations.

Nuclear

Palo Verde Nuclear Generating Station — Palo Verde is a 3-unit nuclear power plant located approximately 50 miles west of Phoenix, Arizona.  APS operates the plant and owns 29.1% of Palo Verde Units 1 and 3 and approximately 17% of Unit 2.  In addition, APS leases approximately 12.1% of Unit 2, resulting in a 29.1% combined ownership and leasehold interest in that unit.  APS has a total entitlement from Palo Verde of 1,146 MW.

Palo Verde Leases — In 1986, APS entered into agreements with three separate lessor trust entities in order to sell and lease back approximately 42% of its share of Palo Verde Unit 2 and certain common facilities.  The leaseback was originally scheduled to expire at the end of 2015 and contained options to renew the leases or to purchase the leased property for fair market value at the end of the lease terms.  On July 7, 2014, APS exercised the fixed rate lease renewal options.  The exercise of the renewal options resulted in APS retaining the assets through 2023 under one lease and 2033 under the other two leases. At the end of the lease renewal periods, APS will have the option to purchase the leased assets at their fair market value, extend the leases for up to two years, or return the assets to the lessors. See Note 18 for additional information regarding the Palo Verde Unit 2 sale leaseback transactions.

Palo Verde Operating Licenses — Operation of each of the three Palo Verde Units requires an operating license from the NRC.  The NRC issued full power operating licenses for Unit 1 in June 1985, Unit 2 in April 1986 and Unit 3 in November 1987, and issued renewed operating licenses for each of the three units in April 2011, which extended the licenses for Units 1, 2 and 3 to June 2045, April 2046 and November 2047, respectively.

Palo Verde Fuel Cycle — The Palo Verde participants are continually identifying their future nuclear fuel resource needs and negotiating arrangements to fill those needs.  The fuel cycle for Palo Verde is comprised of the following stages:

•mining and milling of uranium ore to produce uranium concentrates;

•conversion of uranium concentrates to uranium hexafluoride;

•enrichment of uranium hexafluoride;

•fabrication of fuel assemblies;

•utilization of fuel assemblies in reactors; and

•storage and disposal of spent nuclear fuel.

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The Palo Verde participants have contracted for 100% of Palo Verde’s requirements for uranium concentrates and conversion services through 2018 and 45% of its requirements in 2019-2025.  The participants have also contracted for 100% of Palo Verde’s enrichment services through 2020 and 20% of its enrichment services for 2021-2026; and all of Palo Verde’s fuel assembly fabrication services through 2024.

Spent Nuclear Fuel and Waste Disposal — The Nuclear Waste Policy Act of 1982 (“NWPA”) required the DOE to accept, transport, and dispose of spent nuclear fuel and high level waste generated by the nation’s nuclear power plants by 1998.  The DOE’s obligations are reflected in a contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste (the “Standard Contract”) with each nuclear power plant.  The DOE failed to begin accepting spent nuclear fuel by 1998.  APS is directly and indirectly involved in several legal proceedings related to DOE’s failure to meet its statutory and contractual obligations regarding acceptance of spent nuclear fuel and high level waste.

APS Lawsuit for Breach of Standard Contract — In December 2003, APS, acting on behalf of itself and the participant owners of Palo Verde, filed a lawsuit against DOE in the United States Court of Federal Claims ("Court of Federal Claims") for damages incurred due to DOE’s breach of the Standard Contract.  The Court of Federal Claims ruled in favor of APS and the Palo Verde participants in October 2010 and awarded $30.2 million in damages to APS and the Palo Verde participants for costs incurred through December 2006.

On December 19, 2012, APS, acting on behalf of itself and the participant owners of Palo Verde, filed a second breach of contract lawsuit against the DOE in the Court of Federal Claims. This lawsuit sought to recover damages incurred due to DOE’s breach of the Standard Contract for failing to accept Palo Verde’s spent nuclear fuel and high level waste from January 1, 2007 through June 30, 2011, as it was required to do pursuant to the terms of the Standard Contract and the Nuclear Waste Policy Act. On August 18, 2014, APS and DOE entered into a settlement agreement, stipulating to a dismissal of the lawsuit and payment of $57.4 million by DOE to the Palo Verde owners for certain specified costs incurred by Palo Verde during the period January 1, 2007 through June 30, 2011. APS’s share of this amount is $16.7 million. Amounts recovered in the lawsuit and settlement were recorded as adjustments to a regulatory liability and had no impact on the amount of reported net income. In addition, the settlement agreement provides APS with a method for submitting claims and getting recovery for costs incurred through December 31, 2016, which has been extended to December 31, 2019.

APS has submitted two claims pursuant to the terms of the August 18, 2014 settlement agreement, for two separate time periods during July 1, 2011 through June 30, 2015. The DOE has approved and paid $53.9 million for these claims (APS’s share is $15.7 million). The amounts recovered were primarily recorded as adjustments to a regulatory liability and had no impact on reported net income. APS's next claim pursuant to the terms of the August 18, 2014 settlement agreement was submitted to the DOE on October 31, 2016, and approved on February 1, 2017, in the amount $11.3 million (APS's share is $3.3 million). Payment for the claim is expected in the second quarter of 2017.

The One-Mill Fee — In 2011, the National Association of Regulatory Utility Commissioners and the Nuclear Energy Institute challenged DOE’s 2010 determination of the adequacy of the one tenth of a cent per kWh fee (the “one-mill fee”) paid by the nation’s commercial nuclear power plant owners pursuant to their individual obligations under the Standard Contract.  This fee is recovered by APS in its retail rates.  In June 2012, the U.S. Court of Appeals for the District of Columbia Circuit (the “D.C. Circuit”) held that DOE failed to conduct a sufficient fee analysis in making the 2010 determination.  The D.C. Circuit remanded the 2010 determination to the Secretary of the DOE (“Secretary”) with instructions to conduct a new fee adequacy determination within six months.  In February 2013, upon completion of DOE’s revised one-mill fee adequacy determination, the D.C. Circuit reopened the proceedings.  On November 19, 2013, the D.C. Circuit found that the DOE did not conduct a legally adequate fee assessment and ordered the Secretary to notify Congress of his

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intent to suspend collecting annual fees for nuclear waste disposal from nuclear power plant operators, as he is required to do pursuant to the NWPA and the D.C. Circuit’s order.  On January 3, 2014, the Secretary notified Congress of his intention to suspend collection of the one-mill fee, subject to Congress’ disapproval. On May 16, 2014, the DOE notified all commercial nuclear power plant operators who are party to a Standard Contract that it reduced the one-mill fee to zero, thus effectively terminating the one-mill fee.

DOE’s Construction Authorization Application for Yucca Mountain — The DOE had planned to meet its NWPA and Standard Contract disposal obligations by designing, licensing, constructing, and operating a permanent geologic repository at Yucca Mountain, Nevada.  In June 2008, the DOE submitted its Yucca Mountain construction authorization application to the NRC, but in March 2010, the DOE filed a motion to dismiss with prejudice the Yucca Mountain construction authorization application.  Several interested parties have also intervened in the NRC proceeding.  Additionally, a number of interested parties filed a variety of lawsuits in different jurisdictions around the country challenging the DOE’s authority to withdraw the Yucca Mountain construction authorization application and NRC’s cessation of its review of the Yucca Mountain construction authorization application.  The cases have been consolidated into one matter at the D.C. Circuit.  In August 2013, the D.C. Circuit ordered the NRC to resume its review of the application with available appropriated funds.

On October 16, 2014, the NRC issued Volume 3 of the safety evaluation report developed as part of the Yucca Mountain construction authorization application. This volume addresses repository safety after permanent closure, and its issuance is a key milestone in the Yucca Mountain licensing process. Volume 3 contains the staff’s finding that the DOE’s repository design meets the requirements that apply after the repository is permanently closed, including but not limited to the post-closure performance objectives in NRC’s regulations.

On December 18, 2014, the NRC issued Volume 4 of the safety evaluation report developed as part of the Yucca Mountain construction authorization application. This volume covers administrative and programmatic requirements for the repository. It documents the staff’s evaluation of whether the DOE’s research and development and performance confirmation programs, as well as other administrative controls and systems, meet applicable NRC requirements. Volume 4 contains the staff’s finding that most administrative and programmatic requirements in NRC regulations are met, except for certain requirements relating to ownership of land and water rights.

Publication of Volumes 3 and 4 does not signal whether or when the NRC might authorize construction of the repository.

Waste Confidenceand Continued Storage — On June 8, 2012, the D.C. Circuit issued its decision on a challenge by several states and environmental groups of the NRC’s rulemaking regarding temporary storage and permanent disposal of high level nuclear waste and spent nuclear fuel.  The petitioners had challenged the NRC’s 2010 update to the agency’s Waste Confidence Decision and temporary storage rule (“Waste Confidence Decision”).

The D.C. Circuit found that the agency’s 2010 Waste Confidence Decision update constituted a major federal action, which, consistent with NEPA, requires either an environmental impact statement or a finding of no significant impact from the agency’s actions.  The D.C. Circuit found that the NRC’s evaluation of the environmental risks from spent nuclear fuel was deficient, and therefore remanded the 2010 Waste Confidence Decision update for further action consistent with NEPA.

On September 6, 2012, the NRC Commissioners issued a directive to the NRC staff to proceed directly with development of a generic environmental impact statement to support an updated Waste Confidence

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Decision.  The NRC Commissioners also directed the staff to establish a schedule to publish a final rule and environmental impact study within 24 months of September 6, 2012. 

In September 2013, the NRC issued its draft Generic Environmental Impact Statement (“GEIS”) to support an updated Waste Confidence Decision. On August 26, 2014, the NRC approved a final rule on the environmental effects of continued storage of spent nuclear fuel. Renamed as the Continued Storage Rule, the NRC’s decision adopted the findings of the GEIS regarding the environmental impacts of storing spent fuel at any reactor site after the reactor’s licensed period of operations. As a result, those generic impacts do not need to be re-analyzed in the environmental reviews for individual licenses. Although Palo Verde had not been involved in any licensing actions affected by the D.C. Circuit’s June 8, 2012, decision, the NRC lifted its suspension on final licensing actions on all nuclear power plant licenses and renewals that went into effect when the D.C. Circuit issued its June 2012 decision. The final Continued Storage Rule was subject to continuing legal challenges before the NRC and the Court of Appeals. In June 2016, the D.C. Circuit issued its final decision, rejecting all remaining legal challenges to the Continued Storage Rule. On August 8, 2016, the D.C. Circuit denied a petition for rehearing.

Palo Verde has sufficient capacity at its on-site independent spent fuel storage installation (“ISFSI”) to store all of the nuclear fuel that will be irradiated during the initial operating license period, which ends in December 2027.  Additionally, Palo Verde has sufficient capacity at its on-site ISFSI to store a portion of the fuel that will be irradiated during the period of extended operation, which ends in November 2047.  If uncertainties regarding the United States government’s obligation to accept and store spent fuel are not favorably resolved, APS will evaluate alternative storage solutions that may obviate the need to expand the ISFSI to accommodate all of the fuel that will be irradiated during the period of extended operation.

Nuclear Decommissioning Costs — APS currently relies on an external sinking fund mechanism to meet the NRC financial assurance requirements for decommissioning its interests in Palo Verde Units 1, 2 and 3.  The decommissioning costs of Palo Verde Units 1, 2 and 3 are currently included in APS’s ACC jurisdictional rates.  Decommissioning costs are recoverable through a non-bypassable system benefits charge (paid by all retail customers taking service from the APS system).  Based on current nuclear decommissioning trust asset balances, site specific decommissioning cost studies, anticipated future contributions to the decommissioning trusts, and return projections on the asset portfolios over the expected remaining operating life of the facility, we are on track to meet the current site specific decommissioning costs for Palo Verde at the time the units are expected to be decommissioned. See Note 19 for additional information about APS’s nuclear decommissioning trusts.

Palo Verde Liability and Insurance Matters — See “Palo Verde Nuclear Generating Station — Nuclear Insurance” in Note 10 for a discussion of the insurance maintained by the Palo Verde participants, including APS, for Palo Verde.

Natural Gas and Oil Fueled Generating Facilities

APS has six natural gas power plants located throughout Arizona, consisting of Redhawk, located near Palo Verde; Ocotillo, located in Tempe (discussed below); Sundance, located in Coolidge; West Phoenix, located in southwest Phoenix; Saguaro, located north of Tucson; and Yucca, located near Yuma.  Several of the units at Yucca run on either gas or oil.  APS has one oil-only power plant, Douglas, located in the town of Douglas, Arizona.  APS owns and operates each of these plants with the exception of one oil-only combustion turbine unit and one oil and gas steam unit at Yucca that are operated by APS and owned by the Imperial Irrigation District.  APS has a total entitlement from these plants of 3,179 MW.  Gas for these plants is financially hedged up to three years in advance of purchasing and the gas is generally purchased one month prior to delivery.  APS has long-term gas transportation agreements with three different companies, some of

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which are effective through 2024.  Fuel oil is acquired under short-term purchases delivered primarily to West Phoenix, where it is distributed to APS’s other oil power plants by truck.

Ocotillo is a 330 MW 4-unit gas plant located in the metropolitan Phoenix area.  In early 2014, APS announced a project to modernize the plant, which involves retiring two older 110 MW steam units, adding five 102 MW combustion turbines and maintaining two existing 55 MW combustion turbines.  In total, this increases the capacity of the site by 290 MW, to 620 MW, with completion targeted by summer 2019.  (See Note 3 for proposed rate recovery in our current retail rate case.) On September 9, 2016, Maricopa County issued a final permit decision that authorizes construction of the Ocotillo modernization project and construction will begin in early 2017.

Solar Facilities

APS developed utility scale solar resources through the 170 MW ACC-approved AZ Sun Program.  APS invested approximately $675 million in its AZ Sun Program. These facilities are owned by APS and are located in multiple locations throughout Arizona. In 2016, APS developed the 40MW Red Rock Solar Plant, which it owns and operates. Two of our large customers will purchase renewable energy credits from APS that is equivalent to the amount of renewable energy that Red Rock is projected to generate.

Additionally, APS owns and operates more than forty small solar systems around the state.  Together they have the capacity to produce approximately 4 MW of renewable energy.  This fleet of solar systems includes a 3 MW facility located at the Prescott Airport and 1 MW of small solar in various locations across Arizona.  APS has also developed solar photovoltaic distributed energy systems installed as part of the Community Power Project in Flagstaff, Arizona.  The Community Power Project, approved by the ACC on April 1, 2010, is a pilot program through which APS owns, operates and receives energy from approximately 1 MW of solar photovoltaic distributed energy systems located within a certain test area in Flagstaff, Arizona.  Additionally, APS owns 12 MW of solar photovoltaic systems installed across Arizona through the ACC-approved Schools and Government Program.

In December 2014, the ACC voted that it had no objection to APS implementing an APS-owned rooftop solar research and development program aimed at learning how to efficiently enable the integration of rooftop solar and battery storage with the grid.  The first stage of the program, called the "Solar Partner Program," placed 8 MW of residential rooftop solar on strategically selected distribution feeders in an effort to maximize potential system benefits, as well as made systems available to limited-income customers who could not easily install solar through transactions with third parties. The second stage of the program, which included an additional 2 MW of rooftop solar and energy storage, placed two energy storage systems sized at 2 MW on two different high solar penetration feeders to test various grid-related operation improvements and system interoperability, and was in operation by the end of 2016.  The ACC expressly reserved that any determination of prudency of the residential rooftop solar program for rate making purposes would not be made until the project was fully in service, and APS has requested cost recovery for the project in its currently pending rate case. On September 30, 2016, APS presented its preliminary findings from the residential rooftop solar program in a filing with the ACC.

Purchased Power Contracts

In addition to its own available generating capacity, APS purchases electricity under various arrangements, including long-term contracts and purchases through short-term markets to supplement its owned or leased generation and hedge its energy requirements.  A portion of APS’s purchased power expense is netted against wholesale sales on the Consolidated Statements of Income.  (See Note 16.)  APS continually assesses its need for additional capacity resources to assure system reliability.

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Purchased Power Capacity — APS’s purchased power capacity under long-term contracts as of December 31, 2016 is summarized in the table below.  All capacity values are based on net capacity unless otherwise noted.

Type	Dates Available	Capacity (MW)
Purchase Agreement (a)	Year-round through June 14, 2020	60
Exchange Agreement (b)	May 15 to September 15 annually through February 2021	480
Tolling Agreement	Year-round through May 2017	514
Tolling Agreement	Summer seasons through October 2019	560
Demand Response Agreement (c)	Summer seasons through 2024	25
Tolling Agreement (d)	Summer seasons from Summer 2020 through Summer 2025	565
Renewable Energy (e)	Various	629

(a) Up to 60 MW of capacity is available; however, the amount of electricity available to APS under this agreement is based in large part on customer demand and is adjusted annually.

(b) This is a seasonal capacity exchange agreement under which APS receives electricity during the summer peak season (from May 15 to September 15) and APS returns a like amount of electricity during the winter season (from October 15 to February 15).

(c) The capacity under this agreement may be increased in 5 MW increments in each of 2015 and 2016 and 10 MW increments in years 2017 through 2024, up to a maximum of 50 MW.

(d) This agreement was signed in response to APS's 2016 all source request for proposal seeking capacity resources.

(e) Renewable energy purchased power agreements are described in detail below under “Current and Future Resources — Renewable Energy Standard — Renewable Energy Portfolio.”

Current and Future Resources

Current Demand and Reserve Margin

Electric power demand is generally seasonal.  In Arizona, demand for power peaks during the hot summer months.  APS’s 2016 peak one-hour demand on its electric system was recorded on June 19, 2016 at 7,051 MW, compared to the 2015 peak of 7,031 MW recorded on August 15, 2015.  APS’s reserve margin at the time of the 2016 peak demand, calculated using system load serving capacity, was 30%. For 2017, due to expiring purchase contracts, APS is procuring market resources to maintain its minimum 15% planning reserve criteria.

Future Resources and Resource Plan

APS filed its preliminary 2017 Integrated Resource Plan on March 1, 2016 and an updated preliminary 2017 Integrated Resource Plan on September 30, 2016. APS also held stakeholder meetings in February and November 2016 in addition to an ACC-led Integrated Resource Plan workshop in July 2016. The preliminary Integrated Resource Plan and associated stakeholder meetings are part of a modified planning process that allows time to incorporate implications of the Clean Power Plan as well as input from stakeholder meetings. The final Integrated Resource Plan will be submitted by or on April 3, 2017 and the ACC is expected to complete its review by February 1, 2018.

On September 11, 2014, APS announced that it would close Cholla Unit 2 and cease burning coal at the other APS-owned units (Units 1 and 3) at the plant by the mid-2020s, if EPA approves a compromise proposal offered by APS to meet required environmental and emissions standards and rules. On April 14, 2015, the ACC approved APS's plan to retire Unit 2, without expressing any view on the future recoverability of APS's remaining investment in the Unit. APS closed Unit 2 on October 1, 2015. Previously, APS estimated Cholla

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Unit 2’s end of life to be 2033. APS is currently recovering a return on and of the net book value of the unit in base rates and is seeking recovery of the unit’s decommissioning and other retirement-related costs over the remaining life of the plant in its current retail rate case. APS believes it will be allowed recovery of the remaining net book value of Unit 2 ($116 million as of December 31, 2016), in addition to a return on its investment. In accordance with GAAP, in the third quarter of 2014, Unit 2’s remaining net book value was reclassified from property, plant and equipment to a regulatory asset. If the ACC does not allow full recovery of the remaining net book value of Cholla Unit 2, all or a portion of the regulatory asset will be written off and APS’s net income, cash flows, and financial position will be negatively impacted. (See "Business of Arizona Public Service Company - Energy Sources and Resource Planning - Generation Facilities - Coal-Fueled Generating Facilities - Cholla" above for details regarding the status of the EPA's rule related to Cholla.)

See "Business of Arizona Public Service Company - Energy Sources and Resource Planning - Generation Facilities - Coal-Fueled Generating Facilities - Navajo Generating Station" above for information regarding future plans for the Navajo Plant.

Energy Imbalance Market

In 2015, APS and the CAISO, the operator for the majority of California's transmission grid, signed an agreement for APS to begin participation in the Energy Imbalance Market (“EIM”). APS's participation in the EIM began on October 1, 2016.  The EIM allows for rebalancing supply and demand in 15-minute blocks with dispatching every five minutes before the energy is needed, instead of the traditional one hour blocks.  APS expects that its participation in EIM will lower its fuel costs, improve visibility and situational awareness for system operations in the Western Interconnection power grid, and improve integration of APS’s renewable resources.

Renewable Energy Standard

In 2006, the ACC adopted the RES.  Under the RES, electric utilities that are regulated by the ACC must supply an increasing percentage of their retail electric energy sales from eligible renewable resources, including solar, wind, biomass, biogas and geothermal technologies.  The renewable energy requirement is 7% of retail electric sales in 2017 and increases annually until it reaches 15% in 2025.  In APS’s 2009 retail rate case settlement agreement (the “2009 Settlement Agreement”), APS committed to have 1,700 GWh of new renewable resources in service by year-end 2015 in addition to its RES renewable resource commitments. APS met its settlement commitment and RES target for 2016.

A component of the RES is focused on stimulating development of distributed energy systems.  Accordingly, under the RES, an increasing percentage of that requirement must be supplied from distributed energy resources.  This distributed energy requirement is 30% of the overall RES requirement of 7% in 2017.  The following table summarizes the RES requirement standard (not including the additional commitment required by the 2009 Settlement Agreement) and its timing:

	2017	2020	2025
RES as a % of retail electric sales	7%	10%	15%
Percent of RES to be supplied from distributed energy resources	30%	30%	30%

On April 21, 2015, the RES rules were amended to require utilities to report on all eligible renewable resources in their service territory, irrespective of whether the utility owns renewable energy credits associated with such renewable energy. The rules allow the ACC to consider such information in determining whether APS has satisfied the requirements of the RES.

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Renewable Energy Portfolio.  To date, APS has a diverse portfolio of existing and planned renewable resources totaling 1,480 MW, including solar, wind, geothermal, biomass and biogas.  Of this portfolio, 1,440 MW are currently in operation and 40 MW are under contract for development or are under construction.  Renewable resources in operation include 239 MW of facilities owned by APS, 629 MW of long-term purchased power agreements, and an estimated 539 MW of customer-sited, third-party owned distributed energy resources.

APS’s strategy to achieve its RES requirements includes executing purchased power contracts for new facilities, ongoing development of distributed energy resources and procurement of new facilities to be owned by APS.  See "Energy Sources and Resource Planning - Generation Facilities - Solar Facilities" above for information regarding APS-owned solar facilities.

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The following table summarizes APS’s renewable energy sources currently in operation and under development.  Agreements for the development and completion of future resources are subject to various conditions, including successful siting, permitting and interconnection of the projects to the electric grid.

	Location	Actual/ Target Commercial Operation Date	Term (Years)	Net Capacity In Operation (MW AC)	Net Capacity Planned/Under Development (MW AC)
APS Owned
Solar:
AZ Sun Program:
Paloma	Gila Bend, AZ	2011		17
Cotton Center	Gila Bend, AZ	2011		17
Hyder Phase 1	Hyder, AZ	2011		11
Hyder Phase 2	Hyder, AZ	2012		5
Chino Valley	Chino Valley, AZ	2012		19
Hyder II	Hyder, AZ	2013		14
Foothills	Yuma, AZ	2013		35
Gila Bend	Gila Bend, AZ	2014		32
Luke AFB	Glendale, AZ	2015		10
Desert Star	Buckeye, AZ	2015		10
Subtotal AZ Sun Program				170	—
Multiple Facilities	AZ	Various		4
Red Rock	Red Rock, AZ	2016		40
Distributed Energy:
APS Owned (a)	AZ	Various		25
Total APS Owned				239	—
Purchased Power Agreements
Solar:
Solana	Gila Bend, AZ	2013	30	250
RE Ajo	Ajo, AZ	2011	25	5
Sun E AZ 1	Prescott, AZ	2011	30	10
Saddle Mountain	Tonopah, AZ	2012	30	15
Badger	Tonopah, AZ	2013	30	15
Gillespie	Maricopa County, AZ	2013	30	15
Wind:
Aragonne Mesa	Santa Rosa, NM	2006	20	90
High Lonesome	Mountainair, NM	2009	30	100
Perrin Ranch Wind	Williams, AZ	2012	25	99
Geothermal:
Salton Sea	Imperial County, CA	2006	23	10
Biomass:
Snowflake	Snowflake, AZ	2008	15	14
Biogas:
Glendale Landfill	Glendale, AZ	2010	20	3
NW Regional Landfill	Surprise, AZ	2012	20	3
Total Purchased Power Agreements				629	—
Distributed Energy
Solar (b)
Third-party Owned	AZ	Various		539	40
Agreement 1	Bagdad, AZ	2011	25	15
Agreement 2	AZ	2011-2012	20-21	18
Total Distributed Energy				572	40
Total Renewable Portfolio				1,440	40

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(a) Includes Flagstaff Community Power Project, APS School and Government Program and APS Solar Partner Program.

(b) Includes rooftop solar facilities owned by third parties. Distributed generation is produced in DC and is converted to AC for reporting purposes.

Demand Side Management

 In December 2009, Arizona regulators placed an increased focus on energy efficiency and other demand side management programs to encourage customers to conserve energy, while incentivizing utilities to aid in these efforts that ultimately reduce the demand for energy.  The ACC initiated its Energy Efficiency rulemaking, with a proposed Energy Efficiency Standard (“EES”) of 22% cumulative annual energy savings by 2020.  This standard was adopted and became effective on January 1, 2011.  This standard will likely impact Arizona’s future energy resource needs.  (See Note 3 for energy efficiency and other demand side management obligations).

Competitive Environment and Regulatory Oversight

Retail

The ACC regulates APS’s retail electric rates and its issuance of securities.  The ACC must also approve any significant transfer or encumbrance of APS’s property used to provide retail electric service and approve or receive prior notification of certain transactions between Pinnacle West, APS and their respective affiliates.

APS is subject to varying degrees of competition from other investor-owned electric and gas utilities in Arizona (such as Southwest Gas Corporation), as well as cooperatives, municipalities, electrical districts and similar types of governmental or non-profit organizations.  In addition, some customers, particularly industrial and large commercial customers, may own and operate generation facilities to meet some or all of their own energy requirements.  This practice is becoming more popular with customers installing or having installed products such as rooftop solar panels to meet or supplement their energy needs.

On April 14, 2010, the ACC issued a decision holding that solar vendors that install and operate solar facilities for non-profit schools and governments pursuant to a specific type of contract that calculates payments based on the energy produced are not “public service corporations” under the Arizona Constitution, and are therefore not regulated by the ACC. APS cannot predict when, and the extent to which, additional electric service providers will enter or re-enter APS’s service territory.

On May 9, 2013, the ACC voted to re-examine the facilitation of a deregulated retail electric market in Arizona.  The ACC subsequently opened a docket for this matter and received comments from a number of interested parties on the considerations involved in establishing retail electric deregulation in the state.  One of these considerations was whether various aspects of a deregulated market, including setting utility rates on a “market” basis, would be consistent with the requirements of the Arizona Constitution.  On September 11, 2013, after receiving legal advice from the ACC staff, the ACC voted 4-1 to close the current docket and await full Arizona Constitutional authority before any further examination of this matter.  The motion approved by the ACC also included opening one or more new dockets in the future to explore options to offer more rate choices to customers and innovative changes within the existing cost-of-service regulatory model that could include elements of competition.  The ACC opened a docket on November 4, 2013 to explore technological advances and innovative changes within the electric utility industry.  A series of workshops in this docket were held in 2014 and another in February of 2015. No further workshops are scheduled and no actions were taken as a result of these workshops.

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Wholesale

FERC regulates rates for wholesale power sales and transmission services.  (See Note 3 for information regarding APS’s transmission rates.)  During 2016, approximately 3.5% of APS’s electric operating revenues resulted from such sales and services.  APS’s wholesale activity primarily consists of managing fuel and purchased power supplies to serve retail customer energy requirements.  APS also sells, in the wholesale market, its generation output that is not needed for APS’s Native Load and, in doing so, competes with other utilities, power marketers and independent power producers.  Additionally, subject to specified parameters, APS hedges both electricity and fuels.  The majority of these activities are undertaken to mitigate risk in APS’s portfolio.

Subpoena from Arizona Corporation Commissioner Robert Burns   

On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, filed subpoenas in APS’s current retail rate proceeding to APS and Pinnacle West for the production of records and information relating to a range of expenditures from 2011 through 2016. The subpoenas requested information concerning marketing and advertising expenditures, charitable donations, lobbying expenses, contributions to 501(c)(3) and (c)(4) nonprofits and political contributions.  The return date for the production of information was set as September 15, 2016. The subpoenas also sought testimony from Company personnel having knowledge of the material, including the Chief Executive Officer.

On September 9, 2016, APS filed with the ACC a motion to quash the subpoenas or, alternatively to stay APS's obligations to comply with the subpoenas and decline to decide APS's motion pending court proceedings. Contemporaneously with the filing of this motion, APS and Pinnacle West filed a complaint for special action and declaratory judgment in the Superior Court of Arizona for Maricopa County, seeking a declaratory judgment that Commissioner Burns’ subpoenas are contrary to law. On September 15, 2016, APS produced all non-confidential and responsive documents and offered to produce any remaining responsive documents that are confidential after an appropriate confidentiality agreement is signed.

On February 7, 2017, Commissioner Burns opened a new ACC docket and indicated that its purpose is to study and rectify problems with transparency and disclosure regarding financial contributions from regulated monopolies or other stakeholders who may appear before the ACC that may directly or indirectly benefit an ACC Commissioner, a candidate for ACC Commissioner, or key ACC staff.  As part of this docket, Commissioner Burns set March 24, 2017 as a deadline for APS to produce all information previously requested through the subpoenas.  Commissioner Burns has also scheduled a workshop in this matter for March 17, 2017.  APS and Pinnacle West cannot predict the outcome of this matter.

Environmental Matters

Climate Change

Legislative Initiatives. There have been no recent attempts by Congress to pass legislation that would regulate greenhouse gas ("GHG") emissions, and it is doubtful whether the 115^th Congress will consider a climate change bill. In the event climate change legislation ultimately passes, the actual economic and operational impact of such legislation on APS depends on a variety of factors, none of which can be fully known until a law is written, enacted and the specifics of the resulting program are established. These factors include the terms of the legislation with regard to allowed GHG emissions; the cost to reduce emissions; in the event a cap-and-trade program is established, whether any permitted emissions allowances will be allocated to source operators free of cost or auctioned (and, if so, the cost of those allowances in the marketplace) and

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whether offsets and other measures to moderate the costs of compliance will be available; and, in the event of a carbon tax, the amount of the tax per pound of carbon dioxide (“CO₂”) equivalent emitted.

In addition to federal legislative initiatives, state-specific initiatives may also impact our business. While Arizona has no pending legislation and no proposed agency rule regulating GHGs in Arizona, the California legislature enacted AB 32 and SB 1368 in 2006 to address GHG emissions. In October 2011, the California Air Resources Board approved final regulations that established a state-wide cap on GHG emissions beginning on January 1, 2013 and established a GHG allowance trading program under that cap. The first phase of the program, which applies to, among other entities, importers of electricity, commenced on January 1, 2013. Under the program, entities selling electricity into California, including APS, must hold carbon allowances to cover GHG emissions associated with electricity sales into California from outside the state. APS is authorized to recover the cost of these carbon allowances through the PSA.

Regulatory Initiatives. In 2009, EPA determined that GHG emissions endanger public health and welfare. As a result of this “endangerment finding,” EPA determined that the Clean Air Act required new regulatory requirements for new and modified major GHG emitting sources, including power plants. APS will generally be required to consider the impact of GHG emissions as part of its traditional New Source Review ("NSR") analysis for new major sources and major modifications to existing plants.

On June 2, 2014, EPA issued two proposed rules to regulate GHG emissions from modified and reconstructed electric generating units ("EGUs") pursuant to Section 111(b) of the Clean Air Act and existing fossil fuel-fired power plants pursuant to Clean Air Act Section 111(d).

On August 3, 2015, EPA finalized carbon pollution standards for existing, new, modified, and reconstructed EGUs. EPA’s final rules require newly built fossil fuel-fired EGUs, along with those undergoing modification or reconstruction, to meet CO2 performance standards based on a combination of best operating practices and equipment upgrades. EPA established separate performance standards for two types of EGUs: stationary combustion turbines, typically natural gas; and electric utility steam generating units, typically coal.

With respect to existing power plants, EPA’s recently finalized “Clean Power Plan” imposes state-specific goals or targets to achieve reductions in CO₂ emission rates from existing EGUs measured from a 2012 baseline. In a significant change from the proposed rule, EPA’s final performance standards apply directly to specific units based upon their fuel-type and configuration (i.e., coal- or oil-fired steam plants versus combined cycle natural gas plants). As such, each state’s goal is an emissions performance standard that reflects the fuel mix employed by the EGUs in operation in those states. The final rule provides guidelines to states to help develop their plans for meeting the interim (2022-2029) and final (2030 and beyond) emission performance standards, with three distinct compliance periods within that timeframe. States were originally required to submit their plans to EPA by September 2016, with an optional two-year extension provided to states establishing a need for additional time; however, this timing will be impacted by the court-imposed stay described below.

Prior to the court-imposed stay described below, ADEQ, with input from a technical working group comprised of Arizona utilities and other stakeholders, was working to develop a compliance plan for submittal to EPA. Since the imposition of the stay, ADEQ is continuing to assess alternatives while completing outreach and soliciting feedback from stakeholders. In addition to these ongoing state proceedings, EPA has taken public comments on proposed model rules and a proposed federal compliance plan, which included consideration as to how the Clean Power Plan will apply to EGUs on tribal land such as the Navajo Nation.

The legality of the Clean Power Plan is being challenged in the U.S. Court of Appeals for the D.C. Circuit; the parties raising this challenge include, among others, the ACC. On February 9, 2016, the U.S.

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Supreme Court granted a stay of the Clean Power Plan pending judicial review of the rule, which temporarily delays compliance obligations under the Clean Power Plan. We cannot predict the extent of the delay.

With respect to our Arizona generating units, we are currently evaluating the range of compliance options available to ADEQ, including whether Arizona deploys a rate- or mass-based compliance plan. Based on the fuel-mix and location of our Arizona EGUs, and the significant investments we have made in renewable generation and demand-side energy efficiency, if ADEQ selects a rate-based compliance plan, we believe that we will be able to comply with the Clean Power Plan for our Arizona generating units in a manner that will not have material financial or operational impacts to the Company. On the other hand, if ADEQ selects a mass-based approach to compliance with the Clean Power Plan, our annual cost of compliance could be material. These costs could include costs to acquire mass-based compliance allowances.

As to our facilities on the Navajo Nation, EPA has yet to determine whether or to what extent EGUs on the Navajo Nation will be required to comply with the Clean Power Plan. EPA has proposed to determine that it is necessary or appropriate to impose a federal plan on the Navajo Nation for compliance with the Clean Power Plan. In response, we filed comments with EPA advocating that such a federal plan is neither necessary nor appropriate to protect air quality on the Navajo Nation. If EPA reaches a determination that is consistent with our preferred approach for the Navajo Nation, we believe the Clean Power Plan will not have material financial or operational impacts on our operations within the Navajo Nation.

Alternatively, if EPA determines that a federal plan is necessary or appropriate for the Navajo Nation, and depending on our need for future operations at our EGUs located there, we may be unable to comply with the federal plan unless we acquire mass-based allowances or emission rate credits within established carbon trading markets, or curtail our operations. Subject to the uncertainties set forth below, and assuming that EPA establishes a federal plan for the Navajo Nation that requires carbon allowances or credits to be surrendered for plan compliance, it is possible we will be required to purchase some quantity of credits or allowances, the cost of which could be material.

Because ADEQ has not issued its plan for Arizona, and because we do not know whether EPA will decide to impose a plan or, if so, what that plan will require, there are a number of uncertainties associated with our potential cost exposure. These uncertainties include: whether judicial review will result in the Clean Power Plan being vacated in whole or in part or, if not, the extent of any resulting compliance deadline delays; whether any plan will be imposed for EGUs on the Navajo Nation; the future existence and liquidity of allowance or credit compliance trading markets; the applicability of existing contractual obligations with current and former owners of our participant-owned coal-fired EGUs; the type of federal or state compliance plan (either rate- or mass-based); whether or not the trading of allowances or credits will be authorized mechanisms for compliance with any final EPA or ADEQ plan; and how units that have been closed will be treated for allowance or credit allocation purposes.

In the event that the incurrence of compliance costs is not economically viable or prudent for our operations in Arizona or on the Navajo Nation, or if we do not have the option of acquiring allowances to account for the emissions from our operations, we may explore other options, including reduced levels of output or potential plant closures, as alternatives to purchasing allowances. Given these uncertainties, our analysis of the available compliance options remains ongoing, and additional information or considerations may arise that change our expectations.

Company Response to Climate Change Initiatives. We have undertaken a number of initiatives that address emission concerns, including renewable energy procurement and development, promotion of programs and rates that promote energy conservation, renewable energy use, and energy efficiency. (See “Energy Sources and Resource Planning - Current and Future Resources” above for details of these plans and

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initiatives.) APS currently has a diverse portfolio of renewable resources, including solar, wind, geothermal, biogas, and biomass, and we expect the percentage of renewable energy in our resource portfolio to increase over the coming years.

APS prepares an inventory of GHG emissions from its operations. This inventory is reported to EPA under the EPA GHG Reporting Program and is voluntarily communicated to the public in Pinnacle West’s annual Corporate Responsibility Report, which is available on our website (www.pinnaclewest.com). The report provides information related to the Company and its approach to sustainability and its workplace and environmental performance. The information on Pinnacle West’s website, including the Corporate Responsibility Report, is not incorporated by reference into or otherwise a part of this report.

EPA Environmental Regulation

Regional Haze Rules. In 1999, EPA announced regional haze rules to reduce visibility impairment in national parks and wilderness areas. The rules require states (or, for sources located on tribal land, EPA) to determine what pollution control technologies constitute the BART for certain older major stationary sources, including fossil-fired power plants. EPA subsequently issued the Clean Air Visibility Rule, which provides guidelines on how to perform a BART analysis.

The Four Corners and Navajo Plant participants’ obligations to comply with EPA’s final BART determinations (and Cholla’s obligations to comply with ADEQ’s and EPA’s determinations), coupled with the financial impact of potential future climate change legislation, other environmental regulations, and other business considerations, could jeopardize the economic viability of these plants or the ability of individual participants to continue their participation in these plants.

Cholla. APS believes that EPA’s original 2012 final rule establishing controls constituting BART for Cholla, which would require installation of selective catalytic reduction ("SCR") controls with a cost to APS of approximately $100 million is unsupported and that EPA had no basis for disapproving Arizona’s State Implementation Plan ("SIP") and promulgating a Federal Implementation Plan ("FIP") that is inconsistent with the state’s considered BART determinations under the regional haze program.  Accordingly, on February 1, 2013, APS filed a Petition for Review of the final BART rule in the United States Court of Appeals for the Ninth Circuit.  Briefing in the case was completed in February 2014.

In September 2014, APS met with EPA to propose a compromise BART strategy. Pending certain regulatory approvals, APS would permanently close Cholla Unit 2 and cease burning coal at Units 1 and 3 by the mid-2020s. (See Note 3 for details related to the resulting regulatory asset.) APS made the proposal with the understanding that additional emission control equipment is unlikely to be required in the future because retiring and/or converting the units as contemplated in the proposal is more cost effective than, and will result in increased visibility improvement over, the current BART requirements for NOx imposed on the Cholla units under EPA's BART FIP. APS’s proposal involves state and federal rulemaking processes. In light of these ongoing administrative proceedings, on February 19, 2015, APS, PacifiCorp (owner of Cholla Unit 4), and EPA jointly moved the court to sever and hold in abeyance those claims in the litigation pertaining to Cholla pending regulatory actions by the state and EPA. The court granted the parties' unopposed motion on February 20, 2015.

On October 16, 2015, ADEQ issued a revised operating permit for Cholla, which incorporates APS's proposal, and subsequently submitted a proposed revision to the SIP to the EPA, which would incorporate the new permit terms.  On June 30, 2016, EPA issued a proposed rule approving a revision to the Arizona SIP that incorporates APS’s compromise approach for compliance with the Regional Haze program.  EPA signed the final rule approving the Agency's proposal on January 13, 2017. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot

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predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

Four Corners. Based on EPA’s final standards, APS estimates that its 63% share of the cost of required controls for Four Corners Units 4 and 5 would be approximately $400 million.  In addition, APS and El Paso entered into an asset purchase agreement providing for the purchase by APS, or an affiliate of APS, of El Paso's 7% interest in Four Corners Units 4 and 5. 4CA purchased the El Paso interest on July 6, 2016. NTEC has the option to purchase the interest within a certain timeframe pursuant to an option granted to NTEC. In December 2015, NTEC provided notice of its intent to exercise the option. The cost of the pollution controls related to the 7% interest is approximately $45 million, which will be assumed by the ultimate owner of the 7% interest.

Navajo Plant. On July 28, 2014, EPA issued a final Navajo Plant BART rule. APS estimates that its share of costs for upgrades at the Navajo Plant, based on EPA’s FIP, could be up to approximately $200 million.  In October 2014, a coalition of environmental groups, an Indian tribe and others filed petitions for review in the United States Court of Appeals for the Ninth Circuit asking the Court to review EPA's final BART rule for the Navajo Plant. We cannot predict the outcome of this review process. See "Business of Arizona Public Service Company - Energy Sources and Resource Planning - Generation Facilities - Coal-Fueled Generating Facilities - Navajo Generating Station" above for information regarding future plans for the Navajo Plant.

Mercury and other Hazardous Air Pollutants.In 2011, EPA issued rules establishing maximum achievable control technology standards to regulate emissions of mercury and other hazardous air pollutants from fossil-fired plants.  APS estimates that the cost for the remaining equipment necessary to meet these standards is approximately $8 million for Cholla. No additional equipment is needed for Four Corners Units 4 and 5 to comply with these rules.  SRP, the operating agent for the Navajo Plant, estimates that APS's share of costs for equipment necessary to comply with the rules is approximately $1 million, the majority of which has already been incurred. Litigation concerning the rules, including supplemental analyses EPA has prepared in support of the MATS regulation, is ongoing. These proceedings do not materially impact APS.  Regardless of the results from further judicial or administrative proceedings concerning the MATS rulemaking, the Arizona State Mercury Rule, the stringency of which is roughly equivalent to that of MATS, would still apply to Cholla.

Coal Combustion Waste. On December 19, 2014, EPA issued its final regulations governing the handling and disposal of CCR, such as fly ash and bottom ash. The rule regulates CCR as a non-hazardous waste under Subtitle D of the Resource Conservation and Recovery Act ("RCRA") and establishes national minimum criteria for existing and new CCR landfills and surface impoundments and all lateral expansions consisting of location restrictions, design and operating criteria, groundwater monitoring and corrective action, closure requirements and post closure care, and recordkeeping, notification, and Internet posting requirements. The rule generally requires any existing unlined CCR surface impoundment that is contaminating groundwater above a regulated constituent’s groundwater protection standard to stop receiving CCR and either retrofit or close, and further requires the closure of any CCR landfill or surface impoundment that cannot meet the applicable performance criteria for location restrictions or structural integrity. While EPA has chosen to regulate the disposal of CCR in landfills and surface impoundments as non-hazardous waste under the final rule, the agency makes clear that it will continue to evaluate any risks associated with CCR disposal and leaves open the possibility that it may regulate CCR as a hazardous waste under RCRA Subtitle C in the future.

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On December 16, 2016, President Obama signed the Water Infrastructure Improvements for the Nation ("WIIN") Act into law, which contains a number of provisions requiring EPA to modify the self-implementing provisions of the Agency's current CCR rules under Subtitle D. Such modifications include new EPA authority to directly enforce the CCR rules through the use of administrative orders and providing states, like Arizona, where the Cholla facility is located, the option of developing CCR disposal unit permitting programs, subject to EPA approval. For facilities in states that do not develop state-specific permitting programs, EPA is required to develop a federal permit program, pending the availability of congressional appropriations. By contrast, for facilities located within the boundaries of Native American tribal reservations, such as the Navajo Nation, where the Navajo Plant and Four Corners facilities are located, EPA is required to develop a federal permit program regardless of appropriated funds. Because EPA has yet to undertake rulemaking proceedings to implement the CCR provisions of the WIIN Act, and Arizona has yet to determine whether it will develop a state-specific permitting program, it is unclear what effects the CCR provisions of the WIIN Act will have on APS's management of CCR.     

APS currently disposes of CCR in ash ponds and dry storage areas at Cholla and Four Corners. APS estimates that its share of incremental costs to comply with the CCR rule for Four Corners is approximately $15 million. APS is currently evaluating compliance alternatives for Cholla and estimates that its share of incremental costs to comply with the CCR rule for this plant is in the range of $5 million to $40 million based upon which compliance alternatives are ultimately selected. The Navajo Plant currently disposes of CCR in a dry landfill storage area. APS estimates that its share of incremental costs to comply with the CCR rule for the Navajo Plant is approximately $1 million, the majority of which has already been incurred. Additionally, the CCR rule requires ongoing groundwater monitoring. Depending upon the results of such monitoring at each of Cholla, Four Corners and the Navajo Plant, we may be required to take corrective actions, the costs of which we are unable to reasonably estimate at this time.

Pursuant to a June 24, 2016 order by the D.C. Circuit Court of Appeals in the litigation by industry- and environmental-groups challenging EPA’s CCR regulations, within the next three years EPA is required to complete a rulemaking proceeding concerning whether or not boron must be included on the list of groundwater constituents that might trigger corrective action under EPA’s CCR rules.  EPA is not required to take final action approving the inclusion of boron, but EPA must propose and consider its inclusion.  Should EPA take final action adding boron to the list of groundwater constituents that might trigger corrective action, any resulting corrective action measures may increase APS's costs of compliance with the CCR rule at our coal-fired generating facilities.  At this time, though, APS cannot predict when EPA will commence its rulemaking concerning boron or the eventual results of those proceedings.

Effluent Limitation Guidelines. On September 30, 2015, EPA finalized revised effluent limitation guidelines establishing technology-based wastewater discharge limitations for fossil-fired EGUs.  EPA’s final regulation targets metals and other pollutants in wastewater streams originating from fly ash and bottom ash handling activities, scrubber activities, and coal ash disposal leachate.  Based upon an earlier set of preferred alternatives, the final effluent limitations generally require chemical precipitation and biological treatment for flue gas desulfurization scrubber wastewater, “zero discharge” from fly ash and bottom ash handling, and impoundment for coal ash disposal leachate.  Compliance with these limitations will be required in connection with National Pollution Discharge Elimination System ("NPDES") discharge permit renewals, which occur in five-year intervals, that arise between 2018 and 2023.  Until a draft NPDES permit for Four Corners is proposed during that timeframe, we are uncertain what will be required to control these discharges in compliance with the finalized effluent limitations at that facility.  Cholla and the Navajo Plant do not require NPDES permitting.

Ozone National Ambient Air Quality Standards. On October 1, 2015, EPA finalized revisions to the primary ground-level ozone national ambient air quality standards (“NAAQS”) at a level of 70 parts per billion

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(“ppb”).  With ozone standards becoming more stringent, our fossil generation units will come under increasing pressure to reduce emissions of nitrogen oxides and volatile organic compounds, and to generate emission offsets for new projects or facility expansions located in ozone nonattainment areas.  EPA is expected to designate attainment and nonattainment areas relative to the new 70 ppb standard by October 1, 2017.  Depending on when EPA approves attainment designations for the Arizona and Navajo Nation jurisdictions in which our fossil generation units are located, revisions to SIPs and FIPs, respectively, implementing required controls to achieve the new 70 ppb standard are expected to be in place between 2020 and 2021.  At this time, because proposed SIPs and FIPs implementing the revised ozone NAAQSs have yet to be released, APS is unable to predict what impact the adoption of these standards may have on the Company. APS will continue to monitor these standards as they are implemented within the jurisdictions affecting APS.

Superfund-Related Matters. The Comprehensive Environmental Response Compensation and Liability Act ("Superfund") establishes liability for the cleanup of hazardous substances found contaminating the soil, water or air.  Those who generated, transported or disposed of hazardous substances at a contaminated site are among those who are potentially responsible parties ("PRPs").  PRPs may be strictly, and often are jointly and severally, liable for clean-up.  On September 3, 2003, EPA advised APS that EPA considers APS to be a PRP in the Motorola 52^nd Street Superfund Site, Operable Unit 3 ("OU3") in Phoenix, Arizona.  APS has facilities that are within this Superfund site.  APS and Pinnacle West have agreed with EPA to perform certain investigative activities of the APS facilities within OU3.  In addition, on September 23, 2009, APS agreed with EPA and one other PRP to voluntarily assist with the funding and management of the site-wide groundwater remedial investigation and feasibility study work plan ("RI/FS").  The OU3 working group parties have agreed to a schedule with EPA that calls for the submission of a revised draft RI/FS by June 2017. We estimate that our costs related to this investigation and study will be approximately $2 million.  We anticipate incurring additional expenditures in the future, but because the overall investigation is not complete and ultimate remediation requirements are not yet finalized, at the present time expenditures related to this matter cannot be reasonably estimated.

On August 6, 2013, the Roosevelt Irrigation District ("RID") filed a lawsuit in Arizona District Court against APS and 24 other defendants, alleging that RID’s groundwater wells were contaminated by the release of hazardous substances from facilities owned or operated by the defendants.  The lawsuit also alleges that, under Superfund laws, the defendants are jointly and severally liable to RID.  The allegations against APS arise out of APS’s current and former ownership of facilities in and around OU3.  As part of a state governmental investigation into groundwater contamination in this area, on January 25, 2015, ADEQ sent a letter to APS seeking information concerning the degree to which, if any, APS’s current and former ownership of these facilities may have contributed to groundwater contamination in this area.  APS responded to ADEQ on May 4, 2015. On December 16, 2016, two RID contractors filed ancillary lawsuits for recovery of costs against APS and the other defendants. We are unable to predict the outcome of these matters; however, we do not expect the outcome to have a material impact on our financial position, results of operations or cash flows.

Manufactured Gas PlantSites.Certain properties which APS now owns or which were previously owned by it or its corporate predecessors were at one time sites of, or sites associated with, manufactured gas plants. APS is taking action to voluntarily remediate these sites. APS does not expect these matters to have a material adverse effect on its financial position, results of operations or cash flows.

Federal Agency Environmental Lawsuit Related to Four Corners

On April 20, 2016, several environmental groups filed a lawsuit against OSM and other federal agencies in the District of Arizona in connection with their issuance of the approvals that extended the life of Four Corners and the adjacent mine.  The lawsuit alleges that these federal agencies violated both the ESA and NEPA in providing the federal approvals necessary to extend operations at the Four Corners Power Plant and

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the adjacent Navajo Mine past July 6, 2016.  APS filed a motion to intervene in the proceedings, which was granted on August 3, 2016. Briefing on the merits of this litigation is expected to extend through May 2017. On September 15, 2016, NTEC, the company that owns the adjacent mine, filed a motion to intervene for the purpose of dismissing the lawsuit based on NTEC's tribal sovereign immunity. Because the court has placed a stay on all litigation deadlines pending its decision regarding NTEC's motion to dismiss, the schedule for briefing and the anticipated timeline for completion of this litigation will likely be extended. We cannot predict the outcome of this matter or its potential effect on Four Corners.

Navajo Nation Environmental Issues

Four Corners and the Navajo Plant are located on the Navajo Reservation and are held under easements granted by the federal government, as well as leases from the Navajo Nation. See “Energy Sources and Resource Planning - Generation Facilities - Coal-Fueled Generating Facilities” above for additional information regarding these plants.

In July 1995, the Navajo Nation enacted the Navajo Nation Air Pollution Prevention and Control Act, the Navajo Nation Safe Drinking Water Act, and the Navajo Nation Pesticide Act (collectively, the “Navajo Acts”). The Navajo Acts purport to give the Navajo Nation Environmental Protection Agency authority to promulgate regulations covering air quality, drinking water, and pesticide activities, including those activities that occur at Four Corners and the Navajo Plant. On October 17, 1995, the Four Corners participants and the Navajo Plant participants each filed a lawsuit in the District Court of the Navajo Nation, Window Rock District, challenging the applicability of the Navajo Acts as to Four Corners and the Navajo Plant. The Court has stayed these proceedings pursuant to a request by the parties, and the parties are seeking to negotiate a settlement.

In April 2000, the Navajo Nation Council approved operating permit regulations under the Navajo Nation Air Pollution Prevention and Control Act. APS believes the Navajo Nation exceeded its authority when it adopted the operating permit regulations. On July 12, 2000, the Four Corners participants and the Navajo Plant participants each filed a petition with the Navajo Supreme Court for review of these regulations. Those proceedings have been stayed, pending the settlement negotiations mentioned above. APS cannot currently predict the outcome of this matter.

On May 18, 2005, APS, SRP, as the operating agent for the Navajo Plant, and the Navajo Nation executed a Voluntary Compliance Agreement to resolve their disputes regarding the Navajo Nation Air Pollution Prevention and Control Act. As a result of this agreement, APS sought, and the courts granted, dismissal of the pending litigation in the Navajo Nation Supreme Court and the Navajo Nation District Court, to the extent the claims relate to the Clean Air Act. The agreement does not address or resolve any dispute relating to other Navajo Acts. APS cannot currently predict the outcome of this matter.

Water Supply

Assured supplies of water are important for APS’s generating plants. At the present time, APS has adequate water to meet its needs. The Four Corners region, in which Four Corners is located, has historically experienced drought conditions that may affect the water supply for the plants if adequate moisture is not received in the watershed that supplies the area. However, during the past 12 months the region has received snowfall and precipitation sufficient to recover the Navajo Reservoir to an optimum operating level, reducing the probability of shortage in future years. Although the watershed and reservoirs are in a good condition at this time, APS is continuing to work with area stakeholders to implement agreements to minimize the effect, if any, on future drought conditions that could have an impact on operations of its plants.

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Conflicting claims to limited amounts of water in the southwestern United States have resulted in numerous court actions, which, in addition to future supply conditions, have the potential to impact APS’s operations.

San Juan River Adjudication. Both groundwater and surface water in areas important to APS’s operations have been the subject of inquiries, claims, and legal proceedings, which will require a number of years to resolve. APS is one of a number of parties in a proceeding, filed March 13, 1975, before the Eleventh Judicial District Court in New Mexico to adjudicate rights to a stream system from which water for Four Corners is derived. An agreement reached with the Navajo Nation in 1985, however, provides that if Four Corners loses a portion of its rights in the adjudication, the Navajo Nation will provide, for an agreed upon cost, sufficient water from its allocation to offset the loss. In addition, APS is a party to a water contract that allows the company to secure water for Four Corners in the event of a water shortage and is a party to a shortage sharing agreement, which provides for the apportionment of water supplies to Four Corners in the event of a water shortage in the San Juan River Basin.

Gila River Adjudication. A summons served on APS in early 1986 required all water claimants in the Lower Gila River Watershed in Arizona to assert any claims to water on or before January 20, 1987, in an action pending in Arizona Superior Court. Palo Verde is located within the geographic area subject to the summons. APS’s rights and the rights of the other Palo Verde participants to the use of groundwater and effluent at Palo Verde are potentially at issue in this action. As operating agent of Palo Verde, APS filed claims that dispute the court’s jurisdiction over the Palo Verde participants’ groundwater rights and their contractual rights to effluent relating to Palo Verde. Alternatively, APS seeks confirmation of such rights. Several of APS’s other power plants are also located within the geographic area subject to the summons. APS’s claims dispute the court’s jurisdiction over APS’s groundwater rights with respect to these plants. Alternatively, APS seeks confirmation of such rights. In November 1999, the Arizona Supreme Court issued a decision confirming that certain groundwater rights may be available to the federal government and Indian tribes. In addition, in September 2000, the Arizona Supreme Court issued a decision affirming the lower court’s criteria for resolving groundwater claims. Litigation on both of these issues has continued in the trial court. In December 2005, APS and other parties filed a petition with the Arizona Supreme Court requesting interlocutory review of a September 2005 trial court order regarding procedures for determining whether groundwater pumping is affecting surface water rights. The Arizona Supreme Court denied the petition in May 2007, and the trial court is now proceeding with implementation of its 2005 order. No trial date concerning APS’s water rights claims has been set in this matter.

Little Colorado River Adjudication. APS has filed claims to water in the Little Colorado River Watershed in Arizona in an action pending in the Apache County, Arizona, Superior Court, which was originally filed on September 5, 1985. APS’s groundwater resource utilized at Cholla is within the geographic area subject to the adjudication and, therefore, is potentially at issue in the case. APS’s claims dispute the court’s jurisdiction over its groundwater rights. Alternatively, APS seeks confirmation of such rights. Other claims have been identified as ready for litigation in motions filed with the court. No trial date concerning APS’s water rights claims has been set in this matter.

Although the above matters remain subject to further evaluation, APS does not expect that the described litigation will have a material adverse impact on its financial position, results of operations, or cash flows.

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BUSINESS OF OTHER SUBSIDIARIES

Bright Canyon Energy

On July 31, 2014, Pinnacle West announced its creation of a wholly-owned subsidiary, BCE.  BCE will focus on new growth opportunities that leverage the Company’s core expertise in the electric energy industry.  BCE’s first initiative is a 50/50 joint venture with BHE U.S. Transmission LLC, a subsidiary of Berkshire Hathaway Energy Company.  The joint venture, named TransCanyon, is pursuing independent transmission opportunities within the eleven states that comprise the Western Electricity Coordinating Council, excluding opportunities related to transmission service that would otherwise be provided under the tariffs of the retail service territories of the venture partners’ utility affiliates.  TransCanyon continues to pursue transmission development opportunities in the western United States consistent with its strategy.

On March 29, 2016, TransCanyon entered into a strategic alliance agreement with Pacific Gas and Electric Company ("PG&E") to jointly pursue competitive transmission opportunities solicited by the CAISO, the operator for the majority of California's transmission grid. TransCanyon and PG&E intend to jointly engage in the development of future transmission infrastructure and compete to develop, build, own and operate transmission projects approved by the CAISO.

El Dorado

El Dorado owns minority interests in several energy-related investments and Arizona community-based ventures.  El Dorado’s short-term goal is to prudently realize the value of its existing investments.  As of December 31, 2016, El Dorado had total assets of approximately $11 million. El Dorado is not expected to contribute in any material way to our future financial performance, nor will it require any material amounts of capital over the next three years. 

4CA

See "Business of Arizona Public Service Company - Energy Sources and Resource Planning - Generating Facilities - Coal-Fueled Generating Facilities - Four Corners" above for information regarding 4CA. As of December 31, 2016, 4CA had total assets of approximately $69 million. 

OTHER INFORMATION

Subpoenas

Pinnacle West has received grand jury subpoenas issued in connection with an investigation by the office of the United States Attorney for the District of Arizona. The subpoenas seek information principally pertaining to the 2014 statewide election races in Arizona for Secretary of State and for positions on the ACC. The subpoenas request records involving certain Pinnacle West officers and employees, including the Company’s Chief Executive Officer, as well as communications between Pinnacle West personnel and a former ACC Commissioner. Pinnacle West is cooperating fully with the United States Attorney’s office in this matter.

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Other Information

Pinnacle West, APS and El Dorado are all incorporated in the State of Arizona.  BCE and 4CA are incorporated in Delaware. Additional information for each of these companies is provided below:

	Principal Executive Office Address	Year of Incorporation	Approximate Number of Employees at December 31, 2016
Pinnacle West	400 North Fifth Street Phoenix, AZ 85004	1985	89
APS	400 North Fifth Street P.O. Box 53999 Phoenix, AZ 85072-3999	1920	6,244
BCE	400 East Van Buren Phoenix, AZ 85004	2014	6
El Dorado	400 East Van Buren Phoenix, AZ 85004	1983	—
4CA	400 North Fifth Street Phoenix, AZ 85004	2016	—
Total			6,339

The APS number includes employees at jointly-owned generating facilities (approximately 2,628 employees) for which APS serves as the generating facility manager.  Approximately 1,613 APS employees are union employees, represented by the International Brotherhood of Electrical Workers ("IBEW") or the United Security Professionals of America ("USPA").  APS concluded negotiations with IBEW representatives over the new collective bargaining agreement in April 2015, and the new agreement is in place until March 31, 2018. The contract provides an average wage increase of 2.0% for the first year, 2.25% for the second year and 3.0% for the third year. The Company concluded negotiations with the USPA over the terms of a new collective bargaining agreement in May of 2014, and the new agreement is in place until May 31, 2017.

WHERE TO FIND MORE INFORMATION

We use our website (www.pinnaclewest.com) as a channel of distribution for material Company information.  The following filings are available free of charge on our website as soon as reasonably practicable after they are electronically filed with, or furnished to, the Securities and Exchange Commission (“SEC”):  Annual Reports on Form 10-K, definitive proxy statements for our annual shareholder meetings, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and all amendments to those reports.  Our board and committee charters, Code of Ethics for Financial Executives, Code of Ethics and Business Practices and other corporate governance information is also available on the Pinnacle West website.  Pinnacle West will post any amendments to the Code of Ethics for Financial Executives and Code of Ethics and Business Practices, and any waivers that are required to be disclosed by the rules of either the SEC or the New York Stock Exchange, on its website.  The information on Pinnacle West’s website is not incorporated by reference into this report.

You can request a copy of these documents, excluding exhibits, by contacting Pinnacle West at the following address:  Pinnacle West Capital Corporation, Office of the Corporate Secretary, Mail Station 8602, P.O. Box 53999, Phoenix, Arizona 85072-3999 (telephone 602-250-4400).

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ITEM 1A.  RISK FACTORS

In addition to the factors affecting specific business operations identified in the description of these operations contained elsewhere in this report, set forth below are risks and uncertainties that could affect our financial results.  Unless otherwise indicated or the context otherwise requires, the following risks and uncertainties apply to Pinnacle West and its subsidiaries, including APS.

REGULATORY RISKS

Our financial condition depends upon APS’s ability to recover costs in a timely manner from customers through regulated rates and otherwise execute its business strategy.

APS is subject to comprehensive regulation by several federal, state and local regulatory agencies that significantly influence its business, liquidity, results of operations and its ability to fully recover costs from utility customers in a timely manner.  The ACC regulates APS’s retail electric rates and FERC regulates rates for wholesale power sales and transmission services.  The profitability of APS is affected by the rates it may charge and the timeliness of recovering costs incurred through its rates.  Consequently, our financial condition and results of operations are dependent upon the satisfactory resolution of any APS rate proceedings and ancillary matters which may come before the ACC and FERC, including in some cases how court challenges to these regulatory decisions are resolved. Arizona, like certain other states, has a statute that allows the ACC to reopen prior decisions and modify otherwise final orders under certain circumstances.

APS is currently pursuing certain activities, such as microgrid investments and construction of renewable facilities intended for specific customers. To date, APS has not received regulatory assurance of cost recovery for such investments. As APS engages in these activities, we will have to demonstrate to regulators, as we do with all other capital investments, that these investments are both prudent and useful in providing electric service to customers.

The ACC must also approve APS’s issuance of securities and any significant transfer or encumbrance of APS property used to provide retail electric service, and must approve or receive prior notification of certain transactions between us, APS and our respective affiliates.  Decisions made by the ACC or FERC could have a material adverse impact on our financial condition, results of operations or cash flows.

APS’s ability to conduct its business operations and avoid fines and penalties depends upon compliance with federal, state or local statutes, regulations and ACC requirements, and obtaining and maintaining certain regulatory permits, approvals and certificates.

APS must comply in good faith with all applicable statutes, regulations, rules, tariffs, and orders of agencies that regulate APS’s business, including FERC, NRC, EPA, the ACC, and state and local governmental agencies.  These agencies regulate many aspects of APS’s utility operations, including safety and performance, emissions, siting and construction of facilities, customer service and the rates that APS can charge retail and wholesale customers.  Failure to comply can subject APS to, among other things, fines and penalties.  For example, under the Energy Policy Act of 2005, FERC can impose penalties (up to one million dollars per day per violation) for failure to comply with mandatory electric reliability standards.  APS is also required to have numerous permits, approvals and certificates from these agencies.  APS believes the necessary permits, approvals and certificates have been obtained for its existing operations and that APS’s business is conducted in accordance with applicable laws in all material respects.  However, changes in regulations or the imposition of new or revised laws or regulations could have an adverse impact on our results of operations.  We are also unable to predict the impact on our business and operating results from pending or future regulatory activities of any of these agencies.

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The operation of APS’s nuclear power plant exposes it to substantial regulatory oversight and potentially significant liabilities and capital expenditures.

The NRC has broad authority under federal law to impose safety-related, security-related and other licensing requirements for the operation of nuclear generation facilities.  Events at nuclear facilities of other operators or impacting the industry generally may lead the NRC to impose additional requirements and regulations on all nuclear generation facilities, including Palo Verde.  In the event of noncompliance with its requirements, the NRC has the authority to impose a progressively increased inspection regime that could ultimately result in the shut-down of a unit or civil penalties, or both, depending upon the NRC’s assessment of the severity of the situation, until compliance is achieved.  The increased costs resulting from penalties, a heightened level of scrutiny and implementation of plans to achieve compliance with NRC requirements may adversely affect APS’s financial condition, results of operations and cash flows.

APS is subject to numerous environmental laws and regulations, and changes in, or liabilities under, existing or new laws or regulations may increase APS’s cost of operations or impact its business plans.

APS is, or may become, subject to numerous environmental laws and regulations affecting many aspects of its present and future operations, including air emissions of conventional pollutants and greenhouse gases, water quality, discharges of wastewater and streams originating from fly ash and bottom ash handling facilities, solid waste, hazardous waste, and coal combustion products, which consist of bottom ash, fly ash, and air pollution control wastes.  These laws and regulations can result in increased capital, operating, and other costs, particularly with regard to enforcement efforts focused on power plant emissions obligations.  These laws and regulations generally require APS to obtain and comply with a wide variety of environmental licenses, permits, and other approvals.  If there is a delay or failure to obtain any required environmental regulatory approval, or if APS fails to obtain, maintain, or comply with any such approval, operations at affected facilities could be suspended or subject to additional expenses.  In addition, failure to comply with applicable environmental laws and regulations could result in civil liability as a result of government enforcement actions or private claims or criminal penalties.  Both public officials and private individuals may seek to enforce applicable environmental laws and regulations.  APS cannot predict the outcome (financial or operational) of any related litigation that may arise.

Environmental Clean Up.  APS has been named as a PRP for a Superfund site in Phoenix, Arizona, and it could be named a PRP in the future for other environmental clean-up at sites identified by a regulatory body.  APS cannot predict with certainty the amount and timing of all future expenditures related to environmental matters because of the difficulty of estimating clean-up costs.  There is also uncertainty in quantifying liabilities under environmental laws that impose joint and several liability on all PRPs.

Regional Haze.  APS has received final rulemakings imposing new requirements on Four Corners, Cholla and the Navajo Plant.  Pursuant to these rules, EPA and ADEQ will require these plants to install pollution control equipment that constitutes BART to lessen the impacts of emissions on visibility surrounding the plants.  The financial impact of installing and operating the required pollution control equipment could jeopardize the economic viability of these plants or the ability of individual participants to continue their participation in these plants.

Coal Ash. In December 2014, EPA issued final regulations governing the handling and disposal of CCR, which are generated as a result of burning coal and consist of, among other things, fly ash and bottom ash. The rule regulates CCR as a non-hazardous waste. APS currently disposes of CCR in ash ponds and dry storage areas at Cholla and Four Corners and in a dry landfill storage area at the Navajo Plant. To the extent

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the rule requires the closure or modification of these CCR units or the construction of new CCR units beyond what we currently anticipate, APS would incur significant additional costs for CCR disposal.

Ozone National Ambient Air Quality Standards. In 2015, EPA finalized revisions to the national ambient air quality standards for nitrogen oxides, which set new, more stringent standards intended to protect human health and human welfare. Depending on the final attainment designations for the new standards and the state implementation requirements, APS may be required to invest in new pollution control technologies and to generate emission offsets for new projects or facility expansions located in ozone nonattainment areas.

APS cannot assure that existing environmental regulations will not be revised or that new regulations seeking to protect the environment will not be adopted or become applicable to it.  Revised or additional regulations that result in increased compliance costs or additional operating restrictions, particularly if those costs incurred by APS are not fully recoverable from APS’s customers, could have a material adverse effect on its financial condition, results of operations or cash flows.  Due to current or potential future regulations or legislation coupled with trends in natural gas and coal prices, the economics of continuing to own certain resources, particularly coal facilities, may deteriorate, warranting early retirement of those plants, which may result in asset impairments.  APS would seek recovery in rates for the book value of any remaining investments in the plants as well as other costs related to early retirement, but cannot predict whether it would obtain such recovery.

APS faces potential financial risks resulting from climate change litigation and legislative and regulatory efforts to limit GHG emissions, as well as physical and operational risks related to climate effects.

Concern over climate change has led to significant legislative and regulatory efforts to limit CO2, which is a major byproduct of the combustion of fossil fuel, and other GHG emissions.

Potential Financial Risks - Greenhouse Gas Regulation, the Clean Power Plan and Potential Litigation. In 2015, EPA finalized a rule to limit carbon dioxide emissions from existing power plants. The implementation of this rule within the jurisdictions where APS operates could result in a shift in in-state generation from coal to natural gas and renewable generation. Such a substantial change in APS’s generation portfolio could require additional capital investments and increased operating costs, and thus have a significant financial impact on the Company. See Note 10 for additional risks and uncertainties resulting from the Clean Power Plan.

Depending on the final outcome of the pending judicial review of the Clean Power Plan, or any related legislative or regulatory activity, the utility industry may face alternative efforts from private parties seeking to establish alternative GHG emission limitations from power plants. Alternative GHG emission limitations may arise from litigation under either federal or state common laws or citizen suit provisions of federal environmental statutes that attempt to force federal agency rulemaking or imposing direct facility emission limitations. Such lawsuits may also seek damages from harm alleged to have resulted from power plant GHG emissions.

Physical and Operational Risks.Weather extremes such as drought and high temperature variations are common occurrences in the Southwest’s desert area, and these are risks that APS considers in the normal course of business in the engineering and construction of its electric system. Large increases in ambient temperatures could require evaluation of certain materials used within its system and represent a greater challenge.

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Co-owners of our jointly owned generation facilities may have unaligned goals and positions due to the effects of legislation, regulations, economic conditions or changes in our industry, which could have a significant impact on our ability to continue operations of such facilities.

APS owns certain of our power plants jointly with other owners with varying ownership interests in such facilities. Changes in the nature of our industry and the economic viability of certain plants, including impacts resulting from types and availability of other resources, fuel costs, legislation and regulation, together with timing considerations related to expiration of leases or other agreements for such facilities, could result in unaligned positions among co-owners. Such differences in the co-owners’ willingness or ability to continue their participation could ultimately lead to disagreements among the parties as to how and whether to continue operation of such plants, which could lead to eventual shut down of units or facilities and uncertainty related to the resulting cost recovery of such assets.

Deregulation or restructuring of the electric industry may result in increased competition, which could have a significant adverse impact on APS’s business and its results of operations.

In 1999, the ACC approved rules for the introduction of retail electric competition in Arizona.  Retail competition could have a significant adverse financial impact on APS due to an impairment of assets, a loss of retail customers, lower profit margins or increased costs of capital.  Although some very limited retail competition existed in APS’s service area in 1999 and 2000, there are currently no active retail competitors offering unbundled energy or other utility services to APS’s customers.  On May 9, 2013, the ACC voted to re-examine the facilitation of a deregulated retail electric market in Arizona.  The ACC subsequently opened a docket for this matter and received comments from a number of interested parties on the considerations involved in establishing retail electric deregulation in the state.  One of these considerations is whether various aspects of a deregulated market, including setting utility rates on a “market” basis, would be consistent with the requirements of the Arizona Constitution.  On September 11, 2013, after receiving legal advice from the ACC staff, the ACC voted 4-1 to close the current docket and await full Arizona Constitutional authority before any further examination of this matter.  The motion approved by the ACC also included opening one or more new dockets in the future to explore options to offer more rate choices to customers and innovative changes within the existing cost-of-service regulatory model that could include elements of competition. 

One of these options would be a continuation or expansion of APS’s existing AG (Alternative Generation) - 1 pilot program, which essentially allows up to 200 MW of cumulative load to be served via a buy-through arrangement with competitive suppliers of generation.  On November 25, 2015, the ACC issued an order approving a request by several AG-1 customers and suppliers to extend the term of the program from July 1, 2016 to the conclusion of APS's pending general rate case. The order also authorized APS to defer for future recovery unmitigated unrecovered costs attributable to the program at 90% of the first $10 million per year and at 100% of amounts above $10 million per year.

Proposals to enable or support retail electric competition may be made from time to time through ballot initiatives, legislative or other forums in Arizona. We cannot predict future regulatory or legislative action that might result in increased competition.

Changes in tax legislation or regulation may affect our financial results.

We are subject to taxation by various taxing authorities at the federal, state and local levels. Legislation or regulation could be enacted by any of these governmental authorities which could affect the Company’s tax positions.  The prospects for broad-based federal tax reform have increased due to the results of the 2016 elections.  Any such reform may impact the Company's effective tax rate, cash taxes paid and other financial results such as earnings per share, gross revenues and cash flows.  We cannot predict the timing or extent of

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such tax-related developments which, absent appropriate regulatory treatment, could have a negative impact on our financial results.

OPERATIONAL RISKS

APS’s results of operations can be adversely affected by various factors impacting demand for electricity.

Weather Conditions.  Weather conditions directly influence the demand for electricity and affect the price of energy commodities.  Electric power demand is generally a seasonal business.  In Arizona, demand for power peaks during the hot summer months, with market prices also peaking at that time.  As a result, APS’s overall operating results fluctuate substantially on a seasonal basis.  In addition, APS has historically sold less power, and consequently earned less income, when weather conditions are milder.  As a result, unusually mild weather could diminish APS’s financial condition, results of operations and cash flows.

Higher temperatures may decrease the snowpack, which might result in lowered soil moisture and an increased threat of forest fires.  Forest fires could threaten APS’s communities and electric transmission lines and facilities.  Any damage caused as a result of forest fires could negatively impact APS’s financial condition, results of operations or cash flows.

Effects of Energy Conservation Measures and Distributed Energy Resources.  The ACC has enacted rules regarding energy efficiency that mandate a 22% cumulative annual energy savings requirement by 2020.  This will likely increase participation by APS customers in energy efficiency and conservation programs and other demand-side management efforts, which in turn will impact the demand for electricity.  The rules also include a requirement for the ACC to review and address financial disincentives, recovery of fixed costs and the recovery of net lost income/revenue that would result from lower sales due to increased energy efficiency requirements.  To that end, the settlement agreement in APS’s most recent retail rate case (the “2012 Settlement Agreement”) includes a mechanism, the LFCR, to address these matters.

APS must also meet certain distributed energy requirements.  A portion of APS’s total renewable energy requirement must be met with an increasing percentage of distributed energy resources (generally, small scale renewable technologies located on customers’ properties).  The distributed energy requirement was 25% of the overall RES requirement of 3% in 2011 and increased to 30% of the applicable RES requirement for 2012 and subsequent years.  Customer participation in distributed energy programs would result in lower demand, since customers would be meeting some of their own energy needs. 

In addition to these rules and requirements, energy efficiency technologies and distributed energy resources continue to evolve, which may have similar impacts on demand for electricity. Reduced demand due to these energy efficiency requirements, distributed energy requirements and other emerging technologies, unless substantially offset through ratemaking mechanisms, could have a material adverse impact on APS’s financial condition, results of operations and cash flows.

Actual and Projected Customer and Sales Growth.  Retail customers in APS's service territory increased 1.4% for the year ended December 31, 2016 compared with the prior year. For the three years 2014 through 2016, APS’s retail customer growth averaged 1.3% per year.  We currently project annual customer growth to be 1.5-2.5% for 2017 and to average in the range of 2.0-3.0% for 2017 through 2019 based on our assessment of modestly improving economic conditions in Arizona. 

Retail electricity sales in kWh, adjusted to exclude the effects of weather variations, were flat for the year ended December 31, 2016 compared with the prior year. Improving economic conditions and customer growth and an additional day of sales due to leap year were equally offset by energy savings driven by

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customer conservation, energy efficiency and distributed renewable generation initiatives. For the three years 2014 through 2016, APS experienced annual increases in retail electricity sales averaging 0.2%, adjusted to exclude the effects of weather variations.  We currently project that annual retail electricity sales in kWh will increase in the range of 0-1.0% for 2017 and increase on average in the range of 0.5-1.5% during 2017 through 2019, including the effects of customer conservation and energy efficiency and distributed renewable generation initiatives, but excluding the effects of weather variations. 

Actual customer and sales growth may differ from our projections as a result of numerous factors, such as economic conditions, customer growth, usage patterns and energy conservation, impacts of energy efficiency programs and growth in distributed renewable generation, and responses to retail price changes. Additionally, recovery of a substantial portion of our fixed costs of providing service is based upon the volumetric amount of our sales.  If our customer growth rate does not continue to improve as projected, or if we experience acceleration of expected effects of customer conservation, energy efficiency or distributed renewable generation initiatives, we may be unable to reach our estimated sales projections, which could have a negative impact on our financial condition, results of operations and cash flows.

The operation of power generation facilities and transmission systems involves risks that could result in reduced output or unscheduled outages, which could materially affect APS’s results of operations.

The operation of power generation, transmission and distribution facilities involves certain risks, including the risk of breakdown or failure of equipment, fuel interruption, and performance below expected levels of output or efficiency.  Unscheduled outages, including extensions of scheduled outages due to mechanical failures or other complications, occur from time to time and are an inherent risk of APS’s business.  Because our transmission facilities are interconnected with those of third parties, the operation of our facilities could be adversely affected by unexpected or uncontrollable events occurring on the larger transmission power grid, and the operation or failure of our facilities could adversely affect the operations of others.  Concerns over physical security of these assets include damage to certain of our facilities due to vandalism or other deliberate acts that could lead to outages or other adverse effects. If APS’s facilities operate below expectations, especially during its peak seasons, it may lose revenue or incur additional expenses, including increased purchased power expenses. 

The inability to successfully develop or acquire generation resources to meet reliability requirements and other new or evolving standards or regulations could adversely impact our business.

Potential changes in regulatory standards, impacts of new and existing laws and regulations, including environmental laws and regulations, and the need to obtain various regulatory approvals create uncertainty surrounding our generation portfolio.  The current abundance of low, stably priced natural gas, together with environmental and other concerns surrounding coal-fired generation resources, create strategic challenges as to the appropriate generation portfolio and fuel diversification mix.  In addition, APS is required by the ACC to meet certain energy resource portfolio requirements, including those related to renewables development and energy efficiency measures.  The development of any generation facility is subject to many risks, including those related to financing, siting, permitting, new and evolving technology, the construction of sufficient transmission capacity to support these facilities and stresses to generation and transmission resources from the intermittent generation characteristics of renewable resources.  APS’s inability to adequately develop or acquire the necessary generation resources could have a material adverse impact on our business and results of operations.

In expressing concerns about the environmental and climate-related impacts from continued extraction, transportation, delivery and combustion of fossil fuels, environmental advocacy groups and other third parties have in recent years undertaken greater efforts to oppose the permitting and construction of fossil fuel

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infrastructure projects. These efforts may increase in scope and frequency depending on a number of variables, including the future course of Federal environmental regulation and the increasing financial resources devoted to these opposition activities. APS cannot predict the effect that any such opposition may have on our ability to develop and construct fossil fuel infrastructure projects in the future.

The lack of access to sufficient supplies of water could have a material adverse impact on APS’s business and results of operations.

Assured supplies of water are important for APS’s generating plants.  Water in the southwestern United States is limited, and various parties have made conflicting claims regarding the right to access and use such limited supply of water.  Both groundwater and surface water in areas important to APS’s generating plants have been and are the subject of inquiries, claims and legal proceedings.  In addition, the region in which APS’s power plants are located is prone to drought conditions, which could potentially affect the plants’ water supplies.  APS’s inability to access sufficient supplies of water could have a material adverse impact on our business and results of operations.

We are subject to cybersecurity risksand risks of unauthorized access to our systems.

In the regular course of our business, we handle a range of sensitive security, customer and business systems information. A security breach of our information systems such as theft or the inappropriate release of certain types of information, including confidential customer, employee, financial or system operating information, could have a material adverse impact on our financial condition, results of operations or cash flows. We operate in a highly regulated industry that requires the continued operation of sophisticated information technology systems and network infrastructure.  Despite implementation of security measures, our technology systems are vulnerable to disability, failures or unauthorized access.  Our generation, transmission and distribution facilities, information technology systems and other infrastructure facilities and systems and physical assets could be targets of such unauthorized access.  Failures or breaches of our systems could impact the reliability of our generation, transmission and distribution systems and also subject us to financial harm.  If our technology systems were to fail or be breached and if we are unable to recover in a timely way, we may not be able to fulfill critical business functions and sensitive confidential data could be compromised, which could have a material adverse impact on our financial condition, results of operations or cash flows.

We are subject to laws and rules issued by multiple government agencies concerning safeguarding and maintaining the confidentiality of our security, customer and business information. One of these agencies, NERC, has issued comprehensive regulations and standards surrounding the security of bulk power systems, and is continually in the process of developing updated and additional requirements with which the utility industry must comply. The increasing promulgation of NERC rules and standards will increase our compliance costs and our exposure to the potential risk of violations of the standards, which includes potential financial penalties.

We have experienced, and expect to continue to experience, threats and attempted intrusions to our information technology systems and we could experience such threats and attempted intrusions to our operational control systems. The implementation of additional security measures could increase costs and have a material adverse impact on our financial results. We have obtained cyber insurance to provide coverage for a portion of the losses and damages that may result from a security breach of our information technology systems, but such insurance may not cover the total loss or damage caused by a breach. These types of events could also require significant management attention and resources, and could adversely affect Pinnacle West’s and APS’s reputation with customers and the public. 

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The ownership and operation of power generation and transmission facilities on Indian lands could result in uncertainty related to continued leases, easements and rights-of-way, which could have a significant impact on our business.

Certain APS power plants and portions of certain APS transmission lines are located on Indian lands pursuant to leases, easements or other rights-of-way that are effective for specified periods.  APS is unable to predict the final outcomes of pending and future approvals by the applicable sovereign governing bodies with respect to renewals of these leases, easements and rights-of-way.

There are inherent risks in the ownership and operation of nuclear facilities, such as environmental, health, fuel supply, spent fuel disposal, regulatory and financial risks and the risk of terrorist attack.

APS has an ownership interest in and operates, on behalf of a group of participants, Palo Verde, which is the largest nuclear electric generating facility in the United States.  Palo Verde constitutes approximately 18% of our owned and leased generation capacity.  Palo Verde is subject to environmental, health and financial risks, such as the ability to obtain adequate supplies of nuclear fuel; the ability to dispose of spent nuclear fuel; the ability to maintain adequate reserves for decommissioning; potential liabilities arising out of the operation of these facilities; the costs of securing the facilities against possible terrorist attacks; and unscheduled outages due to equipment and other problems.  APS maintains nuclear decommissioning trust funds and external insurance coverage to minimize its financial exposure to some of these risks; however, it is possible that damages could exceed the amount of insurance coverage.  In addition, APS may be required under federal law to pay up to $111 million (but not more than $16.6 million per year) of liabilities arising out of a nuclear incident occurring not only at Palo Verde, but at any other nuclear power plant in the United States. Although we have no reason to anticipate a serious nuclear incident at Palo Verde, if an incident did occur, it could materially and adversely affect our results of operations and financial condition.  A major incident at a nuclear facility anywhere in the world could cause the NRC to limit or prohibit the operation or licensing of any domestic nuclear unit and to promulgate new regulations that could require significant capital expenditures and/or increase operating costs.

The use of derivative contracts in the normal course of our business could result in financial losses that negatively impact our results of operations.

APS’s operations include managing market risks related to commodity prices.  APS is exposed to the impact of market fluctuations in the price and transportation costs of electricity, natural gas and coal to the extent that unhedged positions exist.  We have established procedures to manage risks associated with these market fluctuations by utilizing various commodity derivatives, including exchange traded futures and options and over-the-counter forwards, options, and swaps.  As part of our overall risk management program, we enter into derivative transactions to hedge purchases and sales of electricity and fuels.  The changes in market value of such contracts have a high correlation to price changes in the hedged commodity.  To the extent that commodity markets are illiquid, we may not be able to execute our risk management strategies, which could result in greater unhedged positions than we would prefer at a given time and financial losses that negatively impact our results of operations.

The Dodd-Frank Wall Street Reform and Consumer Protection Act (“Dodd-Frank Act”) contains measures aimed at increasing the transparency and stability of the over-the counter, or OTC, derivative markets and preventing excessive speculation. The Dodd-Frank Act could restrict, among other things, trading positions in the energy futures markets, require different collateral or settlement positions, or increase regulatory reporting over derivative positions. Based on the provisions included in the Dodd-Frank Act and the implementation of regulations, these changes could, among other things, impact our ability to hedge commodity price and interest rate risk or increase the costs associated with our hedging programs.

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We are exposed to losses in the event of nonperformance or nonpayment by counterparties.  We use a risk management process to assess and monitor the financial exposure of all counterparties.  Despite the fact that the majority of APS’s trading counterparties are rated as investment grade by the rating agencies, there is still a possibility that one or more of these companies could default, which could result in a material adverse impact on our earnings for a given period.

Changes in technology could create challenges for APS’s existing business.

Alternative energy technologies that produce power or reduce power consumption or emissions are being developed and commercialized, including renewable technologies such as photovoltaic (solar) cells, customer-sited generation, energy storage (batteries), and efficiency technologies.  Advances in technology and equipment/appliance efficiency could reduce the demand for supply from conventional generation and increase the complexity of managing APS's information technology and power system operations, which could adversely affect APS’s business.

APS continues to pursue and implement advanced grid technologies, including transmission and distribution system technologies and digital meters enabling two-way communications between the utility and its customers.  Many of the products and processes resulting from these and other alternative technologies have not yet been widely used or tested on a long-term basis, and their use on large-scale systems is not as established or mature as APS’s existing technologies and equipment.  The implementation of new and additional technologies adds complexity to the information technology and operational technology systems, which could require additional infrastructure and resources. Widespread installation and acceptance of new technologies could also enable the entry of new market participants, such as technology companies, into the interface between APS and its customers and could have other unpredictable effects on APS’s traditional business model.

Deployment of renewable energy technologies is expected to continue across the western states and result in a larger portion of the overall energy production coming from these sources. These trends, which have benefited from historical and continuing government support for certain technologies, have the potential to put downward pressure on wholesale power prices throughout the western states which could make APS's existing generating facilities less economical and impact their operational patterns and long-term viability.

We are subject to employee workforce factors that could adversely affect our business and financial condition.

Like most companies in the electric utility industry, our workforce is maturing, with approximately 35% of employees eligible to retire by the end of 2019.  Although we have undertaken efforts to recruit and train new employees, we face increased competition for talent.  We are subject to other employee workforce factors, such as the availability of qualified personnel, the need to negotiate collective bargaining agreements with union employees and potential work stoppages.  These or other employee workforce factors could negatively impact our business, financial condition or results of operations.

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FINANCIAL RISKS

Financial market disruptions or new rules or regulations may increase our financing costs or limit our access to various financial markets, which may adversely affect our liquidity and our ability to implement our financial strategy.

Pinnacle West and APS rely on access to credit markets as a significant source of liquidity and the capital markets for capital requirements not satisfied by cash flow from our operations.  We believe that we will maintain sufficient access to these financial markets.  However, certain market disruptions or rules or regulations may cause our cost of borrowing to increase generally, and/or otherwise adversely affect our ability to access these financial markets.

In addition, the credit commitments of our lenders under our bank facilities may not be satisfied or continued beyond current commitment periods for a variety of reasons, including new rules and regulations, periods of financial distress or liquidity issues affecting our lenders or financial markets, which could materially adversely affect the adequacy of our liquidity sources and the cost of maintaining these sources.

Changes in economic conditions, monetary policy, financial regulation or other factors could result in higher interest rates, which would increase interest expense on our existing variable rate debt and new debt we expect to issue in the future, and thus reduce funds available to us for our current plans.

Additionally, an increase in our leverage, whether as a result of these factors or otherwise, could adversely affect us by:

•causing a downgrade of our credit ratings;

•increasing the cost of future debt financing and refinancing;

•increasing our vulnerability to adverse economic and industry conditions; and

• requiring us to dedicate an increased portion of our cash flow from operations to payments on our debt, which would reduce funds available to us for operations, future investment in our business or other purposes.

A downgrade of our credit ratings could materially and adversely affect our business, financial condition and results of operations.

Our current ratings are set forth in “Liquidity and Capital Resources — Credit Ratings” in Item 7.  We cannot be sure that any of our current ratings will remain in effect for any given period of time or that a rating will not be lowered or withdrawn entirely by a rating agency if, in its judgment, circumstances in the future so warrant.  Any downgrade or withdrawal could adversely affect the market price of Pinnacle West’s and APS’s securities, limit our access to capital and increase our borrowing costs, which would diminish our financial results.  We would be required to pay a higher interest rate for future financings, and our potential pool of investors and funding sources could decrease.  In addition, borrowing costs under our existing credit facilities depend on our credit ratings.  A downgrade could also require us to provide additional support in the form of letters of credit or cash or other collateral to various counterparties.  If our short-term ratings were to be lowered, it could severely limit access to the commercial paper market.  We note that the ratings from rating agencies are not recommendations to buy, sell or hold our securities and that each rating should be evaluated independently of any other rating.

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Investment performance, changing interest rates and other economic, social and political factors could decrease the value of our benefit plan assets and nuclear decommissioning trust funds or increase the valuation of our related obligations, resulting in significant additional funding requirements.  We are subject to risks related to the provision of employee healthcare benefits and healthcare reform legislation.  Any inability to fully recover these costs in our utility rates would negatively impact our financial condition.

We have significant pension plan and other postretirement benefits plan obligations to our employees and retirees, and legal obligations to fund nuclear decommissioning trusts for Palo Verde.  We hold and invest substantial assets in these trusts that are designed to provide funds to pay for certain of these obligations as they arise.  Declines in market values of the fixed income and equity securities held in these trusts may increase our funding requirements into the related trusts.  Additionally, the valuation of liabilities related to our pension plan and other postretirement benefit plans are impacted by a discount rate, which is the interest rate used to discount future pension and other postretirement benefit obligations.  Declining interest rates decrease the discount rate, increase the valuation of the plan liabilities and may result in increases in pension and other postretirement benefit costs, cash contributions, regulatory assets, and charges to OCI.  Changes in demographics, including increased number of retirements or changes in life expectancy and changes in other actuarial assumptions, may also result in similar impacts.  The minimum contributions required under these plans are impacted by federal legislation.  Increasing liabilities or otherwise increasing funding requirements under these plans, resulting from adverse changes in legislation or otherwise, could result in significant cash funding obligations that could have a material impact on our financial position, results of operations or cash flows.

We recover most of the pension costs and other postretirement benefit costs and all of the nuclear decommissioning costs in our regulated rates.  Any inability to fully recover these costs in a timely manner would have a material negative impact on our financial condition, results of operations or cash flows.

Employee healthcare costs in recent years have continued to rise.  While most of the Patient Protection and Affordable Care Act provisions have been implemented, changes to the Act or other potential legislation could increase costs of providing medical insurance for our employees. Any potential changes and resulting cost impacts cannot be determined with certainty at this time.

Our cash flow depends on the performance of APS.

We derive essentially all of our revenues and earnings from our wholly owned subsidiary, APS.  Accordingly, our cash flow and our ability to pay dividends on our common stock is dependent upon the earnings and cash flows of APS and its distributions to us.  APS is a separate and distinct legal entity and has no obligation to make distributions to us.

APS’s financing agreements may restrict its ability to pay dividends, make distributions or otherwise transfer funds to us.  In addition, an ACC financing order requires APS to maintain a common equity ratio of at least 40% and does not allow APS to pay common dividends if the payment would reduce its common equity below that threshold.  The common equity ratio, as defined in the ACC order, is total shareholder equity divided by the sum of total shareholder equity and long-term debt, including current maturities of long-term debt.

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Pinnacle West’s ability to meet its debt service obligations could be adversely affected because its debt securities are structurally subordinated to the debt securities and other obligations of its subsidiaries.

Because Pinnacle West is structured as a holding company, all existing and future debt and other liabilities of our subsidiaries will be effectively senior in right of payment to our debt securities.  The assets and cash flows of our subsidiaries will be available, in the first instance, to service their own debt and other obligations.  Our ability to have the benefit of their cash flows, particularly in the case of any insolvency or financial distress affecting our subsidiaries, would arise only through our equity ownership interests in our subsidiaries and only after their creditors have been satisfied.

The market price of our common stock may be volatile.

The market price of our common stock could be subject to significant fluctuations in response to factors such as the following, some of which are beyond our control:

• variations in our quarterly operating results;

• operating results that vary from the expectations of management, securities analysts and investors;

• changes in expectations as to our future financial performance, including financial estimates by securities analysts and investors;

• developments generally affecting industries in which we operate;

• announcements by us or our competitors of significant contracts, acquisitions, joint marketing relationships, joint ventures or capital commitments;

• announcements by third parties of significant claims or proceedings against us;

• favorable or adverse regulatory or legislative developments;

• our dividend policy;

• future sales by the Company of equity or equity-linked securities; and

• general domestic and international economic conditions.

In addition, the stock market in general has experienced volatility that has often been unrelated to the operating performance of a particular company.  These broad market fluctuations may adversely affect the market price of our common stock.

Certain provisions of our articles of incorporation and bylaws and of Arizona law make it difficult for shareholders to change the composition of our board and may discourage takeover attempts.

These provisions, which could preclude our shareholders from receiving a change of control premium, include the following:

• restrictions on our ability to engage in a wide range of “business combination” transactions with an “interested shareholder” (generally, any person who owns 10% or more of our outstanding voting power or any of our affiliates or associates) or any affiliate or associate of an interested shareholder, unless specific conditions are met;

• anti-greenmail provisions of Arizona law and our bylaws that prohibit us from purchasing shares of our voting stock from beneficial owners of more than 5% of our outstanding shares unless specified conditions are satisfied;

• the ability of the Board of Directors to increase the size of the Board of Directors and fill vacancies on the Board of Directors, whether resulting from such increase, or from death, resignation, disqualification or otherwise; and

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• the ability of our Board of Directors to issue additional shares of common stock and shares of preferred stock and to determine the price and, with respect to preferred stock, the other terms, including preferences and voting rights, of those shares without shareholder approval.

While these provisions have the effect of encouraging persons seeking to acquire control of us to negotiate with our Board of Directors, they could enable the Board of Directors to hinder or frustrate a transaction that some, or a majority, of our shareholders might believe to be in their best interests and, in that case, may prevent or discourage attempts to remove and replace incumbent directors.

ITEM 1B.  UNRESOLVED STAFF COMMENTS

Neither Pinnacle West nor APS has received written comments regarding its periodic or current reports from the SEC staff that were issued 180 days or more preceding the end of its 2016 fiscal year and that remain unresolved.

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ITEM 2.  PROPERTIES

Generation Facilities

APS

APS’s portfolio of owned and leased generating facilities is provided in the table below:

Name	No. of Units	% Owned (a)		Principal Fuels Used	Primary Dispatch Type	Owned Capacity (MW)
Nuclear:
Palo Verde (b)	3	29.1	%	Uranium	Base Load	1,146
Total Nuclear						1,146
Steam:
Four Corners 4, 5 (c)	2	63	%	Coal	Base Load	970
Cholla 1,3 (d)	2			Coal	Base Load	387
Navajo (e)	3	14	%	Coal	Base Load	315
Ocotillo	2			Gas	Peaking	220
Total Steam						1,892
Combined Cycle:
Redhawk	2			Gas	Load Following	984
West Phoenix	5			Gas	Load Following	887
Total Combined Cycle						1,871
Combustion Turbine:
Ocotillo	2			Gas	Peaking	110
Saguaro	3			Gas	Peaking	189
Douglas	1			Oil	Peaking	16
Sundance	10			Gas	Peaking	420
West Phoenix	2			Gas	Peaking	110
Yucca 1, 2, 3	3			Gas	Peaking	93
Yucca 4	1			Oil	Peaking	54
Yucca 5, 6	2			Gas	Peaking	96
Total Combustion Turbine						1,088
Solar:
Cotton Center	1			Solar	As Available	17
Hyder I	1			Solar	As Available	16
Paloma	1			Solar	As Available	17
Chino Valley	1			Solar	As Available	19
Gila Bend	1			Solar	As Available	32
Hyder II	1			Solar	As Available	14
Foothills	1			Solar	As Available	35
Luke AFB	1			Solar	As Available	10
Desert Star	1			Solar	As Available	10
Red Rock	1			Solar	As Available	40
APS Owned Distributed Energy				Solar	As Available	25
Multiple facilities				Solar	As Available	4
Total Solar						239
Total Capacity						6,236

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(a) 100% unless otherwise noted.

(b) See “Business of Arizona Public Service Company — Energy Sources and Resource Planning — Generation Facilities — Nuclear” in Item 1 for details regarding leased interests in Palo Verde.  The other participants are Salt River Project (17.49%), SCE (15.8%), El Paso (15.8%), Public Service Company of New Mexico (10.2%), Southern California Public Power Authority (5.91%), and Los Angeles Department of Water & Power (5.7%).  The plant is operated by APS.

(c) The other participants are Salt River Project (10%), Public Service Company of New Mexico (13%), Tucson Electric Power Company (7%) and 4CA(7%).  The plant is operated by APS. 

(d) Cholla Unit 2's last day of service was on October 1, 2015.

(e) The other participants are Salt River Project (42.9%), Nevada Power Company (11.3%), the United States Government (24.3%) and Tucson Electric Power Company (7.5%).  The plant is operated by Salt River Project. In July 2016, Salt River Project purchased Los Angeles Department of Water & Power's share in this plant (21.2%).

See “Business of Arizona Public Service Company — Environmental Matters” in Item 1 with respect to matters having a possible impact on the operation of certain of APS’s generating facilities.

See “Business of Arizona Public Service Company” in Item 1 for a map detailing the location of APS’s major power plants and principal transmission lines.

4CA

4CA, a wholly-owned subsidiary of Pinnacle West, purchased El Paso's 7% interest in Units 4 and 5 of Four Corners on July 6, 2016. See "Areas of Business Focus - Operational Performance, Reliability and Recent Developments - Four Corners - Asset Purchase Agreement and Coal Supply Matters" in Item 7 for additional information about 4CA's interest in Four Corners.

Transmission and Distribution Facilities

Current Facilities.  APS’s transmission facilities consist of approximately 6,140 pole miles of overhead lines and approximately 49 miles of underground lines, 5,917 miles of which are located in Arizona.  APS’s distribution facilities consist of approximately 11,144 miles of overhead lines and approximately 21,128 miles of underground primary cable, all of which are located in Arizona. APS distribution facilities reflect an actual net gain of 3,124 miles in 2016.  APS shares ownership of some of its transmission facilities with other companies. 

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The following table shows APS’s jointly-owned interests in those transmission facilities recorded on the Consolidated Balance Sheets at December 31, 2016:

	Percent Owned (Weighted-Average)
Morgan — Pinnacle Peak System	65.2	%
Palo Verde — Rudd 500kV System	50.0	%
Round Valley System	50.0	%
ANPP 500kV System	33.6	%
Navajo Southern System	22.5	%
Four Corners Switchyards	51.3	%
Palo Verde — Yuma 500kV System	19.0	%
Phoenix — Mead System	17.1	%
Palo Verde — Morgan System	85.8	%
Hassayampa — North Gila System	80.0	%
Cholla 500 Switchyard	85.7	%
Saguaro 500 Switchyard	75.0	%

Expansion.  Each year APS prepares and files with the ACC a ten-year transmission plan.  In APS’s 2017 plan, APS projects it will develop 52 miles of new transmission lines over the next ten years. One significant project currently under development is a new 500kV path that will span from the Palo Verde hub around the western and northern edges of the Phoenix metropolitan area and terminate at a bulk substation in the northeast part of Phoenix. The Palo Verde to Morgan System includes Palo Verde-Delaney-Sun Valley-Morgan-Pinnacle Peak. The project consists of four phases. The first three phases, Morgan to Pinnacle Peak 500kV, Palo Verde to Delaney 500kV, and Delaney to Sun Valley 500kV are currently in-service. The fourth phase, Morgan to Sun Valley 500kV, has started construction and is expected to be energized by May 2018. In total, the projects consist of over 100 miles of new 500kV lines, with many of those miles constructed with the capability to string a 230kV line as a second circuit.

APS continues to work with regulators to identify transmission projects necessary to support renewable energy facilities. Two such projects, which have been completed and were included in previous APS transmission plans, are the Delaney to Palo Verde line and the North Gila to Hassayampa line, both of which support the transmission of renewable energy to Phoenix and California. The North Gila to Hassayampa line went into service in May 2015 and the Delaney to Palo Verde line went into service in May 2016.

Physical Security Standards. On July 14, 2015, FERC approved version 2 of the proposed Physical Security Reliability Standard CIP-014 (CIP-014-2).  As a result, CIP-014-2, the Physical Security Reliability Standard that requires transmission owners and operators to protect those critical transmission stations and substations and their associated primary control centers that, if rendered inoperable or damaged as a result of a physical attack, could result in widespread instability, uncontrolled separation or cascading within an interconnection, became effective on October 2, 2015, triggering a series of staggered, but interdependent obligations for APS.  As required by the Physical Security Reliability Standard, APS determined its critical transmission stations and substations and associated primary control centers that were required to comply with the standard by October 2, 2015.  However, as contemplated under CIP-014-2, this verification triggered additional requirements and obligations within the Physical Security Reliability Standard.  These remaining obligations, which consist of a risk evaluation and development and verification of a physical security plan, were largely completed in 2016 and the remaining activities are projected to be completed in the second and fourth quarters of 2017.  Until APS has completed all required activities under the Physical Security Reliability Standard, we cannot predict the extent of any financial or operational impacts on APS.

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NERC Critical Infrastructure Protection Reliability Standards.  In 2014, APS initiated a comprehensive project to ensure compliance with Version 5 of NERC's Critical Infrastructure Protection Reliability Standards (CIP V.5), which will become effective pursuant to various implementation dates through 2018.  APS completed a significant portion of its compliance implementation activities in June 2016, meeting an initial compliance date of July 1, 2016.  APS will be incurring incremental capital expenditures through 2018 to meet further upcoming compliance deadlines associated with CIP V.5.  Total expenditures are estimated to be approximately $52 million.

Plant and Transmission Line Leases and Rights-of-Way on Indian Lands

The Navajo Plant and Four Corners are located on land held under leases from the Navajo Nation and also under rights-of-way from the federal government.  The right-of-way and lease for the Navajo Plant expire in 2019 and the right-of-way and lease for Four Corners were scheduled to expire in 2016.  APS, on behalf of the Four Corners participants, negotiated amendments to the facility lease with the Navajo Nation, which extends the Four Corners leasehold interest from 2016 to 2041.  See "Areas of Business Focus - Operational Performance, Reliability and Recent Developments - Four Corners - Lease Extension" in Item 7 for additional information about the Four Corners right-of-way and lease matters. See "Navajo Plant" in Note 3 for information regarding future plans for the Navajo Plant.

Certain portions of our transmission lines are located on Indian lands pursuant to rights-of-way that are effective for specified periods.  Some of these rights-of-way have expired and our renewal applications have not yet been acted upon by the appropriate Indian tribes or federal agencies.  Other rights expire at various times in the future and renewal action by the applicable tribe or federal agencies will be required at that time.  In recent negotiations, certain of the affected Indian tribes have required payments substantially in excess of amounts that we have paid in the past for such rights-of-way.  The ultimate cost of renewal of certain of the rights-of-way for our transmission lines is therefore uncertain.

ITEM 3.  LEGAL PROCEEDINGS

See “Business of Arizona Public Service Company — Environmental Matters” in Item 1 with regard to pending or threatened litigation and other disputes.

 See Note 3 for ACC and FERC-related matters.

See Note 10 for information regarding environmental matters and Superfund–related matters. 

ITEM 4.  MINE SAFETY DISCLOSURES

Not applicable.

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EXECUTIVE OFFICERS OF PINNACLE WEST

Pinnacle West’s executive officers are elected no less often than annually and may be removed by the Board of Directors at any time.  The executive officers, their ages at February 24, 2017, current positions and principal occupations for the past five years are as follows:

Name	Age	Position	Period
Donald E. Brandt	62	Chairman of the Board and Chief Executive Officer of Pinnacle West; Chairman of the Board of APS	2009-Present
		President of APS	2013-Present
		President of Pinnacle West	2008-Present
		Chief Executive Officer of APS	2008-Present
Robert S. Bement	61	Executive Vice President and Chief Nuclear Officer, PVNGS, of APS	2016-Present
		Senior Vice President, Site Operations, PVNGS, of APS	2011-2016
Denise R. Danner	61	Vice President, Controller and Chief Accounting Officer of Pinnacle West; Chief Accounting Officer of APS	2010-Present
		Vice President and Controller of APS	2009-Present
Randall K. Edington (a)	63	Advisor to the CEO of APS	2016-Present
		Executive Vice President of APS	2007-Present
		Chief Nuclear Officer, PVNGS, of APS	2007-2016

David P. Falck	63	Executive Vice President and General Counsel of Pinnacle West and APS	2009-Present
		Secretary of Pinnacle West and APS	2009-2012
Daniel T. Froetscher	55	Senior Vice President, Transmission, Distribution & Customers of APS	2014-Present
		Vice President, Energy Delivery of APS	2008-2014
Barbara M. Gomez (b)	62	Senior Vice President, Human Resources of APS	2016-Present
		Vice President, Human Resources of APS	2014-2016
		Vice President, Chief Procurement Officer of APS	2013-2014
		Vice President, Supply Chain Management of APS	2010-2013
Jeffrey B. Guldner	51	Senior Vice President, Public Policy of APS	2014-Present
		Senior Vice President, Customers and Regulation of APS	2012-2014
		Vice President, Rates and Regulation of APS	2007-2012
James R. Hatfield	59	Executive Vice President of Pinnacle West and APS	2012-Present
		Chief Financial Officer of Pinnacle West and APS	2008-Present
		Senior Vice President of Pinnacle West and APS	2008-2012
John S. Hatfield	51	Vice President, Communications of APS	2010-Present
Lee R. Nickloy	50	Vice President and Treasurer of Pinnacle West and APS	2010-Present
Mark A. Schiavoni	61	Executive Vice President and Chief Operating Officer of APS	2014-Present
		Executive Vice President, Operations of APS	2012-2014
		Senior Vice President, Fossil Operations of APS	2009-2012

(a) Randall K. Edington is retiring from APS on March 22, 2017.

(b) Barbara M. Gomez is retiring from APS in July 2017.

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PART II

ITEM 5.  MARKET FOR REGISTRANTS’ COMMON EQUITY, RELATED

STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

Pinnacle West’s common stock is publicly held and is traded on the New York Stock Exchange.  At the close of business on February 17, 2017, Pinnacle West’s common stock was held of record by approximately 19,581 shareholders.

QUARTERLY STOCK PRICES AND DIVIDENDS PAID PER SHARE

STOCK SYMBOL: PNW

							Dividends
2016	High		Low		Close		Per Share
1st Quarter	$	75.15	$	62.51	$	75.07	$	0.625
2nd Quarter	81.08		70.11		81.06		0.625
3rd Quarter	82.78		73.94		75.99		0.625
4th Quarter	78.97		70.86		78.03		0.655

							Dividends
2015	High		Low		Close		Per Share
1st Quarter	$	73.31	$	61.53	$	63.75	$	0.595
2nd Quarter	64.95		56.01		56.89		0.595
3rd Quarter	65.23		56.77		64.14		0.595
4th Quarter	67.02		60.70		64.48		0.625

APS’s common stock is wholly-owned by Pinnacle West and is not listed for trading on any stock exchange.  As a result, there is no established public trading market for APS’s common stock.

The chart below sets forth the dividends paid on APS’s common stock for each of the four quarters for 2016 and 2015.

Common Stock Dividends

(Dollars in Thousands)

Quarter	2016		2015
1st Quarter	$	69,400	$	65,800
2nd Quarter	69,500		65,900
3rd Quarter	69,500		65,900
4th Quarter	72,900		69,300

The sole holder of APS’s common stock, Pinnacle West, is entitled to dividends when and as declared out of legally available funds.  As of December 31, 2016, APS did not have any outstanding preferred stock.

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ITEM 6.  SELECTED FINANCIAL DATA

PINNACLE WEST CAPITAL CORPORATION – CONSOLIDATED

The selected data presented below as of and for the years ended December 31, 2016, 2015, 2014, 2013 and 2012 are derived from the Consolidated Financial Statements. The data should be read in connection with the Consolidated Financial Statements including the related notes included in Item 8 of this Form 10-K.

	2016		2015		2014		2013		2012
	(dollars in thousands, except per share amounts)
OPERATING RESULTS
Operating revenues	$	3,498,682	$	3,495,443	$	3,491,632	$	3,454,628	$	3,301,804
Income from continuing operations	$	461,527	$	456,190	$	423,696	$	439,966	$	418,993
Loss from discontinued operations – net of income taxes	—		—		—		—		(5,829		)
Net income	461,527		456,190		423,696		439,966		413,164
Less: Net income attributable to noncontrolling interests	19,493		18,933		26,101		33,892		31,622
Net income attributable to common shareholders	$	442,034	$	437,257	$	397,595	$	406,074	$	381,542
COMMON STOCK DATA
Book value per share – year-end	$	43.14	$	41.30	$	39.50	$	38.07	$	36.20
Earnings per weighted-average common share outstanding:
Continuing operations attributable to common shareholders – basic	$	3.97	$	3.94	$	3.59	$	3.69	$	3.54
Net income attributable to common shareholders – basic	$	3.97	$	3.94	$	3.59	$	3.69	$	3.48
Continuing operations attributable to common shareholders – diluted	$	3.95	$	3.92	$	3.58	$	3.66	$	3.50
Net income attributable to common shareholders – diluted	$	3.95	$	3.92	$	3.58	$	3.66	$	3.45
Dividends declared per share	$	2.56	$	2.44	$	2.33	$	2.23	$	2.67
Weighted-average common shares outstanding – basic	111,408,729		111,025,944		110,626,101		109,984,160		109,510,296
Weighted-average common shares outstanding – diluted	112,046,043		111,552,130		111,178,141		110,805,943		110,527,311
BALANCE SHEET DATA
Total assets	$	16,004,253	$	15,028,258	$	14,288,890	$	13,486,826	$	13,357,123
Liabilities and equity:
Current liabilities	$	1,292,946	$	1,442,317	$	1,559,143	$	1,618,644	$	1,083,542
Long-term debt less current maturities	4,021,785		3,462,391		3,006,573		2,774,605		3,176,596
Deferred credits and other	5,753,610		5,404,093		5,204,072		4,753,117		4,994,696
Total liabilities	11,068,341		10,308,801		9,769,788		9,146,366		9,254,834
Total equity	4,935,912		4,719,457		4,519,102		4,340,460		4,102,289
Total liabilities and equity	$	16,004,253	$	15,028,258	$	14,288,890	$	13,486,826	$	13,357,123

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SELECTED FINANCIAL DATA

ARIZONA PUBLIC SERVICE COMPANY – CONSOLIDATED

	2016		2015		2014		2013		2012
	(dollars in thousands)
OPERATING RESULTS
Electric operating revenues	$	3,489,754	$	3,492,357	$	3,488,946	$	3,451,251	$	3,293,489
Fuel and purchased power costs	1,082,625		1,101,298		1,179,829		1,095,709		994,790
Other operating expenses	1,789,149		1,779,075		1,716,325		1,733,677		1,693,170
Operating income	617,980		611,984		592,792		621,865		605,529
Other income	46,744		33,332		36,358		20,797		16,358
Interest expense — net of allowance for borrowed funds	183,090		176,109		181,830		183,801		194,777
Net income	481,634		469,207		447,320		458,861		427,110
Less: Net income attributable to noncontrolling interests	19,493		18,933		26,101		33,892		31,613
Net income attributable to common shareholder	$	462,141	$	450,274	$	421,219	$	424,969	$	395,497
BALANCE SHEET DATA
Total assets	$	15,931,175	$	14,982,182	$	14,190,362	$	13,359,517	$	13,220,050
Liabilities and equity:
Total equity	$	5,037,970	$	4,814,794	$	4,629,852	$	4,454,874	$	4,222,483
Long-term debt less current maturities	4,021,785		3,337,391		2,881,573		2,649,604		3,051,596
Total capitalization	9,059,755		8,152,185		7,511,425		7,104,478		7,274,079
Current liabilities	1,094,037		1,424,708		1,532,464		1,580,847		1,043,087
Deferred credits and other	5,777,383		5,405,289		5,146,473		4,674,192		4,902,884
Total liabilities and equity	$	15,931,175	$	14,982,182	$	14,190,362	$	13,359,517	$	13,220,050

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ITEM 7.  MANAGEMENT’S DISCUSSION AND ANALYSIS

OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

INTRODUCTION

The following discussion should be read in conjunction with Pinnacle West’s Consolidated Financial Statements and APS’s Consolidated Financial Statements and the related Notes that appear in Item 8 of this report.  For information on factors that may cause our actual future results to differ from those we currently seek or anticipate, see “Forward-Looking Statements” at the front of this report and “Risk Factors” in Item 1A.

OVERVIEW

Pinnacle West owns all of the outstanding common stock of APS.  APS is a vertically-integrated electric utility that provides either retail or wholesale electric service to most of the state of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona.  APS currently accounts for essentially all of our revenues and earnings.

Areas of Business Focus

Operational Performance, Reliability and Recent Developments.

Nuclear. APS operates and is a joint owner of Palo Verde. Palo Verde experienced strong performance during 2016, with the completion of two refueling outages. The fall refueling outage was completed in 28 days with the lowest collective radiation exposure dose for any pressurized water reactor outage.

Coal and Related Environmental Matters and Transactions.  APS is a joint owner of three coal-fired power plants and acts as operating agent for two of the plants.  APS is focused on the impacts on its coal fleet that may result from increased regulation and potential legislation concerning GHG emissions.  On June 2, 2014, EPA proposed a rule to limit carbon dioxide emissions from existing power plants (the "Clean Power Plan"), and EPA finalized its proposal on August 3, 2015. 

EPA’s nationwide CO₂ emissions reduction goal is 32% below 2005 emission levels.  As finalized for the state of Arizona and the Navajo Nation, compliance with the Clean Power Plan could involve a shift in generation from coal to natural gas and renewable generation.  Until implementation plans for these jurisdictions are finalized, we are unable to determine the actual impacts to APS.  (See Note 10 for information regarding challenges to the legality of the Clean Power Plan and a court-ordered stay of the Clean Power Plan pending judicial review of the rule, which temporarily delays compliance obligations.) APS continually analyzes its long-range capital management plans to assess the potential effects of these changes, understanding that any resulting regulation and legislation could impact the economic viability of certain plants, as well as the willingness or ability of power plant participants to continue participation in such plants.

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Cholla

On September 11, 2014, APS announced that it would close its 260 MW Unit 2 at Cholla and cease burning coal at Units 1 and 3 by the mid-2020s if EPA approves a compromise proposal offered by APS to meet required air emissions standards and rules. On April 14, 2015, the ACC approved APS's plan to retire Unit 2, without expressing any view on the future recoverability of APS's remaining investment in the Unit. (See Note 3 for details related to the resulting regulatory asset and Note 10 for details of the proposal.) APS believes that the environmental benefits of this proposal are greater in the long-term than the benefits that would have resulted from adding emissions control equipment. APS closed Unit 2 on October 1, 2015. On January 13, 2017, EPA approved a final rule incorporating APS's compromise proposal. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

Four Corners

Asset Purchase Agreement and Coal Supply Matters.  On December 30, 2013, APS purchased SCE’s 48% interest in each of Units 4 and 5 of Four Corners. The final purchase price for the interest was approximately $182 million. In connection with APS’s prior retail rate case with the ACC, the ACC reserved the right to review the prudence of the Four Corners transaction for cost recovery purposes upon the closing of the transaction. On December 23, 2014, the ACC approved rate adjustments related to APS’s acquisition of SCE’s interest in Four Corners resulting in a revenue increase of $57.1 million on an annual basis. On February 23, 2015, the ACC decision approving the rate adjustments was appealed. APS has intervened and is actively participating in the proceeding. The Arizona Court of Appeals suspended the appeal pending the Arizona Supreme Court's decision in the SIB matter discussed below. On August 8, 2016, the Arizona Supreme Court issued its opinion in the SIB matter, and the Arizona Court of Appeals has now ordered supplemental briefing on how that SIB decision should affect the challenge to the Four Corners rate adjustment. We cannot predict when or how this matter will be resolved.

Concurrently with the closing of the SCE transaction described above, BHP Billiton, the parent company of BNCC, the coal supplier and operator of the mine that serves Four Corners, transferred its ownership of BNCC to NTEC, a company formed by the Navajo Nation to own the mine and develop other energy projects. BHP Billiton was retained by NTEC under contract as the mine manager and operator through 2016. Also occurring concurrently with the closing, the Four Corners’ co-owners executed the 2016 Coal Supply Agreement for the supply of coal to Four Corners from July 2016 through 2031. El Paso, a 7% owner in Units 4 and 5 of Four Corners, did not sign the 2016 Coal Supply Agreement. Under the 2016 Coal Supply Agreement, APS agreed to assume the 7% shortfall obligation. On February 17, 2015, APS and El Paso entered into an asset purchase agreement providing for the purchase by APS, or an affiliate of APS, of El Paso’s 7% interest in each of Units 4 and 5 of Four Corners. 4CA purchased the El Paso interest on July 6, 2016. The purchase price was immaterial in amount, and 4CA assumed El Paso's reclamation and decommissioning obligations associated with the 7% interest.

NTEC has the option to purchase the 7% interest within a certain timeframe pursuant to an option granted to NTEC. On December 29, 2015, NTEC provided notice of its intent to exercise the option. The 2016 Coal Supply Agreement contains alternate pricing terms for the 7% shortfall obligations in the event NTEC does not purchase the interest.

Lease Extension.  APS, on behalf of the Four Corners participants, negotiated amendments to an existing facility lease with the Navajo Nation, which extends the Four Corners leasehold interest from 2016 to

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2041.  The Navajo Nation approved these amendments in March 2011.  The effectiveness of the amendments also required the approval of the DOI, as did a related federal rights-of-way grant.  A federal environmental review was undertaken as part of the DOI review process, and culminated in the issuance by DOI of a record of decision on July 17, 2015 justifying the agency action extending the life of the plant and the adjacent mine.  

On April 20, 2016, several environmental groups filed a lawsuit against OSM and other federal agencies in the District of Arizona in connection with their issuance of the approvals that extended the life of Four Corners and the adjacent mine.  The lawsuit alleges that these federal agencies violated both the ESA and NEPA in providing the federal approvals necessary to extend operations at the Four Corners Power Plant and the adjacent Navajo Mine past July 6, 2016.  APS filed a motion to intervene in the proceedings, which was granted on August 3, 2016. Briefing on the merits of this litigation is expected to extend through May 2017. On September 15, 2016, NTEC filed a motion to intervene for the purpose of dismissing the lawsuit based on NTEC's tribal sovereign immunity. Because the court has placed a stay on all litigation deadlines pending its decision regarding NTEC's motion to dismiss, the schedule for briefing and the anticipated timeline for completion of this litigation will likely be extended. We cannot predict the outcome of this matter or its potential effect on Four Corners.

Navajo Plant

On February 13, 2017, the co-owners of the Navajo Plant voted not to pursue continued operation of the plant beyond December 2019, the expiration of the current lease term, and to pursue a new lease or lease extension with the Navajo Nation that would allow decommissioning activities to begin after December 2019 instead of later this year. Various stakeholders including regulators, tribal representatives and others interested in the continued operation of the plant intend to meet to determine if an alternate solution can be reached that would permit continued operation of the plant beyond 2019. We cannot predict whether any alternate solutions will be found that would be acceptable to all of the stakeholders and feasible to implement. APS is currently recovering depreciation and a return on the net book value of its interest in the Navajo Plant. APS will seek continued recovery in rates for the book value of its remaining investment in the plant ($108 million as of December 31, 2016, see Note 9 for additional details) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and which may be material. We cannot predict whether APS would obtain such recovery.

On February 14, 2017, the ACC opened a docket titled "ACC Investigation Concerning the Future of the Navajo Generating Station" with the stated goal of engaging stakeholders and negotiating a sustainable pathway for the Navajo Plant to continue operating in some form after December 2019. APS cannot predict the outcome of this proceeding.

Natural Gas.  APS has six natural gas power plants located throughout Arizona, including Ocotillo. Ocotillo is a 330 MW 4-unit gas plant located in the metropolitan Phoenix area.  In early 2014, APS announced a project to modernize the plant, which involves retiring two older 110 MW steam units, adding five 102 MW combustion turbines and maintaining two existing 55 MW combustion turbines.  In total, this increases the capacity of the site by 290 MW, to 620 MW, with completion targeted by summer 2019.  (See Note 3 for proposed rate recovery in our current retail rate case filing.) On September 9, 2016, Maricopa County issued a final permit decision that authorizes construction of the Ocotillo modernization project.

Transmission and Delivery.  APS is working closely with regulators to identify and plan for transmission needs that continue to support system reliability, access to markets and renewable energy development.  The capital expenditures table presented in the "Liquidity and Capital Resources" section below includes new APS transmission projects through 2019, along with other transmission costs for upgrades and replacements.  APS is also working to establish and expand advanced grid technologies throughout its service

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territory to provide long-term benefits both to APS and its customers.  APS is strategically deploying a variety of technologies that are intended to allow customers to better manage their energy usage, minimize system outage durations and frequency, enable customer choice for behind-the-meter technologies, and facilitate greater cost savings to APS through improved reliability and the automation of certain distribution functions.

Energy Imbalance Market. In 2015, APS and the CAISO, the operator for the majority of California's transmission grid, signed an agreement for APS to begin participation in EIM. APS's participation in the EIM began on October 1, 2016.  The EIM allows for rebalancing supply and demand in 15-minute blocks with dispatching every five minutes before the energy is needed, instead of the traditional one hour blocks.  APS expects that its participation in EIM will lower its fuel costs, improve visibility and situational awareness for system operations in the Western Interconnection power grid, and improve integration of APS’s renewable resources.

Renewable Energy.  The ACC approved the RES in 2006.  The renewable energy requirement is 7% of retail electric sales in 2017 and increases annually until it reaches 15% in 2025.  In the 2009 Settlement Agreement, APS agreed to exceed the RES standards, committing to use APS’s best efforts to obtain 1,700 GWh of new renewable resources to be in service by year-end 2015, in addition to its RES renewable resource commitments.  APS met its settlement commitment and RES target for 2016. A component of the RES targets development of distributed energy systems.

In December 2014, the ACC voted that it had no objection to APS implementing an APS-owned rooftop solar research and development program aimed at learning how to efficiently enable the integration of rooftop solar and battery storage with the grid.  The first stage of the program, called the "Solar Partner Program," placed 8 MW of residential rooftop solar on strategically selected distribution feeders in an effort to maximize potential system benefits, as well as made systems available to limited-income customers who could not easily install solar through transactions with third parties. The second stage of the program, which included an additional 2 MW of rooftop solar and energy storage, placed two energy storage systems sized at 2 MW on two different high solar penetration feeders to test various grid-related operation improvements and system interoperability, and was in operation by the end of 2016.  The ACC expressly reserved that any determination of prudency of the residential rooftop solar program for rate making purposes would not be made until the project was fully in service, and APS has requested cost recovery for the project in its currently pending rate case. On September 30, 2016, APS presented its preliminary findings from the residential rooftop solar program in a filing with the ACC.

On July 1, 2015, APS filed its 2016 RES Implementation Plan and proposed a RES budget of approximately $148 million. On January 12, 2016, the ACC approved APS’s plan and requested budget.

On July 1, 2016, APS filed its 2017 RES Implementation Plan and proposed a budget of approximately $150 million. APS’s budget request included additional funding to process the high volume of residential rooftop solar interconnection requests and also requested a permanent waiver of the residential distributed energy requirement for 2017 contained in the RES rules. The ACC has not yet ruled on the Company’s 2017 RES Implementation Plan.

In September of 2016, the ACC initiated a proceeding which will examine the possible modernization and expansion of the RES.  The ACC noted that many of the provisions of the original rule may no longer be appropriate, and the underlying economic assumptions associated with the rule have changed dramatically.  The proceeding will review such issues as the rapidly declining cost of solar generation, an increased interest in community solar projects, energy storage options, and the decline in fossil fuel generation due to stringent EPA regulations.  The proceeding will also examine the feasibility of increasing the standard to 30% of retail sales by 2030, in contrast to the current standard of 15% of retail sales by 2025.  APS cannot predict the outcome of this proceeding.

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Demand Side Management.  In December 2009, Arizona regulators placed an increased focus on energy efficiency and other demand side management programs to encourage customers to conserve energy, while incentivizing utilities to aid in these efforts that ultimately reduce the demand for energy.  The ACC initiated an Energy Efficiency rulemaking, with a proposed Energy Efficiency Standard of 22% cumulative annual energy savings by 2020.  The 22% figure represents the cumulative reduction in future energy usage through 2020 attributable to energy efficiency initiatives.  This standard became effective on January 1, 2011.

In March 2014, the ACC approved a Resource Savings Initiative that allows APS to count towards compliance with the ACC Electric Energy Efficiency Standards, savings from improvements to APS’s transmission and delivery system, generation and facilities that have been approved through a DSM Plan.

On March 20, 2015, APS filed an application with the ACC requesting a budget of $68.9 million for 2015 and minor modifications to its DSM portfolio going forward, including for the first time three resource savings projects which reflect energy savings on APS's system. The ACC approved APS’s 2015 DSM budget on November 25, 2015. In its decision, the ACC also approved that verified energy savings from APS’s resource savings projects could be counted toward compliance with the Electric Energy Efficiency Standard, however, the ACC ruled that APS was not allowed to count savings from systems savings projects toward determination of its achievement tier level for its performance incentive, nor may APS include savings from conservation voltage reduction in the calculation of its LFCR mechanism.

On June 1, 2015, APS filed its 2016 DSM Plan requesting a budget of $68.9 million and minor modifications to its DSM portfolio to increase energy savings and cost effectiveness of the programs. On April 1, 2016, APS filed an amended 2016 DSM Plan that sought minor modifications to its existing DSM Plan and requested to continue the current DSMAC and current budget of $68.9 million. On July 12, 2016, the ACC approved APS’s amended DSM Plan and directed APS to spend up to an additional $4 million on a new residential demand response or load management program that facilitates energy storage technology. On December 5, 2016, APS filed for ACC approval of a $4 million Residential Demand Response, Energy Storage and Load Management Program.

On June 1, 2016, the Company filed its 2017 DSM Implementation Plan, in which APS proposes programs and measures that specifically focus on reducing peak demand, shifting load to off-peak periods and educating customers about strategies to manage their energy and demand.  The requested budget in the 2017 DSM Implementation Plan is $62.6 million.  On January 27, 2017, APS filed an updated and modified 2017 DSM Implementation Plan that incorporated the proposed Residential Demand Response, Energy Storage and Load Management Program and the requested budget increased to $66.6 million. The ACC has not yet ruled on the Company’s 2017 DSM Plan.    

Electric Energy Efficiency. On June 27, 2013, the ACC voted to open a new docket investigating whether the Electric Energy Efficiency Standards should be modified.  The ACC held a series of three workshops in March and April 2014 to investigate methodologies used to determine cost effective energy efficiency programs, cost recovery mechanisms, incentives, and potential changes to the Electric Energy Efficiency and Resource Planning Rules.

On November 4, 2014, the ACC staff issued a request for informal comment on a draft of possible amendments to Arizona’s Electric Utility Energy Efficiency Standards. The draft proposed substantial changes to the rules and energy efficiency standards. The ACC accepted written comments and took public comment regarding the possible amendments on December 19, 2014. On July 12, 2016, the ACC ordered that ACC staff convene a workshop within 120 days to discuss a number of issues related to the Electric Energy Efficiency Standards, including the process of determining the cost effectiveness of DSM programs and the treatment of

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peak demand and capacity reductions, among others. ACC staff convened the workshop on November 29, 2016 and sought public comment on potential revisions to the Electric Energy Efficiency Standards. APS cannot predict the outcome of this proceeding.

Rate Matters.  APS needs timely recovery through rates of its capital and operating expenditures to maintain its financial health.  APS’s retail rates are regulated by the ACC and its wholesale electric rates (primarily for transmission) are regulated by FERC.  See Note 3 for information on APS’s FERC rates.

On June 1, 2016, APS filed an application with the ACC for an annual increase in retail base rates of $165.9 million. This amount excludes amounts that are currently collected on customer bills through adjustor mechanisms. The application requests that some of the balances in these adjustor accounts (aggregating to approximately $267.6 million as of December 31, 2015) be transferred into base rates through the ratemaking process. This transfer would not have an incremental effect on average customer bills. The average annual customer bill impact of APS’s request is an increase of 5.74% (the average annual bill impact for a typical APS residential customer is 7.96%). See Note 3 for details regarding the principal provisions of APS's application.

APS requested that the increase become effective July 1, 2017.  On July 22, 2016, the ALJ set a procedural schedule for the rate proceeding, which supported completing the case within 12 months. The ACC staff and intervenors began filing their direct testimony in late December 2016 and additional filings of testimony are ongoing. On January 12, 2017, APS began settlement discussions with all parties.  On January 13, 2017, the ALJ hearing the case before the ACC issued a procedural order delaying hearings on the case from the originally scheduled March 22, 2017 to April 24, 2017, to allow parties to participate in settlement discussions and prepare testimony on the distributed generation ("DG") rate design issues addressed in the value and cost of DG decision described below.  According to the procedural order, settlement discussions are to be completed and, if applicable, any related settlement must be filed by March 17, 2017.  The procedural order also extended the rate case completion date as calculated by Commission rule for an additional 33 days. APS cannot predict the outcome of this case. 

APS has several recovery mechanisms in place that provide more timely recovery to APS of its fuel and transmission costs, and costs associated with the promotion and implementation of its demand side management and renewable energy efforts and customer programs.  These mechanisms are described more fully in Note 3.

As part of APS’s acquisition of SCE’s interest in Four Corners Units 4 and 5, APS and SCE agreed, via a "Transmission Termination Agreement" that, upon closing of the acquisition, the companies would terminate an existing transmission agreement ("Transmission Agreement") between the parties that provides transmission capacity on a system (the "Arizona Transmission System") for SCE to transmit its portion of the output from Four Corners to California.  APS previously submitted a request to FERC related to this termination, which resulted in a FERC order denying rate recovery of $40 million that APS agreed to pay SCE associated with the termination.  On December 22, 2015, APS and SCE agreed to terminate the Transmission Termination Agreement and allow for the Transmission Agreement to expire according to its terms, which includes settling obligations in accordance with the terms of the Transmission Agreement.  APS established a regulatory asset of $12 million in 2015 in connection with the payment required under the terms of the Transmission Agreement. On July 1, 2016, FERC issued an order denying APS’s request to recover the regulatory asset through its FERC-jurisdictional rates.  APS and SCE completed the termination of the Transmission Agreement on July 6, 2016. APS made the required payment to SCE and wrote-off the $12 million regulatory asset and charged operating revenues to reflect the effects of this order in the second quarter of 2016.  On July 29, 2016, APS filed for a rehearing with FERC. In its order denying recovery, FERC also referred to its enforcement division a question of whether the agreement between APS and SCE relating to the settlement of obligations under the

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Transmission Agreement was a jurisdictional contract that should have been filed with FERC. APS cannot predict the outcome of either matter.

Net Metering.      In 2015, the ACC voted to conduct a generic evidentiary hearing on the value and cost of distributed generation to gather information that will inform the ACC on net metering issues and cost of service studies in upcoming utility rate cases.  A hearing was held in April 2016. On October 7, 2016, an ALJ issued a recommendation in the docket concerning the value and cost of DG solar installations. On December 20, 2016, the ACC completed its open meeting to consider the recommended decision by the ALJ. After making several amendments, the ACC approved the recommended decision by a 4-1 vote. As a result of the ACC’s action, effective following APS’s pending rate case, the current net metering tariff that governs payments for energy exported to the grid from rooftop solar systems will be replaced by a more formula-driven approach that will utilize inputs from historical wholesale solar power costs and eventually an avoided cost methodology.

As amended, the decision provides that payments by utilities for energy exported to the grid from DG solar facilities will be determined using a resource comparison proxy methodology, a method that is based on the price that APS pays for utility-scale solar projects on a five year rolling average, while a forecasted avoided cost methodology is being developed.  The price established by this resource comparison proxy method will be updated annually (between rate cases) but will not be decreased by more than 10% per year. Once the avoided cost methodology is developed, the ACC will determine in APS's subsequent rate cases which method (or a combination of methods) is appropriate to determine the actual price to be paid by that utility for exported distributed energy.

In addition, the ACC made the following determinations:

• Customers who have interconnected a DG system or submitted an application for interconnection for DG systems prior to the date new rates are effective based on APS's pending rate case will be grandfathered for a period of 20 years from the date of interconnection;

• Customers with DG solar systems are to be considered a separate class of customers for ratemaking purposes; and

• Once an export price is set for APS, no netting or banking of retail credits will be available for new DG customers, and the then-applicable export price will be guaranteed for new customers for a period of 10 years.

This decision of the ACC addresses policy determinations only. The decision states that its principles will be applied in future rate cases, and the policy determinations themselves may be subject to future change as are all ACC policies. The determination of the initial export energy price to be paid by APS will be made in APS’s currently pending rate case, which is scheduled for hearing by the ACC in April 2017.  APS cannot predict the outcome of this determination.

The ACC’s decision did not make any policy determinations as to any specific costs to be charged to DG solar system customers for their use of the grid. The determination of any such costs will be made in APS's future rate cases.

On January 23, 2017, The Alliance for Solar Choice ("TASC") sought rehearing of the ACC's decision regarding the value and cost of DG. TASC asserts that the ACC improperly ignored the Administrative Procedure Act, failed to give adequate notice regarding the scope of the proceedings, and relied on information that was not submitted as evidence, among other alleged defects. TASC's request for rehearing is required for

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TASC to challenge this decision in court. To date, the ACC has taken no action on the rehearing request. The ACC's decision is expected to remain in effect during any legal challenge.

Appellate Review of Third-Party Regulatory Decision ("System Improvement Benefits" or "SIB"). In a recent appellate challenge to an ACC rate decision involving a water company, the Arizona Court of Appeals considered the question of how the ACC should determine the “fair value” of a utility’s property, as specified in the Arizona Constitution, in connection with authorizing the recovery of costs through rate adjustors outside of a rate case.  The Court of Appeals reversed the ACC’s method of finding fair value in that case, and raised questions concerning the relationship between the need for fair value findings and the recovery of capital and certain other utility costs through adjustors. The ACC sought review by the Arizona Supreme Court of this decision, and APS filed a brief supporting the ACC’s petition to the Arizona Supreme Court for review of the Court of Appeals’ decision.  On February 9, 2016, the Arizona Supreme Court granted review of the decision and on August 8, 2016, the Arizona Supreme Court vacated the Court of Appeals opinion and affirmed the ACC’s orders approving the water company’s SIB adjustor.

System Benefits Charge. The 2012 Settlement Agreement  provides that once APS achieved full funding of its decommissioning obligation under the sale leaseback agreements covering Unit 2 of Palo Verde, APS was required to implement a reduced System Benefits charge effective January 1, 2016.  Beginning on January 1, 2016, APS began implementing a reduced System Benefits charge.  The impact on APS retail revenues from the new System Benefits charge is an overall reduction of approximately $14.6 million per year with a corresponding reduction in depreciation and amortization expense.

Subpoena from Arizona Corporation Commissioner Robert Burns. On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, filed subpoenas in APS’s current retail rate proceeding to APS and Pinnacle West for the production of records and information relating to a range of expenditures from 2011 through 2016. The subpoenas requested information concerning marketing and advertising expenditures, charitable donations, lobbying expenses, contributions to 501(c)(3) and (c)(4) nonprofits and political contributions. The return date for the production of information was set as September 15, 2016. The subpoenas also sought testimony from Company personnel having knowledge of the material, including the Chief Executive Officer.

On September 9, 2016, APS filed with the ACC a motion to quash the subpoenas or, alternatively to stay APS's obligations to comply with the subpoenas and decline to decide APS's motion pending court proceedings. Contemporaneously with the filing of this motion, APS and Pinnacle West filed a complaint for special action and declaratory judgment in the Superior Court of Arizona for Maricopa County, seeking a declaratory judgment that Commissioner Burns’ subpoenas are contrary to law. On September 15, 2016, APS produced all non-confidential and responsive documents and offered to produce any remaining responsive documents that are confidential after an appropriate confidentiality agreement is signed.

On February 7, 2017, Commissioner Burns opened a new ACC docket and indicated that its purpose is to study and rectify problems with transparency and disclosure regarding financial contributions from regulated monopolies or other stakeholders who may appear before the ACC that may directly or indirectly benefit an ACC Commissioner, a candidate for ACC Commissioner, or key ACC staff.  As part of this docket, Commissioner Burns set March 24, 2017 as a deadline for APS to produce all information previously requested through the subpoenas.  Commissioner Burns has also scheduled a workshop in this matter for March 17, 2017.  APS and Pinnacle West cannot predict the outcome of this matter.

Financial Strength and Flexibility.  Pinnacle West and APS currently have ample borrowing capacity under their respective credit facilities, and may readily access these facilities ensuring adequate liquidity for

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each company.  Capital expenditures will be funded with internally generated cash and external financings, which may include issuances of long-term debt and Pinnacle West common stock.

Other Subsidiaries.

Bright Canyon Energy. On July 31, 2014, Pinnacle West announced its creation of a wholly-owned subsidiary, BCE.  BCE will focus on new growth opportunities that leverage the Company’s core expertise in the electric energy industry.  BCE’s first initiative is a 50/50 joint venture with BHE U.S. Transmission LLC, a subsidiary of Berkshire Hathaway Energy Company.  The joint venture, named TransCanyon, is pursuing independent transmission opportunities within the eleven states that comprise the Western Electricity Coordinating Council, excluding opportunities related to transmission service that would otherwise be provided under the tariffs of the retail service territories of the venture partners’ utility affiliates.  TransCanyon continues to pursue transmission development opportunities in the western United States consistent with its strategy.

On March 29, 2016, TransCanyon entered into a strategic alliance agreement with PG&E to jointly pursue competitive transmission opportunities solicited by the CAISO, the operator for the majority of California's transmission grid. TransCanyon and PG&E intend to jointly engage in the development of future transmission infrastructure and compete to develop, build, own and operate transmission projects approved by the CAISO.

El Dorado. The operations of El Dorado are not expected to have any material impact on our financial results, or to require any material amounts of capital, over the next three years.

4CA. See "Four Corners - Asset Purchase Agreement and Coal Supply Matters" above for information regarding 4CA.

Key Financial Drivers

In addition to the continuing impact of the matters described above, many factors influence our financial results and our future financial outlook, including those listed below.  We closely monitor these factors to plan for the Company’s current needs, and to adjust our expectations, financial budgets and forecasts appropriately.

Electric Operating Revenues.  For the years 2014 through 2016, retail electric revenues comprised approximately 94% of our total electric operating revenues.  Our electric operating revenues are affected by customer growth or decline, variations in weather from period to period, customer mix, average usage per customer and the impacts of energy efficiency programs, distributed energy additions, electricity rates and tariffs, the recovery of PSA deferrals and the operation of other recovery mechanisms.  These revenue transactions are affected by the availability of excess generation or other energy resources and wholesale market conditions, including competition, demand and prices.

Actual and Projected Customer and Sales Growth.  Retail customers in APS’s service territory increased 1.4% for the year ended December 31, 2016 compared with the prior year.  For the three years 2014 through 2016, APS’s customer growth averaged 1.3% per year. We currently project annual customer growth to be 1.5-2.5% for 2017 and to average in the range of 2.0-3.0% for 2017 through 2019 based on our assessment of modestly improving economic conditions in Arizona.

Retail electricity sales in kWh, adjusted to exclude the effects of weather variations, were flat for the year ended December 31, 2016 compared with the prior year. Improving economic conditions and customer

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growth and an additional day of sales due to the leap year were equally offset by energy savings driven by customer conservation, energy efficiency and distributed renewable generation initiatives.  For the three years 2014 through 2016, APS experienced annual increases in retail electricity sales averaging 0.2%, adjusted to exclude the effects of weather variations.  We currently project that annual retail electricity sales in kWh will increase in the range of 0-1.0% for 2017 and increase on average in the range of 0.5-1.5% during 2017 through 2019, including the effects of customer conservation and energy efficiency and distributed renewable generation initiatives, but excluding the effects of weather variations.  A slower recovery of the Arizona economy or acceleration of the expected effects of customer conservation, energy efficiency or distributed renewable generation initiatives could further impact these estimates.

Actual sales growth, excluding weather-related variations, may differ from our projections as a result of numerous factors, such as economic conditions, customer growth, usage patterns and energy conservation, impacts of energy efficiency programs and growth in distributed generation, and responses to retail price changes.  Based on past experience, a reasonable range of variation in our kWh sales projections attributable to such economic factors under normal business conditions can result in increases or decreases in annual net income of up to $10 million.

Weather.  In forecasting the retail sales growth numbers provided above, we assume normal weather patterns based on historical data.  Historically, extreme weather variations have resulted in annual variations in net income in excess of $20 million.  However, our experience indicates that the more typical variations from normal weather can result in increases or decreases in annual net income of up to $10 million.

Fuel and Purchased Power Costs.  Fuel and purchased power costs included on our Consolidated Statements of Income are impacted by our electricity sales volumes, existing contracts for purchased power and generation fuel, our power plant performance, transmission availability or constraints, prevailing market prices, new generating plants being placed in service in our market areas, changes in our generation resource allocation, our hedging program for managing such costs and PSA deferrals and the related amortization.

Operations and Maintenance Expenses.  Operations and maintenance expenses are impacted by customer and sales growth, power plant operations, maintenance of utility plant (including generation, transmission, and distribution facilities), inflation, outages, renewable energy and demand side management related expenses (which are offset by the same amount of operating revenues) and other factors. 

Depreciation and Amortization Expenses.  Depreciation and amortization expenses are impacted by net additions to utility plant and other property (such as new generation, transmission, and distribution facilities), and changes in depreciation and amortization rates.  See "Capital Expenditures" below for information regarding the planned additions to our facilities.  See Note 3 regarding deferral of certain costs pursuant to an ACC order.

Property Taxes.  Taxes other than income taxes consist primarily of property taxes, which are affected by the value of property in-service and under construction, assessment ratios, and tax rates.  The average property tax rate in Arizona for APS, which owns essentially all of our property, was 11.2% of the assessed value for 2016, 11.0% for 2015 and 10.7% for 2014.  We expect property taxes to increase as we add new generating units and continue with improvements and expansions to our existing generating units, transmission and distribution facilities.  (See Note 3 for property tax deferrals contained in the 2012 Settlement Agreement.)

Income Taxes.  Income taxes are affected by the amount of pretax book income, income tax rates, certain deductions and non-taxable items, such as AFUDC.  In addition, income taxes may also be affected by the settlement of issues with taxing authorities. The prospects for broad-based federal tax reform have increased due to the results of the 2016 elections. Any such reform may impact the Company's effective tax

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rate, cash taxes paid and other financial results such as earnings per share, gross revenues and cash flows. Given the number of unknown variables and the lack of detailed legislative reform language, we are unable to predict any impacts to the Company at this time.

Interest Expense.  Interest expense is affected by the amount of debt outstanding and the interest rates on that debt (see Note 6).  The primary factors affecting borrowing levels are expected to be our capital expenditures, long-term debt maturities, equity issuances and internally generated cash flow.  An allowance for borrowed funds used during construction offsets a portion of interest expense while capital projects are under construction.  We stop accruing AFUDC on a project when it is placed in commercial operation.

RESULTS OF OPERATIONS

Pinnacle West’s only reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electric service to Native Load customers) and related activities and includes electricity generation, transmission and distribution.

Operating Results – 2016 compared with 2015.

Our consolidated net income attributable to common shareholders for the year ended December 31, 2016 was $442 million, compared with $437 million for the prior year.  The results reflect an increase of approximately $4 million for the regulated electricity segment primarily due to higher transmission revenues, higher retail revenues due to customer growth and changes in customer usage patterns and related pricing, partially offset by higher operations and maintenance expense primarily related to transmission, distribution and customer service costs.

The following table presents net income attributable to common shareholders by business segment compared with the prior year:

	Year Ended December 31,
	2016			2015			Net change
	(dollars in millions)
Regulated Electricity Segment:
Operating revenues less fuel and purchased power expenses	$	2,407		$	2,391		$	16
Operations and maintenance	(906		)	(868		)	(38		)
Depreciation and amortization	(485		)	(494		)	9
Taxes other than income taxes	(166		)	(172		)	6
All other income and expenses, net	35			19			16
Interest charges, net of allowance for borrowed funds used during construction	(186		)	(179		)	(7		)
Income taxes	(237		)	(239		)	2
Less income related to noncontrolling interests (Note 18)	(19		)	(19		)	—
Regulated electricity segment income	443			439			4
All other	(1		)	(2		)	1
Net Income Attributable to Common Shareholders	$	442		$	437		$	5

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Operating revenues less fuel and purchased power expenses.  Regulated electricity segment operating revenues less fuel and purchased power expenses were $16 million higher for the year ended December 31, 2016 compared with the prior year.  The following table summarizes the major components of this change:

	Increase (Decrease)
	Operating revenues			Fuel and purchased power expenses			Net change
	(dollars in millions)
Lost fixed cost recovery	$	17		$	—		$	17
Effects of weather	6			2			4
Transmission revenues (Note 3):
Higher transmission revenues	27			—			27
FERC disallowance	(12		)	—			(12		)
Higher retail revenues due to changes in customer usage patterns and related pricing	10			—			10
Changes in net fuel and purchased power costs, including off-system sales margins and related deferrals	(15		)	(17		)	2
Palo Verde system benefits charge (offset in depreciation and amortization, see Note 3)	(14		)	—			(14		)
Lower demand side management regulatory surcharges and renewable energy regulatory surcharges and purchased power partially offset in operations and maintenance costs	(16		)	(1		)	(15		)
Miscellaneous items, net	(6		)	(3		)	(3		)
Total	$	(3	)	$	(19	)	$	16

Operations and maintenance.  Operations and maintenance expenses increased $38 million for the year ended December 31, 2016 compared with the prior year primarily because of:

• An increase of $16 million for transmission, distribution, and customer service costs primarily related to increased maintenance costs and implementation of new systems;

• An increase of $9 million primarily for costs to support the company's positions on a solar net metering ballot initiative in Arizona and increased political participation costs;

• An increase of $8 million in fossil generation costs primarily related to $33 million in higher planned outage costs, partially offset by $25 million of lower other fossil operating costs;

• An increase of $7 million for costs related to legal, regulatory, information systems and other corporate support;

• An increase of $5 million for employee benefit costs primarily related to increased pension, medical claims and other benefit costs;

• An increase of $5 million related to higher nuclear generation costs;

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• An offsetting decrease of $13 million related to costs for demand-side management, renewable energy and similar regulatory programs, which is partially offset in operating revenues and purchased power; and

• An increase of $1 million related to miscellaneous other factors.

Additionally, stock compensation costs were flat compared to the prior year as a $12 million increase in costs was offset by a one-time $12 million reduction for the adoption of new stock compensation guidance (See Notes 2 and 15);

Depreciation and amortization.  Depreciation and amortization expenses were $9 million lower for the year ended December 31, 2016 compared with the prior year primarily related to:

• A decrease of $20 million related to the regulatory treatment of the Palo Verde sale leaseback lease extension;

• A decrease of $14 million due to lower Palo Verde decommissioning expense recovered through the system benefits charge (offset in operating revenues); and

• An increase of $25 million due to increased plant in service.

Taxes other than income taxes.  Taxes other than income taxes were $6 million lower for the year ended December 31, 2016 compared with the prior year primarily due to lower assessed values resulting from a lower Arizona statutory rate, partially offset by higher property tax rates.

All other income and expenses, net.  All other income and expenses, net, were $16 million higher for the year ended December 31, 2016 compared with the prior year primarily due to higher allowance for equity funds used during construction and the gain on sale of a transmission line.

Interest charges, net of allowance for borrowed funds used during construction.  Interest charges, net of allowance for borrowed funds used during construction, increased $7 million for the year ended December 31, 2016 compared with the prior year, primarily because of higher debt balances in the current year.

Operating Results – 2015 compared with 2014.

Our consolidated net income attributable to common shareholders for the year ended December 31, 2015 was $437 million, compared with $398 million for the prior year.  The results reflect an increase of approximately $34 million for the regulated electricity segment primarily due to the Four Corners-related rate change, lower operations and maintenance expenses, and higher retail sales due to customer growth and changes in customer usage patterns and related pricing, partially offset by higher depreciation and amortization. The all other segment's income was higher by $5 million primarily related to El Dorado's investment losses in 2014.

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The following table presents net income attributable to common shareholders by business segment compared with the prior year:

	Year Ended December 31,
	2015			2014			Net change
	(dollars in millions)
Regulated Electricity Segment:
Operating revenues less fuel and purchased power expenses	$	2,391		$	2,309		$	82
Operations and maintenance	(868		)	(908		)	40
Depreciation and amortization	(494		)	(417		)	(77		)
Taxes other than income taxes	(172		)	(172		)	—
All other income and expenses, net	19			28			(9		)
Interest charges, net of allowance for borrowed funds used during construction	(179		)	(185		)	6
Income taxes	(239		)	(224		)	(15		)
Less income related to noncontrolling interests (Note 18)	(19		)	(26		)	7
Regulated electricity segment income	439			405			34
All other	(2		)	(7		)	5
Net Income Attributable to Common Shareholders	$	437		$	398		$	39

Operating revenues less fuel and purchased power expenses.  Regulated electricity segment operating revenues less fuel and purchased power expenses were $82 million higher for the year ended December 31, 2015 compared with the prior year.  The following table summarizes the major components of this change:

	Increase (Decrease)
	Operating revenues			Fuel and purchased power expenses			Net change
	(dollars in millions)
Four Corners-related rate change	$	56		$	—		$	56
Higher retail sales due to customer growth and changes in customer usage patterns and related pricing	25			6			19
Lost fixed cost recovery	12			—			12
Effects of weather	16			6			10
Changes in net fuel and purchased power costs, including off-system sales margins and related deferrals	(69		)	(68		)	(1		)
Changes in long-term wholesale contracted sales	(40		)	(25		)	(15		)
Miscellaneous items, net	3			2			1
Total	$	3		$	(79	)	$	82

Operations and maintenance.  Operations and maintenance expenses decreased $40 million for the year ended December 31, 2015 compared with the prior year primarily because of:

• A decrease of $21 million for employee benefit costs;

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• A decrease of $14 million in fossil generation costs primarily related to lower planned outage costs;

• A decrease of $13 million for costs related to corporate support;

• A decrease of $8 million related to costs for demand-side management, renewable energy and similar regulatory programs, which is partially offset in operating revenues and purchased power;

• An increase of $9 million related to higher nuclear generation costs;

• An increase of $6 million in customer service costs including costs related to a new customer information system; and

• An increase of $1 million related to other miscellaneous factors.

Depreciation and amortization.  Depreciation and amortization expenses were $77 million higher for the year ended December 31, 2015 compared with the prior year primarily related to:

• An increase of $34 million related to the absence of 2014 Four Corners cost deferrals and the related 2015 amortization;

• An increase of $16 million related to the Four Corners acquisition adjustment;

• An increase of $20 million due to increased plant in service;

• An increase of $10 million related to the regulatory treatment of the Palo Verde sale leaseback, which is offset in noncontrolling interests; and

• A decrease of $3 million due to other miscellaneous factors.

All other income and expenses, net.  All other income and expenses, net, were $9 million lower for the year ended December 31, 2015 compared with the prior year primarily due to the return on the Four Corners acquisition in 2014.

Interest charges, net of allowance for borrowed funds used during construction.  Interest charges, net of allowance for borrowed funds used during construction, decreased $6 million for the year ended December 31, 2015 compared with the prior year, primarily because of lower interest rates on our debt in the current year.

Income taxes.  Income taxes were $15 million higher for the year ended December 31, 2015 compared with the prior year primarily due to the effects of higher pretax income in the current year.

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LIQUIDITY AND CAPITAL RESOURCES

Overview

Pinnacle West’s primary cash needs are for dividends to our shareholders and principal and interest payments on our indebtedness.  The level of our common stock dividends and future dividend growth will be dependent on declaration by our Board of Directors and based on a number of factors, including our financial condition, payout ratio, free cash flow and other factors.

Our primary sources of cash are dividends from APS and external debt and equity issuances.  An ACC order requires APS to maintain a common equity ratio of at least 40%.  As defined in the related ACC order, the common equity ratio is defined as total shareholder equity divided by the sum of total shareholder equity and long-term debt, including current maturities of long-term debt.  At December 31, 2016, APS’s common equity ratio, as defined, was 54%.  Its total shareholder equity was approximately $4.9 billion, and total capitalization was approximately $9.1 billion.  Under this order, APS would be prohibited from paying dividends if such payment would reduce its total shareholder equity below approximately $3.6 billion, assuming APS’s total capitalization remains the same.  This restriction does not materially affect Pinnacle West’s ability to meet its ongoing cash needs or ability to pay dividends to shareholders.

APS’s capital requirements consist primarily of capital expenditures and maturities of long-term debt.  APS funds its capital requirements with cash from operations and, to the extent necessary, external debt financing and equity infusions from Pinnacle West.

Many of APS’s current capital expenditure projects qualify for bonus depreciation. On December 18, 2015, President Obama signed into law the Consolidated Appropriations Act, 2016 (H.R. 2029), which contained an extension of bonus depreciation through 2019.  Enactment of this legislation is expected to generate approximately $300-$350 million of cash tax benefits over the next three years, which is expected to be fully realized by APS and Pinnacle West during this time frame.  The cash generated by the extension of bonus depreciation is an acceleration of the tax benefits that APS would have otherwise received over 20 years and reduces rate base for ratemaking purposes.  At Pinnacle West Consolidated, the extension of bonus depreciation will, in turn, delay until 2019 full cash realization of approximately $98 million of currently unrealized Investment Tax Credits, which are recorded as a deferred tax asset on the Condensed Consolidated Balance Sheet as of December 31, 2016.

Summary of Cash Flows

The following tables present net cash provided by (used for) operating, investing and financing activities for the years ended December 31, 2016, 2015 and 2014 (dollars in millions):

Pinnacle West Consolidated

	2016			2015			2014
Net cash flow provided by operating activities	$	1,023		$	1,094		$	1,100
Net cash flow used for investing activities	(1,252		)	(1,066		)	(923		)
Net cash flow provided by (used for) financing activities	198			4			(179		)
Net increase (decrease) in cash and cash equivalents	$	(31	)	$	32		$	(2	)

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Arizona Public Service Company

	2016			2015			2014
Net cash flow provided by operating activities	$	1,010		$	1,100		$	1,124
Net cash flow used for investing activities	(1,219		)	(1,060		)	(922		)
Net cash flow used for financing activities	196			(22		)	(201		)
Net increase (decrease) in cash and cash equivalents	$	(13	)	$	18		$	1

Operating Cash Flows

2016 Compared with 2015. Pinnacle West’s consolidated net cash provided by operating activities was $1,023 million in 2016 compared to $1,094 million in 2015. The decrease of $71 million in net cash provided is primarily due to higher operations and maintenance costs.

2015 Compared with 2014. Pinnacle West’s consolidated net cash provided by operating activities was $1,094 million in 2015 compared to $1,100 million in 2014, a decrease of $6 million in net cash provided.  The decrease is primarily related to a $135 million income tax refund received in the first quarter of 2014, which is partially offset by a $48 million change in cash collateral posted, and other changes in working capital including increased cash receipts for the Four Corners-related rate change of $56 million.

Retirement plans and other postretirement benefits. Pinnacle West sponsors a qualified defined benefit pension plan and a non-qualified supplemental excess benefit retirement plan for the employees of Pinnacle West and our subsidiaries.  The requirements of the Employee Retirement Income Security Act of 1974 ("ERISA") require us to contribute a minimum amount to the qualified plan.  We contribute at least the minimum amount required under ERISA regulations, but no more than the maximum tax-deductible amount.  The minimum required funding takes into consideration the value of plan assets and our pension benefit obligations.  Under ERISA, the qualified pension plan was 116% funded as of January 1, 2016 and 115% as of January 1, 2017.  Under GAAP, the qualified pension plan was 88% funded as of January 1, 2016 and January 1, 2017. See Note 7 for additional details. The assets in the plan are comprised of fixed-income, equity, real estate, and short-term investments.  Future year contribution amounts are dependent on plan asset performance and plan actuarial assumptions.  We have made voluntary contributions to our pension plan of $100 million in 2016, $100 million in 2015 and $175 million in 2014. The minimum required contributions for the pension plan are zero for the next three years. We expect to make voluntary contributions up to a total of $300 million during the 2017-2019 period. With regard to our contributions to our other postretirement benefit plans, we made a contribution of approximately $1 million in each of 2016, 2015 and 2014. We expect to make contributions of less than $1 million in total for the next three years to our other postretirement benefit plans.

Investing Cash Flows

2016 Compared with 2015. Pinnacle West’s consolidated net cash used for investing activities was $1,252 million in 2016, compared to $1,066 million in 2015. The increase of $186 million in net cash used primarily related to increased capital expenditures.

2015 Compared with 2014. Pinnacle West’s consolidated net cash used for investing activities was $1,066 million in 2015, compared to $923 million in 2014, an increase of $143 million in net cash used primarily related to increased capital expenditures.

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Capital Expenditures.  The following table summarizes the estimated capital expenditures for the next three years:

Capital Expenditures

(dollars in millions)

	Estimated for the Year Ended December 31,
	2017		2018		2019
APS
Generation:
Nuclear Fuel	$	69	$	71	$	65
Renewables	4		1		—
Environmental	195		105		61
New Gas Generation	237		119		8
Other Generation	150		213		149
Distribution	402		406		480
Transmission	206		137		150
Other (a)	74		72		81
Total APS	$	1,337	$	1,124	$	994

 (a) Primarily information systems and facilities projects.

Generation capital expenditures are comprised of various improvements to APS’s existing fossil, renewable and nuclear plants.  Examples of the types of projects included in this category are additions, upgrades and capital replacements of various power plant equipment, such as turbines, boilers and environmental equipment.  We have not included estimated costs for Cholla's compliance with EPA’s regional haze rule since we have challenged the rule judicially and we have proposed a compromise strategy to EPA, which would allow us to avoid expenditures related to environmental control equipment. (See Note 10 for details regarding the status of the final rule for Cholla and a related executive memorandum.) We are monitoring the status of other environmental matters, which, depending on their final outcome, could require modification to our planned environmental expenditures.

On February 17, 2015, APS and El Paso entered into an asset purchase agreement providing for the purchase by APS, or an affiliate of APS, of El Paso’s 7% interest in each of Units 4 and 5 of Four Corners. On December 29, 2015, NTEC notified APS of its intent to exercise its option to purchase the 7% interest in July 2017. 4CA purchased the El Paso interest on July 6, 2016. The table above does not include capital expenditures related to 4CA's interest in Four Corners Units 4 and 5 of approximately $27 million in 2017, $15 million in 2018 and $6 million in 2019, which will be assumed by the ultimate owner of the 7% interest.

Distribution and transmission capital expenditures are comprised of infrastructure additions and upgrades, capital replacements, and new customer construction.  Examples of the types of projects included in the forecast include power lines, substations, and line extensions to new residential and commercial developments.

Capital expenditures will be funded with internally generated cash and external financings, which may include issuances of long-term debt and Pinnacle West common stock.

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Financing Cash Flows and Liquidity

2016 Compared with 2015. Pinnacle West’s consolidated net cash provided by financing activities was $198 million in 2016, compared to $4 million in 2015, an increase of $194 million in net cash provided.  The increase in net cash provided by financing activities is primarily due to a $325 million net increase in short-term borrowings and $45 million in lower long-term debt repayments partially offset by $149 million lower issuances of long-term debt through December 31, 2016 (see below).

2015 Compared with 2014. Pinnacle West’s consolidated net cash provided by financing activities was $4 million in 2015, compared to $179 million net cash used in 2014, an increase of $183 million in net cash provided.  The increase in net cash provided by financing activities is primarily due to $237 million lower repayments of long-term debt and $111 million higher issuances of long-term debt (see below), partially offset by a $142 million net change in short-term borrowings.

Significant Financing Activities.  On December 21, 2016, the Pinnacle West Board of Directors declared a dividend of $0.655 per share of common stock, payable on March 1, 2017 to shareholders of record on February 1, 2017. During 2016, Pinnacle West increased its indicated annual dividend from $2.50 per share to $2.62 per share. For the year ended December 31, 2016, Pinnacle West's total dividends paid per share of common stock were $2.53 per share, which resulted in dividend payments of $274 million.

On December 27, 2016, Pinnacle West infused cash to APS of $42 million. APS used these funds to repay commercial paper borrowings.     

On April 22, 2016, APS entered into a $100 million term loan facility that matures April 22, 2019. Interest rates are based on APS's senior unsecured debt credit ratings. APS used the proceeds to repay and refinance existing short-term indebtedness.

On May 6, 2016, APS issued $350 million of 3.75% unsecured senior notes that mature on May 15, 2046. The net proceeds from the sale were used to redeem and cancel pollution control bonds (see details below), and to repay commercial paper borrowings and replenish cash temporarily used to fund capital expenditures.

On June 1, 2016, APS redeemed at par and canceled all $64 million of the Navajo County, Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Cholla Project), 2009 Series D and E.

On June 1, 2016, APS redeemed at par and canceled all $13 million of the Coconino County, Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Navajo Project), 2009 Series A.

On August 1, 2016, APS repaid at maturity APS's $250 million aggregate principal amount of 6.25% senior notes due August 1, 2016.

On September 20, 2016, APS issued $250 million of 2.55% unsecured senior notes that mature on September 15, 2026. The net proceeds from the sale were used to repay commercial paper borrowings and replenish cash temporarily used in connection with the payment at maturity of our $250 million aggregate principal amount of 6.25% Notes due August 1, 2016.

On September 20, 2016, APS redeemed at par and canceled all $27 million of the Coconino County Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Navajo Project), 2009 Series B.

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On December 6, 2016, APS redeemed at par and canceled all $17 million of the Coconino County Arizona Pollution Control Corporation Revenue Bonds (Arizona Public Service Company Project), Series 1998.

Available Credit Facilities. Pinnacle West and APS maintain committed revolving credit facilities in order to enhance liquidity and provide credit support for their commercial paper programs.

During the first quarter of 2016, APS increased its commercial paper program from $250 million to $500 million.

On May 13, 2016, Pinnacle West replaced its $200 million revolving credit facility that would have matured in May 2019, with a new $200 million facility that matures in May 2021. Pinnacle West has the option to increase the amount of the facility up to a maximum of $300 million upon the satisfaction of certain conditions and with the consent of the lenders.  At December 31, 2016, Pinnacle West had no outstanding borrowings under its credit facility, no letters of credit outstanding and $1.7 million in commercial paper borrowings.

On May 13, 2016, APS replaced its $500 million revolving credit facility that would have matured in May 2019, with a new $500 million facility that matures in May 2021.

On August 31, 2016, PNW entered into a $75 million 364-day unsecured revolving credit facility that matures in August 2017. PNW will use the new facility to fund or otherwise support obligations related to 4CA, and borrowings under the facility will bear interest at LIBOR plus 0.80% per annum. At December 31, 2016, Pinnacle West had $40 million outstanding under the facility.

At December 31, 2016, APS had two revolving credit facilities totaling $1 billion, including a $500 million credit facility that matures in September 2020 and the $500 million facility that matures in May 2021.  APS may increase the amount of each facility up to a maximum of $700 million, for a total of $1.4 billion, upon the satisfaction of certain conditions and with the consent of the lenders.  Interest rates are based on APS’s senior unsecured debt credit ratings. These facilities are available to support APS’s $500 million commercial paper program, for bank borrowings or for issuances of letters of credit.  At December 31, 2016, APS had $135.5 million of commercial paper outstanding and no outstanding borrowings or letters of credit under its revolving credit facilities.

 See "Financial Assurances" in Note 10 for a discussion of APS’s separate outstanding letters of credit.

Other Financing Matters.  See Note 16 for information related to the change in our margin and collateral accounts.

Debt Provisions

Pinnacle West’s and APS’s debt covenants related to their respective bank financing arrangements include maximum debt to capitalization ratios.  Pinnacle West and APS comply with this covenant.  For both Pinnacle West and APS, this covenant requires that the ratio of consolidated debt to total consolidated capitalization not exceed 65%.  At December 31, 2016, the ratio was approximately 48% for Pinnacle West and 47% for APS.  Failure to comply with such covenant levels would result in an event of default which, generally speaking, would require the immediate repayment of the debt subject to the covenants and could "cross-default" other debt.  See further discussion of "cross-default" provisions below.

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Neither Pinnacle West’s nor APS’s financing agreements contain "rating triggers" that would result in an acceleration of the required interest and principal payments in the event of a rating downgrade.  However, our bank credit agreements and term loan facilities contain a pricing grid in which the interest rates we pay for borrowings thereunder are determined by our current credit ratings.

All of Pinnacle West’s loan agreements contain "cross-default" provisions that would result in defaults and the potential acceleration of payment under these loan agreements if Pinnacle West or APS were to default under certain other material agreements.  All of APS’s bank agreements contain "cross-default" provisions that would result in defaults and the potential acceleration of payment under these bank agreements if APS were to default under certain other material agreements.  Pinnacle West and APS do not have a material adverse change restriction for credit facility borrowings.

See Note 6 for further discussions of liquidity matters.

Credit Ratings

The ratings of securities of Pinnacle West and APS as of February 17, 2017 are shown below.  We are disclosing these credit ratings to enhance understanding of our cost of short-term and long-term capital and our ability to access the markets for liquidity and long-term debt.  The ratings reflect the respective views of the rating agencies, from which an explanation of the significance of their ratings may be obtained.  There is no assurance that these ratings will continue for any given period of time.  The ratings may be revised or withdrawn entirely by the rating agencies if, in their respective judgments, circumstances so warrant.  Any downward revision or withdrawal may adversely affect the market price of Pinnacle West’s or APS’s securities and/or result in an increase in the cost of, or limit access to, capital.  Such revisions may also result in substantial additional cash or other collateral requirements related to certain derivative instruments, insurance policies, natural gas transportation, fuel supply, and other energy-related contracts.  At this time, we believe we have sufficient available liquidity resources to respond to a downward revision to our credit ratings.

	Moody’s	Standard & Poor’s	Fitch
Pinnacle West
Corporate credit rating	A3	A-	A-
Commercial paper	P-2	A-2	F2
Outlook	Stable	Stable	Stable
APS
Corporate credit rating	A2	A-	A-
Senior unsecured	A2	A-	A
Commercial paper	P-1	A-2	F2
Outlook	Stable	Stable	Stable

Off-Balance Sheet Arrangements

See Note 18 for a discussion of the impacts on our financial statements of consolidating certain VIEs.

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Contractual Obligations

The following table summarizes Pinnacle West’s consolidated contractual requirements as of December 31, 2016 (dollars in millions):

	2017		2018- 2019		2020- 2021		Thereafter		Total
Long-term debt payments, including interest: (a)
APS	$	187	$	1,033	$	523	$	5,248	$	6,991
Pinnacle West	127		—		—		—		127
Total long-term debt payments, including interest	314		1,033		523		5,248		7,118
Short-term debt payments, including interest (b)	177		—		—		—		177
Fuel and purchased power commitments (c)	617		1,135		1,033		7,127		9,912
Renewable energy credits (d)	40		80		80		420		620
Purchase obligations (e)	360		200		16		212		788
Coal reclamation	18		40		46		258		362
Nuclear decommissioning funding requirements	2		4		4		58		68
Noncontrolling interests (f)	23		46		46		204		319
Operating lease payments	12		20		13		60		105
Total contractual commitments	$	1,563	$	2,558	$	1,761	$	13,587	$	19,469

(a) The long-term debt matures at various dates through 2046 and bears interest principally at fixed rates.  Interest on variable-rate long-term debt is determined by using average rates at December 31, 2016 (see Note 6).

(b) See Note 5 - Lines of credit and short-term borrowings for further details.

(c) Our fuel and purchased power commitments include purchases of coal, electricity, natural gas, renewable energy, nuclear fuel, and natural gas transportation (see Notes 3 and 10).

(d) Contracts to purchase renewable energy credits in compliance with the RES (see Note 3).

(e) These contractual obligations include commitments for capital expenditures and other obligations.

(f) Payments to the noncontrolling interests relate to the Palo Verde Sale Leaseback (see Note 18).

This table excludes $36 million in unrecognized tax benefits because the timing of the future cash outflows is uncertain.  Estimated minimum required pension contributions are zero for 2017, 2018 and 2019 (see Note 7).

CRITICAL ACCOUNTING POLICIES

In preparing the financial statements in accordance with accounting principles generally accepted in the United States of America (“GAAP”), management must often make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements and during the reporting period.  Some of those judgments can be subjective and complex, and actual results could differ from those estimates.  We consider the following accounting policies to be our most critical because of the uncertainties, judgments and complexities of the underlying accounting standards and operations involved.

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Regulatory Accounting

Regulatory accounting allows for the actions of regulators, such as the ACC and FERC, to be reflected in our financial statements.  Their actions may cause us to capitalize costs that would otherwise be included as an expense in the current period by unregulated companies.  Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer rates.  Regulatory liabilities generally represent expected future costs that have already been collected from customers.  Management continually assesses whether our regulatory assets are probable of future recovery by considering factors such as applicable regulatory environment changes and recent rate orders to other regulated entities in the same jurisdiction.  This determination reflects the current political and regulatory climate in Arizona and is subject to change in the future.  If future recovery of costs ceases to be probable, the assets would be written off as a charge in current period earnings.  We had $1,420 million of regulatory assets and $1,049 million of regulatory liabilities on the Consolidated Balance Sheets at December 31, 2016.

Included in the balance of regulatory assets at December 31, 2016 is a regulatory asset of $711 million for pension benefits.  This regulatory asset represents the future recovery of these costs through retail rates as these amounts are charged to earnings.  If all or a portion of these costs are disallowed by the ACC, this regulatory asset would be charged to OCI and result in lower future earnings.

See Notes 1 and 3 for more information.

Pensions and Other Postretirement Benefit Accounting

Changes in our actuarial assumptions used in calculating our pension and other postretirement benefit liability and expense can have a significant impact on our earnings and financial position.  The most relevant actuarial assumptions are the discount rate used to measure our liability and net periodic cost, the expected long-term rate of return on plan assets used to estimate earnings on invested funds over the long-term, the mortality assumptions, and the assumed healthcare cost trend rates.  We review these assumptions on an annual basis and adjust them as necessary.

The following chart reflects the sensitivities that a change in certain actuarial assumptions would have had on the December 31, 2016 reported pension liability on the Consolidated Balance Sheets and our 2016 reported pension expense, after consideration of amounts capitalized or billed to electric plant participants, on Pinnacle West’s Consolidated Statements of Income (dollars in millions): 

	Increase (Decrease)
Actuarial Assumption (a)	Impact on Pension Liability			Impact on Pension Expense
Discount rate:
Increase 1%	$	(344	)	$	(12	)
Decrease 1%	418			15
Expected long-term rate of return on plan assets:
Increase 1%	—			(12		)
Decrease 1%	—			12

(a) Each fluctuation assumes that the other assumptions of the calculation are held constant while the rates are changed by one percentage point.

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The following chart reflects the sensitivities that a change in certain actuarial assumptions would have had on the December 31, 2016 other postretirement benefit obligation and our 2016 reported other postretirement benefit expense, after consideration of amounts capitalized or billed to electric plant participants, on Pinnacle West’s Consolidated Statements of Income (dollars in millions): 

	Increase (Decrease)
Actuarial Assumption (a)	Impact on Other Postretirement  Benefit Obligation			Impact on Other Postretirement Benefit Expense
Discount rate:
Increase 1%	$	(91	)	$	(3	)
Decrease 1%	116			5
Healthcare cost trend rate (b):
Increase 1%	108			8
Decrease 1%	(87		)	(5		)
Expected long-term rate of return on plan assets – pretax:
Increase 1%	—			(4		)
Decrease 1%	—			4

(a) Each fluctuation assumes that the other assumptions of the calculation are held constant while the rates are changed by one percentage point.

(b) This assumes a 1% change in the initial and ultimate healthcare cost trend rate.

See Note 7 for further details about our pension and other postretirement benefit plans.

Fair Value Measurements

We account for derivative instruments, investments held in our nuclear decommissioning trust fund, certain cash equivalents, and plan assets held in our retirement and other benefit plans at fair value on a recurring basis.  Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.  We use inputs, or assumptions that market participants would use, to determine fair market value. We utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs.  The significance of a particular input determines how the instrument is classified in a fair value hierarchy.  The determination of fair value sometimes requires subjective and complex judgment.  Our assessment of the inputs and the significance of a particular input to fair value measurement may affect the valuation of the instruments and their placement within a fair value hierarchy.  Actual results could differ from our estimates of fair value.  See Note 1 for a discussion on accounting policies and Note 13 for fair value measurement disclosures.

OTHER ACCOUNTING MATTERS

During the fourth quarter of 2016, we early adopted a new accounting standard relating to stock-based compensation; see Notes 2 and 15 for discussion of how this standard impacted our financial statements and results of operations.

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We are currently evaluating the impacts of the pending adoption of new accounting standards relating to revenue recognition, leases, financial instruments and the definition of a business. See Note 2 for information relating to these accounting matters.

MARKET AND CREDIT RISKS

Market Risks

Our operations include managing market risks related to changes in interest rates, commodity prices and investments held by our nuclear decommissioning trust fund and benefit plan assets.

Interest Rate and Equity Risk

We have exposure to changing interest rates.  Changing interest rates will affect interest paid on variable-rate debt and the market value of fixed income securities held by our nuclear decommissioning trust fund (see Note 13 and Note 19) and benefit plan assets.  The nuclear decommissioning trust fund and benefit plan assets also have risks associated with the changing market value of their equity and other non-fixed income investments.  Nuclear decommissioning and benefit plan costs are recovered in regulated electricity prices.

The tables below present contractual balances of our consolidated long-term and short-term debt at the expected maturity dates, as well as the fair value of those instruments on December 31, 2016 and 2015.  The interest rates presented in the tables below represent the weighted-average interest rates as of December 31, 2016 and 2015 (dollars in millions):

Pinnacle West – Consolidated

	Short-Term Debt				Variable-Rate Long-Term Debt				Fixed-Rate Long-Term Debt
	Interest				Interest				Interest
2016	Rates		Amount		Rates		Amount		Rates		Amount
2017	1.01	%	$	177	1.52	%	$	125	—	%	$	—
2018	—		—		1.37	%	50		1.75	%	32
2019	—		—		1.46	%	100		8.75	%	500
2020	—		—		—		—		2.20	%	250
2021	—		—		—		—		—		—
Years thereafter	—		—		0.81	%	36		4.37	%	3,090
Total			$	177			$	311			$	3,872
Fair value			$	177			$	311			$	4,115

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	Variable-Rate Long-Term Debt				Fixed-Rate Long-Term Debt
	Interest				Interest
2015	Rates		Amount		Rates		Amount
2016	0.01	%	$	44	6.15	%	$	314
2017	1.17	%	125		—		—
2018	1.02	%	50		1.75	%	32
2019	—		—		8.75	%	500
2020	—		—		2.20	%	250
Years thereafter	0.23	%	49		4.64	%	2,490
Total			$	268			$	3,586
Fair value			$	268			$	3,839

The tables below present contractual balances of APS’s long-term debt at the expected maturity dates, as well as the fair value of those instruments on December 31, 2016 and 2015.  The interest rates presented in the tables below represent the weighted-average interest rates as of December 31, 2016 and 2015 (dollars in millions):

APS — Consolidated

	Short-Term Debt				Variable-Rate Long-Term Debt				Fixed-Rate Long-Term Debt
	Interest				Interest				Interest
2016	Rates		Amount		Rates		Amount		Rates		Amount
2017	0.88	%	$	135	—	%	$	—	—	%	$	—
2018	—		—		1.37	%	50		1.75	%	32
2019	—		—		1.46	%	100		8.75	%	500
2020	—		—		—		—		2.20	%	250
2021	—		—		—		—		—		—
Years thereafter	—		—		0.81	%	36		4.37	%	3,090
Total			$	135			$	186			$	3,872
Fair value			$	135			$	186			$	4,115

	Variable-Rate Long-Term Debt				Fixed-Rate Long-Term Debt
	Interest				Interest
2015	Rates		Amount		Rates		Amount
2016	0.01	%	$	44	6.15	%	$	314
2017	—		—		—		—
2018	1.02	%	50		1.75	%	32
2019	—		—		8.75	%	500
2020	—		—		2.20	%	250
Years thereafter	0.23	%	49		4.64	%	2,490
Total			$	143			$	3,586
Fair value			$	143			$	3,839

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Commodity Price Risk

We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity and natural gas.  Our risk management committee, consisting of officers and key management personnel, oversees company-wide energy risk management activities to ensure compliance with our stated energy risk management policies.  We manage risks associated with these market fluctuations by utilizing various commodity instruments that may qualify as derivatives, including futures, forwards, options and swaps.  As part of our risk management program, we use such instruments to hedge purchases and sales of electricity and fuels.  The changes in market value of such contracts have a high correlation to price changes in the hedged commodities.

The following table shows the net pretax changes in mark-to-market of our derivative positions in 2016 and 2015 (dollars in millions):

	2016			2015
Mark-to-market of net positions at beginning of year	$	(154	)	$	(115	)
Decrease (Increase) in regulatory asset	101			(44		)
Recognized in OCI:
Change in mark-to-market losses for future deliveries	—			(1		)
Mark-to-market losses realized during the period	4			6
Change in valuation techniques	—			—
Mark-to-market of net positions at end of year	$	(49	)	$	(154	)

The table below shows the fair value of maturities of our derivative contracts (dollars in millions) at December 31, 2016 by maturities and by the type of valuation that is performed to calculate the fair values, classified in their entirety based on the lowest level of input that is significant to the fair value measurement.  See Note 1, “Derivative Accounting” and “Fair Value Measurements,” for more discussion of our valuation methods.

Source of Fair Value	2017			2018			2019			2020			Total  fair  value
Observable prices provided by other external sources	$	7		$	(4	)	$	(4	)	$	—		$	(1	)
Prices based on unobservable inputs	(9		)	(20		)	(16		)	(3		)	(48		)
Total by maturity	$	(2	)	$	(24	)	$	(20	)	$	(3	)	$	(49	)

76

The table below shows the impact that hypothetical price movements of 10% would have on the market value of our risk management assets and liabilities included on Pinnacle West’s Consolidated Balance Sheets at December 31, 2016 and 2015 (dollars in millions):

	December 31, 2016 Gain (Loss)					December 31, 2015 Gain (Loss)
	Price Up  10%		Price Down 10%			Price Up  10%		Price Down 10%
Mark-to-market changes reported in:
Regulatory asset (liability) or OCI (a)
Electricity	$	2	$	(2	)	$	2	$	(2	)
Natural gas	46		(46		)	35		(35		)
Total	$	48	$	(48	)	$	37	$	(37	)

(a) These contracts are economic hedges of our forecasted purchases of natural gas and electricity.  The impact of these hypothetical price movements would substantially offset the impact that these same price movements would have on the physical exposures being hedged.  To the extent the amounts are eligible for inclusion in the PSA, the amounts are recorded as either a regulatory asset or liability.

Credit Risk

We are exposed to losses in the event of non-performance or non-payment by counterparties.  See Note 16 for a discussion of our credit valuation adjustment policy.

ITEM 7A.  QUANTITATIVE AND QUALITATIVE

DISCLOSURES ABOUT MARKET RISK

See “Market and Credit Risks” in Item 7 above for a discussion of quantitative and qualitative disclosures about market risks.

77

ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

INDEX TO FINANCIAL STATEMENTS AND

FINANCIAL STATEMENT SCHEDULES

	Page
Management’s Report on Internal Control over Financial Reporting (Pinnacle West Capital Corporation)	79
Report of Independent Registered Public Accounting Firm	80
Pinnacle West Consolidated Statements of Income for 2016, 2015 and 2014	82
Pinnacle West Consolidated Statements of Comprehensive Income for 2016, 2015, and 2014	83
Pinnacle West Consolidated Balance Sheets as of December 31, 2016 and 2015	84
Pinnacle West Consolidated Statements of Cash Flows for 2016, 2015 and 2014	86
Pinnacle West Consolidated Statements of Changes in Equity for 2016, 2015 and 2014	87
Management’s Report on Internal Control over Financial Reporting (Arizona Public Service Company)	88
Report of Independent Registered Public Accounting Firm	89
APS Consolidated Statements of Income for 2016, 2015 and 2014	91
APS Consolidated Statements of Comprehensive Income for 2016, 2015 and 2014	92
APS Consolidated Balance Sheets as of December 31, 2016 and 2015	93
APS Consolidated Statements of Cash Flows for 2016, 2015 and 2014	95
APS Consolidated Statements of Changes in Equity for 2016, 2015 and 2014	96
Combined Notes to Consolidated Financial Statements	97
Note 1. Summary of Significant Accounting Policies	97
Note 2. New Accounting Standards	104
Note 3. Regulatory Matters	106
Note 4. Income Taxes	118
Note 5. Lines of Credit and Short-Term Borrowings	122
Note 6. Long-Term Debt and Liquidity Matters	123
Note 7. Retirement Plans and Other Postretirement Benefits	126
Note 8. Leases	134
Note 9. Jointly-Owned Facilities	136
Note 10. Commitments and Contingencies	137
Note 11. Asset Retirement Obligations	146
Note 12. Selected Quarterly Financial Data (Unaudited)	148
Note 13. Fair Value Measurements	149
Note 14. Earnings Per Share	157
Note 15. Stock-Based Compensation	157
Note 16. Derivative Accounting	160
Note 17. Other Income and Other Expense	165
Note 18. Palo Verde Sale Leaseback Variable Interest Entities	166
Note 19. Nuclear Decommissioning Trusts	167
Note 20. Changes in Accumulated Other Comprehensive Loss	168

See Note 12 for the selected quarterly financial data (unaudited) required to be presented in this Item.

78

MANAGEMENT’S REPORT ON INTERNAL CONTROL

OVER FINANCIAL REPORTING

(PINNACLE WEST CAPITAL CORPORATION)

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rules 13a-15(f), for Pinnacle West.  Management conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.  Based on our evaluation under the framework in Internal Control — Integrated Framework (2013), our management concluded that our internal control over financial reporting was effective as of December 31, 2016.  The effectiveness of our internal control over financial reporting as of December 31, 2016 has been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report which is included herein and also relates to the Company’s consolidated financial statements.

February 24, 2017

79

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Stockholders of

Pinnacle West Capital Corporation

Phoenix, Arizona

We have audited the accompanying consolidated balance sheets of Pinnacle West Capital Corporation and subsidiaries (the “Company”) as of December 31, 2016 and 2015, and the related consolidated statements of income, comprehensive income, changes in equity, and cash flows for each of the three years in the period ended December 31, 2016.  Our audits also included the financial statement schedules listed in the Index at Item 15.  We also have audited the Company’s internal control over financial reporting as of December 31, 2016, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.  The Company’s management is responsible for these financial statements and financial statement schedules, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Report on Internal Control over Financial Reporting.  Our responsibility is to express an opinion on these financial statements and financial statement schedules and an opinion on the Company’s internal control over financial reporting based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States).  Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement and whether effective internal control over financial reporting was maintained in all material respects.  Our audits of the financial statements included examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation.  Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk.  Our audits also included performing such other procedures as we considered necessary in the circumstances.  We believe that our audits provide a reasonable basis for our opinions.

A company’s internal control over financial reporting is a process designed by, or under the supervision of, the company’s principal executive and principal financial officers, or persons performing similar functions, and effected by the company’s board of directors, management, and other personnel to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles.  A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of the inherent limitations of internal control over financial reporting, including the possibility of collusion or improper management override of controls, material misstatements due to error or fraud may not be prevented or detected on a timely basis.  Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become

80

inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of Pinnacle West Capital Corporation and subsidiaries as of December 31, 2016 and 2015, and the results of their operations and their cash flows for each of the three years in the period ended December 31, 2016, in conformity with accounting principles generally accepted in the United States of America.  Also, in our opinion, such financial statement schedules, when considered in relation to the basic consolidated financial statements taken as a whole, present fairly, in all material respects, the information set forth therein.  Also, in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2016, based on the criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

/s/ Deloitte & Touche LLP

Phoenix, Arizona

February 24, 2017

81

PINNACLE WEST CAPITAL CORPORATION

CONSOLIDATED STATEMENTS OF INCOME

(dollars and shares in thousands, except per share amounts)

	Year Ended December 31,
	2016			2015			2014
OPERATING REVENUES	$	3,498,682		$	3,495,443		$	3,491,632
OPERATING EXPENSES
Fuel and purchased power	1,075,510			1,101,298			1,179,829
Operations and maintenance	911,319			868,377			908,025
Depreciation and amortization	485,829			494,422			417,358
Taxes other than income taxes	166,499			171,812			172,295
Other expenses	3,541			4,932			2,883
Total	2,642,698			2,640,841			2,680,390
OPERATING INCOME	855,984			854,602			811,242
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction (Note 1)	42,140			35,215			30,790
Other income (Note 17)	901			621			9,608
Other expense (Note 17)	(15,337		)	(17,823		)	(21,746		)
Total	27,704			18,013			18,652
INTEREST EXPENSE
Interest charges	205,720			194,964			200,950
Allowance for borrowed funds used during construction (Note 1)	(19,970		)	(16,259		)	(15,457		)
Total	185,750			178,705			185,493
INCOME BEFORE INCOME TAXES	697,938			693,910			644,401
INCOME TAXES (Note 4)	236,411			237,720			220,705
NET INCOME	461,527			456,190			423,696
Less: Net income attributable to noncontrolling interests (Note 18)	19,493			18,933			26,101
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$	442,034		$	437,257		$	397,595
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — BASIC	111,409			111,026			110,626
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — DILUTED	112,046			111,552			111,178
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders — basic	$	3.97		$	3.94		$	3.59
Net income attributable to common shareholders — diluted	$	3.95		$	3.92		$	3.58

The accompanying notes are an integral part of the financial statements.

82

PINNACLE WEST CAPITAL CORPORATION

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
NET INCOME	$	461,527		$	456,190		$	423,696
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX
Derivative instruments:
Net unrealized loss, net of tax (expense) of $(585), $(342), and $(438) (Note 16)	(538		)	(957		)	(810		)
Reclassification of net realized loss, net of tax benefit of $985, $1,801 and $7,932 (Note 16)	2,941			4,187			13,483
Pension and other postretirement benefits activity, net of tax benefit (expense) of $633, $(13,302), and $1,307 (Note 7)	(1,477		)	20,163			(2,761		)
Total other comprehensive income	926			23,393			9,912
COMPREHENSIVE INCOME	462,453			479,583			433,608
Less: Comprehensive income attributable to noncontrolling interests	19,493			18,933			26,101
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$	442,960		$	460,650		$	407,507

The accompanying notes are an integral part of the financial statements.

83

PINNACLE WEST CAPITAL CORPORATION

CONSOLIDATED BALANCE SHEETS

(dollars in thousands)

	December 31,
	2016			2015
ASSETS
CURRENT ASSETS
Cash and cash equivalents	$	8,881		$	39,488
Customer and other receivables	250,491			274,691
Accrued unbilled revenues	107,949			96,240
Allowance for doubtful accounts	(3,037		)	(3,125		)
Materials and supplies (at average cost)	253,979			234,234
Fossil fuel (at average cost)	28,608			45,697
Income tax receivable (Note 4)	3,751			589
Assets from risk management activities (Note 16)	19,694			15,905
Deferred fuel and purchased power regulatory asset (Note 3)	12,465			—
Other regulatory assets (Note 3)	94,410			149,555
Other current assets	45,028			37,242
Total current assets	822,219			890,516
INVESTMENTS AND OTHER ASSETS
Assets from risk management activities (Note 16)	1			12,106
Nuclear decommissioning trust (Notes 13 and 19)	779,586			735,196
Other assets	69,063			52,518
Total investments and other assets	848,650			799,820
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	17,341,888			16,222,232
Accumulated depreciation and amortization	(5,970,100		)	(5,594,094		)
Net	11,371,788			10,628,138
Construction work in progress	1,019,947			816,307
Palo Verde sale leaseback, net of accumulated depreciation of $237,535 and $233,665 (Note 18)	113,515			117,385
Intangible assets, net of accumulated amortization of $603,637 and $546,038	90,022			123,975
Nuclear fuel, net of accumulated amortization of $147,202 and $146,228	119,004			123,139
Total property, plant and equipment	12,714,276			11,808,944
DEFERRED DEBITS
Regulatory assets (Notes 1, 3 and 4)	1,313,428			1,214,146
Assets for other postretirement benefits (Note 7)	166,206			185,997
Other	139,474			128,835
Total deferred debits	1,619,108			1,528,978
TOTAL ASSETS	$	16,004,253		$	15,028,258

The accompanying notes are an integral part of the financial statements.

84

PINNACLE WEST CAPITAL CORPORATION

CONSOLIDATED BALANCE SHEETS

(dollars in thousands)

	December 31,
	2016			2015
LIABILITIES AND EQUITY
CURRENT LIABILITIES
Accounts payable	$	264,631		$	297,480
Accrued taxes (Note 4)	138,964			138,600
Accrued interest	52,835			56,305
Common dividends payable	72,926			69,363
Short-term borrowings (Note 5)	177,200			—
Current maturities of long-term debt (Note 6)	125,000			357,580
Customer deposits	82,520			73,073
Liabilities from risk management activities (Note 16)	25,836			77,716
Liabilities for asset retirements (Note 11)	9,135			28,573
Deferred fuel and purchased power regulatory liability (Note 3)	—			9,688
Other regulatory liabilities (Note 3)	99,899			136,078
Other current liabilities	244,000			197,861
Total current liabilities	1,292,946			1,442,317
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 6)	4,021,785			3,462,391
DEFERRED CREDITS AND OTHER
Deferred income taxes (Note 4)	2,945,232			2,723,425
Regulatory liabilities (Notes 1, 3, 4 and 7)	948,916			994,152
Liabilities for asset retirements (Note 11)	615,340			415,003
Liabilities for pension benefits (Note 7)	509,310			480,998
Liabilities from risk management activities (Note 16)	47,238			89,973
Customer advances	88,672			115,609
Coal mine reclamation	221,910			201,984
Deferred investment tax credit	210,162			187,080
Unrecognized tax benefits (Note 4)	10,046			9,524
Other	156,784			186,345
Total deferred credits and other	5,753,610			5,404,093
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 111,392,053 and 111,095,402 issued at respective dates	2,596,030			2,541,668
Treasury stock at cost; 55,317 shares at end of 2016 and 115,030 shares at end of 2015	(4,133		)	(5,806		)
Total common stock	2,591,897			2,535,862
Retained earnings	2,255,547			2,092,803
Accumulated other comprehensive loss:
Pension and other postretirement benefits (Note 7)	(39,070		)	(37,593		)
Derivative instruments (Note 16)	(4,752		)	(7,155		)
Total accumulated other comprehensive loss	(43,822		)	(44,748		)
Total shareholders’ equity	4,803,622			4,583,917
Noncontrolling interests (Note 18)	132,290			135,540
Total equity	4,935,912			4,719,457
TOTAL LIABILITIES AND EQUITY	$	16,004,253		$	15,028,258

The accompanying notes are an integral part of the financial statements.

85

PINNACLE WEST CAPITAL CORPORATION

CONSOLIDATED STATEMENTS OF CASH FLOWS

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$	461,527		$	456,190		$	423,696
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	565,011			571,664			496,487
Deferred fuel and purchased power	(60,303		)	14,997			(26,927		)
Deferred fuel and purchased power amortization	38,152			1,617			40,757
Allowance for equity funds used during construction	(42,140		)	(35,215		)	(30,790		)
Deferred income taxes	206,870			236,819			159,023
Deferred investment tax credit	23,082			8,473			26,246
Change in derivative instruments fair value	(403		)	(381		)	339
Stock compensation	18,883			18,756			33,059
Changes in current assets and liabilities:
Customer and other receivables	(2,489		)	(22,219		)	(52,672		)
Accrued unbilled revenues	(11,709		)	4,293			(3,737		)
Materials, supplies and fossil fuel	(1,491		)	(23,945		)	3,724
Income tax receivable	(3,162		)	2,509			132,419
Other current assets	(23,324		)	3,145			4,384
Accounts payable	(66,917		)	(34,266		)	(353		)
Accrued taxes	447			(2,013		)	9,615
Other current liabilities	29,594			603			17,892
Change in margin and collateral accounts — assets	673			(324		)	(343		)
Change in margin and collateral accounts — liabilities	17,735			22,776			(24,975		)
Change in unrecognized tax benefits	1,628			(10,328		)	2,778
Change in long-term regulatory liabilities	14,682			(20,535		)	59,618
Change in other long-term assets	(60,163		)	2,426			(56,561		)
Change in other long-term liabilities	(82,793		)	(100,715		)	(114,052		)
Net cash flow provided by operating activities	1,023,390			1,094,327			1,099,627
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,275,472		)	(1,076,087		)	(910,634		)
Contributions in aid of construction	64,296			46,546			20,325
Allowance for borrowed funds used during construction	(19,970		)	(16,259		)	(15,457		)
Proceeds from nuclear decommissioning trust sales	633,410			478,813			356,195
Investment in nuclear decommissioning trust	(635,691		)	(496,062		)	(373,444		)
Other	(18,651		)	(3,184		)	347
Net cash flow used for investing activities	(1,252,078		)	(1,066,233		)	(922,668		)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	693,151			842,415			731,126
Repayment of long-term debt	(370,430		)	(415,570		)	(652,578		)
Short-term borrowings and payments — net	137,200			(147,400		)	(5,725		)
Short-term debt borrowings under revolving credit facility	40,000			—			—
Dividends paid on common stock	(274,229		)	(260,027		)	(246,671		)
Common stock equity issuance and purchases - net	(4,867		)	19,373			15,288
Distributions to noncontrolling interests	(22,744		)	(35,002		)	(20,482		)
Other	—			1			161
Net cash flow provided by (used for) financing activities	198,081			3,790			(178,881		)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(30,607		)	31,884			(1,922		)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	39,488			7,604			9,526
CASH AND CASH EQUIVALENTS AT END OF YEAR	$	8,881		$	39,488		$	7,604

 The accompanying notes are an integral part of the financial statements.

86

PINNACLE WEST CAPITAL CORPORATION

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(dollars in thousands, except per share amounts)

	Common Stock			Treasury Stock					Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests			Total
	Shares	Amount		Shares		Amount
Balance, December 31, 2013	110,280,703	$	2,491,558	(98,944	)	$	(4,308	)	$	1,785,273		$	(78,053	)	$	145,990		$	4,340,460
Net income		—				—			397,595			—			26,101			423,696
Other comprehensive income		—				—			—			9,912			—			9,912
Dividends on common stock ($2.33 per share)		—				—			(256,803		)	—			—			(256,803		)
Issuance of common stock	369,059	21,412				—			—			—			—			21,412
Purchase of treasury stock (a)		—		(139,746	)	(7,893		)	—			—			—			(7,893		)
Reissuance of treasury stock for stock-based compensation and other		—		160,290		8,800			—			—			—			8,800
Net capital activities by noncontrolling interests		—				—			—			—			(20,482		)	(20,482		)
Balance, December 31, 2014	110,649,762	2,512,970		(78,400	)	(3,401		)	1,926,065			(68,141		)	151,609			4,519,102
Net income		—				—			437,257			—			18,933			456,190
Other comprehensive income		—				—			—			23,393			—			23,393
Dividends on common stock ($2.44 per share)		—				—			(270,519		)	—			—			(270,519		)
Issuance of common stock	445,640	28,698				—			—			—			—			28,698
Purchase of treasury stock (a)		—		(154,751	)	(10,136		)	—			—			—			(10,136		)
Reissuance of treasury stock for stock-based compensation and other		—		118,121		7,731			—			—			—			7,731
Net capital activities by noncontrolling interests		—				—			—			—			(35,002		)	(35,002		)
Balance, December 31, 2015	111,095,402	2,541,668		(115,030	)	(5,806		)	2,092,803			(44,748		)	135,540			4,719,457
Net income		—				—			442,034			—			19,493			461,527
Other comprehensive income		—				—			—			926			—			926
Dividends on common stock ($2.56 per share)		—				—			(284,765		)	—			—			(284,765		)
Issuance of common stock	296,651	13,982				—			—			—			—			13,982
Purchase of treasury stock (a)		—		(128,105	)	(9,087		)	—			—			—			(9,087		)
Reissuance of treasury stock for stock-based compensation and other		—		187,818		10,760			—			—			—			10,760
Stock compensation cumulative effect adjustments (See Note 2)		40,380				—			5,475			—			—			45,855
Net capital activities by noncontrolling interests		—				—			—			—			(22,743		)	(22,743		)
Balance, December 31, 2016	111,392,053	$	2,596,030	(55,317	)	$	(4,133	)	$	2,255,547		$	(43,822	)	$	132,290		$	4,935,912

(a)    Primarily represents shares of common stock withheld from certain stock awards for tax purposes.

The accompanying notes are an integral part of the financial statements.

87

MANAGEMENT’S REPORT ON INTERNAL CONTROL

OVER FINANCIAL REPORTING

(ARIZONA PUBLIC SERVICE COMPANY)

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rules 13a-15(f), for APS.  Management conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.  Based on our evaluation under the framework in Internal Control — Integrated Framework (2013), our management concluded that our internal control over financial reporting was effective as of December 31, 2016.  The effectiveness of our internal control over financial reporting as of December 31, 2016 has been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report which is included herein and also relates to the Company’s financial statements.

February 24, 2017

88

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Stockholder of

Arizona Public Service Company

Phoenix, Arizona

We have audited the accompanying consolidated balance sheets of Arizona Public Service Company and subsidiary (the “Company”) as of December 31, 2016 and 2015, and the related consolidated statements of income, comprehensive income, changes in equity, and cash flows for each of the three years in the period ended December 31, 2016.  Our audits also included the financial statement schedule listed in the Index at Item 15.  We also have audited the Company’s internal control over financial reporting as of December 31, 2016, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.  The Company’s management is responsible for these financial statements and financial statement schedule, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Report on Internal Control over Financial Reporting.  Our responsibility is to express an opinion on these financial statements and financial statement schedule and an opinion on the Company’s internal control over financial reporting based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States).  Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement and whether effective internal control over financial reporting was maintained in all material respects.  Our audits of the financial statements included examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation.  Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk.  Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

A company’s internal control over financial reporting is a process designed by, or under the supervision of, the company’s principal executive and principal financial officers, or persons performing similar functions, and effected by the company’s board of directors, management, and other personnel to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles.  A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of the inherent limitations of internal control over financial reporting, including the possibility of collusion or improper management override of controls, material misstatements due to error or fraud may not be prevented or detected on a timely basis.  Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become

89

inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of Arizona Public Service Company and subsidiary as of December 31, 2016 and 2015, and the results of their operations and their cash flows for each of the three years in the period ended December 31, 2016, in conformity with accounting principles generally accepted in the United States of America.  Also, in our opinion, such financial statement schedule, when considered in relation to the basic consolidated financial statements taken as a whole, presents fairly, in all material respects, the information set forth therein.  Also, in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2016, based on the criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

/s/ Deloitte & Touche LLP

Phoenix, Arizona

February 24, 2017

90

ARIZONA PUBLIC SERVICE COMPANY

CONSOLIDATED STATEMENTS OF INCOME

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
ELECTRIC OPERATING REVENUES	$	3,489,754		$	3,492,357		$	3,488,946
OPERATING EXPENSES
Fuel and purchased power	1,082,625			1,101,298			1,179,829
Operations and maintenance	879,108			853,135			882,442
Depreciation and amortization	484,909			494,298			417,264
Income taxes (Note 4)	259,353			260,143			245,036
Taxes other than income taxes	165,779			171,499			171,583
Total	2,871,774			2,880,373			2,896,154
OPERATING INCOME	617,980			611,984			592,792
OTHER INCOME (DEDUCTIONS)
Income taxes (Note 4)	13,511			14,302			7,676
Allowance for equity funds used during construction (Note 1)	42,140			35,215			30,790
Other income (Note 17)	8,607			2,834			11,295
Other expense (Note 17)	(17,514		)	(19,019		)	(13,403		)
Total	46,744			33,332			36,358
INTEREST EXPENSE
Interest on long-term debt	189,828			180,123			186,323
Interest on short-term borrowings	7,983			7,376			6,796
Debt discount, premium and expense	4,760			4,793			4,168
Allowance for borrowed funds used during construction (Note 1)	(19,481		)	(16,183		)	(15,457		)
Total	183,090			176,109			181,830
NET INCOME	481,634			469,207			447,320
Less: Net income attributable to noncontrolling interests (Note 18)	19,493			18,933			26,101
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER	$	462,141		$	450,274		$	421,219

The accompanying notes are an integral part of the financial statements.

91

ARIZONA PUBLIC SERVICE COMPANY

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
NET INCOME	$	481,634		$	469,207		$	447,320
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX
Derivative instruments:
Net unrealized loss, net of tax (expense) of $(585), $(342), and $(438) (Note 16)	(538		)	(957		)	(809		)
Reclassification of net realized loss, net of tax benefit of $985, $1,801, and $7,932 (Note 16)	2,941			4,187			13,483
Pension and other postretirement benefits activity, net of tax (expense) benefit of $293, $(11,776), and $4,655 (Note 7)	(729		)	18,006			(7,635		)
Total other comprehensive income	1,674			21,236			5,039
COMPREHENSIVE INCOME	483,308			490,443			452,359
Less: Comprehensive income attributable to noncontrolling interests	19,493			18,933			26,101
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER	$	463,815		$	471,510		$	426,258

The accompanying notes are an integral part of the financial statements.

92

ARIZONA PUBLIC SERVICE COMPANY

CONSOLIDATED BALANCE SHEETS

(dollars in thousands)

	December 31,
	2016			2015
ASSETS
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	$	17,228,787		$	16,218,724
Accumulated depreciation and amortization	(5,881,941		)	(5,590,937		)
Net	11,346,846			10,627,787
Construction work in progress	989,497			812,845
Palo Verde sale leaseback, net of accumulated depreciation of $237,535 and $233,665 (Note 18)	113,515			117,385
Intangible assets, net of accumulated amortization of $603,637 and $546,038	89,868			123,820
Nuclear fuel, net of accumulated amortization of $147,202 and $146,228	119,004			123,139
Total property, plant and equipment	12,658,730			11,804,976
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Notes 13 and 19)	779,586			735,196
Assets from risk management activities (Note 16)	1			12,106
Other assets	48,320			34,455
Total investments and other assets	827,907			781,757
CURRENT ASSETS
Cash and cash equivalents	8,840			22,056
Customer and other receivables	262,611			274,428
Accrued unbilled revenues	107,949			96,240
Allowance for doubtful accounts	(3,037		)	(3,125		)
Materials and supplies (at average cost)	252,777			234,234
Fossil fuel (at average cost)	28,608			45,697
Income tax receivable	11,174			—
Assets from risk management activities (Note 16)	19,694			15,905
Deferred fuel and purchased power regulatory asset (Note 3)	12,465			—
Other regulatory assets (Note 3)	94,410			149,555
Other current assets	41,849			35,765
Total current assets	837,340			870,755
DEFERRED DEBITS
Regulatory assets (Notes 1, 3, and 4)	1,313,428			1,214,146
Assets for other postretirement benefits (Note 7)	162,911			182,625
Other	130,859			127,923
Total deferred debits	1,607,198			1,524,694
TOTAL ASSETS	$	15,931,175		$	14,982,182

The accompanying notes are an integral part of the financial statements.

93

ARIZONA PUBLIC SERVICE COMPANY

CONSOLIDATED BALANCE SHEETS

(dollars in thousands)

	December 31,
	2016			2015
LIABILITIES AND EQUITY
CAPITALIZATION
Common stock	$	178,162		$	178,162
Additional paid-in capital	2,421,696			2,379,696
Retained earnings	2,331,245			2,148,493
Accumulated other comprehensive (loss):
Pension and other postretirement benefits (Note 7)	(20,671		)	(19,942		)
Derivative instruments (Note 16)	(4,752		)	(7,155		)
Total accumulated other comprehensive loss	(25,423		)	(27,097		)
Total shareholder equity	4,905,680			4,679,254
Noncontrolling interests (Note 18)	132,290			135,540
Total equity	5,037,970			4,814,794
Long-term debt less current maturities (Note 6)	4,021,785			3,337,391
Total capitalization	9,059,755			8,152,185
CURRENT LIABILITIES
Short-term borrowings (Note 5)	135,500			—
Current maturities of long-term debt (Note 6)	—			357,580
Accounts payable	259,161			291,574
Accrued taxes (Note 4)	130,576			144,488
Accrued interest	52,525			56,003
Common dividends payable	72,900			69,400
Customer deposits	82,520			73,073
Liabilities from risk management activities (Note 16)	25,836			77,716
Liabilities for asset retirements (Note 11)	8,703			28,573
Deferred fuel and purchased power regulatory liability (Note 3)	—			9,688
Other regulatory liabilities (Note 3)	99,899			136,078
Other current liabilities	226,417			180,535
Total current liabilities	1,094,037			1,424,708
DEFERRED CREDITS AND OTHER
Deferred income taxes (Note 4)	2,999,295			2,764,489
Regulatory liabilities (Notes 1, 3, and 4)	948,916			994,152
Liabilities for asset retirements (Note 11)	607,234			415,003
Liabilities for pension benefits (Note 7)	488,253			459,065
Liabilities from risk management activities (Note 16)	47,238			89,973
Customer advances	88,672			115,609
Coal mine reclamation	206,645			201,984
Deferred investment tax credit	210,162			187,080
Unrecognized tax benefits (Note 4)	37,408			35,251
Other	143,560			142,683
Total deferred credits and other	5,777,383			5,405,289
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
TOTAL LIABILITIES AND EQUITY	$	15,931,175		$	14,982,182

The accompanying notes are an integral part of the financial statements.

94

ARIZONA PUBLIC SERVICE COMPANY

CONSOLIDATED STATEMENTS OF CASH FLOWS

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$	481,634		$	469,207		$	447,320
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	564,091			571,540			496,393
Deferred fuel and purchased power	(60,303		)	14,997			(26,927		)
Deferred fuel and purchased power amortization	38,152			1,617			40,757
Allowance for equity funds used during construction	(42,140		)	(35,215		)	(30,790		)
Deferred income taxes	221,167			223,069			155,401
Deferred investment tax credit	23,082			8,473			26,246
Change in derivative instruments fair value	(403		)	(381		)	339
Changes in current assets and liabilities:
Customer and other receivables	(1,601		)	(21,040		)	(52,466		)
Accrued unbilled revenues	(11,709		)	4,293			(3,737		)
Materials, supplies and fossil fuel	(1,454		)	(23,945		)	3,724
Income tax receivable	(14,567		)	—			135,179
Other current assets	(21,640		)	4,498			3,766
Accounts payable	(67,543		)	(34,891		)	(2,355		)
Accrued taxes	(13,912		)	13,378			8,650
Other current liabilities	5,097			(3,718		)	33,970
Change in margin and collateral accounts — assets	673			(324		)	(343		)
Change in margin and collateral accounts — liabilities	17,735			22,776			(24,975		)
Change in long-term regulatory liabilities	14,682			(20,535		)	59,618
Change in unrecognized tax benefits	1,628			(10,328		)	2,778
Change in other long-term assets	(45,866		)	(813		)	(62,739		)
Change in other long-term liabilities	(76,855		)	(82,628		)	(85,642		)
Net cash flow provided by operating activities	1,009,948			1,100,030			1,124,167
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,248,010		)	(1,072,053		)	(910,084		)
Contributions in aid of construction	64,296			46,546			20,325
Allowance for borrowed funds used during construction	(19,481		)	(16,183		)	(15,457		)
Proceeds from nuclear decommissioning trust sales	633,410			478,813			356,195
Investment in nuclear decommissioning trust	(635,691		)	(496,062		)	(373,444		)
Other	(13,865		)	(1,093		)	347
Net cash flow used for investing activities	(1,219,341		)	(1,060,032		)	(922,118		)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	693,151			842,415			606,126
Repayment of long-term debt	(370,430		)	(415,570		)	(527,578		)
Short-term borrowings and payments — net	135,500			(147,400		)	(5,725		)
Dividends paid on common stock	(281,300		)	(266,900		)	(253,600		)
Equity infusion from Pinnacle West	42,000			—			—
Noncontrolling interests	(22,744		)	(35,002		)	(20,482		)
Net cash flow provided by (used for) financing activities	196,177			(22,457		)	(201,259		)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(13,216		)	17,541			790
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	22,056			4,515			3,725
CASH AND CASH EQUIVALENTS AT END OF YEAR	$	8,840		$	22,056		$	4,515
Supplemental disclosure of cash flow information:
Cash paid (received) during the year for:
Income taxes, net of refunds	$	26,864		$	14,831		$	(86,054	)
Interest, net of amounts capitalized	181,809			167,670			173,436
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	114,874		$	83,798		$	44,712
Dividends declared but not paid	72,900			69,400			65,800

The accompanying notes are an integral part of the financial statements.

95

ARIZONA PUBLIC SERVICE COMPANY

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(dollars in thousands)

	Common Stock			Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests			Total
	Shares	Amount
Balance, December 31, 2013	71,264,947	$	178,162	$	2,379,696	$	1,804,398		$	(53,372	)	$	145,990		$	4,454,874
Net income		—		—		421,219			—			26,101			447,320
Other comprehensive income		—		—		—			5,039			—			5,039
Dividends on common stock		—		—		(256,900		)	—			—			(256,900		)
Other		—		—		1			—			—			1
Net capital activities by noncontrolling interests		—		—		—			—			(20,482		)	(20,482		)
Balance, December 31, 2014	71,264,947	178,162		2,379,696		1,968,718			(48,333		)	151,609			4,629,852
Net income		—		—		450,274			—			18,933			469,207
Other comprehensive income		—		—		—			21,236			—			21,236
Dividends on common stock		—		—		(270,500		)	—			—			(270,500		)
Other		—		—		1			—			—			1
Net capital activities by noncontrolling interests		—		—		—			—			(35,002		)	(35,002		)
Balance, December 31, 2015	71,264,947	178,162		2,379,696		2,148,493			(27,097		)	135,540			4,814,794
Equity infusion from Pinnacle West		—		42,000		—			—			—			42,000
Net income		—		—		462,141			—			19,493			481,634
Other comprehensive income		—		—		—			1,674			—			1,674
Dividends on common stock		—		—		(284,800		)	—			—			(284,800		)
Stock compensation cumulative effect adjustments (See Note 2)		—		—		5,411			—			—			5,411
Net capital activities by noncontrolling interests		—		—		—			—			(22,743		)	(22,743		)
Balance, December 31, 2016	71,264,947	$	178,162	$	2,421,696	$	2,331,245		$	(25,423	)	$	132,290		$	5,037,970

The accompanying notes are an integral part of the financial statements.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.    Summary of Significant Accounting Policies

Description of Business and Basis of Presentation

Pinnacle West is a holding company that conducts business through its subsidiaries, APS, El Dorado, BCE and 4CA. APS, our wholly-owned subsidiary, is a vertically-integrated electric utility that provides either retail or wholesale electric service to substantially all of the state of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona.  APS accounts for essentially all of our revenues and earnings, and is expected to continue to do so.  El Dorado is an investment firm. BCE is a subsidiary that was formed in 2014 that focuses on growth opportunities that leverage the Company's core expertise in the electric energy industry. BCE is currently pursuing transmission opportunities through a joint venture arrangement. 4CA is a subsidiary that was formed in 2016 as a result of the purchase of El Paso's 7% interest in Four Corners.

Pinnacle West’s Consolidated Financial Statements include the accounts of Pinnacle West and our subsidiaries:  APS, El Dorado, BCE and 4CA. APS’s consolidated financial statements include the accounts of APS and certain VIEs relating to the Palo Verde sale leaseback.  Intercompany accounts and transactions between the consolidated companies have been eliminated.

We consolidate VIEs for which we are the primary beneficiary.  We determine whether we are the primary beneficiary of a VIE through a qualitative analysis that identifies which variable interest holder has the controlling financial interest in the VIE.  In performing our primary beneficiary analysis, we consider all relevant facts and circumstances, including the design and activities of the VIE, the terms of the contracts the VIE has entered into, and which parties participated significantly in the design or redesign of the entity.  We continually evaluate our primary beneficiary conclusions to determine if changes have occurred which would impact our primary beneficiary assessments.  We have determined that APS is the primary beneficiary of certain VIE lessor trusts relating to the Palo Verde sale leaseback, and therefore APS consolidates these entities (see Note 18).

Our consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as otherwise disclosed in the notes) that we believe are necessary for the fair presentation of our financial position, results of operations and cash flows for the periods presented.

Certain line items are presented in more detail on the Consolidated Statements of Cash Flows than was presented in the prior years. The prior year amounts were reclassified to conform to the current year presentation. These reclassifications have no impact on net cash flows provided by operating activities. The following tables show the impacts of the reclassifications of the prior years (previously reported) amounts (dollars in thousands):

Statement of Cash Flows for the Year Ended December 31, 2015	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	18,756		$	18,756
Change in other long term liabilities	(81,959		)	(18,756		)	(100,715		)

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Statement of Cash Flows for the Year Ended December 31, 2014	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	33,059		$	33,059
Change in other long-term liabilities	(80,993		)	(33,059		)	(114,052		)

Accounting Records and Use of Estimates

Our accounting records are maintained in accordance with GAAP.  The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period.  Actual results could differ from those estimates.

Regulatory Accounting

APS is regulated by the ACC and FERC.  The accompanying financial statements reflect the rate-making policies of these commissions.  As a result, we capitalize certain costs that would be included as expense in the current period by unregulated companies.  Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer rates.  Regulatory liabilities generally represent expected future costs that have already been collected from customers.

Management continually assesses whether our regulatory assets are probable of future recovery by considering factors such as changes in the applicable regulatory environment and recent rate orders applicable to APS or other regulated entities in the same jurisdiction.  This determination reflects the current political and regulatory climate in Arizona and is subject to change in the future.  If future recovery of costs ceases to be probable, the assets would be written off as a charge in current period earnings.

See Note 3 for additional information.

Electric Revenues

We derive electric revenues primarily from sales of electricity to our regulated Native Load customers.  Revenues related to the sale of electricity are generally recorded when service is rendered or electricity is delivered to customers.  The billing of electricity sales to individual Native Load customers is based on the reading of their meters, which occurs on a systematic basis throughout the month.  Unbilled revenues are estimated by applying an average revenue/kWh by customer class to the number of estimated kWhs delivered but not billed.  Differences historically between the actual and estimated unbilled revenues are immaterial.  We exclude sales taxes and franchise fees on electric revenues from both revenue and taxes other than income taxes.

Revenues from our Native Load customers and non-derivative instruments are reported on a gross basis on Pinnacle West’s Consolidated Statements of Income.  In the electricity business, some contracts to purchase energy are netted against other contracts to sell energy.  This is called a “book-out” and usually occurs for contracts that have the same terms (quantities and delivery points) and for which power does not flow.  We net these book-outs, which reduces both revenues and fuel and purchased power costs.

98

COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Some of our cost recovery mechanisms are alternative revenue programs.  For alternative revenue programs that meet specified accounting criteria, we recognize revenues when the specific events permitting billing of the additional revenues have been completed.

Allowance for Doubtful Accounts

The allowance for doubtful accounts represents our best estimate of existing accounts receivable that will ultimately be uncollectible.  The allowance is calculated by applying estimated write-off factors to various classes of outstanding receivables, including accrued utility revenues.  The write-off factors used to estimate uncollectible accounts are based upon consideration of both historical collections experience and management’s best estimate of future collections success given the existing collections environment.

Property, Plant and Equipment

Utility plant is the term we use to describe the business property and equipment that supports electric service, consisting primarily of generation, transmission and distribution facilities.  We report utility plant at its original cost, which includes:

• material and labor;

• contractor costs;

• capitalized leases;

• construction overhead costs (where applicable); and

• allowance for funds used during construction.

Pinnacle West’s property, plant and equipment included in the December 31, 2016 and 2015 consolidated balance sheets is composed of the following (dollars in thousands):

Property, Plant and Equipment:	2016			2015
Generation	$	7,874,898		$	7,336,902
Transmission	2,746,508			2,494,744
Distribution	5,738,801			5,543,561
General plant	981,681			847,025
Plant in service and held for future use	17,341,888			16,222,232
Accumulated depreciation and amortization	(5,970,100		)	(5,594,094		)
Net	11,371,788			10,628,138
Construction work in progress	1,019,947			816,307
Palo Verde sale leaseback, net of accumulated depreciation	113,515			117,385
Intangible assets, net of accumulated amortization	90,022			123,975
Nuclear fuel, net of accumulated amortization	119,004			123,139
Total property, plant and equipment	$	12,714,276		$	11,808,944

Property, plant and equipment balances and classes for APS are not materially different than Pinnacle West.

We expense the costs of plant outages, major maintenance and routine maintenance as incurred.  We charge retired utility plant to accumulated depreciation.  Liabilities associated with the retirement of tangible long-lived assets are recognized at fair value as incurred and capitalized as part of the related tangible long-

99

COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

lived assets.  Accretion of the liability due to the passage of time is an operating expense, and the capitalized cost is depreciated over the useful life of the long-lived asset.  See Note 11.

APS records a regulatory liability for the difference between the amount that has been recovered in regulated rates and the amount calculated in accordance with guidance on accounting for asset retirement obligations.  APS believes it can recover in regulated rates the costs calculated in accordance with this accounting guidance.

We record depreciation on utility plant on a straight-line basis over the remaining useful life of the related assets.  The approximate remaining average useful lives of our utility property at December 31, 2016 were as follows:

•Fossil plant — 19 years;

•Nuclear plant — 27 years;

•Other generation — 26 years;

•Transmission — 39 years;

•Distribution — 33 years; and

•General plant — 7 years.

Pursuant to an ACC order, we deferred operating costs in 2013 and 2014 related to APS's acquisition of additional interests in Units 4 and 5 and the related closure of Units 1-3 of Four Corners. See Note 3 for further discussion. These costs were deferred and are now being amortized on the depreciation line of the Consolidated Statements of Income.

Depreciation of utility property, plant and equipment is computed on a straight-line, remaining-life basis. Depreciation expense was $422 million in 2016, $430 million in 2015, and $396 million in 2014. For the years 2014 through 2016, the depreciation rates ranged from a low of 0.30% to a high of 14.12%.  The weighted-average depreciation rate was 2.66% in 2016, 2.74% in 2015, and 2.77% in 2014.

Allowance for Funds Used During Construction

AFUDC represents the approximate net composite interest cost of borrowed funds and an allowed return on the equity funds used for construction of regulated utility plant.  Both the debt and equity components of AFUDC are non-cash amounts within the Consolidated Statements of Income.  Plant construction costs, including AFUDC, are recovered in authorized rates through depreciation when completed projects are placed into commercial operation.

AFUDC was calculated by using a composite rate of 7.17% for 2016, 8.02% for 2015, and 8.47% for 2014.  APS compounds AFUDC semi-annually and ceases to accrue AFUDC when construction work is completed and the property is placed in service.

Materials and Supplies

APS values materials, supplies and fossil fuel inventory using a weighted-average cost method.  APS materials, supplies and fossil fuel inventories are carried at the lower of weighted-average cost or market, unless evidence indicates that the weighted-average cost (even if in excess of market) will be recovered.

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Fair Value Measurements

We account for derivative instruments, investments held in our nuclear decommissioning trust, certain cash equivalents and plan assets held in our retirement and other benefit plans at fair value on a recurring basis.  Due to the short-term nature of net accounts receivable, accounts payable, and short-term borrowings, the carrying values of these instruments approximate fair value.  Fair value measurements may also be applied on a nonrecurring basis to other assets and liabilities in certain circumstances such as impairments.  We also disclose fair value information for our long-term debt, which is carried at amortized cost (see Note 6).

Fair value is the price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market which we can access for the asset or liability in an orderly transaction between willing market participants on the measurement date.  Inputs to fair value may include observable and unobservable data.  We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

We determine fair market value using observable inputs such as actively-quoted prices for identical instruments when available.  When actively quoted prices are not available for the identical instruments, we use other observable inputs, such as prices for similar instruments, other corroborative market information, or prices provided by other external sources.  For options, long-term contracts and other contracts for which observable price data are not available, we use models and other valuation methods, which may incorporate unobservable inputs to determine fair market value.

The use of models and other valuation methods to determine fair market value often requires subjective and complex judgment.  Actual results could differ from the results estimated through application of these methods.

See Note 13 for additional information about fair value measurements.

Derivative Accounting

We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal and in interest rates.  We manage risks associated with market volatility by utilizing various physical and financial instruments including futures, forwards, options and swaps.  As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and fuels.  The changes in market value of such contracts have a high correlation to price changes in the hedged transactions.  We also enter into derivative instruments for economic hedging purposes.  Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power expenses in our Consolidated Statements of Income, but does not impact our financial condition, net income or cash flows.

We account for our derivative contracts in accordance with derivatives and hedging guidance, which requires all derivatives not qualifying for a scope exception to be measured at fair value on the balance sheet as either assets or liabilities.  Transactions with counterparties that have master netting arrangements are reported net on the balance sheet.  See Note 16 for additional information about our derivative instruments.

Loss Contingencies and Environmental Liabilities

Pinnacle West and APS are involved in certain legal and environmental matters that arise in the normal course of business.  Contingent losses and environmental liabilities are recorded when it is determined that it is

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probable that a loss has occurred and the amount of the loss can be reasonably estimated.  When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, Pinnacle West and APS record a loss contingency at the minimum amount in the range.  Unless otherwise required by GAAP, legal fees are expensed as incurred.

Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan for the employees of Pinnacle West and its subsidiaries.  We also sponsor an other postretirement benefit plan for the employees of Pinnacle West and its subsidiaries that provides medical and life insurance benefits to retired employees.  Pension and other postretirement benefit expense are determined by actuarial valuations, based on assumptions that are evaluated annually.  See Note 7 for additional information on pension and other postretirement benefits.

Nuclear Fuel

APS amortizes nuclear fuel by using the unit-of-production method.  The unit-of-production method is based on actual physical usage.  APS divides the cost of the fuel by the estimated number of thermal units it expects to produce with that fuel.  APS then multiplies that rate by the number of thermal units produced within the current period.  This calculation determines the current period nuclear fuel expense.

APS also charges nuclear fuel expense for the interim storage and permanent disposal of spent nuclear fuel.  The DOE is responsible for the permanent disposal of spent nuclear fuel and charged APS $0.001 per kWh of nuclear generation through May 2014, at which point the DOE suspended the fee.  In accordance with a settlement agreement with the DOE in August 2014, we will now accrue a receivable for incurred claims and an offsetting regulatory liability through the settlement period ending December of 2016. See Note 10 for information on spent nuclear fuel disposal costs.

Income Taxes

Income taxes are provided using the asset and liability approach prescribed by guidance relating to accounting for income taxes.  We file our federal income tax return on a consolidated basis, and we file our state income tax returns on a consolidated or unitary basis.  In accordance with our intercompany tax sharing agreement, federal and state income taxes are allocated to each first-tier subsidiary as though each first-tier subsidiary filed a separate income tax return.  Any difference between that method and the consolidated (and unitary) income tax liability is attributed to the parent company.  The income tax accounts reflect the tax and interest associated with management’s estimate of the largest amount of tax benefit that is greater than 50% likely of being realized upon settlement for all known and measurable tax exposures (see Note 4).

Cash and Cash Equivalents

We consider all highly liquid investments with a remaining maturity of three months or less at acquisition to be cash equivalents.

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The following table summarizes supplemental Pinnacle West cash flow information for each of the last three years (dollars in thousands):

	Year ended December 31,
	2016		2015		2014
Cash paid (received) during the period for:
Income taxes, net of refunds	$	9,956	$	6,550	$	(102,154	)
Interest, net of amounts capitalized	184,462		170,209		177,074
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	114,855	$	83,798	$	44,712
Dividends declared but not paid	72,926		69,363		65,790

Intangible Assets

We have no goodwill recorded and have separately disclosed other intangible assets, primarily APS's software, on Pinnacle West’s Consolidated Balance Sheets. The intangible assets are amortized over their finite useful lives.  Amortization expense was $58 million in 2016, $58 million in 2015, and $53 million in 2014.  Estimated amortization expense on existing intangible assets over the next five years is $41 million in 2017, $23 million in 2018, $12 million in 2019, $4 million in 2020, and $1 million in 2021.  At December 31, 2016, the weighted-average remaining amortization period for intangible assets was 6 years.

Investments

El Dorado accounts for its investments using either the equity method (if significant influence) or the cost method (if less than 20% ownership and no significant influence).

Our investments in the nuclear decommissioning trust fund are accounted for in accordance with guidance on accounting for certain investments in debt and equity securities. See Note 13 and Note 19 for more information on these investments.

Business Segments

Pinnacle West’s reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electricity service to Native Load customers) and related activities and includes electricity generation, transmission and distribution. All other segment activities are insignificant.

Preferred Stock

At December 31, 2016, Pinnacle West had 10 million shares of serial preferred stock authorized with no par value, none of which was outstanding, and APS had 15,535,000 shares of various types of preferred stock authorized with $25, $50 and $100 par values, none of which was outstanding.

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2.    New Accounting Standards

ASU 2016-09, Stock Compensation: Improvements to Employee Share-Based Payment Accounting

In March 2016, new stock compensation accounting guidance was issued intended to simplify the accounting for employee share-based payments. The new guidance impacts several aspects of the accounting for share-based payments including: modifies the tax withholding threshold that triggers liability classification of an award, requires all excess income tax benefits and deficiencies arising from share-based payments to be recognized in earnings in the period they occur, simplifies the accounting for forfeitures, and clarifies certain cash flow presentation matters. Certain aspects of the standard must be adopted using a prospective approach and other aspects must be adopted using a modified retrospective approach.

During the fourth quarter of 2016, we elected to early adopt this standard, and accordingly have applied the guidance effective as of January 1, 2016. Prior to adoption of the new standard, our stock compensation awards were generally classified as liability awards and accounted for at fair value until settled because employees could withhold at more than the minimum statutory tax withholding rate. In accordance with the new guidance, certain of these stock compensation awards are now classified as equity awards and accounted for at grant date fair value. As a result of adopting the new standard, Pinnacle West recorded a cumulative effect adjustment to retained earnings of $6 million. The other provisions of the standard did not have a material impact on our consolidated financial statements. See Note 15 for additional details of the adoption impacts.

ASU 2015-07, Fair Value Measurement: Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent)

In May 2015, new accounting guidance was issued that removes the requirement to categorize certain investments valued using net asset value, as a practical expedient, within the fair value hierarchy. We retrospectively adopted this guidance during the first quarter of 2016. The adoption of this guidance modifies our fair value disclosures, but does not impact the methodology for valuing these instruments, or our financial statement results.  See Note 7 and Note 13.  

ASU 2014-09, Revenue from Contracts with Customers

In May 2014, a new revenue recognition accounting standard was issued. This standard provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. Since the issuance of the new revenue standard, additional guidance was issued to clarify certain aspects of the new revenue standard, including principal versus agent considerations, identifying performance obligations, and other narrow scope improvements. The new revenue standard, and related amendments, will be effective for us on January 1, 2018. The standard may be adopted using a full retrospective application or a simplified transition method that allows entities to record a cumulative effect adjustment in retained earnings at the date of initial application.

We plan on adopting this standard on January 1, 2018, and are currently evaluating the transition method and the effect on our financial statements. As part of our evaluation we continue to actively monitor certain industry issues being addressed by the American Institute of Certified Public Accountants’ Revenue Recognition Working Group and the Financial Accounting Standards Board’s Transition Resource Group. Conclusions reached by these groups may impact our application of the standard, specifically in regards to the treatment of contributions in aid of construction.

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ASU 2016-01, Financial Instruments: Recognition and Measurement

In January 2016, a new accounting standard was issued relating to the recognition and measurement of financial instruments. The new guidance will require certain investments in equity securities to be measured at fair value with changes in fair value recognized in net income, and modifies the impairment assessment of certain equity securities. The new standard is effective for us on January 1, 2018. Certain aspects of the standard may require a cumulative effect adjustment and other aspects of the standard are required to be adopted prospectively. We plan on adopting this standard on January 1, 2018, and continue to evaluate the impacts the new guidance may have on our financial statements.

ASU 2016-02, Leases

In February 2016, a new lease accounting standard was issued. This new standard supersedes the existing lease accounting model, and modifies both lessee and lessor accounting. The new standard will require a lessee to reflect most operating lease arrangements on the balance sheet by recording a right-of-use asset and a lease liability that will initially be measured at the present value of lease payments. Among other changes, the new standard also modifies the definition of a lease, and requires expanded lease disclosures. The new standard will be effective for us on January 1, 2019, with early application permitted. The standard must be adopted using a modified retrospective approach, with various optional practical expedients provided to facilitate transition. We are currently evaluating this new accounting standard and the impacts it may have on our financial statements.

ASU 2016-13, Financial Instruments: Measurement of Credit Losses

In June 2016, a new accounting standard was issued that amends the measurement of credit losses on certain financial instruments. The new standard will require entities to use a current expected credit loss model to measure impairment of certain investments in debt securities, trade accounts receivables, and other financial instruments. The new standard is effective for us on January 1, 2020 and must be adopted using a modified retrospective approach for certain aspects of the standard, and a prospective approach for other aspects of the standard. We are currently evaluating this new accounting standard and the impacts it may have on our financial statements.

ASU 2017-01, Business Combinations: Clarifying the Definition of a Business

                In January 2017, a new accounting standard was issued that clarifies the definition of a business. This standard is intended to assist entities with evaluating whether a transaction should be accounted for as an acquisition (or disposal) of assets or a business.  The definition of a business  affects many areas of accounting including acquisitions, disposals, goodwill, and consolidation. The new standard is effective for us on January 1, 2018 using a prospective approach. We are evaluating the impacts of adopting this new standard, and the impacts it may have on our financial statements.  

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3.    Regulatory Matters

Retail Rate Case Filing with the Arizona Corporation Commission

On June 1, 2016, APS filed an application with the ACC for an annual increase in retail base rates of $165.9 million. This amount excludes amounts that are currently collected on customer bills through adjustor mechanisms. The application requests that some of the balances in these adjustor accounts (aggregating to approximately $267.6 million as of December 31, 2015) be transferred into base rates through the ratemaking process. This transfer would not have an incremental effect on average customer bills. The average annual customer bill impact of APS’s request is an increase of 5.74% (the average annual bill impact for a typical APS residential customer is 7.96%).

The principal provisions of the application are:

• a test year ended December 31, 2015, adjusted as described below;

• an original cost rate base of $6.8 billion, which approximates the ACC-jurisdictional portion of the book value of utility assets, net of accumulated depreciation and other credits, as of December 31, 2015;

• the following proposed capital structure and costs of capital:

	Capital Structure		Cost of Capital
Long-term debt	44.20	%	5.13	%
Common stock equity	55.80	%	10.50	%
Weighted-average cost of capital			8.13	%

• a 1% return on the increment of fair value rate base above APS’s original cost rate base, as provided for by Arizona law;

• a base rate for fuel and purchased power costs of $0.029882 per kWh based on estimated 2017 prices (a decrease from the current base fuel rate of $0.03207 per kWh);

• authorization to defer for potential future recovery its share of the construction costs associated with installing selective catalytic reduction equipment at Four Corners (estimated at approximately $400 million in direct costs). APS proposes that the rates established in this rate case be increased through a step mechanism beginning in 2019 to reflect these deferred costs;

• authorization to defer for potential future recovery in the Company’s next general rate case the construction costs APS incurs for its Ocotillo power plant modernization project, once the project reaches commercial operation. APS estimates the direct construction costs at approximately $500 million and that the new facility will be fully in service by early 2019;

• authorization to defer until the Company’s next general rate case the increase or decrease in its Arizona property taxes attributable to tax rate changes after the date the rate application is adjudicated;

• updates and modifications to four of APS’s adjustor mechanisms - the PSA, the LFCR, the TCA and the Environmental Improvement Surcharge (“EIS”);

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• a number of proposed rate design changes for residential customers, including:

◦ change the on-peak time of use period from 12 p.m. - 7 p.m. to 3 p.m. - 8 p.m. Monday through Friday, excluding holidays;

◦ reduce the difference in the on- and off-peak energy price and lower all energy charges;

◦ offer four rate plan options, three of which have demand charges and a fourth that is available to non-partial requirements customers using less than 600 kWh on average per month; and

◦ modify the current net metering tariff to provide for a credit at the retail rate for the portion of generation by rooftop solar customers that offsets their own load, and for a credit for excess energy delivered to the grid at an export rate.

• proposed rate design changes for commercial customers, including an aggregation rider that allows certain large customers to qualify for a reduced rate, an extra-high load factor rate schedule for certain customers, and an economic development rate offering for new loads meeting certain criteria.

The Company requested that the increase become effective July 1, 2017.  On July 22, 2016, the ALJ set a procedural schedule for the rate proceeding, which supported completing the case within 12 months.

The ACC staff and intervenors began filing their direct testimony in late December 2016 and additional filings of testimony are ongoing. On January 12, 2017, APS began settlement discussions with all parties.  On January 13, 2017, the ALJ hearing the case before the ACC issued a procedural order delaying hearings on the case from the originally scheduled March 22, 2017 to April 24, 2017, to allow parties to participate in settlement discussions and prepare testimony on the distributed generation rate design issues addressed in the value and cost of DG decision.  According to the procedural order, settlement discussions are to be completed and, if applicable, any related settlement must be filed by March 17, 2017.  The procedural order also extended the rate case completion date as calculated by Commission rule for an additional 33 days. APS cannot predict the outcome of this case.

Prior Rate Case Filing

On June 1, 2011, APS filed an application with the ACC for a net retail base rate increase of $95.5 million.  APS requested that the increase become effective July 1, 2012.  The request would have increased the average retail customer bill by approximately 6.6%.  On January 6, 2012, APS and other parties to the general retail rate case entered into the 2012 Settlement Agreement detailing the terms upon which the parties agreed to settle the rate case.  On May 15, 2012, the ACC approved the 2012 Settlement Agreement without material modifications.

Settlement Agreement

The 2012 Settlement Agreement provides for a zero net change in base rates, consisting of:  (1) a non-fuel base rate increase of $116.3 million; (2) a fuel-related base rate decrease of $153.1 million (to be implemented by a change in the Base Fuel Rate from $0.03757 to $0.03207 per kWh); and (3) the transfer of cost recovery for certain renewable energy projects from the RES surcharge to base rates in an estimated amount of $36.8 million.

Other key provisions of the 2012 Settlement Agreement include the following:

•An authorized return on common equity of 10.0%;

•A capital structure comprised of 46.1% debt and 53.9% common equity;

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• A test year ended December 31, 2010, adjusted to include plant that is in service as of March 31, 2012;

• Deferral for future recovery or refund of property taxes above or below a specified 2010 test year level caused by changes to the Arizona property tax rate as follows:

• Deferral of increases in property taxes of 25% in 2012, 50% in 2013 and 75% for 2014 and subsequent years if Arizona property tax rates increase; and

•Deferral of 100% in all years if Arizona property tax rates decrease;

• A procedure to allow APS to request rate adjustments prior to its next general rate case related to APS’s acquisition of additional interests in Units 4 and 5 and the related closure of Units 1-3 of Four Corners (APS made its filing under this provision on December 30, 2013, see "Four Corners" below);

• Implementation of a “Lost Fixed Cost Recovery” rate mechanism to support energy efficiency and distributed renewable generation;

• Modifications to the Environmental Improvement Surcharge to allow for the recovery of carrying costs for capital expenditures associated with government-mandated environmental controls, subject to an existing cents per kWh cap on cost recovery that could produce up to approximately $5 million in revenues annually;

•Modifications to the PSA, including the elimination of the 90/10 sharing provision;

• A limitation on the use of the RES surcharge and the DSMAC to recoup capital expenditures not required under the terms of the settlement agreement for the 2009 retail rate case (the "2009 Settlement Agreement");

• Allowing a negative credit that existed in the PSA rate to continue until February 2013, rather than being reset on the anticipated July 1, 2012 rate effective date;

• Modification of the TCA to streamline the process for future transmission-related rate changes; and

• Implementation of various changes to rate schedules, including the adoption of an experimental “buy-through” rate that could allow certain large commercial and industrial customers to select alternative sources of generation to be supplied by APS.

The 2012 Settlement Agreement was approved by the ACC on May 15, 2012, with new rates effective on July 1, 2012.  This accomplished a goal set by the parties to the 2009 Settlement Agreement to process subsequent rate cases within twelve months of sufficiency findings from the ACC staff, which generally occurs within 30 days after the filing of a rate case.

Cost Recovery Mechanisms

APS has received regulatory decisions that allow for more timely recovery of certain costs through the following recovery mechanisms.

Renewable Energy Standard.  In 2006, the ACC approved the RES.  Under the RES, electric utilities that are regulated by the ACC must supply an increasing percentage of their retail electric energy sales from eligible renewable resources, including solar, wind, biomass, biogas and geothermal technologies.  In order to achieve these requirements, the ACC allows APS to include a RES surcharge as part of customer bills to

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recover the approved amounts for use on renewable energy projects. Each year APS is required to file a five-year implementation plan with the ACC and seek approval for funding the upcoming year’s RES budget.

In December 2014, the ACC voted that it had no objection to APS implementing an APS-owned rooftop solar research and development program aimed at learning how to efficiently enable the integration of rooftop solar and battery storage with the grid.  The first stage of the program, called the "Solar Partner Program," placed 8 MW of residential rooftop solar on strategically selected distribution feeders in an effort to maximize potential system benefits, as well as made systems available to limited-income customers who could not easily install solar through transactions with third parties. The second stage of the program, which included an additional 2 MW of rooftop solar and energy storage, placed two energy storage systems sized at 2 MW on two different high solar penetration feeders to test various grid-related operation improvements and system interoperability, and was in operation by the end of 2016.  The ACC expressly reserved that any determination of prudency of the residential rooftop solar program for rate making purposes would not be made until the project was fully in service, and APS has requested cost recovery for the project in its currently pending rate case. On September 30, 2016, APS presented its preliminary findings from the residential rooftop solar program in a filing with the ACC.

On July 1, 2015, APS filed its 2016 RES implementation plan and proposed a RES budget of approximately $148 million. On January 12, 2016, the ACC approved APS’s plan and requested budget.

On July 1, 2016, APS filed its 2017 RES Implementation Plan and proposed a budget of approximately $150 million. APS’s budget request included additional funding to process the high volume of residential rooftop solar interconnection requests and also requested a permanent waiver of the residential distributed energy requirement for 2017 contained in the RES rules. The ACC has not yet ruled on the Company’s 2017 RES Implementation Plan.

In September of 2016, the ACC initiated a proceeding which will examine the possible modernization and expansion of the RES.  The ACC noted that many of the provisions of the original rule may no longer be appropriate, and the underlying economic assumptions associated with the rule have changed dramatically.  The proceeding will review such issues as the rapidly declining cost of solar generation, an increased interest in community solar projects, energy storage options, and the decline in fossil fuel generation due to stringent regulations of the EPA.  The proceeding will also examine the feasibility of increasing the standard to 30% of retail sales by 2030, in contrast to the current standard of 15% of retail sales by 2025.  APS cannot predict the outcome of this proceeding.

Demand Side Management Adjustor Charge. The ACC Electric Energy Efficiency Standards require APS to submit a Demand Side Management Implementation Plan ("DSM Plan") for review by and approval of the ACC. In March 2014, the ACC approved a Resource Savings Initiative that allows APS to count towards compliance with the ACC Electric Energy Efficiency Standards, savings from improvements to APS’s transmission and delivery system, generation and facilities that have been approved through a DSM Plan. 

On March 20, 2015, APS filed an application with the ACC requesting a budget of $68.9 million for 2015 and minor modifications to its DSM portfolio going forward, including for the first time three resource savings projects which reflect energy savings on APS's system. The ACC approved APS’s 2015 DSM budget on November 25, 2015. In its decision, the ACC also approved that verified energy savings from APS's resource savings projects could be counted toward compliance with the Electric Energy Efficiency Standard, however, the ACC ruled that APS was not allowed to count savings from systems savings projects toward determination of its achievement tier level for its performance incentive, nor may APS include savings from conservation voltage reduction in the calculation of its LFCR mechanism.

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On June 1, 2015, APS filed its 2016 DSM Plan requesting a budget of $68.9 million and minor modifications to its DSM portfolio to increase energy savings and cost effectiveness of the programs. On April 1, 2016, APS filed an amended 2016 DSM Plan that sought minor modifications to its existing DSM Plan and requested to continue the current DSMAC and current budget of $68.9 million. On July 12, 2016, the ACC approved APS’s amended DSM Plan and directed APS to spend up to an additional $4 million on a new residential demand response or load management program that facilitates energy storage technology. On December 5, 2016, APS filed for ACC approval of a $4 million Residential Demand Response, Energy Storage and Load Management Program.

On June 1, 2016, the Company filed its 2017 DSM Implementation Plan, in which APS proposes programs and measures that specifically focus on reducing peak demand, shifting load to off-peak periods and educating customers about strategies to manage their energy and demand.  The requested budget in the 2017 DSM Implementation Plan is $62.6 million. On January 27, 2017, APS filed an updated and modified 2017 DSM Implementation Plan that incorporated the proposed Residential Demand Response, Energy Storage and Load Management Program and the requested budget increased to $66.6 million. The ACC has not yet ruled on the Company’s 2017 DSM Plan.    

Electric Energy Efficiency. On June 27, 2013, the ACC voted to open a new docket investigating whether the Electric Energy Efficiency Standards should be modified. The ACC held a series of three workshops in March and April 2014 to investigate methodologies used to determine cost effective energy efficiency programs, cost recovery mechanisms, incentives, and potential changes to the Electric Energy Efficiency and Resource Planning Rules.

On November 4, 2014, the ACC staff issued a request for informal comment on a draft of possible amendments to Arizona’s Electric Energy Efficiency Standards. The draft proposed substantial changes to the rules and energy efficiency standards. The ACC accepted written comments and took public comment regarding the possible amendments on December 19, 2014. On July 12, 2016, the ACC ordered that ACC staff convene a workshop within 120 days to discuss a number of issues related to the Electric Energy Efficiency Standards, including the process of determining the cost effectiveness of DSM programs and the treatment of peak demand and capacity reductions, among others. ACC staff convened the workshop on November 29, 2016 and sought public comment on potential revisions to the Electric Energy Efficiency Standards. APS cannot predict the outcome of this proceeding.

PSA Mechanism and Balance.  The PSA provides for the adjustment of retail rates to reflect variations in retail fuel and purchased power costs. The PSA is subject to specified parameters and procedures, including the following:

• APS records deferrals for recovery or refund to the extent actual retail fuel and purchased power costs vary from the Base Fuel Rate;

• An adjustment to the PSA rate is made annually each February 1 (unless otherwise approved by the ACC) and goes into effect automatically unless suspended by the ACC;

• The PSA uses a forward-looking estimate of fuel and purchased power costs to set the annual PSA rate, which is reconciled to actual costs experienced for each PSA Year (February 1 through January 31) (see the following bullet point);

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• The PSA rate includes (a) a “Forward Component,” under which APS recovers or refunds differences between expected fuel and purchased power costs for the upcoming calendar year and those embedded in the Base Fuel Rate; (b) a “Historical Component,” under which differences between actual fuel and purchased power costs and those recovered through the combination of the Base Fuel Rate and the Forward Component are recovered during the next PSA Year; and (c) a “Transition Component,” under which APS may seek mid-year PSA changes due to large variances between actual fuel and purchased power costs and the combination of the Base Fuel Rate and the Forward Component; and

• The PSA rate may not be increased or decreased more than $0.004 per kWh in a year without permission of the ACC.

The following table shows the changes in the deferred fuel and purchased power regulatory asset (liability) for 2016 and 2015 (dollars in thousands):

	Year Ended December 31,
	2016			2015
Beginning balance	$	(9,688	)	$	6,926
Deferred fuel and purchased power costs - current period	60,303			(14,997		)
Amounts charged to customers	(38,150		)	(1,617		)
Ending balance	$	12,465		$	(9,688	)

The PSA rate for the PSA year beginning February 1, 2017 is $(0.001348) per kWh, as compared to $0.001678 per kWh for the prior year.  This new rate is comprised of a forward component of $(0.001027) per kWh and a historical component of $(0.000321) per kWh. 

Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters.  In July 2008, FERC approved an Open Access Transmission Tariff for APS to move from fixed rates to a formula rate-setting methodology in order to more accurately reflect and recover the costs that APS incurs in providing transmission services.  A large portion of the rate represents charges for transmission services to serve APS’s retail customers ("Retail Transmission Charges").  In order to recover the Retail Transmission Charges, APS was previously required to file an application with, and obtain approval from, the ACC to reflect changes in Retail Transmission Charges through the TCA.  Under the terms of the 2012 Settlement Agreement, however, an adjustment to rates to recover the Retail Transmission Charges will be made annually each June 1 and will go into effect automatically unless suspended by the ACC.

The formula rate is updated each year effective June 1 on the basis of APS’s actual cost of service, as disclosed in APS’s FERC Form 1 report for the previous fiscal year.  Items to be updated include actual capital expenditures made as compared with previous projections, transmission revenue credits and other items.  The resolution of proposed adjustments can result in significant volatility in the revenues to be collected.  APS reviews the proposed formula rate filing amounts with the ACC staff.  Any items or adjustments which are not agreed to by APS and the ACC staff can remain in dispute until settled or litigated at FERC.  Settlement or litigated resolution of disputed issues could require an extended period of time and could have a significant effect on the Retail Transmission Charges because any adjustment, though applied prospectively, may be calculated to account for previously over- or under-collected amounts.

Effective June 1, 2015, APS’s annual wholesale transmission rates for all users of its transmission system decreased by approximately $17.6 million for the twelve-month period beginning June 1, 2015 in

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accordance with the FERC-approved formula.  An adjustment to APS’s retail rates to recover FERC-approved transmission charges went into effect automatically on June 1, 2015.

Effective June 1, 2016, APS's annual wholesale transmission rates for all users of its transmission system increased by approximately $24.9 million for the twelve-month period beginning June 1, 2016 in accordance with the FERC-approved formula.  An adjustment to APS’s retail rates to recover FERC approved transmission charges went into effect automatically on June 1, 2016.

APS's formula rate protocols have been in effect since 2008. Recent FERC orders suggest that FERC is examining the structure of formula rate protocols and may require companies to make changes to their protocols in the future. As a result, APS is evaluating how its formula rate protocols compare with more recently approved formula rate protocols and anticipates that it will make a filing to update its formula rate protocols in the first quarter of 2017.

Lost Fixed Cost Recovery Mechanism. The LFCR mechanism permits APS to recover on an after-the-fact basis a portion of its fixed costs that would otherwise have been collected by APS in the kWh sales lost due to APS energy efficiency programs and to distributed generation such as rooftop solar arrays.  The fixed costs recoverable by the LFCR mechanism were established in the 2012 Settlement Agreement and amount to approximately 3.1 cents per residential kWh lost and 2.3 cents per non-residential kWh lost.  The LFCR adjustment has a year-over-year cap of 1% of retail revenues.  Any amounts left unrecovered in a particular year because of this cap can be carried over for recovery in a future year.  The kWh’s lost from energy efficiency are based on a third-party evaluation of APS’s energy efficiency programs.  Distributed generation sales losses are determined from the metered output from the distributed generation units.

APS files for a LFCR adjustment every January.  APS filed its 2015 annual LFCR adjustment on January 15, 2015, requesting an LFCR adjustment of $38.5 million, which was approved on March 2, 2015, effective for the first billing cycle of March. APS filed its 2016 annual LFCR adjustment on January 15, 2016, requesting an LFCR adjustment of $46.4 million (a $7.9 million annual increase), to be effective for the first billing cycle of March 2016. The ACC approved the 2016 annual LFCR to be effective in May 2016. Because the LFCR mechanism has a balancing account that trues up any under or over recoveries, the two month delay in implementation did not have an adverse effect on APS. APS filed its 2017 LFCR adjustment on January 13, 2017. APS requested an adjustment of $63.7 million (a $17.3 million per year increase over 2016 levels), to be effective the first billing cycle of March 2017.

Net Metering

In 2015, the ACC voted to conduct a generic evidentiary hearing on the value and cost of distributed generation to gather information that will inform the ACC on net metering issues and cost of service studies in upcoming utility rate cases.  A hearing was held in April 2016. On October 7, 2016, the ALJ issued a recommendation in the docket concerning the value and cost of DG solar installations. On December 20, 2016, the ACC completed its open meeting to consider the recommended decision by the ALJ. After making several amendments, the ACC approved the recommended decision by a 4-1 vote. As a result of the ACC’s action, effective following APS’s pending rate case, the current net metering tariff that governs payments for energy exported to the grid from rooftop solar systems will be replaced by a more formula-driven approach that will utilize inputs from historical wholesale solar power costs and eventually an avoided cost methodology.

As amended, the decision provides that payments by utilities for energy exported to the grid from DG solar facilities will be determined using a resource comparison proxy methodology, a method that is based on the price that APS pays for utility-scale solar projects on a five year rolling average, while a forecasted avoided

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cost methodology is being developed.  The price established by this resource comparison proxy method will be updated annually (between rate cases) but will not be decreased by more than 10% per year. Once the avoided cost methodology is developed, the ACC will determine in APS's subsequent rate cases which method (or a combination of methods) is appropriate to determine the actual price to be paid by that utility for exported distributed energy.

In addition, the ACC made the following determinations:

• Customers who have interconnected a DG system or submitted an application for interconnection for DG systems prior to the date new rates are effective based on APS' pending rate case will be grandfathered for a period of 20 years from the date of interconnection;

• Customers with DG solar systems are to be considered a separate class of customers for ratemaking purposes; and

• Once an export price is set for APS, no netting or banking of retail credits will be available for new DG customers, and the then-applicable export price will be guaranteed for new customers for a period of 10 years.

This decision of the ACC addresses policy determinations only. The decision states that its principles will be applied in future rate cases, and the policy determinations themselves may be subject to future change as are all ACC policies. The determination of the initial export energy price to be paid by APS will be made in APS’s currently pending rate case, which is scheduled for hearing by the ACC in April 2017.  APS cannot predict the outcome of this determination.

The ACC’s decision did not make any policy determinations as to any specific costs to be charged to DG solar system customers for their use of the grid. The determination of any such costs will be made in APS's future rate cases.

On January 23, 2017, The Alliance for Solar Choice ("TASC") sought rehearing of the ACC's decision regarding the value and cost of DG. TASC asserts that the ACC improperly ignored the Administrative Procedure Act, failed to give adequate notice regarding the scope of the proceedings, and relied on information that was not submitted as evidence, among other alleged defects. TASC's request for rehearing is required for TASC to challenge this decision in court. To date, the ACC has taken no action on the rehearing request. The ACC's decision is expected to remain in effect during any legal challenge.

Appellate Review of Third-Party Regulatory Decision ("System Improvement Benefits" or "SIB")

In a recent appellate challenge to an ACC rate decision involving a water company, the Arizona Court of Appeals considered the question of how the ACC should determine the “fair value” of a utility’s property, as specified in the Arizona Constitution, in connection with authorizing the recovery of costs through rate adjustors outside of a rate case.  The Court of Appeals reversed the ACC’s method of finding fair value in that case, and raised questions concerning the relationship between the need for fair value findings and the recovery of capital and certain other utility costs through adjustors. The ACC sought review by the Arizona Supreme Court of this decision, and APS filed a brief supporting the ACC’s petition to the Arizona Supreme Court for review of the Court of Appeals’ decision.  On February 9, 2016, the Arizona Supreme Court granted review of the decision and on August 8, 2016, the Arizona Supreme Court vacated the Court of Appeals opinion and affirmed the ACC’s orders approving the water company’s SIB adjustor.

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System Benefits Charge

The 2012 Settlement Agreement  provided that once APS achieved full funding of its decommissioning obligation under the sale leaseback agreements covering Unit 2 of Palo Verde, APS was required to implement a reduced System Benefits charge effective January 1, 2016.  Beginning on January 1, 2016, APS began implementing a reduced System Benefits charge.  The impact on APS retail revenues from the new System Benefits charge is an overall reduction of approximately $14.6 million per year with a corresponding reduction in depreciation and amortization expense.

Subpoena from Arizona Corporation Commissioner Robert Burns

On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, filed subpoenas in APS’s current retail rate proceeding to APS and Pinnacle West for the production of records and information relating to a range of expenditures from 2011 through 2016. The subpoenas requested information concerning marketing and advertising expenditures, charitable donations, lobbying expenses, contributions to 501(c)(3) and (c)(4) nonprofits and political contributions. The return date for the production of information was set as September 15, 2016. The subpoenas also sought testimony from Company personnel having knowledge of the material, including the Chief Executive Officer.

On September 9, 2016, APS filed with the ACC a motion to quash the subpoenas or, alternatively to stay APS's obligations to comply with the subpoenas and decline to decide APS's motion pending court proceedings. Contemporaneously with the filing of this motion, APS and Pinnacle West filed a complaint for special action and declaratory judgment in the Superior Court of Arizona for Maricopa County, seeking a declaratory judgment that Commissioner Burns’ subpoenas are contrary to law. On September 15, 2016, APS produced all non-confidential and responsive documents and offered to produce any remaining responsive documents that are confidential after an appropriate confidentiality agreement is signed.

On February 7, 2017, Commissioner Burns opened a new ACC docket and indicated that its purpose is to study and rectify problems with transparency and disclosure regarding financial contributions from regulated monopolies or other stakeholders who may appear before the ACC that may directly or indirectly benefit an ACC Commissioner, a candidate for ACC Commissioner, or key ACC staff.  As part of this docket, Commissioner Burns set March 24, 2017 as a deadline for APS to produce all information previously requested through the subpoenas.  Commissioner Burns has also scheduled a workshop in this matter for March 17, 2017.  APS and Pinnacle West cannot predict the outcome of this matter.

Four Corners

On December 30, 2013, APS purchased SCE’s 48% ownership interest in each of Units 4 and 5 of Four Corners.  The 2012 Settlement Agreement includes a procedure to allow APS to request rate adjustments prior to its next general rate case related to APS’s acquisition of the additional interests in Units 4 and 5 and the related closure of Units 1-3 of Four Corners.  APS made its filing under this provision on December 30, 2013.  On December 23, 2014, the ACC approved rate adjustments resulting in a revenue increase of $57.1 million on an annual basis.  This includes the deferral for future recovery of all non-fuel operating costs for the acquired SCE interest in Four Corners, net of the non-fuel operating costs savings resulting from the closure of Units 1-3 from the date of closing of the purchase through its inclusion in rates.  The 2012 Settlement Agreement also provides for deferral for future recovery of all unrecovered costs incurred in connection with the closure of Units 1-3.  The deferral balance related to the acquisition of SCE’s interest in Units 4 and 5 and the closure of Units 1-3 was $64 million as of December 31, 2016 and is being amortized in rates over a total of 10 years. On February 23, 2015, the Arizona School Boards Association and the Association of Business Officials filed a

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notice of appeal in Division 1 of the Arizona Court of Appeals of the ACC decision approving the rate adjustments. APS has intervened and is actively participating in the proceeding. The Arizona Court of Appeals suspended the appeal pending the Arizona Supreme Court's decision in the SIB matter discussed above. On August 8, 2016, the Arizona Supreme Court issued its opinion in the SIB matter, and the Arizona Court of Appeals has now ordered supplemental briefing on how that SIB decision should affect the challenge to the Four Corners rate adjustment. We cannot predict when or how this matter will be resolved.

As part of APS’s acquisition of SCE’s interest in Units 4 and 5, APS and SCE agreed, via a “Transmission Termination Agreement” that, upon closing of the acquisition, the companies would terminate an existing transmission agreement (“Transmission Agreement”) between the parties that provides transmission capacity on a system (the “Arizona Transmission System”) for SCE to transmit its portion of the output from Four Corners to California.  APS previously submitted a request to FERC related to this termination, which resulted in a FERC order denying rate recovery of $40 million that APS agreed to pay SCE associated with the termination.   On December 22, 2015, APS and SCE agreed to terminate the Transmission Termination Agreement and allow for the Transmission Agreement to expire according to its terms, which includes settling obligations in accordance with the terms of the Transmission Agreement. APS established a regulatory asset of $12 million in 2015 in connection with the payment required under the terms of the Transmission Agreement. On July 1, 2016, FERC issued an order denying APS’s request to recover the regulatory asset through its FERC-jurisdictional rates.  APS and SCE completed the termination of the Transmission Agreement on July 6, 2016. APS made the required payment to SCE and wrote-off the $12 million regulatory asset and charged operating revenues to reflect the effects of this order in the second quarter of 2016.  On July 29, 2016, APS filed a request for rehearing with FERC. In its order denying recovery, FERC also referred to its enforcement division a question of whether the agreement between APS and SCE relating to the settlement of obligations under the Transmission Agreement was a jurisdictional contract that should have been filed with FERC. APS cannot predict the outcome of either matter.

Cholla

On September 11, 2014, APS announced that it would close Cholla Unit 2 and cease burning coal at the other APS-owned units (Units 1 and 3) at the plant by the mid-2020s, if EPA approves a compromise proposal offered by APS to meet required environmental and emissions standards and rules. On April 14, 2015, the ACC approved APS's plan to retire Unit 2, without expressing any view on the future recoverability of APS's remaining investment in the Unit. APS closed Unit 2 on October 1, 2015. On January 13, 2017, EPA approved a final rule incorporating APS's compromise proposal. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

Previously, APS estimated Cholla Unit 2’s end of life to be 2033. APS is currently recovering a return on and of the net book value of the unit in base rates and is seeking recovery of the unit’s decommissioning and other retirement-related costs over the previously estimated remaining life of the plant in its current retail rate case. APS believes it will be allowed recovery of the remaining net book value of Unit 2 ($116 million as of December 31, 2016), in addition to a return on its investment. In accordance with GAAP, in the third quarter of 2014, Unit 2’s remaining net book value was reclassified from property, plant and equipment to a regulatory asset. If the ACC does not allow full recovery of the remaining net book value of Cholla Unit 2, all or a portion of the regulatory asset will be written off and APS’s net income, cash flows, and financial position will be negatively impacted.

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Navajo Plant

On February 13, 2017, the co-owners of the Navajo Plant voted not to pursue continued operation of the plant beyond December 2019, the expiration of the current lease term, and to pursue a new lease or lease extension with the Navajo Nation that would allow decommissioning activities to begin after December 2019 instead of later this year. Various stakeholders including regulators, tribal representatives and others interested in the continued operation of the plant intend to meet to determine if an alternate solution can be reached that would permit continued operation of the plant beyond 2019. We cannot predict whether any alternate solutions will be found that would be acceptable to all of the stakeholders and feasible to implement. APS is currently recovering depreciation and a return on the net book value of its interest in the Navajo Plant. APS will seek continued recovery in rates for the book value of its remaining investment in the plant ($108 million as of December 31, 2016, see Note 9 for additional details) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and which may be material. We cannot predict whether APS would obtain such recovery.

On February 14, 2017, the ACC opened a docket titled "ACC Investigation Concerning the Future of the Navajo Generating Station" with the stated goal of engaging stakeholders and negotiating a sustainable pathway for the Navajo Plant to continue operating in some form after December 2019. APS cannot predict the outcome of this proceeding.

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Regulatory Assets and Liabilities

The detail of regulatory assets is as follows (dollars in thousands):

S	Amortization Through	December 31, 2016				December 31, 2015
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	711,059	$	—	$	619,223
Retired power plant costs	2033	9,913		117,591		9,913		127,518
Income taxes - AFUDC equity	2046	6,305		152,118		5,495		133,712
Deferred fuel and purchased power — mark-to-market (Note 16)	2020	—		42,963		71,852		69,697
Four Corners cost deferral	2024	6,689		56,894		6,689		63,582
Income taxes — investment tax credit basis adjustment	2046	2,120		54,356		1,766		48,462
Lost fixed cost recovery	2017	61,307		—		45,507		—
Palo Verde VIEs (Note 18)	2046	—		18,775		—		18,143
Deferred compensation	2036	—		35,595		—		34,751
Deferred property taxes	(d)	—		73,200		—		50,453
Loss on reacquired debt	2038	1,637		16,942		1,515		16,375
AG-1 deferral	2018	—		5,868		—		—
Demand side management (b)	2017	3,744		—		—		—
Tax expense of Medicare subsidy	2024	1,513		10,589		1,520		12,163
Transmission vegetation management	2016	—		—		4,543		—
Mead-Phoenix transmission line CIAC	2050	332		10,708		332		11,040
Deferred fuel and purchased power (b) (c)	2017	12,465		—		—		—
Coal reclamation	2026	418		5,182		418		6,085
Other	Various	432		1,588		5		2,942
Total regulatory assets (e)		$	106,875	$	1,313,428	$	149,555	$	1,214,146

(a) This asset represents the future recovery of pension benefit obligations through retail rates.  If these costs are disallowed by the ACC, this regulatory asset would be charged to OCI and result in lower future revenues.  See Note 7 for further discussion.

(b) See “Cost Recovery Mechanisms” discussion above.

(c) Subject to a carrying charge.

(d) Per the provision of the 2012 Settlement Agreement.

(e) There are no regulatory assets for which the ACC has allowed recovery of costs, but not allowed a return by exclusion from rate base.  FERC rates are set using a formula rate as described in “Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters.”

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The detail of regulatory liabilities is as follows (dollars in thousands):

	Amortization Through	December 31, 2016				December 31, 2015
		Current		Non-Current		Current		Non-Current
Asset retirement obligations	2057	$	—	$	279,976	$	—	$	277,554
Removal costs	(a)	29,899		223,145		39,746		240,367
Other postretirement benefits	(d)	32,662		123,913		34,100		179,521
Income taxes — deferred investment tax credit	2046	4,368		108,827		3,604		97,175
Income taxes - change in rates	2045	1,771		70,898		1,113		72,454
Spent nuclear fuel	2047	—		71,726		3,051		67,437
Renewable energy standard (b)	2017	26,809		—		43,773		4,365
Demand side management (b)	2019	—		20,472		6,079		19,115
Sundance maintenance	2030	—		15,287		—		13,678
Deferred fuel and purchased power (b) (c)	2016	—		—		9,688		—
Deferred gains on utility property	2018	2,063		8,895		2,062		6,001
Four Corners coal reclamation	2031	—		18,248		—		8,920
Other	Various	2,327		7,529		2,550		7,565
Total regulatory liabilities		$	99,899	$	948,916	$	145,766	$	994,152

(a) In accordance with regulatory accounting guidance, APS accrues for removal costs for its regulated assets, even if there is no legal obligation for removal (see Note 11).

(b) See “Cost Recovery Mechanisms” discussion above.

(c) Subject to a carrying charge.

(d) See Note 7.

4.    Income Taxes

Certain assets and liabilities are reported differently for income tax purposes than they are for financial statement purposes.  The tax effect of these differences is recorded as deferred taxes.  We calculate deferred taxes using currently enacted income tax rates.

APS has recorded regulatory assets and regulatory liabilities related to income taxes on its Balance Sheets in accordance with accounting guidance for regulated operations.  The regulatory assets are for certain temporary differences, primarily the allowance for equity funds used during construction, investment tax credit basis adjustment and tax expense of Medicare subsidy.  The regulatory liabilities primarily relate to deferred taxes resulting from investment tax credits (“ITC”) and the change in income tax rates.

In accordance with regulatory requirements, APS ITCs are deferred and are amortized over the life of the related property with such amortization applied as a credit to reduce current income tax expense in the statement of income.

Net income associated with the Palo Verde sale leaseback VIEs is not subject to tax (see Note 18).  As a result, there is no income tax expense associated with the VIEs recorded on the Pinnacle West Consolidated and APS Consolidated Statements of Income.

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The following is a tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year that are included in accrued taxes and unrecognized tax benefits (dollars in thousands):

	Pinnacle West Consolidated									APS Consolidated
	2016			2015			2014			2016			2015			2014
Total unrecognized tax benefits, January 1	$	34,447		$	44,775		$	41,997		$	34,447		$	44,775		$	41,997
Additions for tax positions of the current year	2,695			2,175			4,309			2,695			2,175			4,309
Additions for tax positions of prior years	886			—			751			886			—			751
Reductions for tax positions of prior years for:
Changes in judgment	(1,953		)	(10,244		)	(2,282		)	(1,953		)	(10,244		)	(2,282		)
Settlements with taxing authorities	—			—			—			—			—			—
Lapses of applicable statute of limitations	—			(2,259		)	—			—			(2,259		)	—
Total unrecognized tax benefits, December 31	$	36,075		$	34,447		$	44,775		$	36,075		$	34,447		$	44,775

Included in the balances of unrecognized tax benefits are the following tax positions that, if recognized, would decrease our effective tax rate (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	2016		2015		2014		2016		2015		2014
Tax positions, that if recognized, would decrease our effective tax rate	$	11,313	$	9,523	$	11,207	$	11,313	$	9,523	$	11,207

As of the balance sheet date, the tax year ended December 31, 2013 and all subsequent tax years remain subject to examination by the IRS.  With a few exceptions, we are no longer subject to state income tax examinations by tax authorities for years before 2012.

We reflect interest and penalties, if any, on unrecognized tax benefits in the Pinnacle West Consolidated and APS Consolidated Statements of Income as income tax expense.  The amount of interest expense or benefit recognized related to unrecognized tax benefits are as follows (dollars in thousands): 

	Pinnacle West Consolidated							APS Consolidated
	2016		2015			2014		2016		2015			2014
Unrecognized tax benefit interest expense/(benefit) recognized	$	529	$	(161	)	$	752	$	529	$	(161	)	$	752

Following are the total amount of accrued liabilities for interest recognized related to unrecognized benefits that could reverse and decrease our effective tax rate to the extent matters are settled favorably (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	2016		2015		2014		2016		2015		2014
Unrecognized tax benefit interest accrued	$	1,333	$	804	$	965	$	1,333	$	804	$	965

Additionally, as of December 31, 2016, we have recognized less than $1 million of interest expense to be paid on the underpayment of income taxes for certain adjustments that we have filed, or will file, with the IRS.

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The components of income tax expense are as follows (dollars in thousands):

	Pinnacle West Consolidated							APS Consolidated
	Year Ended December 31,							Year Ended December 31,
	2016		2015			2014		2016		2015		2014
Current:
Federal	$	8,630	$	(12,335	)	$	25,054	$	711	$	6,485	$	40,115
State	1,259		4,763			10,382		4,276		7,813		15,598
Total current	9,889		(7,572		)	35,436		4,987		14,298		55,713
Deferred:
Federal	201,743		221,505			167,365		215,178		208,326		165,027
State	24,779		23,787			17,904		25,677		23,217		16,620
Total deferred	226,522		245,292			185,269		240,855		231,543		181,647
Income tax expense	$	236,411	$	237,720		$	220,705	$	245,842	$	245,841	$	237,360

On the APS Consolidated Statements of Income, federal and state income taxes are allocated between operating income and other income.

The following chart compares pretax income at the 35% federal income tax rate to income tax expense (dollars in thousands):

	Pinnacle West Consolidated									APS Consolidated
	Year Ended December 31,									Year Ended December 31,
	2016			2015			2014			2016			2015			2014
Federal income tax expense at 35% statutory rate	$	244,278		$	242,869		$	225,540		$	254,617		$	250,267		$	239,638
Increases (reductions) in tax expense resulting from:
State income tax net of federal income tax benefit	16,311			18,265			18,149			18,750			20,433			21,148
Credits and favorable adjustments related to prior years resolved in current year	—			(2,169		)	—			—			(1,892		)	—
Medicare Subsidy Part-D	844			837			830			844			837			830
Allowance for equity funds used during construction (see Note 1)	(11,724		)	(9,711		)	(8,523		)	(11,724		)	(9,711		)	(8,523		)
Palo Verde VIE noncontrolling interest (see Note 18)	(6,823		)	(6,626		)	(9,135		)	(6,823		)	(6,626		)	(9,135		)
Investment tax credit amortization	(5,887		)	(5,527		)	(4,928		)	(5,887		)	(5,527		)	(4,928		)
Other	(588		)	(218		)	(1,228		)	(3,935		)	(1,940		)	(1,670		)
Income tax expense	$	236,411		$	237,720		$	220,705		$	245,842		$	245,841		$	237,360

    On February 17, 2011, Arizona enacted legislation (H.B. 2001) that included a four-year phase-in of corporate income tax rate reductions beginning in 2014.  As a result of these tax rate reductions, Pinnacle West has revised the tax rate applicable to reversing temporary items in Arizona.  In accordance with accounting for regulated companies, the benefit of this rate reduction is substantially offset by a regulatory liability.  As of December 31, 2016, APS has recorded a regulatory liability of $74 million, with a corresponding decrease in accumulated deferred income tax liabilities, to reflect the impact of this change in tax law.

On April 4, 2013, New Mexico enacted legislation (H.B. 641) that included a five-year phase-in of corporate income tax rate reductions beginning in 2014.  As a result of these tax rate reductions, Pinnacle West

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has revised the tax rate applicable to reversing temporary items in New Mexico. In accordance with accounting for regulated companies, the benefit of this rate reduction is substantially offset by a regulatory liability.  As of December 31, 2016, APS has recorded a regulatory liability of $2 million, with a corresponding decrease in accumulated deferred income tax liabilities, to reflect the impact of this change in tax law.

The components of the net deferred income tax liability were as follows (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	December 31,						December 31,
	2016			2015			2016			2015
DEFERRED TAX ASSETS
Risk management activities	$	26,614		$	70,498		$	26,614		$	70,498
Regulatory liabilities:
Asset retirement obligation and removal costs	200,140			216,765			200,140			216,765
Unamortized investment tax credits	113,195			100,779			113,195			100,779
Other postretirement benefits	60,375			83,034			60,375			83,034
Other	63,311			60,707			63,311			60,707
Pension liabilities	204,436			191,028			194,981			181,787
Renewable energy incentives	56,379			60,956			56,379			60,956
Credit and loss carryforwards	75,944			59,557			1,645			—
Other	158,421			149,033			187,453			176,016
Total deferred tax assets	958,815			992,357			904,093			950,542
DEFERRED TAX LIABILITIES
Plant-related	(3,297,989		)	(3,116,752		)	(3,297,989		)	(3,116,752		)
Risk management activities	(7,594		)	(10,626		)	(7,594		)	(10,626		)
Other postretirement assets	(63,477		)	(71,737		)	(62,819		)	(70,986		)
Regulatory assets:
Allowance for equity funds used during construction	(61,088		)	(54,110		)	(61,088		)	(54,110		)
Deferred fuel and purchased power — mark-to-market	(21,396		)	(55,020		)	(21,396		)	(55,020		)
Pension benefits	(274,184		)	(240,692		)	(274,184		)	(240,692		)
Retired power plant costs (see Note 3)	(49,166		)	(53,420		)	(49,166		)	(53,420		)
Other	(123,987		)	(108,441		)	(123,987		)	(108,441		)
Other	(5,166		)	(4,984		)	(5,165		)	(4,984		)
Total deferred tax liabilities	(3,904,047		)	(3,715,782		)	(3,903,388		)	(3,715,031		)
Deferred income taxes — net	$	(2,945,232	)	$	(2,723,425	)	$	(2,999,295	)	$	(2,764,489	)

As of December 31, 2016, the deferred tax assets for credit and loss carryforwards relate primarily to federal general business credits of approximately $98 million, which first begin to expire in 2031, and other federal and state loss carryforwards of $5 million, which first begin to expire in 2019. The credit and loss carryforwards amount above has been reduced by $27 million of unrecognized tax benefits.

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5.Lines of Credit and Short-Term Borrowings

Pinnacle West and APS maintain committed revolving credit facilities in order to enhance liquidity and provide credit support for their commercial paper programs, to refinance indebtedness, and for other general corporate purposes.

The table below presents the consolidated credit facilities and the amounts available and outstanding as of December 31, 2016 and 2015 (dollars in thousands):

	December 31, 2016									December 31, 2015
	Pinnacle West			APS			Total			Pinnacle West		APS		Total
Commitments under Credit Facilities	$	275,000		$	1,000,000		$	1,275,000		$	200,000	$	1,000,000	$	1,200,000
Outstanding Commercial Paper and Revolving Credit Facility Borrowings	(41,700		)	(135,500		)	(177,200		)	—		—		—
Amount of Credit Facilities Available	$	233,300		$	864,500		$	1,097,800		$	200,000	$	1,000,000	$	1,200,000
Weighted-Average Commitment Fees	0.125%			0.100%						0.125%		0.100%

Pinnacle West

On May 13, 2016, Pinnacle West replaced its $200 million revolving credit facility that would have matured in May 2019, with a new $200 million facility that matures in May 2021. Pinnacle West has the option to increase the amount of the facility up to a maximum of $300 million upon the satisfaction of certain conditions and with the consent of the lenders.  At December 31, 2016, Pinnacle West had no outstanding borrowings under its credit facility, no letters of credit outstanding and $1.7 million commercial paper borrowings.

On August 31, 2016, PNW entered into a $75 million364-day unsecured revolving credit facility that matures in August 2017. PNW will use the new facility to fund or otherwise support obligations related to 4CA, and borrowings under the facility will bear interest at LIBOR plus 0.80% per annum. At December 31, 2016, Pinnacle West had $40 million outstanding under the facility.

APS

During the first quarter of 2016, APS increased its commercial paper program from $250 million to $500 million.

On May 13, 2016, APS replaced its $500 million revolving credit facility that would have matured in May 2019, with a new $500 million facility that matures in May 2021.

At December 31, 2016, APS had two revolving credit facilities totaling $1 billion, including a $500 million credit facility that matures in September 2020 and the $500 million facility that matures in May 2021. APS may increase the amount of each facility up to a maximum of $700 million, for a total of $1.4 billion, upon the satisfaction of certain conditions and with the consent of the lenders. Interest rates are based on APS’s senior unsecured debt credit ratings. These facilities are available to support APS’s $500 million commercial paper program, for bank borrowings or for issuances of letters of credit. At December 31, 2016, APS had $135.5 million of commercial paper outstanding and no outstanding borrowings or letters of credit

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under its revolving credit facilities. See "Financial Assurances" in Note 10 for a discussion of APS's other outstanding letters of credit.

Debt Provisions

On February 6, 2013, the ACC issued a financing order in which, subject to specified parameters and procedures, it approved APS’s short-term debt authorization equal to a sum of 7% of APS’s capitalization, and $500 million (which is required to be used for costs relating to purchases of natural gas and power). This financing order is set to expire on December 31, 2017. See Note 6 for additional long-term debt provisions.

6.    Long-Term Debt and Liquidity Matters

All of Pinnacle West’s and APS’s debt is unsecured.  The following table presents the components of long-term debt on the Consolidated Balance Sheets outstanding at December 31, 2016 and 2015 (dollars in thousands):

	Maturity	Interest	December 31,
	Dates (a)	Rates	2016			2015
APS
Pollution control bonds:
Variable	2029	(b)	$	35,975		$	92,405
Fixed	2024-2029	1.75%-4.70%	147,150			211,150
Total pollution control bonds			183,125			303,555
Senior unsecured notes	2019-2046	2.20%-8.75%	3,725,000			3,375,000
Term loans	2018-2019	(c)	150,000			50,000
Unamortized discount			(11,816		)	(10,374		)
Unamortized premium			4,506			4,686
Unamortized debt issuance cost			(29,030		)	(27,896		)
Total APS long-term debt			4,021,785			3,694,971
Less current maturities			—			357,580
Total APS long-term debt less current maturities			4,021,785			3,337,391
Pinnacle West
Term loan	2017	(d)	125,000			125,000
Less current maturities			125,000			—
Total PNW long-term debt less current maturities			—			125,000
TOTAL LONG-TERM DEBTLESS CURRENT MATURITIES			$	4,021,785		$	3,462,391

(a) This schedule does not reflect the timing of redemptions that may occur prior to maturities.

(b) The weighted-average rate for the variable rate pollution control bonds was 0.81% at December 31, 2016 and 0.01%-0.24% at December 31, 2015.

(c) The weighted-average interest rate was 1.427% at December 31, 2016, and 1.024% at December 31, 2015.

(d) The interest rate was 1.520% at December 31, 2016 and 1.174% at December 31, 2015.

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The following table shows principal payments due on Pinnacle West’s and APS’s total long-term debt (dollars in thousands):

Year	Consolidated Pinnacle West		Consolidated APS
2017	$	125,000	$	—
2018	82,000		82,000
2019	600,000		600,000
2020	250,000		250,000
2021	—		—
Thereafter	3,126,125		3,126,125
Total	$	4,183,125	$	4,058,125

Debt Fair Value

Our long-term debt fair value estimates are based on quoted market prices for the same or similar issues, and are classified within Level 2 of the fair value hierarchy.  Certain of our debt instruments contain third-party credit enhancements and, in accordance with GAAP, we do not consider the effect of these credit enhancements when determining fair value.  The following table represents the estimated fair value of our long-term debt, including current maturities (dollars in thousands):

	As of December 31, 2016				As of December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Pinnacle West	$	125,000	$	125,000	$	125,000	$	125,000
APS	4,021,785		4,300,789		3,694,971		3,981,367
Total	$	4,146,785	$	4,425,789	$	3,819,971	$	4,106,367

Credit Facilities and Debt Issuances

APS

On April 22, 2016, APS entered into a $100 million term loan facility that matures April 22, 2019. Interest rates are based on APS's senior unsecured debt credit ratings. APS used the proceeds to repay and refinance existing short-term indebtedness.

On May 6, 2016, APS issued $350 million of 3.75% unsecured senior notes that mature on May 15, 2046. The net proceeds from the sale were used to redeem and cancel pollution control bonds (see details below), and to repay commercial paper borrowings and replenish cash temporarily used to fund capital expenditures.

On June 1, 2016, APS redeemed at par and canceled all $64 million of the Navajo County, Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Cholla Project), 2009 Series D and E.

On June 1, 2016, APS redeemed at par and canceled all $13 million of the Coconino County, Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Navajo Project), 2009 Series A.

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On August 1, 2016, APS repaid at maturity APS's $250 million aggregate principal amount of 6.25% senior notes due August 1, 2016.

On September 20, 2016, APS issued $250 million of 2.55% unsecured senior notes that mature on September 15, 2026. The net proceeds from the sale were used to repay commercial paper borrowings and replenish cash temporarily used in connection with the payment at maturity of our $250 million aggregate principal amount of 6.25% Notes due August 1, 2016.

On September 20, 2016, APS redeemed at par and canceled all $27 million of the Coconino County Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Navajo Project), 2009 Series B.

On December 6, 2016, APS redeemed at par and canceled all $17 million of the Coconino County Arizona Pollution Control Corporation Revenue Bonds (Arizona Public Service Company Project), Series 1998.

See “Lines of Credit and Short-Term Borrowings” in Note 5 and “Financial Assurances” in Note 10 for discussion of APS’s separate outstanding letters of credit.

Debt Provisions

Pinnacle West’s and APS’s debt covenants related to their respective bank financing arrangements include maximum debt to capitalization ratios. Pinnacle West and APS comply with this covenant.  For both Pinnacle West and APS, this covenant requires that the ratio of consolidated debt to total consolidated capitalization not exceed 65%.  At December 31, 2016, the ratio was approximately 48% for Pinnacle West and 47% for APS.  Failure to comply with such covenant levels would result in an event of default which, generally speaking, would require the immediate repayment of the debt subject to the covenants and could cross-default other debt.  See further discussion of “cross-default” provisions below.

Neither Pinnacle West’s nor APS’s financing agreements contain “rating triggers” that would result in an acceleration of the required interest and principal payments in the event of a rating downgrade.  However, our bank credit agreements contain a pricing grid in which the interest rates we pay for borrowings thereunder are determined by our current credit ratings.

All of Pinnacle West’s loan agreements contain “cross-default” provisions that would result in defaults and the potential acceleration of payment under these loan agreements if Pinnacle West or APS were to default under certain other material agreements.  All of APS’s bank agreements contain "cross-default" provisions that would result in defaults and the potential acceleration of payment under these bank agreements if APS were to default under certain other material agreements.  Pinnacle West and APS do not have a material adverse change restriction for credit facility borrowings.

An existing ACC order requires APS to maintain a common equity ratio of at least 40%.  As defined in the ACC order, the common equity ratio is total shareholder equity divided by the sum of total shareholder equity and long-term debt, including current maturities of long-term debt.  At December 31, 2016, APS was in compliance with this common equity ratio requirement.  Its total shareholder equity was approximately $4.9 billion, and total capitalization was approximately $9.1 billion.  APS would be prohibited from paying dividends if the payment would reduce its total shareholder equity below approximately $3.6 billion, assuming APS’s total capitalization remains the same. APS was in compliance with this common equity ratio requirement as of December 31, 2016.

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Although provisions in APS’s articles of incorporation and ACC financing orders establish maximum amounts of preferred stock and debt that APS may issue, APS does not expect any of these provisions to limit its ability to meet its capital requirements. On February 6, 2013, the ACC issued a financing order in which, subject to specified parameters and procedures, it approved an increase in APS’s long-term debt authorization from $4.2 billion to $5.1 billion in light of the projected growth of APS and its customer base and the resulting projected financing needs, and authorized APS to enter into derivative financial instruments for the purpose of managing interest rate risk associated with its long- and short-term debt. This financing order is set to expire on December 31, 2017. See Note 5 for additional short-term debt provisions.

7.    Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan (The Pinnacle West Capital Corporation Retirement Plan) and a non-qualified supplemental excess benefit retirement plan for the employees of Pinnacle West and its subsidiaries.  All new employees participate in the account balance plan.  Defined benefit plans specify the amount of benefits a plan participant is to receive using information about the participant.  The pension plan covers nearly all employees.  The supplemental excess benefit retirement plan covers officers of the Company and highly compensated employees designated for participation by the Board of Directors.  Our employees do not contribute to the plans.  We calculate the benefits based on age, years of service and pay.

Pinnacle West also sponsors other postretirement benefit plans (Pinnacle West Capital Corporation Group Life and Medical Plan and Pinnacle West Capital Corporation Post-65 Retiree Health Reimbursement Arrangement) for the employees of Pinnacle West and its subsidiaries.  These plans provide medical and life insurance benefits to retired employees.  Employees must retire to become eligible for these retirement benefits, which are based on years of service and age.  For the medical insurance plan, retirees make contributions to cover a portion of the plan costs.  For the life insurance plan, retirees do not make contributions.  We retain the right to change or eliminate these benefits.

On September 30, 2014, Pinnacle West announced plan design changes to the other postretirement benefit plan, which required an interim remeasurement of the benefit obligation for the plan. Effective January 1, 2015, those eligible retirees and dependents over age 65 and on Medicare can choose to be enrolled in a Health Reimbursement Arrangement (HRA). The Company is providing a subsidy allowing post-65 retirees to purchase a Medicare supplement plan on a private exchange network. The remeasurement of the benefit obligation included updating the assumptions. The remeasurement reduced net periodic benefit costs in 2014 by $10 million ($5 million of which reduced expense). The remeasurement also resulted in a decrease in Pinnacle West’s other postretirement benefit obligation of $316 million, which was offset by the related regulatory asset and accumulated other comprehensive income.

Because of the plan changes, the Company is currently in the process of seeking IRS approval to move up to $140 million of the other postretirement benefit trust assets into a new trust account to pay for active union employee medical costs. In December 2016, FERC approved a methodology for determining the amount of other postretirement benefit trust assets to move into a new account to pay for active union employee medical costs. As of December 31, 2016, such methodology would result in an amount of approximately $140 million being transferred to the new account.

Pinnacle West uses a December 31 measurement date each year for its pension and other postretirement benefit plans.  The market-related value of our plan assets is their fair value at the measurement date.  See Note 13 for further discussion of how fair values are determined.  Due to subjective and complex judgments, which

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may be required in determining fair values, actual results could differ from the results estimated through the application of these methods.

A significant portion of the changes in the actuarial gains and losses of our pension and postretirement plans is attributable to APS and therefore is recoverable in rates.  Accordingly, these changes are recorded as a regulatory asset or regulatory liability.  In its 2009 retail rate case settlement, APS received approval to defer a portion of pension and other postretirement benefit cost increases incurred in 2011 and 2012.  We deferred pension and other postretirement benefit costs of approximately $14 million in 2012 and $11 million in 2011.  Pursuant to an ACC regulatory order, we began amortizing the regulatory asset over three years beginning in July 2012.  We amortized approximately $5 million in 2015, $8 million in 2014, $8 million in 2013 and $4 million in 2012.

The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged to the regulatory asset or liability) (dollars in thousands):

	Pension									Other Benefits
	2016			2015			2014			2016			2015			2014
Service cost-benefits earned during the period	$	53,792		$	59,627		$	53,080		$	14,993		$	16,827		$	18,139
Interest cost on benefit obligation	131,647			123,983			129,194			29,721			28,102			41,243
Expected return on plan assets	(173,906		)	(179,231		)	(158,998		)	(36,495		)	(36,855		)	(46,400		)
Amortization of:
Prior service cost (credit)	527			594			869			(37,883		)	(37,968		)	(9,626		)
Net actuarial loss	40,717			31,056			10,963			4,589			4,881			1,175
Net periodic benefit cost	$	52,777		$	36,029		$	35,108		$	(25,075	)	$	(25,013	)	$	4,531
Portion of cost charged to expense	$	26,172		$	20,036		$	21,985		$	(12,435	)	$	(10,391	)	$	6,000

The following table shows the plans’ changes in the benefit obligations and funded status for the years 2016 and 2015 (dollars in thousands):

	Pension						Other Benefits
	2016			2015			2016			2015
Change in Benefit Obligation
Benefit obligation at January 1	$	3,033,803		$	3,078,648		$	647,020		$	682,335
Service cost	53,792			59,627			14,993			16,827
Interest cost	131,647			123,983			29,721			28,102
Benefit payments	(142,247		)	(137,115		)	(26,231		)	(24,988		)
Actuarial (gain) loss	127,467			(91,340		)	50,942			(55,256		)
Benefit obligation at December 31	3,204,462			3,033,803			716,445			647,020
Change in Plan Assets
Fair value of plan assets at January 1	2,542,774			2,615,404			833,017			834,625
Actual return on plan assets	166,408			(44,690		)	63,463			(2,399		)
Employer contributions	100,000			100,000			819			791
Benefit payments	(133,825		)	(127,940		)	(14,648		)	—
Fair value of plan assets at December 31	2,675,357			2,542,774			882,651			833,017
Funded Status at December 31	$	(529,105	)	$	(491,029	)	$	166,206		$	185,997

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The following table shows the projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets as of December 31, 2016 and 2015 (dollars in thousands):

	2016		2015
Projected benefit obligation	$	3,204,462	$	3,033,803
Accumulated benefit obligation	3,049,406		2,873,467
Fair value of plan assets	2,675,357		2,542,774

The following table shows the amounts recognized on the Consolidated Balance Sheets as of December 31, 2016 and 2015 (dollars in thousands):

	Pension						Other Benefits
	2016			2015			2016		2015
Noncurrent asset	$	—		$	—		$	166,206	$	185,997
Current liability	(19,795		)	(10,031		)	—		—
Noncurrent liability	(509,310		)	(480,998		)	—		—
Net amount recognized	$	(529,105	)	$	(491,029	)	$	166,206	$	185,997

The following table shows the details related to accumulated other comprehensive loss as of December 31, 2016 and 2015 (dollars in thousands): 

	Pension						Other Benefits
	2016			2015			2016			2015
Net actuarial loss	$	773,750		$	679,501		$	146,509		$	127,124
Prior service cost (credit)	81			609			(303,417		)	(341,301		)
APS’s portion recorded as a regulatory (asset) liability	(711,059		)	(619,223		)	156,575			213,621
Income tax expense (benefit)	(24,202		)	(23,663		)	833			925
Accumulated other comprehensive loss	$	38,570		$	37,224		$	500		$	369

The following table shows the estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets and liabilities into net periodic benefit cost in 2017 (dollars in thousands):

	Pension		Other Benefits
Net actuarial loss	$	46,971	$	5,181
Prior service cost (credit)	81		(37,842		)
Total amounts estimated to be amortized from accumulated other comprehensive loss (gain) and regulatory assets (liabilities) in 2017	$	47,052	$	(32,661	)

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The following table shows the weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs:

	Benefit Obligations As of December 31,				Benefit Costs For the Years Ended December 31,
	2016		2015		2016		2015		2014
									January - September		October - December
Discount rate – pension	4.08	%	4.37	%	4.37	%	4.02	%	4.88	%	4.88	%
Discount rate – other benefits	4.17	%	4.52	%	4.52	%	4.14	%	5.10	%	4.41	%
Rate of compensation increase	4.00	%	4.00	%	4.00	%	4.00	%	4.00	%	4.00	%
Expected long-term return on plan assets - pension	N/A		N/A		6.90	%	6.90	%	6.90	%	6.90	%
Expected long-term return on plan assets - other benefits	N/A		N/A		4.45	%	4.45	%	6.80	%	4.25	%
Initial healthcare cost trend rate (pre-65 participants)	7.00	%	7.00	%	7.00	%	7.00	%	7.50	%	7.50	%
Initial healthcare cost trend rate (post-65 participants)	5.00	%	5.00	%	5.00	%	5.00	%	7.50	%	5.00	%
Ultimate healthcare cost trend rate	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%
Number of years to ultimate trend rate (pre-65 participants)	4		4		4		4		4		4
Number of years to ultimate trend rate (post-65 participants)	0		0		0		0		4		0

In selecting the pretax expected long-term rate of return on plan assets, we consider past performance and economic forecasts for the types of investments held by the plan.  For 2017, we are assuming a 6.55% long-term rate of return for pension assets and 6.37% (before tax) for other benefit assets, which we believe is reasonable given our asset allocation in relation to historical and expected performance.

In October 2014, the Society of Actuaries’ Retirement Plans Experience Committee issued its final reports on its recommended mortality basis (“RP-2014 Mortality Tables Report” and "Mortality Improvement Scale MP-2014 Report").  At December 31, 2014, we updated our mortality assumptions using the recommended basis with modifications to better reflect our plan experience and additional data regarding mortality trends.  The updated mortality assumptions resulted in a $67 million increase in Pinnacle West’s pension and other postretirement obligations, which was offset by the related regulatory asset, regulatory liability and accumulated other comprehensive income.

In selecting our healthcare trend rates, we consider past performance and forecasts of healthcare costs.  A one percentage point change in the assumed initial and ultimate healthcare cost trend rates would have the following effects (dollars in thousands): 

	1% Increase		1% Decrease
Effect on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants	$	8,430	$	(5,455	)
Effect on service and interest cost components of net periodic other postretirement benefit costs	8,440		(6,527		)
Effect on the accumulated other postretirement benefit obligation	108,046		(86,651		)

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Plan Assets

The Board of Directors has delegated oversight of the pension and other postretirement benefit plans’ assets to an Investment Management Committee (“Committee”).  The Committee has adopted investment policy statements (“IPS”) for the pension and the other postretirement benefit plans’ assets. The investment strategies for these plans include external management of plan assets, and prohibition of investments in Pinnacle West securities.

The overall strategy of the pension plan’s IPS is to achieve an adequate level of trust assets relative to the benefit obligations.  To achieve this objective, the plan’s investment policy provides for mixes of investments including long-term fixed income assets and return-generating assets.  The target allocation between return-generating and long-term fixed income assets is defined in the IPS and is a function of the plan’s funded status.  The plan’s funded status is reviewed on at least a monthly basis.

Changes in the value of long-term fixed income assets, also known as liability-hedging assets, are intended to offset changes in the benefit obligations due to changes in interest rates.  Long-term fixed income assets consist primarily of fixed income debt securities issued by the U.S. Treasury and other government agencies, U.S Treasury Futures Contracts, and fixed income debt securities issued by corporations.  Long-term fixed income assets may also include interest rate swaps, and other instruments.

Return-generating assets are intended to provide a reasonable long-term rate of investment return with a prudent level of volatility.  Return-generating assets are composed of U.S. equities, international equities, and alternative investments.  International equities include investments in both developed and emerging markets.  Alternative investments include investments in real estate, private equity and various other strategies.  The plan may also hold investments in return-generating assets by holding securities in partnerships, common and collective trusts and mutual funds.

Based on the IPS, and given the pension plan’s funded status at year-end 2016, the long-term fixed income assets had a target allocation of 58% with a permissible range of 55% to 61% and the return-generating assets had a target allocation of 42% with a permissible range of 39% to 45%.  The return-generating assets have additional target allocations, as a percent of total plan assets, of 22% equities in U.S. and other developed markets, 6% equities in emerging markets, and 14% in alternative investments.  The pension plan IPS does not provide for a specific mix of long-term fixed income assets, but does expect the average credit quality of such assets to be investment grade.  As of December 31, 2016, long-term fixed income assets represented 57% of total pension plan assets, and return-generating assets represented 43% of total pension plan assets.

As of December 31, 2016, the asset allocation for other postretirement benefit plan assets is governed by the IPS for those plans, which provides for different asset allocation target mixes depending on the characteristics of the liability.  Some of these asset allocation target mixes vary with the plan’s funded status.  As of December 31, 2016, investment in fixed income assets represented 51% of the other postretirement benefit plan total assets, and non-fixed income assets represented 49% of the other postretirement benefit plan’s assets. 

See Note 13 for a discussion on the fair value hierarchy and how fair value methodologies are applied.  The plans invest directly in fixed income, U.S Treasury Futures Contracts, and equity securities, in addition to investing indirectly in fixed income securities, equity securities and real estate through the use of mutual funds, partnerships and common and collective trusts.  Equity securities held directly by the plans are valued using quoted active market prices from the published exchange on which the equity security trades, and are classified as Level 1.  U.S Treasury Future Contracts are valued using the quoted active market prices from the exchange

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on which they trade, and are classified as Level 1. Fixed income securities issued by the U.S. Treasury held directly by the plans are valued using quoted active market prices, and are classified as Level 1.  Fixed income securities issued by corporations, municipalities, and other agencies are primarily valued using quoted inactive market prices, or quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield, maturity and credit quality.  These instruments are classified as Level 2.

Mutual funds, partnerships, and common and collective trusts are valued utilizing a net asset value (NAV) concept or its equivalent. Mutual funds, classified as Level 1, are valued using a NAV that is observable and based on the active market in which the fund trades.

Common and collective trusts, are maintained by banks or investment companies and hold certain investments in accordance with a stated set of objectives (such as tracking the performance of the S&P 500 Index).  The trust's shares are offered to a limited group of investors, and are not traded in an active market. Investments in common and collective trusts are valued using NAV, as a practical expedient and accordingly are not classified in the fair value hierarchy. The NAV for trusts investing in exchange traded equities is derived from the quoted active market prices of the underlying securities held by the trusts. The NAV for trusts investing in real estate is derived from the appraised values of the trust's underlying real estate assets.  As of December 31, 2016, the plans were able to transact in the common and collective trusts at NAV.

Investments in partnerships are also valued using the concept of NAV, as a practical expedient and accordingly are not classified in the fair value hierarchy. The NAV for these investments is derived from the value of the partnerships' underlying assets. The plan's partnerships holdings relate to investments in high-yield fixed income instruments and assets of privately held portfolio companies. Certain partnerships also include funding commitments that may require the plan to contribute up to $75 million to these partnerships; as of December 31, 2016, approximately $54 million of these commitments have been funded.

The plans’ trustee provides valuation of our plan assets by using pricing services that utilize methodologies described to determine fair market value.  We have internal control procedures to ensure this information is consistent with fair value accounting guidance.  These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustee’s internal operating controls and valuation processes.

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The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2016, by asset category, are as follows (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Other (a)		Balance at December 31, 2016
Pension Plan:
Cash and cash equivalents	$	13,995	$	—	$	—	$	13,995
Fixed income securities:
Corporate	—		1,210,453		—		1,210,453
U.S. Treasury	112,583		—		—		112,583
Other (b)	—		102,170		—		102,170
Common stock equities (c)	235,109		—		—		235,109
Mutual funds (d)	251,506		—		—		251,506
Common and collective trusts:
Equities	—		—		266,840		266,840
Real estate	—		—		161,449		161,449
Partnerships	—		—		208,915		208,915
Short-term investments and other (e)	—		—		112,337		112,337
Total	$	613,193	$	1,312,623	$	749,541	$	2,675,357
Other Benefits:
Cash and cash equivalents	$	304	$	—	$	—	$	304
Fixed income securities:
Corporate	—		268,193		—		268,193
U.S. Treasury	145,255		—		—		145,255
Other (b)	—		34,506		—		34,506
Common stock equities (c)	243,741		—		—		243,741
Mutual funds (d)	67,418		—		—		67,418
Common and collective trusts:
Equities	—		—		95,814		95,814
Real estate	—		—		14,509		14,509
Partnerships	—		—		3,060		3,060
Short-term investments and other (e)	—		—		9,851		9,851
Total	$	456,718	$	302,699	$	123,234	$	882,651

(a) These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.

(b) This category consists primarily of debt securities issued by municipalities.

(c) This category primarily consists of US common stock equities.

(d) These funds invest in US and international common stock equities.

(e) This category includes plan receivables and payables.

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The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2015, by asset category, are as follows (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Other (a)		Balance at December 31, 2015
Pension Plan:
Cash and cash equivalents	$	1,893	$	—	$	—	$	1,893
Fixed Income Securities:
Corporate	—		1,108,736		—		1,108,736
U.S. Treasury	274,778		—		—		274,778
Other (b)	—		113,008		—		113,008
Common stock equities (c)	247,701		—		—		247,701
Mutual funds - International equities	116,307		—		—		116,307
Common and collective trusts:
Equities	—		—		315,989		315,989
Real Estate	—		—		150,359		150,359
Partnerships	—		—		169,937		169,937
Short-term investments and other (d)	—		—		44,066		44,066
Total	$	640,679	$	1,221,744	$	680,351	$	2,542,774
Other Benefits:
Cash and cash equivalents	$	240	$	—	$	—	$	240
Fixed Income Securities:
Corporate	—		217,026		—		217,026
U.S. Treasury	131,435		—		—		131,435
Other (b)	—		31,106		—		31,106
Common stock equities (c)	265,583		—		—		265,583
Mutual funds - International equities	52,568		—		—		52,568
Common and collective trusts:
Equities	—		—		110,055		110,055
Real Estate	—		—		13,512		13,512
Short-term investments and other (d)	—		—		11,492		11,492
Total	$	449,826	$	248,132	$	135,059	$	833,017

(a) These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.

(b) This category consists primarily of debt securities issued by municipalities.

(c) This category primarily consists of US common stock equities.

(d) This category includes plan receivables and payables.

Contributions

Future year contribution amounts are dependent on plan asset performance and plan actuarial assumptions.  We made contributions to our pension plan totaling $100 million in 2016, $100 million in 2015, and $175 million in 2014.  The minimum required contributions for the pension plan are zero for the next three years.  We expect to make voluntary contributions up to a total of $300 million during the 2017-2019 period.  With regard to contributions to our other postretirement benefit plans, we made a contribution of

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approximately $1 million in each of 2016, 2015 and 2014.  We expect to make contributions of less than $1 million in total for the next three years to our other postretirement benefit plans. APS funds its share of the contributions.  APS’s share of the pension plan contribution was approximately $100 million in 2016, $100 million in 2015 and $175 million in 2014.  APS’s share of the contributions to the other postretirement benefit plan was approximately $1 million in 2016, 2015 and 2014.

Estimated Future Benefit Payments

Benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter, are estimated to be as follows (dollars in thousands):

Year	Pension		Other Benefits
2017	$	172,859	$	31,126
2018	173,232		33,795
2019	182,944		36,195
2020	191,037		37,998
2021	196,292		39,368
Years 2022-2026	1,049,149		201,944

Electric plant participants contribute to the above amounts in accordance with their respective participation agreements.

Employee Savings Plan Benefits

Pinnacle West sponsors a defined contribution savings plan for eligible employees of Pinnacle West and its subsidiaries.  In 2016, costs related to APS’s employees represented 99% of the total cost of this plan.  In a defined contribution savings plan, the benefits a participant receives result from regular contributions participants make to their own individual account, the Company’s matching contributions and earnings or losses on their investments.  Under this plan, the Company matches a percentage of the participants’ contributions in cash which is then invested in the same investment mix as participants elect to invest their own future contributions.  Pinnacle West recorded expenses for this plan of approximately $10 million for 2016, $9 million for 2015, and $9 million for 2014.

8.    Leases

We lease certain vehicles, land, buildings, equipment and miscellaneous other items through operating rental agreements with varying terms, provisions and expiration dates. See Note 2 for a discussion of the new lease accounting standard.

Total lease expense recognized in the Consolidated Statements of Income was $16 million in 2016, $17 million in 2015, and $18 million in 2014.  APS’s lease expense was $15 million in 2016, $14 million in 2015, and $15 million in 2014.

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Estimated future minimum lease payments for Pinnacle West’s and APS’s operating leases, excluding purchased power agreements, are approximately as follows (dollars in thousands):

Year	Pinnacle West Consolidated		APS
2017	$	12,330	$	11,919
2018	10,987		10,690
2019	9,019		8,767
2020	7,688		7,439
2021	5,266		5,020
Thereafter	59,647		57,207
Total future lease commitments	$	104,937	$	101,042

In 1986, APS entered into agreements with three separate lessor trust entities in order to sell and lease back interests in Palo Verde Unit 2 and related common facilities.  These lessor trust entities have been deemed VIEs for which APS is the primary beneficiary.  As the primary beneficiary, APS consolidated these lessor trust entities.  The impacts of these sale leaseback transactions are excluded from our lease disclosures as lease accounting is eliminated upon consolidation.  See Note 18 for a discussion of VIEs.

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9.    Jointly-Owned Facilities

APS shares ownership of some of its generating and transmission facilities with other companies.  We are responsible for our share of operating costs which are included in the corresponding operating expenses on our Consolidated Statements of Income. We are also responsible for providing our own financing.  Our share of operating expenses and utility plant costs related to these facilities is accounted for using proportional consolidation.  The following table shows APS’s interests in those jointly-owned facilities recorded on the Consolidated Balance Sheets at December 31, 2016 (dollars in thousands):

	Percent Owned			Plant in Service		Accumulated Depreciation		Construction Work in Progress
Generating facilities:
Palo Verde Units 1 and 3	29.1	%		$	1,770,324	$	1,080,072	$	17,615
Palo Verde Unit 2 (a)	16.8	%		581,572		360,757		9,717
Palo Verde Common	28.0	%	(b)	672,799		242,649		62,479
Palo Verde Sale Leaseback			(a)	351,050		237,535		—
Four Corners Generating Station	63.0	%		934,837		578,924		248,072
Navajo Generating Station Units 1, 2 and 3	14.0	%		279,629		176,931		5,761
Cholla common facilities (c)	63.3	%	(b)	159,707		58,276		806		(d)
Transmission facilities:
ANPP 500kV System	33.6	%	(b)	127,970		38,610		2,291
Navajo Southern System	22.5	%	(b)	62,135		20,491		334
Palo Verde — Yuma 500kV System	19.0	%	(b)	13,699		5,368		408
Four Corners Switchyards	51.3	%	(b)	39,850		10,474		1,044
Phoenix — Mead System	17.1	%	(b)	39,330		13,725		85
Palo Verde — Rudd 500kV System	50.0	%	(b)	91,904		19,818		227
Morgan — Pinnacle Peak System	65.2	%	(b)	140,374		13,557		—
Round Valley System	50.0	%	(b)	515		127		—
Palo Verde — Morgan System	85.8	%	(b)	125,908		1,326		28,949
Hassayampa — North Gila System	80.0	%	(b)	142,541		3,231		—
Cholla 500kV Switchyard	85.7	%	(b)	5,078		1,201		—
Saguaro 500kV Switchyard	75.0	%	(b)	20,456		12,426		2

(a) See Note 18.

(b) Weighted-average of interests.

(c) PacifiCorp owns Cholla Unit 4 and APS operates the unit for PacifiCorp.  The common facilities at Cholla are jointly-owned.

(d) Due to the closure of Cholla Unit 2 in 2015, all new Cholla common facilities construction is owned by APS at 50.5%

4CA is a subsidiary that was formed in 2016 as a result of the purchase of El Paso's 7% interest in Four Corners. At December 31, 2016, 4CA had plant in service of $110 million, accumulated depreciation of $79 million and construction work in progress of $30 million.

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10.    Commitments and Contingencies

Palo Verde Nuclear Generating Station

Spent Nuclear Fuel and Waste Disposal

On December 19, 2012, APS, acting on behalf of itself and the participant owners of Palo Verde, filed a second breach of contract lawsuit against the DOE in the Court of Federal Claims.  The lawsuit sought to recover damages incurred due to DOE’s breach of the Standard Contract for failing to accept Palo Verde's spent nuclear fuel and high level waste from January 1, 2007 through June 30, 2011, as it was required to do pursuant to the terms of the Standard Contract and the Nuclear Waste Policy Act.  On August 18, 2014, APS and DOE entered into a settlement agreement, stipulating to a dismissal of the lawsuit and payment of $57.4 million by DOE to the Palo Verde owners for certain specified costs incurred by Palo Verde during the period January 1, 2007 through June 30, 2011. APS’s share of this amount is $16.7 million. Amounts recovered in the lawsuit and settlement were recorded as adjustments to a regulatory liability and had no impact on the amount of reported net income. In addition, the settlement agreement provides APS with a method for submitting claims and getting recovery for costs incurred through December 31, 2016, which has been extended to December 31, 2019.

APS has submitted two claims pursuant to the terms of the August 18, 2014 settlement agreement, for two separate time periods during July 1, 2011 through June 30, 2015. The DOE has approved and paid $53.9 million for these claims (APS’s share is $15.7 million). The amounts recovered were primarily recorded as adjustments to a regulatory liability and had no impact on reported net income. APS’s next claim pursuant to the terms of the August 18, 2014 settlement agreement was submitted to the DOE on October 31, 2016, and approved on February 1, 2017, in the amount of $11.3 million (APS’s share is $3.3 million). Payment for the claim is expected in the second quarter of 2017.

Nuclear Insurance

Public liability for incidents at nuclear power plants is governed by the Price-Anderson Nuclear Industries Indemnity Act ("Price-Anderson Act"), which limits the liability of nuclear reactor owners to the amount of insurance available from both commercial sources and an industry-wide retrospective payment plan.  In accordance with the Price-Anderson Act, the Palo Verde participants are insured against public liability for a nuclear incident up to approximately $13.4 billion per occurrence.  Palo Verde maintains the maximum available nuclear liability insurance in the amount of $375 million (on January 1, 2017 this coverage was increased to $450 million), which is provided by American Nuclear Insurers ("ANI").  The remaining balance of approximately $13.1 billion (on January 1, 2017 this balance was decreased to $13.0 billion) of liability coverage is provided through a mandatory industry-wide retrospective premium program.  If losses at any nuclear power plant covered by the program exceed the accumulated funds, APS could be responsible for retrospective premiums.  The maximum retrospective premium per reactor under the program for each nuclear liability incident is approximately $127.3 million, subject to a maximum annual premium of $18.9 million per incident.  Based on APS’s ownership interest in the three Palo Verde units, APS’s maximum retrospective premium per incident for all three units is approximately $111.1 million, with a maximum annual retrospective premium of approximately $16.6 million.

The Palo Verde participants maintain insurance for property damage to, and decontamination of, property at Palo Verde in the aggregate amount of $2.8 billion.  APS has also secured accidental outage insurance for a sudden and unforeseen accidental outage of any of the three units. The property damage, decontamination, and accidental outage insurance are provided by Nuclear Electric Insurance Limited

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

("NEIL").  APS is subject to retrospective premium adjustments under all NEIL policies if NEIL’s losses in any policy year exceed accumulated funds.  The maximum amount APS could incur under the current NEIL policies totals approximately $23.8 million for each retrospective premium assessment declared by NEIL’s Board of Directors due to losses.  In addition, NEIL policies contain rating triggers that would result in APS providing approximately $64 million of collateral assurance within 20 business days of a rating downgrade to non-investment grade.  The insurance coverage discussed in this and the previous paragraph is subject to certain policy conditions, sublimits and exclusions.

Fuel and Purchased Power Commitments and Purchase Obligations

APS is party to various fuel and purchased power contracts and purchase obligations with terms expiring between 2017 and 2043 that include required purchase provisions.  APS estimates the contract requirements to be approximately $977 million in 2017; $737 million in 2018; $598 million in 2019; $525 million in 2020; $524 million in 2021; and $7.3 billion thereafter.  However, these amounts may vary significantly pursuant to certain provisions in such contracts that permit us to decrease required purchases under certain circumstances.

Of the various fuel and purchased power contracts mentioned above, some of those contracts for coal supply include take-or-pay provisions.  The current coal contracts with take-or-pay provisions have terms expiring through 2031.

The following table summarizes our estimated coal take-or-pay commitments (dollars in thousands):

	Years Ended December 31,
	2017		2018		2019		2020		2021		Thereafter
Coal take-or-pay commitments (a)	$	195,428	$	189,588	$	193,818	$	198,160	$	202,619	$	2,068,355

(a) Total take-or-pay commitments are approximately $3.0 billion.  The total net present value of these commitments is approximately $2.1 billion.

APS may spend more to meet its actual fuel requirements than the minimum purchase obligations in our coal take-or-pay contracts. The following table summarizes actual amounts purchased under the coal contracts which include take-or-pay provisions for each of the last three years (dollars in thousands):

	Year Ended December 31,
	2016		2015		2014
Total purchases	$	160,066	$	211,327	$	236,773

Renewable Energy Credits

APS has entered into contracts to purchase renewable energy credits to comply with the RES.  APS estimates the contract requirements to be approximately $40 million in 2017; $40 million in 2018; $40 million in 2019; $40 million in 2020; $40 million in 2021; and $420 million thereafter.  These amounts do not include purchases of renewable energy credits that are bundled with energy.

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Coal Mine Reclamation Obligations

APS and 4CA must reimburse certain coal providers for amounts incurred for final and contemporaneous coal mine reclamation.  We account for contemporaneous reclamation costs as part of the cost of the delivered coal.  We utilize site-specific studies of costs expected to be incurred in the future to estimate our final reclamation obligation.  These studies utilize various assumptions to estimate the future costs.  Based on the most recent reclamation studies, APS recorded an obligation for the coal mine final reclamation of approximately $207 million at December 31, 2016 and $202 million at December 31, 2015. 4CA recorded an obligation for the coal mine final reclamation of approximately $15 million at December 31, 2016. Under our current coal supply agreements, APS expects to make payments for the final mine reclamation as follows:  $17 million in 2017; $18 million in 2018; $19 million in 2019; $21 million in 2020; $22 million in 2021; and $241 million thereafter.  4CA expects to make payments for the final mine reclamation as follows: $1 million in 2017; $1 million in 2018; $1 million in 2019; $1 million in 2020; $2 million in 2021; and $17 million thereafter. Any amendments to current coal supply agreements may change the timing of the contribution. Portions of these funds will be held in an escrow account and distributed to certain coal providers under the terms of the applicable coal supply agreements.

Superfund-Related Matters

Superfund establishes liability for the cleanup of hazardous substances found contaminating the soil, water or air.  Those who generated, transported or disposed of hazardous substances at a contaminated site are among those who are PRPs.  PRPs may be strictly, and often are jointly and severally, liable for clean-up.  On September 3, 2003, EPA advised APS that EPA considers APS to be a PRP in the Motorola 52^nd Street Superfund Site, OU3 in Phoenix, Arizona.  APS has facilities that are within this Superfund site.  APS and Pinnacle West have agreed with EPA to perform certain investigative activities of the APS facilities within OU3.  In addition, on September 23, 2009, APS agreed with EPA and one other PRP to voluntarily assist with the funding and management of the site-wide groundwater RI/FS work plan.  The OU3 working group parties have agreed to a schedule with EPA that calls for the submission of a revised draft RI/FS by June 2017. We estimate that our costs related to this investigation and study will be approximately $2 million.  We anticipate incurring additional expenditures in the future, but because the overall investigation is not complete and ultimate remediation requirements are not yet finalized, at the present time expenditures related to this matter cannot be reasonably estimated.

On August 6, 2013, RID filed a lawsuit in Arizona District Court against APS and 24 other defendants, alleging that RID’s groundwater wells were contaminated by the release of hazardous substances from facilities owned or operated by the defendants.  The lawsuit also alleges that, under Superfund laws, the defendants are jointly and severally liable to RID.  The allegations against APS arise out of APS’s current and former ownership of facilities in and around OU3.  As part of a state governmental investigation into groundwater contamination in this area, on January 25, 2015, ADEQ sent a letter to APS seeking information concerning the degree to which, if any, APS’s current and former ownership of these facilities may have contributed to groundwater contamination in this area.  APS responded to ADEQ on May 4, 2015. On December 16, 2016, two RID contractors filed ancillary lawsuits for recovery of costs against APS and the other defendants. We are unable to predict the outcome of these matters; however, we do not expect the outcome to have a material impact on our financial position, results of operations or cash flows.

Southwest Power Outage

On September 8, 2011 at approximately 3:30 PM, a 500 kV transmission line running between the Hassayampa and North Gila substations in southwestern Arizona tripped out of service due to a fault that

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occurred at a switchyard operated by APS.  Approximately ten minutes after the transmission line went off-line, generation and transmission resources for the Yuma area were lost, resulting in approximately 69,700 APS customers losing service.

On September 6, 2013, a purported consumer class action complaint was filed in Federal District Court in San Diego, California, naming APS and Pinnacle West as defendants and seeking damages for loss of perishable inventory and sales as a result of interruption of electrical service.  APS and Pinnacle West filed a motion to dismiss, which the court granted on December 9, 2013.  On January 13, 2014, the plaintiffs appealed the lower court’s decision.  On March 2, 2016, the United States Court of Appeals for the Ninth Circuit unanimously affirmed the District Court's decision. The plaintiffs filed a Petition for Rehearing En Banc, which was denied on April 11, 2016.

Environmental Matters

APS is subject to numerous environmental laws and regulations affecting many aspects of its present and future operations, including air emissions of both conventional pollutants and greenhouse gases, water quality, wastewater discharges, solid waste, hazardous waste, and CCRs.  These laws and regulations can change from time to time, imposing new obligations on APS resulting in increased capital, operating, and other costs.  Associated capital expenditures or operating costs could be material.  APS intends to seek recovery of any such environmental compliance costs through our rates, but cannot predict whether it will obtain such recovery.  The following proposed and final rules involve material compliance costs to APS.

Regional Haze Rules.  APS has received the final rulemaking imposing new requirements on Four Corners and the Navajo Plant. EPA will require these plants to install pollution control equipment that constitutes BART to lessen the impacts of emissions on visibility surrounding the plants. EPA recently approved a proposed rule for Regional Haze compliance at Cholla that does not involve the installation of new pollution controls and that will replace an earlier BART determination for this facility. See below for details of the recent Cholla rule approval.

Four Corners. Based on EPA’s final standards, APS estimates that its 63% share of the cost of required controls for Four Corners Units 4 and 5 would be approximately $400 million.  In addition, APS and El Paso entered into an asset purchase agreement providing for the purchase by APS, or an affiliate of APS, of El Paso's 7% interest in Four Corners Units 4 and 5. 4CA purchased the El Paso interest on July 6, 2016. NTEC has the option to purchase the interest within a certain timeframe pursuant to an option granted to NTEC. In December 2015, NTEC notified APS of its intent to exercise the option. The cost of the pollution controls related to the 7% interest is approximately $45 million, which will be assumed by the ultimate owner of the 7% interest.

Navajo Plant. APS estimates that its share of costs for upgrades at the Navajo Plant, based on EPA’s FIP, could be up to approximately $200 million.  In October 2014, a coalition of environmental groups, an Indian tribe and others filed petitions for review in the United States Court of Appeals for the Ninth Circuit asking the Court to review EPA's final BART rule for the Navajo Plant. We cannot predict the outcome of this review process. See "Navajo Plant" in Note 3 for information regarding future plans for the Navajo Plant.

Cholla. APS believes that EPA’s original 2012 final rule establishing controls constituting BART for Cholla, which would require installation of SCR controls with a cost to APS of approximately $100 million is unsupported and that EPA had no basis for disapproving Arizona’s SIP and promulgating a FIP that is inconsistent with the state’s considered BART determinations under the regional haze program.  Accordingly,

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on February 1, 2013, APS filed a Petition for Review of the final BART rule in the United States Court of Appeals for the Ninth Circuit.  Briefing in the case was completed in February 2014.

In September 2014, APS met with EPA to propose a compromise BART strategy. Pending certain regulatory approvals, APS would permanently close Cholla Unit 2 and cease burning coal at Units 1 and 3 by the mid-2020s. (See Note 3 for details related to the resulting regulatory asset.) APS made the proposal with the understanding that additional emission control equipment is unlikely to be required in the future because retiring and/or converting the units as contemplated in the proposal is more cost effective than, and will result in increased visibility improvement over, the current BART requirements for NOx imposed on the Cholla units under EPA's BART FIP. APS’s proposal involves state and federal rulemaking processes. In light of these ongoing administrative proceedings, on February 19, 2015, APS, PacifiCorp (owner of Cholla Unit 4), and EPA jointly moved the court to sever and hold in abeyance those claims in the litigation pertaining to Cholla pending regulatory actions by the state and EPA. The court granted the parties' unopposed motion on February 20, 2015.

On October 16, 2015, ADEQ issued a revised operating permit for Cholla, which incorporates APS's proposal, and subsequently submitted a proposed revision to the SIP to the EPA, which would incorporate the new permit terms.  On June 30, 2016, EPA issued a proposed rule approving a revision to the Arizona SIP that incorporates APS’s compromise approach for compliance with the Regional Haze program.  EPA signed the final rule approving the Agency's proposal on January 13, 2017. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

Mercury and Air Toxic Standards ("MATS"). In 2011, EPA issued rules establishing maximum achievable control technology standards to regulate emissions of mercury and other hazardous air pollutants from fossil-fired plants.  APS estimates that the cost for the remaining equipment necessary to meet these standards is approximately $8 million for Cholla. No additional equipment is needed for Four Corners Units 4 and 5 to comply with these rules.  SRP, the operating agent for the Navajo Plant, estimates that APS's share of costs for equipment necessary to comply with the rules is approximately $1 million, the majority of which has already been incurred. Litigation concerning the rules, including supplemental analyses EPA has prepared in support of the MATS regulation, is ongoing. These proceedings do not materially impact APS.  Regardless of the results from further judicial or administrative proceedings concerning the MATS rulemaking, the Arizona State Mercury Rule, the stringency of which is roughly equivalent to that of MATS, would still apply to Cholla.

Coal Combustion Waste.On December 19, 2014, EPA issued its final regulations governing the handling and disposal of CCR, such as fly ash and bottom ash. The rule regulates CCR as a non-hazardous waste under Subtitle D of RCRA and establishes national minimum criteria for existing and new CCR landfills and surface impoundments and all lateral expansions consisting of location restrictions, design and operating criteria, groundwater monitoring and corrective action, closure requirements and post closure care, and recordkeeping, notification, and Internet posting requirements. The rule generally requires any existing unlined CCR surface impoundment that is contaminating groundwater above a regulated constituent’s groundwater protection standard to stop receiving CCR and either retrofit or close, and further requires the closure of any CCR landfill or surface impoundment that cannot meet the applicable performance criteria for location restrictions or structural integrity. While EPA has chosen to regulate the disposal of CCR in landfills and surface impoundments as non-hazardous waste under the final rule, the agency makes clear that it will

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continue to evaluate any risks associated with CCR disposal and leaves open the possibility that it may regulate CCR as a hazardous waste under RCRA Subtitle C in the future.

On December 16, 2016, President Obama signed the WIIN Act into law, which contains a number of provisions requiring EPA to modify the self-implementing provisions of the Agency's current CCR rules under Subtitle D. Such modifications include new EPA authority to directly enforce the CCR rules through the use of administrative orders and providing states, like Arizona, where the Cholla facility is located, the option of developing CCR disposal unit permitting programs, subject to EPA approval. For facilities in states that do not develop state-specific permitting programs, EPA is required to develop a federal permit program, pending the availability of congressional appropriations. By contrast, for facilities located within the boundaries of Native American tribal reservations, such as the Navajo Nation, where the Navajo Plant and Four Corners facilities are located, EPA is required to develop a federal permit program regardless of appropriated funds. Because EPA has yet to undertake rulemaking proceedings to implement the CCR provisions of the WIIN Act, and Arizona has yet to determine whether it will develop a state-specific permitting program, it is unclear what effects the CCR provisions of the WIIN Act will have on APS's management of CCR.

APS currently disposes of CCR in ash ponds and dry storage areas at Cholla and Four Corners. APS estimates that its share of incremental costs to comply with the CCR rule for Four Corners is approximately $15 million. APS is currently evaluating compliance alternatives for Cholla and estimates that its share of incremental costs to comply with the CCR rule for this plant is in the range of $5 million to $40 million based upon which compliance alternatives are ultimately selected. The Navajo Plant currently disposes of CCR in a dry landfill storage area. APS estimates that its share of incremental costs to comply with the CCR rule for the Navajo Plant is approximately $1 million, the majority of which has already been incurred. Additionally, the CCR rule requires ongoing groundwater monitoring. Depending upon the results of such monitoring at each of Cholla, Four Corners and the Navajo Plant, we may be required to take corrective actions, the costs of which we are unable to reasonably estimate at this time.

Pursuant to a June 24, 2016 order by the D.C. Circuit Court of Appeals in the litigation by industry- and environmental-groups challenging EPA’s CCR regulations, within the next 3 years EPA is required to complete a rulemaking proceeding concerning whether or not boron must be included on the list of groundwater constituents that might trigger corrective action under EPA’s CCR rules.  EPA is not required to take final action approving the inclusion of boron, but EPA must propose and consider its inclusion.  Should EPA take final action adding boron to the list of groundwater constituents that might trigger corrective action, any resulting corrective action measures may increase APS's costs of compliance with the CCR rule at our coal-fired generating facilities.  At this time, though, APS cannot predict when EPA will commence its rulemaking concerning boron or the eventual results of those proceedings.

Clean Power Plan. On August 3, 2015, EPA finalized carbon pollution standards for existing, new, modified, and reconstructed EGUs. EPA’s final rules require newly built fossil fuel-fired EGUs, along with those undergoing modification or reconstruction, to meet CO₂ performance standards based on a combination of best operating practices and equipment upgrades. EPA established separate performance standards for two types of EGUs: stationary combustion turbines, typically natural gas; and electric utility steam generating units, typically coal.

With respect to existing power plants, EPA’s recently finalized “Clean Power Plan” imposes state-specific goals or targets to achieve reductions in CO₂ emission rates from existing EGUs measured from a 2012 baseline. In a significant change from the proposed rule, EPA’s final performance standards apply directly to specific units based upon their fuel-type and configuration (i.e., coal- or oil-fired steam plants versus combined cycle natural gas plants). As such, each state’s goal is an emissions performance standard

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that reflects the fuel mix employed by the EGUs in operation in those states. The final rule provides guidelines to states to help develop their plans for meeting the interim (2022-2029) and final (2030 and beyond) emission performance standards, with three distinct compliance periods within that timeframe. States were originally required to submit their plans to EPA by September 2016, with an optional two-year extension provided to states establishing a need for additional time; however, this timing will be impacted by the court-imposed stay described below.

Prior to the court-imposed stay described below, ADEQ, with input from a technical working group comprised of Arizona utilities and other stakeholders, was working to develop a compliance plan for submittal to EPA. Since the imposition of the stay, ADEQ is continuing to assess alternatives while completing outreach and soliciting feedback from stakeholders. In addition to these ongoing state proceedings, EPA has taken public comments on proposed model rules and a proposed federal compliance plan, which included consideration as to how the Clean Power Plan will apply to EGUs on tribal land such as the Navajo Nation.

The legality of the Clean Power Plan is being challenged in the U.S. Court of Appeals for the D.C. Circuit; the parties raising this challenge include, among others, the ACC. On February 9, 2016, the U.S. Supreme Court granted a stay of the Clean Power Plan pending judicial review of the rule, which temporarily delays compliance obligations under the Clean Power Plan. We cannot predict the extent of such a delay.

With respect to our Arizona generating units, we are currently evaluating the range of compliance options available to ADEQ, including whether Arizona deploys a rate- or mass-based compliance plan. Based on the fuel-mix and location of our Arizona EGUs, and the significant investments we have made in renewable generation and demand-side energy efficiency, if ADEQ selects a rate-based compliance plan, we believe that we will be able to comply with the Clean Power Plan for our Arizona generating units in a manner that will not have material financial or operational impacts to the Company. On the other hand, if ADEQ selects a mass-based approach to compliance with the Clean Power Plan, our annual cost of compliance could be material. These costs could include costs to acquire mass-based compliance allowances.

As to our facilities on the Navajo Nation, EPA has yet to determine whether or to what extent EGUs on the Navajo Nation will be required to comply with the Clean Power Plan. EPA has proposed to determine that it is necessary or appropriate to impose a federal plan on the Navajo Nation for compliance with the Clean Power Plan. In response, we filed comments with EPA advocating that such a federal plan is neither necessary nor appropriate to protect air quality on the Navajo Nation. If EPA reaches a determination that is consistent with our preferred approach for the Navajo Nation, we believe the Clean Power Plan will not have material financial or operational impacts on our operations within the Navajo Nation.

Alternatively, if EPA determines that a federal plan is necessary or appropriate for the Navajo Nation, and depending on our need for future operations at our EGUs located there, we may be unable to comply with the federal plan unless we acquire mass-based allowances or emission rate credits within established carbon trading markets, or curtail our operations. Subject to the uncertainties set forth below, and assuming that EPA establishes a federal plan for the Navajo Nation that requires carbon allowances or credits to be surrendered for plan compliance, it is possible we will be required to purchase some quantity of credits or allowances, the cost of which could be material.

Because ADEQ has not issued its plan for Arizona, and because we do not know whether EPA will decide to impose a plan or, if so, what that plan will require, there are a number of uncertainties associated with our potential cost exposure. These uncertainties include: whether judicial review will result in the Clean Power Plan being vacated in whole or in part or, if not, the extent of any resulting compliance deadline delays; whether any plan will be imposed for EGUs on the Navajo Nation; the future existence and liquidity of

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allowance or credit compliance trading markets; the applicability of existing contractual obligations with current and former owners of our participant-owned coal-fired EGUs; the type of federal or state compliance plan (either rate- or mass-based); whether or not the trading of allowances or credits will be authorized mechanisms for compliance with any final EPA or ADEQ plan; and how units that have been closed will be treated for allowance or credit allocation purposes.

In the event that the incurrence of compliance costs is not economically viable or prudent for our operations in Arizona or on the Navajo Nation, or if we do not have the option of acquiring allowances to account for the emissions from our operations, we may explore other options, including reduced levels of output or potential plant closures, as alternatives to purchasing allowances. Given these uncertainties, our analysis of the available compliance options remains ongoing, and additional information or considerations may arise that change our expectations.

Other environmental rules that could involve material compliance costs include those related to effluent limitations, the ozone national ambient air quality standard and other rules or matters involving the Clean Air Act, Clean Water Act, Endangered Species Act, RCRA, Superfund, the Navajo Nation, and water supplies for our power plants.  The financial impact of complying with current and future environmental rules could jeopardize the economic viability of our coal plants or the willingness or ability of power plant participants to fund any required equipment upgrades or continue their participation in these plants.  The economics of continuing to own certain resources, particularly our coal plants, may deteriorate, warranting early retirement of those plants, which may result in asset impairments.  APS would seek recovery in rates for the book value of any remaining investments in the plants as well as other costs related to early retirement, but cannot predict whether it would obtain such recovery.

Federal Agency Environmental Lawsuit Related to Four Corners

On April 20, 2016, several environmental groups filed a lawsuit against OSM and other federal agencies in the District of Arizona in connection with their issuance of the approvals that extended the life of Four Corners and the adjacent mine.  The lawsuit alleges that these federal agencies violated both the ESA and NEPA in providing the federal approvals necessary to extend operations at the Four Corners Power Plant and the adjacent Navajo Mine past July 6, 2016.  APS filed a motion to intervene in the proceedings, which was granted on August 3, 2016. Briefing on the merits of this litigation is expected to extend through May 2017. On September 15, 2016, NTEC, the company that owns the adjacent mine, filed a motion to intervene for the purpose of dismissing the lawsuit based on NTEC's tribal sovereign immunity. Because the court has placed a stay on all litigation deadlines pending its decision regarding NTEC's motion to dismiss, the schedule for briefing and the anticipated timeline for completion of this litigation will likely be extended. We cannot predict the outcome of this matter or its potential effect on Four Corners.

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New Mexico Tax Matter

On May 23, 2013, the New Mexico Taxation and Revenue Department ("NMTRD") issued a notice of assessment for coal severance surtax, penalty, and interest totaling approximately $30 million related to coal supplied under the coal supply agreement for Four Corners (the “Assessment”).  APS’s share of the Assessment is approximately $12 million.  For procedural reasons, on behalf of the Four Corners co-owners, including APS, the coal supplier made a partial payment of the Assessment in the amount of $0.8 million and immediately filed a refund claim with respect to that partial payment in August 2013.  The NMTRD denied the refund claim.  On December 19, 2013, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, filed a complaint with the New Mexico District Court contesting both the validity of the Assessment and the refund claim denial.  On June 30, 2015, the court ruled that the Assessment was not valid and further ruled that APS and the other Four Corners co-owners receive a refund of all of the contested amounts previously paid under the applicable tax statute. The NMTRD filed an appeal of the decision on August 31, 2015.

On March 16, 2016, APS and the coal supplier entered into a final settlement agreement with the NMTRD with respect to the Assessment. Pursuant to the final settlement agreement, the NMTRD agreed to release the Assessment, dismiss its filed appeal, and release its rights to any other surtax claims with respect to the coal supply agreement. APS and the other Four Corners co-owners agreed to forgo refund rights with respect to all of the contested amounts previously paid under the applicable tax statute, as well as pay $1 million. APS's share of this settlement payment, together with its share of the partial payment described above, is approximately $0.8 million.

Peabody Bankruptcy

On April 13, 2016, Peabody Energy Corporation and certain affiliated entities filed a petition for relief under chapter 11 of the Bankruptcy Code in the United States Bankruptcy Court for the Eastern District of Missouri.  Under a Coal Supply Agreement, dated December 21, 2005, Peabody supplied coal to APS and PacifiCorp (collectively, the “Buyers”) for use at the Cholla power plant in Arizona.  APS believes that the Coal Supply Agreement terminated automatically on April 13, 2016 as a result of Peabody's bankruptcy filing. The Buyers filed a motion requesting that the Bankruptcy Court enter an order determining that the Buyers are authorized to enforce the termination provisions in the Coal Supply Agreement.  

On May 13, 2016, Peabody filed a complaint against the Buyers in the bankruptcy court in which Peabody alleged that the Buyers breached the Agreement. On January 27, 2017, the bankruptcy court approved a settlement between the parties, and on February 6, 2017 the parties executed an amendment to the Coal Supply Agreement that allows for continuation of the agreement with modified terms and conditions acceptable to the parties.

Financial Assurances

In the normal course of business, we obtain standby letters of credit and surety bonds from financial institutions and other third parties. These instruments guarantee our own future performance and provide third parties with financial and performance assurance in the event we do not perform. These instruments support certain commodity contract collateral obligations and other transactions. As of December 31, 2016, standby letters of credit totaled $35 million and will expire in 2017. As of December 31, 2016, surety bonds expiring through 2019 totaled $53 million. The underlying liabilities insured by these instruments are reflected on our balance sheets, where applicable. Therefore, no additional liability is reflected for the letters of credit and surety bonds themselves.

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We enter into agreements that include indemnification provisions relating to liabilities arising from or related to certain of our agreements.  Most significantly, APS has agreed to indemnify the equity participants and other parties in the Palo Verde sale leaseback transactions with respect to certain tax matters.  Generally, a maximum obligation is not explicitly stated in the indemnification provisions and, therefore, the overall maximum amount of the obligation under such indemnification provisions cannot be reasonably estimated.  Based on historical experience and evaluation of the specific indemnities, we do not believe that any material loss related to such indemnification provisions is likely.

Pinnacle West has issued parental guarantees and has provided indemnification under certain surety bonds for APS which were not material at December 31, 2016. Effective July 6, 2016, Pinnacle West has issued two parental guarantees for 4CArelating to payment obligations arising from 4CA’s acquisition of El Paso’s 7% interest in Four Corners, and pursuant to the Four Corners participation agreement payment obligations arising from 4CA’s ownership interest in Four Corners.

11.     Asset Retirement Obligations

APS has asset retirement obligations for its Palo Verde nuclear facilities and certain other generation assets. 

The Palo Verde asset retirement obligation primarily relates to final plant decommissioning.  This obligation is based on the NRC’s requirements for disposal of radiated property or plant and agreements APS reached with the ACC for final decommissioning of the plant.  The non-nuclear generation asset retirement obligations primarily relate to requirements for removing portions of those plants at the end of the plant life or lease term and coal ash pond closures. Some of APS’s transmission and distribution assets have asset retirement obligations because they are subject to right of way and easement agreements that require final removal.  These agreements have a history of uninterrupted renewal that APS expects to continue.  As a result, APS cannot reasonably estimate the fair value of the asset retirement obligation related to such transmission and distribution assets. Additionally, APS has aquifer protection permits for some of its generation sites that require the closure of certain facilities at those sites.

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In 2016, APS recognized an ARO for the Ocotillo steam units as a condition of the air permit (issued in 2016) to allow the construction and operation of five new turbine units. This resulted in an increase to the ARO in the amount of $10 million. In addition, 4CA acquired El Paso's share of Four Corners Units 4 & 5 and the associated ARO. This resulted in an increase to the ARO in the amount of $9 million. In addition, Four Corners spent $16 million in actual decommissioning costs. Finally, in 2016, APS received a new decommissioning study for the Palo Verde Nuclear Generating Station. This resulted in an increase to the ARO in the amount of $151 million, an increase in plant in service of $131 million, and a reduction of the regulatory liability of $20 million.

In 2015, a revision to the estimated cash flows for the decommissioning study was completed for the Four Corners coal-fired plant, which resulted in an increase to the ARO in the amount of $24 million. Also in 2015, Four Corners spent $32 million in actual decommissioning costs. In addition, APS recognized an ARO for Cholla as a result of new CCR environmental rules that were published in the Federal Register in the second quarter of 2015. See Note 10 for additional information related to the CCR environmental rules. This resulted in an increase to the ARO in the amount of $39 million, an increase in plant in service of $23 million and a reduction of the regulatory liability of $16 million. Finally, in 2015 there was a revision in estimated cash flows for the Cholla decommissioning, which resulted in a decrease of the ARO in the amount of $3 million.

The following table shows the change in our asset retirement obligations for 2016 and 2015 (dollars in thousands):

	2016			2015
Asset retirement obligations at the beginning of year	$	443,576		$	390,750
Changes attributable to:
Accretion expense	26,656			25,163
Settlements	(15,732		)	(32,048		)
Estimated cash flow revisions	151,046			17,556
Newly incurred or acquired obligations	18,929			42,155
Asset retirement obligations at the end of year	$	624,475		$	443,576

Decommissioning activities for Four Corners Units 1-3 began in January 2014. Thus, $9 million of the total ARO of $624 million at December 31, 2016, is classified as a current liability on the balance sheet. At December 31, 2015, $29 million of the total ARO of $444 million was classified as a current liability on the balance sheet.

In accordance with regulatory accounting, APS accrues removal costs for its regulated utility assets, even if there is no legal obligation for removal.  See detail of regulatory liabilities in Note 3.

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12.    Selected Quarterly Financial Data (Unaudited)

Consolidated quarterly financial information for 2016 and 2015 is provided in the tables below (dollars in thousands, except per share amounts).  Weather conditions cause significant seasonal fluctuations in our revenues; therefore, results for interim periods do not necessarily represent results expected for the year.

	2016 Quarter Ended								2016
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	677,167	$	915,394	$	1,166,922	$	739,199	$	3,498,682
Operations and maintenance	243,195		242,279		217,568		208,277		911,319
Operating income	50,162		231,748		451,258		122,816		855,984
Income taxes	1,914		65,742		141,446		27,309		236,411
Net income	9,326		126,182		267,900		58,119		461,527
Net income attributable to common shareholders	4,453		121,308		263,027		53,246		442,034
Earnings Per Share:
Net income attributable to common shareholders — Basic	$	0.04	$	1.09	$	2.36	$	0.48	$	3.97
Net income attributable to common shareholders — Diluted	0.04		1.08		2.35		0.47		3.95

	2015 Quarter Ended								2015
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	671,219	$	890,648	$	1,199,146	$	734,430	$	3,495,443
Operations and maintenance	214,944		210,965		220,449		222,019		868,377
Operating income	67,684		231,973		445,111		109,834		854,602
Income taxes	7,947		67,371		139,555		22,847		237,720
Net income	20,727		127,507		261,978		45,978		456,190
Net income attributable to common shareholders	16,122		122,902		257,116		41,117		437,257
Earnings Per Share:
Net income attributable to common shareholders — Basic	$	0.15	$	1.11	$	2.32	$	0.37	$	3.94
Net income attributable to common shareholders — Diluted	0.14		1.10		2.30		0.37		3.92

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Selected Quarterly Financial Data (Unaudited) - APS

APS's quarterly financial information for 2016 and 2015 is as follows (dollars in thousands):

	2016 Quarter Ended,								2016
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	676,632	$	909,757	$	1,166,359	$	737,006	$	3,489,754
Operations and maintenance	238,711		233,712		209,366		197,319		879,108
Operating income	48,930		165,684		307,601		95,765		617,980
Net income attributable to common shareholder	7,253		127,188		269,220		58,480		462,141

	2015 Quarter Ended,								2015
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	670,668	$	889,723	$	1,198,380	$	733,586	$	3,492,357
Operations and maintenance	209,947		208,031		216,011		219,146		853,135
Operating income	61,333		162,704		301,238		86,709		611,984
Net income attributable to common shareholder	19,868		125,362		261,187		43,857		450,274

13.    Fair Value Measurements

We classify our assets and liabilities that are carried at fair value within the fair value hierarchy.  This hierarchy ranks the quality and reliability of the inputs used to determine fair values, which are then classified and disclosed in one of three categories.  The three levels of the fair value hierarchy are:

Level 1 — Unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date.  Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide information on an ongoing basis.  This category includes exchange traded equities, exchange traded derivative instruments, exchange traded mutual funds, cash equivalents, and investments in U.S. Treasury securities.

Level 2 — Utilizes quoted prices in active markets for similar assets or liabilities; quoted prices in markets that are not active; and model-derived valuations whose inputs are observable (such as yield curves).  This category includes non-exchange traded contracts such as forwards, options, swaps and certain investments in fixed income securities.

Level 3 — Valuation models with significant unobservable inputs that are supported by little or no market activity.  Instruments in this category include long-dated derivative transactions where valuations are unobservable due to the length of the transaction, options, and transactions in locations where observable market data does not exist.  The valuation models we employ utilize spot prices, forward prices, historical market data and other factors to forecast future prices.

Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.  Thus, a valuation may be classified in Level 3 even though the valuation may include significant inputs that are readily observable.  We maximize the use of observable inputs and minimize the use of unobservable inputs.  We rely primarily on the market approach of using prices and other market information for identical and/or comparable assets and liabilities.  If market data is not readily available, inputs

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may reflect our own assumptions about the inputs market participants would use.  Our assessment of the inputs and the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities as well as their placement within the fair value hierarchy levels.  We assess whether a market is active by obtaining observable broker quotes, reviewing actual market activity, and assessing the volume of transactions.  We consider broker quotes observable inputs when the quote is binding on the broker, we can validate the quote with market activity, or we can determine that the inputs the broker used to arrive at the quoted price are observable.

Certain instruments have been valued using the concept of Net Asset Value (“NAV”), as a practical expedient. These instruments are typically structured as investment companies offering shares or units to multiple investors for the purpose of providing a return. These instruments are similar to mutual funds; however, they are not traded on an exchange. During the first quarter of 2016 we retrospectively adopted new accounting guidance that requires certain instruments valued using NAV to no longer be classified within the fair value hierarchy. As such, certain instruments valued using NAV are included in our fair value disclosures and tables in a separate column; however, these investments are not classified within any of the fair value hierarchy levels. Prior to the adoption of this guidance these instruments were typically reported within Level 2 or Level 3. The adoption of this guidance changes our fair value disclosures, but does not impact the methodology for valuing these instruments, or our financial statement results.

Recurring Fair Value Measurements

We apply recurring fair value measurements to certain cash equivalents, derivative instruments, investments held in our nuclear decommissioning trust, plan assets held in our retirement and other benefit plans and coal reclamation trust investments.  See Note 7 for the fair value discussion of plan assets held in our retirement and other benefit plans.

Cash Equivalents

Cash equivalents represent short-term investments with original maturities of three months or less in exchange traded money market funds that are valued using quoted prices in active markets.

Coal Reclamation Trust Investments

The coal reclamation trust holds cash equivalent investments in money market funds that are valued using quoted prices in active markets, and are reported within Level 1.

Risk Management Activities — Derivative Instruments

Exchange traded commodity contracts are valued using unadjusted quoted prices.  For non-exchange traded commodity contracts, we calculate fair value based on the average of the bid and offer price, discounted to reflect net present value.  We maintain certain valuation adjustments for a number of risks associated with the valuation of future commitments.  These include valuation adjustments for liquidity and credit risks.  The liquidity valuation adjustment represents the cost that would be incurred if all unmatched positions were closed out or hedged.  The credit valuation adjustment represents estimated credit losses on our net exposure to counterparties, taking into account netting agreements, expected default experience for the credit rating of the counterparties and the overall diversification of the portfolio.  We maintain credit policies that management believes minimize overall credit risk.

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Certain non-exchange traded commodity contracts are valued based on unobservable inputs due to the long-term nature of contracts, characteristics of the product, or the unique location of the transactions.  Our long-dated energy transactions consist of observable valuations for the near-term portion and unobservable valuations for the long-term portions of the transaction.  We rely primarily on broker quotes to value these instruments.  When our valuations utilize broker quotes, we perform various control procedures to ensure the quote has been developed consistent with fair value accounting guidance.  These controls include assessing the quote for reasonableness by comparison against other broker quotes, reviewing historical price relationships, and assessing market activity.  When broker quotes are not available, the primary valuation technique used to calculate the fair value is the extrapolation of forward pricing curves using observable market data for more liquid delivery points in the same region and actual transactions at more illiquid delivery points.

Option contracts are primarily valued using a Black-Scholes option valuation model, which utilizes both observable and unobservable inputs such as broker quotes, interest rates and price volatilities.

When the unobservable portion is significant to the overall valuation of the transaction, the entire transaction is classified as Level 3.  Our classification of instruments as Level 3 is primarily reflective of the long-term nature of our energy transactions and the use of option valuation models with significant unobservable inputs.

Our energy risk management committee, consisting of officers and key management personnel, oversees our energy risk management activities to ensure compliance with our stated energy risk management policies.  We have a risk control function that is responsible for valuing our derivative commodity instruments in accordance with established policies and procedures.  The risk control function reports to the chief financial officer’s organization.

Investments Held in our Nuclear Decommissioning Trust

The nuclear decommissioning trust invests in fixed income securities and equity securities. Equity securities are held indirectly through commingled funds.  The commingled funds are valued using the funds' NAV as a practical expedient. The funds' NAV is primarily derived from the quoted active market prices of the underlying equity securities held by the funds. We may transact in these commingled funds on a semi-monthly basis at the NAV.  The commingled funds are maintained by a bank and hold investments in accordance with the stated objective of tracking the performance of the S&P 500 Index.  Because the commingled funds' shares are offered to a limited group of investors, they are not considered to be traded in an active market. As these instruments are valued using NAV, as a practical expedient, they have not been classified within the fair value hierarchy.

Cash equivalents reported within Level 1 represent investments held in a short-term investment exchange-traded mutual fund, which invests in certificates of deposit, variable rate notes, time deposit accounts, U.S. Treasury and Agency obligations, U.S. Treasury repurchase agreements, and commercial paper.

Fixed income securities issued by the U.S. Treasury held directly by the nuclear decommissioning trust are valued using quoted active market prices and are typically classified as Level 1.  Fixed income securities issued by corporations, municipalities, and other agencies, including mortgage-backed instruments, are valued using quoted inactive market prices, quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield curves and spreads relative to such yield curves.  These instruments are classified as Level 2.  Whenever possible, multiple market quotes are obtained which enables a cross-check validation.  A primary price source is identified based on asset type, class, or issue of securities.

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We price securities using information provided by our trustee for our nuclear decommissioning trust assets. Our trustee uses pricing services that utilize the valuation methodologies described to determine fair market value. We have internal control procedures designed to ensure this information is consistent with fair value accounting guidance. These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustee’s internal operating controls and valuation processes.  See Note 19 for additional discussion about our nuclear decommissioning trust.

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Fair Value Tables

The following table presents the fair value at December 31, 2016 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other				Balance at December 31, 2016
Assets
Coal reclamation trust - cash equivalents (b)	$	14,521	$	—		$	—		$	—			$	14,521
Risk management activities — derivative instruments:
Commodity contracts	—		43,722			11,076			(35,103		)	(c)	19,695
Nuclear decommissioning trust:
U.S. commingled equity funds	—		—			—			353,261			(d)	353,261
Fixed income securities:
Cash and cash equivalent funds	—		—			—			795			(e)	795
U.S. Treasury	95,441		—			—			—				95,441
Corporate debt	—		111,623			—			—				111,623
Mortgage-backed securities	—		115,337			—			—				115,337
Municipal bonds	—		80,997			—			—				80,997
Other	—		22,132			—			—				22,132
Subtotal nuclear decommissioning trust	95,441		330,089			—			354,056				779,586
Total	$	109,962	$	373,811		$	11,076		$	318,953			$	813,802
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(45,641	)	$	(58,482	)	$	31,049		(c)	$	(73,074	)

(a) Primarily consists of long-dated electricity contracts.

(b) Represents investments restricted for coal mine reclamation funding related to Four Corners. These assets are included in the Other Assets line item, reported under the Investments and Other Assets section of our Consolidated Balance Sheets.

(c) Represents counterparty netting, margin and collateral.  See Note 16.

(d) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

(e) Represents nuclear decommissioning trust net pending securities sales and purchases.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table presents the fair value at December 31, 2015 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other				Balance at December 31, 2015
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	22,992		$	30,364		$	(25,345	)	(b)	$	28,011
Nuclear decommissioning trust:
U.S. commingled equity funds	—		—			—			314,957			(c)	314,957
Fixed income securities:
Cash and cash equivalent funds	12,260		—			—			(335		)	(d)	11,925
U.S. Treasury	117,245		—			—			—				117,245
Corporate debt	—		96,243			—			—				96,243
Mortgage-backed securities	—		99,065			—			—				99,065
Municipal bonds	—		72,206			—			—				72,206
Other	—		23,555			—			—				23,555
Subtotal nuclear decommissioning trust	129,505		291,069			—			314,622				735,196
Total	$	129,505	$	314,061		$	30,364		$	289,277			$	763,207
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(144,044	)	$	(63,343	)	$	39,698		(b)	$	(167,689	)

(a) Primarily consists of heat rate options and other long-dated electricity contracts.

(b) Represents counterparty netting, margin and collateral.  See Note 16.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

(d) Represents nuclear decommissioning trust net pending securities sales and purchases.

Fair Value Measurements Classified as Level 3

The significant unobservable inputs used in the fair value measurement of our energy derivative contracts include broker quotes that cannot be validated as an observable input primarily due to the long-term nature of the quote and option model inputs.  Significant changes in these inputs in isolation would result in significantly higher or lower fair value measurements.  Changes in our derivative contract fair values, including changes relating to unobservable inputs, typically will not impact net income due to regulatory accounting treatment (see Note 3).

Because our forward commodity contracts classified as Level 3 are currently in a net purchase position, we would expect price increases of the underlying commodity to result in increases in the net fair value of the related contracts.  Conversely, if the price of the underlying commodity decreases, the net fair value of the related contracts would likely decrease.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Our option contracts classified as Level 3 primarily relate to purchase heat rate options.  The remaining option contract expired on October 1, 2016. The significant unobservable inputs at December 31, 2015 for these instruments include electricity prices, and volatilities.  If electricity prices and electricity price volatilities increase, we would expect the fair value of these options to increase, and if these valuation inputs decrease, we would expect the fair value of these options to decrease.  If natural gas prices and natural gas price volatilities increase, we would expect the fair value of these options to decrease, and if these inputs decrease, we would expect the fair value of the options to increase.  The commodity prices and volatilities do not always move in corresponding directions.  The options’ fair values are impacted by the net changes of these various inputs.

Other unobservable valuation inputs include credit and liquidity reserves which do not have a material impact on our valuations; however, significant changes in these inputs could also result in higher or lower fair value measurements.

The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at December 31, 2016 and December 31, 2015:

	December 31, 2016 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	10,648	$	32,042	Discounted cash flows	Electricity forward price (per MWh)	$16.43 - $41.07	$	29.86
Natural Gas:
Forward Contracts (a)	428		26,440		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.32 - $3.60	$	2.81
Total	$	11,076	$	58,482

(a) Includes swaps and physical and financial contracts.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

	December 31, 2015 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	24,543	$	54,679	Discounted cash flows	Electricity forward price (per MWh)	$15.92 - $40.73	$	26.86
Option Contracts (b)	—		5,628		Option model	Electricity forward price (per MWh)	$23.87 - $44.13	$	33.91
						Electricity price volatilities	40% - 59%	52		%
						Natural gas price volatilities	32% - 40%	35		%
Natural Gas:
Forward Contracts (a)	5,821		3,036		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.18 - $3.14	$	2.61
Total	$	30,364	$	63,343

(a) Includes swaps and physical and financial contracts.

(b) Electricity and natural gas price volatilities are estimated based on historical forward price movements due to lack of market quotes for implied volatilities.

The following table shows the changes in fair value for our risk management activities’ assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs for the years ended December 31, 2016 and 2015 (dollars in thousands):

	Year Ended December 31,
Commodity Contracts	2016			2015
Net derivative balance at beginning of period	$	(32,979	)	$	(41,386	)
Total net gains (losses) realized/unrealized:
Included in earnings	—			—
Included in OCI	88			(452		)
Deferred as a regulatory asset or liability	(37,543		)	(4,009		)
Settlements	15,146			14,809
Transfers into Level 3 from Level 2	1,900			(6,256		)
Transfers from Level 3 into Level 2	5,982			4,315
Net derivative balance at end of period	$	(47,406	)	$	(32,979	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—

Amounts included in earnings are recorded in either operating revenues or fuel and purchased power depending on the nature of the underlying contract.

Transfers reflect the fair market value at the beginning of the period and are triggered by a change in the lowest significant input as of the end of the period.  We had no significant Level 1 transfers to or from any other hierarchy level.  Transfers in or out of Level 3 are typically related to our long-dated energy transactions that extend beyond available quoted periods.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Financial Instruments Not Carried at Fair Value

The carrying value of our net accounts receivable, accounts payable and short-term borrowings approximate fair value.  Our short-term borrowings are classified within Level 2 of the fair value hierarchy.  See Note 6 for our long-term debt fair values.

14.    Earnings Per Share

The following table presents the calculation of Pinnacle West’s basic and diluted earnings per share for continuing operations attributable to common shareholders for the years ended December 31, 2016, 2015 and 2014 (in thousands, except per share amounts):

	2016		2015		2014
Net income attributable to common shareholders	$	442,034	$	437,257	$	397,595
Weighted average common shares outstanding — basic	111,409		111,026		110,626
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units	637		526		552
Weighted average common shares outstanding — diluted	112,046		111,552		111,178
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic	$	3.97	$	3.94	$	3.59
Net Income attributable to common shareholders - diluted	$	3.95	$	3.92	$	3.58

15.    Stock-Based Compensation

Pinnacle West has incentive compensation plans under which stock-based compensation is granted to officers, key-employees, and non-officer members of the Board of Directors. Awards granted under the 2012 Long-Term Incentive Plan (“2012 Plan”) may be in the form of stock grants, restricted stock units, stock units, performance shares, restricted stock, dividend equivalents, performance share units, performance cash, incentive and non-qualified stock options, and stock appreciation rights.  The 2012 Plan authorizes up to 4.6 million common shares to be available for grant.  As of December 31, 2016, 2.5 million common shares were available for issuance under the 2012 Plan. During 2016, 2015, and 2014, the Company granted awards in the form of restricted stock units, stock units, stock grants, and performance shares. Awards granted from 2007 to 2011 were issued under the 2007 Long-Term Incentive Plan (“2007 Plan”), and no new awards may be granted under the 2007 Plan.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Stock-Based Compensation Expense and Activity

During the fourth quarter of 2016, we adopted new stock-based compensation accounting guidance prescribed by ASU 2016-09, see Note 2. Prior to the adoption of this guidance we had certain awards that were accounted for as liability awards due to the ability of the employee to withhold taxes beyond the minimum statutory tax withholding rate. Under the new standard, the tax withholding terms of our awards no longer trigger liability treatment. Accordingly, effective, January 1, 2016 certain awards that were previously classified as liability awards are now accounted for as equity awards. The impacts of this accounting change relating to prior years have been applied using a modified retrospective approach, resulting in a $6 million cumulative-effect adjustment, net of income tax expense of $3 million, to increase Retained Earnings as of January 1, 2016. The impacts of this accounting change relating to the current year, resulted in a pre-tax $12 million adjustment to decrease operations and maintenance expense that was recognized during the fourth quarter of 2016. Due to this transition approach, the following discussion reflects this change in the 2016 expense and activity; however, expense and activities relating to 2015 and 2014 reflect the historical treatment. The new standard also requires excess income tax benefits and deficiencies arising from stock based compensation to now be recognized in the period incurred, simplifies accounting for forfeitures, and clarifies certain cash flow presentation matters. These other provisions of the standard did not have a material impact on our consolidated financial statements.

Compensation cost included in net income for stock-based compensation plans was $19 million in 2016, $19 million in 2015, and $33 million in 2014.  The compensation cost capitalized is immaterial for all years. Income tax benefits related to stock-based compensation arrangements were $10 million in 2016, $7 million in 2015, and $13 million in 2014.

As of December 31, 2016, there were approximately $13 million of unrecognized compensation costs related to nonvested stock-based compensation arrangements. We expect to recognize these costs over a weighted-average period of 2 years. 

The total fair value of shares vested was $22 million in 2016, $21 million in 2015 and $22 million in 2014.

The following table is a summary of awards granted and the weighted-average grant date fair value for the three years ended 2016, 2015 and 2014.

	Restricted Stock Units, Stock Grants, and Stock Units (a)						Performance Shares (b)
	2016		2015		2014		2016		2015		2014
Units granted	141,811		152,651		179,291		166,666		151,430		166,244
Weighted-average grant date fair value	$	67.34	$	64.12	$	54.89	$	66.60	$	64.97	$	54.86

(a) Units granted includes awards that will be cash settled of 43,952 in 2016, 45,104 in 2015, and 49,018 in 2014.

(b) Reflects the target payout level.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table is a summary of the status of non-vested awards as of December 31, 2016 and changes during the year.

	Restricted Stock Units, Stock Grants, and Stock Units					Performance Shares
	Shares			Weighted-Average Grant Date Fair Value		Shares (b)		Weighted-Average Grant Date Fair Value
Nonvested at January 1, 2016	428,287			$	56.69	305,832		$	58.86
Granted	141,811			67.34		166,666		66.60
Change in performance factor	—			—		15,573		54.09
Vested	(230,881	)		55.07		(171,303	)	54.09
Forfeited (c)	(3,958	)		62.86		(4,044	)	62.34
Nonvested at December 31, 2016	335,259		(a)	62.04		312,724		65.32
Vested Awards Outstanding at December 31, 2016	174,201					171,303

(a) Includes 112,554 of awards that will be cash settled.

(b) The nonvested performance shares are reflected at target payout level.  The performance metric component increase or decrease in the number of shares from the target level to the estimated actual payout level is included in the increase for performance factor amounts in the year the award vests.

(c) We account for forfeitures as they occur.

Share-based liabilities paid relating to restricted stock units were $3 million, $10 million and $9 million in 2016, 2015 and 2014, respectively. This includes cash used to settle restricted stock units of $3 million for each of the years 2016, 2015 and 2014. Restricted stock units that are cash settled are classified as liability awards. Share-based liabilities paid relating to performance shares were $16 million in 2015 and $12 million in 2014. In 2016, performance shares were classified as equity awards.

Restricted Stock Units, Stock Grants, and Stock Units

Restricted stock units are granted to officers and key employees.  Restricted stock units typically vest and settle in equal annual installments over a 4-year period after the grant date.  Vesting is typically dependent upon continuous service during the vesting period; however, awards granted to retirement-eligible employees will vest upon the employee's retirement. Awardees elect to receive payment in either 100% stock, or 50% in cash and 50% in stock. Restricted stock unit awards typically include a dividend equivalent feature. This feature allows each award to accrue dividend rights equal to the dividends they would have received had they directly owned the stock. Interest on dividend rights compounds quarterly. If the award is forfeited the employee is not entitled to the dividends on those shares.

In December 2012, the Company granted a retention award of 50,617 performance-linked restricted stock units to the Chairman of the Board and Chief Executive Officer of Pinnacle West.  This award vested on December 31, 2016, because he remained employed with the Company through that date.  The Board can increase the number of awards that vest, up to an additional 33,745 restricted stock units, payable in stock, if certain performance requirements are met.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Compensation cost for restricted stock unit awards is based on the fair value of the award, with the fair value being the market price of our stock on the measurement date. Restricted stock unit awards that will be settled in cash are accounted for as liability awards, with compensation cost initially calculated on the date of grant using the Company’s closing stock price, and remeasured at each balance sheet date. Restricted stock unit awards that will be settled in shares are accounted for as equity awards, with compensation cost calculated using the Company's closing stock price on the date of grant. Compensation cost is recognized over the requisite service period based on the fair value of the award.

Stock grants are issued to non-officer members of the Board of Directors. They may elect to receive the stock grant, or to defer receipt until a later date and receive stock units in lieu of the stock grant.  The members of the Board of Directors who elect to defer may elect to receive payment in either 100% stock, or 50% in cash and 50% in stock.  Each stock unit is convertible to one share of stock. The stock units accrue dividend rights, equal to the amount of dividends the Directors would have received had they directly owned stock equal to the number of vested restricted stock units or stock units from the date of grant to the date of payment, plus interest compounded quarterly.  The dividends and interest are paid, based on the Director’s election, in either stock, or 50% in cash and 50% in stock.

Performance Share Awards

Performance share awards are granted to officers and key employees.  The awards contain two separate performance criteria that affect the number of shares that may be received if after the end of a 3-year performance period the performance criteria are met. For the first criteria, the number of shares that will vest is based upon six non-financial separate performance metrics (i.e., the metric component). The other criteria is based upon Pinnacle West's total shareholder return (TSR) in relation to the TSR of other companies in a specified utility index (i.e., the TSR component). The exact number of shares issued will vary from 0% to 200% of the target award.  Shares received include dividend rights paid in stock equal to the amount of dividends that they would have received had they directly owned stock, equal to the number of vested performance shares from the date of grant to the date of payment plus interest compounded quarterly. If the award is forfeited or if the performance criteria are not achieved the employee is not entitled to the dividends on those shares.

Performance share awards are accounted for as equity awards, with compensation cost based on the fair value of the award on grant date. Compensation cost relating to the metric component of the award is based on the Company’s closing stock price on the date of grant, with compensation cost recognized over the requisite service period based on the number of shares expected to vest. Management evaluates the probability of meeting the metric component at each balance sheet date. If the metric component criteria are not ultimately achieved, no compensation cost is recognized relating to the metric component, and any previously recognized compensation cost is reversed. Compensation cost relating to the TSR component of the award is determined using a Monte Carlo simulation valuation model, with compensation cost recognized ratably over the requisite service period, regardless of the number of shares that actually vest.

16.    Derivative Accounting

We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal, emissions allowances and in interest rates.  We manage risks associated with market volatility by utilizing various physical and financial derivative instruments, including futures, forwards, options and swaps.  As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and fuels.  Derivative instruments that meet certain hedge accounting

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

criteria may be designated as cash flow hedges and are used to limit our exposure to cash flow variability on forecasted transactions.  The changes in market value of such instruments have a high correlation to price changes in the hedged transactions.  We also enter into derivative instruments for economic hedging purposes.  While we believe the economic hedges mitigate exposure to fluctuations in commodity prices, these instruments have not been designated as accounting hedges.  Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power costs in our Consolidated Statements of Income, but does not impact our financial condition, net income or cash flows.

Our derivative instruments, excluding those qualifying for a scope exception, are recorded on the balance sheet as an asset or liability and are measured at fair value.  See Note 13 for a discussion of fair value measurements.  Derivative instruments may qualify for the normal purchases and normal sales scope exception if they require physical delivery and the quantities represent those transacted in the normal course of business.  Derivative instruments qualifying for the normal purchases and sales scope exception are accounted for under the accrual method of accounting and excluded from our derivative instrument discussion and disclosures below.

Hedge effectiveness is the degree to which the derivative instrument contract and the hedged item are correlated and is measured based on the relative changes in fair value of the derivative instrument contract and the hedged item over time.  We assess hedge effectiveness both at inception and on a continuing basis.  These assessments exclude the time value of certain options.  For accounting hedges that are deemed an effective hedge, the effective portion of the gain or loss on the derivative instrument is reported as a component of OCI and reclassified into earnings in the same period during which the hedged transaction affects earnings.  We recognize in current earnings, subject to the PSA, the gains and losses representing hedge ineffectiveness, and the gains and losses on any hedge components which are excluded from our effectiveness assessment.  As cash flow hedge accounting has been discontinued for the significant majority of our contracts, after May 31, 2012, effectiveness testing is no longer being performed for these contracts.

For its regulated operations, APS defers for future rate treatment 100% of the unrealized gains and losses on derivatives pursuant to the PSA mechanism that would otherwise be recognized in income.  Realized gains and losses on derivatives are deferred in accordance with the PSA to the extent the amounts are above or below the Base Fuel Rate (see Note 3).  Gains and losses from derivatives in the following tables represent the amounts reflected in income before the effect of PSA deferrals.

As of December 31, 2016, we had the following outstanding gross notional volume of derivatives, which represent both purchases and sales (does not reflect net position):

Commodity	Quantity
Power	1,314	GWh
Gas	194	Billion cubic feet

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Gains and Losses from Derivative Instruments

The following table provides information about gains and losses from derivative instruments in designated cash flow accounting hedging relationships during the years ended December 31, 2016, 2015 and 2014 (dollars in thousands):

	Financial Statement	Year Ended December 31,
Commodity Contracts	Location	2016			2015			2014
Gain (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	OCI — derivative instruments	$	47		$	(615	)	$	(372	)
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized) (a)	Fuel and purchased power (b)	(3,926		)	(5,988		)	(21,415		)

(a) During the years ended December 31, 2016, 2015, and 2014, we had no losses reclassified from accumulated OCI to earnings related to discontinued cash flow hedges.

(b) Amounts are before the effect of PSA deferrals.

During the next twelve months, we estimate that a net loss of $3 million before income taxes will be reclassified from accumulated OCI as an offset to the effect of market price changes for the related hedged transactions.  In accordance with the PSA, most of these amounts will be recorded as either a regulatory asset or liability and have no immediate effect on earnings.

The following table provides information about gains and losses from derivative instruments not designated as accounting hedging instruments during the years ended December 31, 2016, 2015 and 2014 (dollars in thousands):

	Financial Statement	Year Ended December 31,
Commodity Contracts	Location	2016		2015			2014
Net Gain Recognized in Income	Operating revenues	$	771	$	574		$	324
Net Gain (Loss) Recognized in Income	Fuel and purchased power (a)	25,711		(108,973		)	(66,367		)
Total		$	26,482	$	(108,399	)	$	(66,043	)

(a) Amounts are before the effect of PSA deferrals.

Derivative Instruments in the Consolidated Balance Sheets

Our derivative transactions are typically executed under standardized or customized agreements, which include collateral requirements and, in the event of a default, would allow for the netting of positive and negative exposures associated with a single counterparty.  Agreements that allow for the offsetting of positive and negative exposures associated with a single counterparty are considered master netting arrangements.  Transactions with counterparties that have master netting arrangements are offset and reported net on the Consolidated Balance Sheets.  Transactions that do not allow for offsetting of positive and negative positions are reported gross on the Consolidated Balance Sheets.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

We do not offset a counterparty’s current derivative contracts with the counterparty’s non-current derivative contracts, although our master netting arrangements would allow current and non-current positions to be offset in the event of a default.  Additionally, in the event of a default, our master netting arrangements would allow for the offsetting of all transactions executed under the master netting arrangement.  These types of transactions may include non-derivative instruments, derivatives qualifying for scope exceptions, trade receivables and trade payables arising from settled positions, and other forms of non-cash collateral (such as letters of credit).  These types of transactions are excluded from the offsetting tables presented below.

The significant majority of our derivative instruments are not currently designated as hedging instruments.  The Consolidated Balance Sheets as of December 31, 2016 and December 31, 2015, include gross liabilities of $2 million and $3 million, respectively, of derivative instruments designated as hedging instruments.

The following tables provide information about the fair value of our risk management activities reported on a gross basis, and the impacts of offsetting as of December 31, 2016 and 2015.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Consolidated Balance Sheets.

As of December 31, 2016: (dollars in thousands)	Gross  Recognized  Derivatives (a)			Amounts  Offset (b)			Net Recognized Derivatives			Other (c)			Amount  Reported on  Balance Sheet
Current assets	$	48,094		$	(28,400	)	$	19,694		$	—		$	19,694
Investments and other assets	6,704			(6,703		)	1			—			1
Total assets	54,798			(35,103		)	19,695			—			19,695
Current liabilities	(50,182		)	28,400			(21,782		)	(4,054		)	(25,836		)
Deferred credits and other	(53,941		)	6,703			(47,238		)	—			(47,238		)
Total liabilities	(104,123		)	35,103			(69,020		)	(4,054		)	(73,074		)
Total	$	(49,325	)	$	—		$	(49,325	)	$	(4,054	)	$	(53,379	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting.

(c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,054.

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

As of December 31, 2015: (dollars in thousands)	Gross Recognized Derivatives (a)			Amounts Offset  (b)			Net Recognized Derivatives			Other (c)			Amount Reported on Balance Sheet
Current assets	$	37,396		$	(22,163	)	$	15,233		$	672		$	15,905
Investments and other assets	15,960			(3,854		)	12,106			—			12,106
Total assets	53,356			(26,017		)	27,339			672			28,011
Current liabilities	(113,560		)	40,223			(73,337		)	(4,379		)	(77,716		)
Deferred credits and other	(93,827		)	3,854			(89,973		)	—			(89,973		)
Total liabilities	(207,387		)	44,077			(163,310		)	(4,379		)	(167,689		)
Total	$	(154,031	)	$	18,060		$	(135,971	)	$	(3,707	)	$	(139,678	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) Includes cash collateral provided to counterparties of $18,060.

(c) Represents cash collateral and cash margin that is not subject to offsetting.  Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,379, and cash margin provided to counterparties of $672. 

Credit Risk and Credit Related Contingent Features

We are exposed to losses in the event of nonperformance or nonpayment by counterparties and have risk management contracts with many counterparties. As of December 31, 2016, we have no counterparties with positive exposures of greater than 10% of risk management assets. Our risk management process assesses and monitors the financial exposure of all counterparties.  Despite the fact that the great majority of trading counterparties' debt is rated as investment grade by the credit rating agencies, there is still a possibility that one or more of these companies could default, resulting in a material impact on consolidated earnings for a given period. Counterparties in the portfolio consist principally of financial institutions, major energy companies, municipalities and local distribution companies.  We maintain credit policies that we believe minimize overall credit risk to within acceptable limits.  Determination of the credit quality of our counterparties is based upon a number of factors, including credit ratings and our evaluation of their financial condition.  To manage credit risk, we employ collateral requirements and standardized agreements that allow for the netting of positive and negative exposures associated with a single counterparty.  Valuation adjustments are established representing our estimated credit losses on our overall exposure to counterparties.

Certain of our derivative instrument contracts contain credit-risk-related contingent features including, among other things, investment grade credit rating provisions, credit-related cross-default provisions, and adequate assurance provisions.  Adequate assurance provisions allow a counterparty with reasonable grounds for uncertainty to demand additional collateral based on subjective events and/or conditions.  For those derivative instruments in a net liability position, with investment grade credit contingencies, the counterparties could demand additional collateral if our debt credit rating were to fall below investment grade (below BBB- for Standard & Poor’s or Fitch or Baa3 for Moody’s).

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COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table provides information about our derivative instruments that have credit-risk-related contingent features at December 31, 2016 (dollars in thousands):

	December 31, 2016
Aggregate fair value of derivative instruments in a net liability position	$	104,123
Cash collateral posted	—
Additional cash collateral in the event credit-risk related contingent features were fully triggered (a)	23,914

(a) This amount is after counterparty netting and includes those contracts which qualify for scope exceptions, which are excluded from the derivative details above.

We also have energy related non-derivative instrument contracts with investment grade credit-related contingent features, which could also require us to post additional collateral of approximately $144 million if our debt credit ratings were to fall below investment grade.

17.    Other Income and Other Expense

The following table provides detail of Pinnacle West's Consolidated other income and other expense for 2016, 2015 and 2014 (dollars in thousands):

	2016			2015			2014
Other income:
Interest income	$	884		$	493		$	1,010
Debt return on the purchase of Four Corners units 4 & 5	—			—			8,386
Miscellaneous	17			128			212
Total other income	$	901		$	621		$	9,608
Other expense:
Non-operating costs	$	(9,235	)	$	(11,292	)	$	(9,657	)
Investment losses — net	(1,747		)	(2,080		)	(9,426		)
Miscellaneous	(4,355		)	(4,451		)	(2,663		)
Total other expense	$	(15,337	)	$	(17,823	)	$	(21,746	)

Other Income and Other Expense - APS

The following table provides detail of APS’s other income and other expense for 2016, 2015 and 2014 (dollars in thousands):

165

	2016			2015			2014
Other income:
Interest income	$	261		$	163		$	689
Debt return on the purchase of Four Corners units 4 & 5	—			—			8,386
Gain on disposition of property	5,745			716			1,197
Miscellaneous	2,601			1,955			1,023
Total other income	$	8,607		$	2,834		$	11,295
Other expense:
Non-operating costs (a)	$	(11,034	)	$	(11,648	)	$	(10,397	)
Loss on disposition of property	(1,246		)	(2,219		)	(615		)
Miscellaneous	(5,234		)	(5,152		)	(2,391		)
Total other expense	$	(17,514	)	$	(19,019	)	$	(13,403	)

(a)As defined by FERC, includes non-operating utility income and expense (items excluded from utility rate recovery).

18.    Palo Verde Sale Leaseback Variable Interest Entities

In 1986, APS entered into agreements with three separate VIE lessor trust entities in order to sell and lease back interests in Palo Verde Unit 2 and related common facilities.  APS will retain the assets through 2023 under one lease and 2033 under the other two leases. APS will be required to make payments relating to these leases of approximately $23 million annually for the period 2017 through 2023, and about $16 million annually for the period 2024 through 2033. At the end of the lease period, APS will have the option to purchase the leased assets at their fair market value, extend the leases for up to two years, or return the assets to the lessors.

The leases' terms give APS the ability to utilize the assets for a significant portion of the assets' economic life, and therefore provide APS with the power to direct activities of the VIEs that most significantly impact the VIEs' economic performance. Predominantly due to the lease terms, APS has been deemed the primary beneficiary of these VIEs and therefore consolidates the VIEs.

As a result of consolidation, we eliminate lease accounting and instead recognize depreciation expense, resulting in an increase in net income for 2016, 2015 and 2014 of $19 million, $19 million and $26 million, respectively, entirely attributable to the noncontrolling interests.  Income attributable to Pinnacle West shareholders is not impacted by the consolidation.

Our Consolidated Balance Sheets at December 31, 2016 and December 31, 2015 include the following amounts relating to the VIEs (dollars in thousands):

	December 31, 2016		December 31, 2015
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	$	113,515	$	117,385
Equity-Noncontrolling interests	132,290		135,540

Assets of the VIEs are restricted and may only be used for payment to the noncontrolling interest holders.  These assets are reported on our consolidated financial statements.

166

COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

APS is exposed to losses relating to these VIEs upon the occurrence of certain events that APS does not consider reasonably likely to occur.  Under certain circumstances (for example, the NRC issuing specified violation orders with respect to Palo Verde or the occurrence of specified nuclear events), APS would be required to make specified payments to the VIEs’ noncontrolling equity participants and take title to the leased Unit 2 interests, which, if appropriate, may be required to be written down in value.  If such an event were to occur during the lease periods, APS may be required to pay the noncontrolling equity participants approximately $291 million beginning in 2017, and up to $456 million over the lease extension term.

For regulatory ratemaking purposes, the agreements continue to be treated as operating leases and, as a result, we have recorded a regulatory asset relating to the arrangements.

19.    Nuclear Decommissioning Trusts

To fund the costs APS expects to incur to decommission Palo Verde, APS established external decommissioning trusts in accordance with NRC regulations.  Third-party investment managers are authorized to buy and sell securities per stated investment guidelines.  The trust funds are invested in fixed income securities and equity securities.  APS classifies investments in decommissioning trust funds as available for sale.  As a result, we record the decommissioning trust funds at their fair value on our Consolidated Balance Sheets.  See Note 13 for a discussion of how fair value is determined and the classification of the nuclear decommissioning trust investments within the fair value hierarchy.  Because of the ability of APS to recover decommissioning costs in rates and in accordance with the regulatory treatment for decommissioning trust funds, we have deferred realized and unrealized gains and losses (including other-than-temporary impairments on investment securities) in other regulatory liabilities.  The following table includes the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS’s nuclear decommissioning trust fund assets at December 31, 2016 and December 31, 2015 (dollars in thousands):

	Fair Value		Total  Unrealized  Gains		Total  Unrealized  Losses
December 31, 2016
Equity securities	$	353,261	$	188,091	$	—
Fixed income securities	425,530		9,820		(4,962		)
Net receivables (a)	795		—		—
Total	$	779,586	$	197,911	$	(4,962	)

	Fair Value			Total  Unrealized  Gains		Total  Unrealized  Losses
December 31, 2015
Equity securities	$	314,957		$	157,098	$	(115	)
Fixed income securities	420,574			11,955		(2,645		)
Net payables (a)	(335		)	—		—
Total	$	735,196		$	169,053	$	(2,760	)

(a) Net receivables/(payables) relate to pending purchases and sales of securities.

167

COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The costs of securities sold are determined on the basis of specific identification.  The following table sets forth approximate gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds (dollars in thousands):

	Year Ended December 31,
	2016			2015			2014
Realized gains	$	11,213		$	5,189		$	4,725
Realized losses	(10,106		)	(6,225		)	(4,525		)
Proceeds from the sale of securities (a)	633,410			478,813			356,195

(a) Proceeds are reinvested in the trust.

The fair value of fixed income securities, summarized by contractual maturities, at December 31, 2016 is as follows (dollars in thousands):

	Fair Value
Less than one year	$	13,063
1 year – 5 years	119,292
5 years – 10 years	105,612
Greater than 10 years	187,563
Total	$	425,530

20.    Changes in Accumulated Other Comprehensive Loss

The following table shows the changes in Pinnacle West's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2016 and 2015 (dollars in thousands): 

	Year Ended December 31,
	2016			2015
Balance at beginning of period	$	(44,748	)	$	(68,141	)
Derivative Instruments
OCI (loss) before reclassifications	(538		)	(957		)
Amounts reclassified from accumulated other comprehensive loss (a)	2,941			4,187
Net current period OCI (loss)	2,403			3,230
Pension and Other Postretirement Benefits
OCI (loss) before reclassifications	(4,509		)	16,980
Amounts reclassified from accumulated other comprehensive loss (b)	3,032			3,183
Net current period OCI (loss)	(1,477		)	20,163
Balance at end of period	$	(43,822	)	$	(44,748	)

(a) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA.  See Note 16.

(b) These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost.  See Note 7.

168

COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Changes in Accumulated Other Comprehensive Loss - APS

The following table shows the changes in APS's accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2016 and 2015 (dollars in thousands): 

	Year Ended December 31,
	2016			2015
Balance at beginning of period	$	(27,097	)	$	(48,333	)
Derivative Instruments
OCI (loss) before reclassifications	(538		)	(957		)
Amounts reclassified from accumulated other comprehensive loss (a)	2,941			4,187
Net current period OCI (loss)	2,403			3,230
Pension and Other Postretirement Benefits
OCI (loss) before reclassifications	(3,821		)	14,726
Amounts reclassified from accumulated other comprehensive loss (b)	3,092			3,280
Net current period OCI (loss)	(729		)	18,006
Balance at end of period	$	(25,423	)	$	(27,097	)

(a) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA.  See Note 16.

(b) These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost.  See Note 7.

169

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED STATEMENTS OF COMPREHENSIVE INCOME

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
Operating revenues	$	370		$	550		$	642
Operating expenses	26,424			12,733			23,507
Operating loss	(26,054		)	(12,183		)	(22,865		)
Other
Equity in earnings of subsidiaries	462,027			446,508			411,528
Other expense	(1,771		)	(3,302		)	(3,276		)
Total	460,256			443,206			408,252
Interest expense	3,151			2,672			3,663
Income before income taxes	431,051			428,351			381,724
Income tax benefit	(10,983		)	(8,906		)	(15,871		)
Net income attributable to common shareholders	442,034			437,257			397,595
Other comprehensive income — attributable to common shareholders	926			23,393			9,912
Total comprehensive income — attributable to common shareholders	$	442,960		$	460,650		$	407,507

See Combined Notes to Consolidated Financial Statements.

170

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED BALANCE SHEETS

(dollars in thousands)

	December 31,
	2016			2015
ASSETS
Current assets
Cash and cash equivalents	$	41		$	17,432
Accounts receivable	81,751			93,093
Income tax receivable	—			14,895
Other current assets	340			197
Total current assets	82,132			125,617
Investments and other assets
Investments in subsidiaries	5,084,035			4,815,236
Deferred income taxes	53,805			41,065
Other assets	38,500			43,422
Total investments and other assets	5,176,340			4,899,723
Total Assets	$	5,258,472		$	5,025,340
LIABILITIES AND EQUITY
Current liabilities
Accounts payable	$	5,421		$	5,901
Accrued taxes	12,050			6,904
Common dividends payable	72,926			69,363
Short-term borrowings	41,700			—
Current maturities of long-term debt	125,000			—
Other current liabilities	31,182			33,120
Total current liabilities	288,279			115,288
Long-term debt less current maturities	—			125,000
Pension liabilities	21,057			21,933
Other	13,224			43,662
Total deferred credits and other	34,281			65,595
Common stock equity
Common stock	2,591,897			2,535,862
Accumulated other comprehensive loss	(43,822		)	(44,748		)
Retained earnings	2,255,547			2,092,803
Total Pinnacle West Shareholders’ equity	4,803,622			4,583,917
Noncontrolling interests	132,290			135,540
Total Equity	4,935,912			4,719,457
Total Liabilities and Equity	$	5,258,472		$	5,025,340

See Combined Notes to Consolidated Financial Statements.

171

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED STATEMENTS OF CASH FLOWS

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
Cash flows from operating activities
Net income	$	442,034		$	437,257		$	397,595
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in earnings of subsidiaries — net	(462,027		)	(446,508		)	(411,528		)
Depreciation and amortization	85			92			94
Deferred income taxes	(12,402		)	12,967			4,406
Accounts receivable	15,823			11,336			(22,945		)
Accounts payable	10,402			637			2,017
Accrued taxes and income tax receivables — net	20,041			(12,882		)	(1,795		)
Dividends received from subsidiaries	239,300			266,900			253,600
Other	5,514			(6,995		)	18,432
Net cash flow provided by operating activities	258,770			262,804			239,876
Cash flows from investing activities
Construction work in progress	(18,457		)	(3,462		)	—
Investments in subsidiaries	(19,242		)	(3,491		)	(10,236		)
Repayments of loans from subsidiaries	1,026			157			322
Advances of loans to subsidiaries	(2,092		)	(1,010		)	(1,450		)
Net cash flow used for investing activities	(38,765		)	(7,806		)	(11,364		)
Cash flows from financing activities
Issuance of long-term debt	—			—			125,000
Short-term debt borrowings under revolving credit facility	40,000			—			—
Commercial Paper - net	1,700			—			—
Dividends paid on common stock	(274,229		)	(260,027		)	(246,671		)
Repayment of long-term debt	—			—			(125,000		)
Common stock equity issuance - net of purchases	(4,867		)	19,373			15,288
Other	—			—			161
Net cash flow used for financing activities	(237,396		)	(240,654		)	(231,222		)
Net increase (decrease) in cash and cash equivalents	(17,391		)	14,344			(2,710		)
Cash and cash equivalents at beginning of year	17,432			3,088			5,798
Cash and cash equivalents at end of year	$	41		$	17,432		$	3,088

     See Combined Notes to Consolidated Financial Statements.

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

NOTES TO FINANCIAL STATEMENTS OF HOLDING COMPANY

The Combined Notes to Consolidated Financial Statements in Part II, Item 8 should be read in conjunction with the Pinnacle West Capital Corporation Holding Company Financial Statements.

The Pinnacle West Capital Corporation Holding Company Financial Statements have been prepared to present the financial position, results of operations and cash flows of the Pinnacle West Capital Corporation on a stand-alone basis as a holding company. Investments in subsidiaries are accounted for using the equity method.

172

PINNACLE WEST CAPITAL CORPORATION

SCHEDULE II — RESERVE FOR UNCOLLECTIBLES

(dollars in thousands)

Column A	Column B		Column C				Column D		Column E
			Additions
Description	Balance at beginning of period		Charged to cost and expenses		Charged to other accounts		Deductions		Balance at end of period
Reserve for uncollectibles:
2016	$	3,125	$	4,025	$	—	$	4,113	$	3,037
2015	3,094		4,073		—		4,042		3,125
2014	3,203		3,942		—		4,051		3,094

173

ARIZONA PUBLIC SERVICE COMPANY

SCHEDULE II — RESERVE FOR UNCOLLECTIBLES

(dollars in thousands)

Column A	Column B		Column C				Column D		Column E
			Additions
Description	Balance at beginning of period		Charged to cost and expenses		Charged to other accounts		Deductions		Balance at end of period
Reserve for uncollectibles:
2016	$	3,125	$	4,025	$	—	$	4,113	$	3,037
2015	3,094		4,073		—		4,042		3,125
2014	3,203		3,942		—		4,051		3,094

174

ITEM 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS

ON ACCOUNTING AND FINANCIAL DISCLOSURE

None. 

ITEM 9A.  CONTROLS AND PROCEDURES

(a)Disclosure Controls and Procedures

The term “disclosure controls and procedures” means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Securities Exchange Act of 1934 (the “Exchange Act”) (15 U.S.C. 78a et seq.) is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms.  Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to a company’s management, including its principal executive and principal financial officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

Pinnacle West’s management, with the participation of Pinnacle West’s Chief Executive Officer and Chief Financial Officer, have evaluated the effectiveness of Pinnacle West’s disclosure controls and procedures as of December 31, 2016.  Based on that evaluation, Pinnacle West’s Chief Executive Officer and Chief Financial Officer have concluded that, as of that date, Pinnacle West’s disclosure controls and procedures were effective.

APS’s management, with the participation of APS’s Chief Executive Officer and Chief Financial Officer, have evaluated the effectiveness of APS’s disclosure controls and procedures as of December 31, 2016.  Based on that evaluation, APS’s Chief Executive Officer and Chief Financial Officer have concluded that, as of that date, APS’s disclosure controls and procedures were effective.

(b)Management’s Annual Reports on Internal Control Over Financial Reporting

Reference is made to “Management’s Report on Internal Control over Financial Reporting (Pinnacle West Capital Corporation)” in Item 8 of this report and “Management’s Report on Internal Control over Financial Reporting (Arizona Public Service Company)” in Item 8 of this report.

(c)Attestation Reports of the Registered Public Accounting Firm

Reference is made to “Report of Independent Registered Public Accounting Firm” in Item 8 of this report and “Report of Independent Registered Public Accounting Firm” in Item 8 of this report on the internal control over financial reporting of Pinnacle West and APS, respectively.

(d)Changes In Internal Control Over Financial Reporting

No change in Pinnacle West’s or APS’s internal control over financial reporting occurred during the fiscal quarter ended December 31, 2016 that materially affected, or is reasonably likely to materially affect, Pinnacle West’s or APS’s internal control over financial reporting.

175

ITEM 9B.  OTHER INFORMATION

None.

PART III

ITEM 10.  DIRECTORS, EXECUTIVE OFFICERS

AND CORPORATE GOVERNANCE OF PINNACLE WEST

Reference is hereby made to “Information About Our Board and Corporate Governance,” “Proposal 1 — Election of Directors” and to “Section 16(a) Beneficial Ownership Reporting Compliance” in the Pinnacle West Proxy Statement relating to the Annual Meeting of Shareholders to be held on May 17, 2017 (the “2017 Proxy Statement”) and to the “Executive Officers of Pinnacle West” section in Part I of this report.

Pinnacle West has adopted a Code of Ethics for Financial Executives that applies to financial executives including Pinnacle West’s Chief Executive Officer, Chief Financial Officer, Chief Accounting Officer, Controller, Treasurer, and General Counsel, the President and Chief Operating Officer of APS and other persons designated as financial executives by the Chair of the Audit Committee.  The Code of Ethics for Financial Executives is posted on Pinnacle West’s website (www.pinnaclewest.com).  Pinnacle West intends to satisfy the requirements under Item 5.05 of Form 8-K regarding disclosure of amendments to, or waivers from, provisions of the Code of Ethics for Financial Executives by posting such information on Pinnacle West’s website.

ITEM 11.  EXECUTIVE COMPENSATION

Reference is hereby made to “Directors’ Compensation,” “Report of the Human Resources Committee,” “Executive Compensation,” and “Human Resources Committee Interlocks and Insider Participation” in the 2017 Proxy Statement.

ITEM 12.  SECURITY OWNERSHIP OF

CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

AND RELATED STOCKHOLDER MATTERS

Reference is hereby made to “Ownership of Pinnacle West Stock” and "Equity Compensation Plan Table" in the 2017 Proxy Statement.

ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED

TRANSACTIONS, AND DIRECTOR INDEPENDENCE

Reference is hereby made to “Information About Our Board and Corporate Governance” and “Related Party Transactions” in the 2017 Proxy Statement.

176

ITEM 14.  PRINCIPAL ACCOUNTANT

FEES AND SERVICES

Pinnacle West

Reference is hereby made to “Accounting and Auditing Matters — Audit Fees and — Pre-Approval Policies” in the 2017 Proxy Statement.

APS

The following fees were paid to APS’s independent registered public accountants, Deloitte & Touche LLP, for the last two fiscal years:

Type of Service	2015		2016
Audit Fees (1)	$	2,014,747	$	2,137,925
Audit-Related Fees (2)	233,555		283,070
All Other Fees (3)	10,000		—

(1)The aggregate fees billed for services rendered for the audit of annual financial statements and for review of financial statements included in Reports on Form 10-Q.

(2)The aggregate fees billed for assurance and related services that are reasonably related to the performance of the audit or review of the financial statements and are not included in Audit Fees reported above, which primarily consist of fees for employee benefit plan audits performed in 2016 and 2015.

(3)    The aggregate fees billed for advice relating to the development of a statement of work for the Company's system integrator for its new Customer Information System in 2015.

Pinnacle West’s Audit Committee pre-approves each audit service and non-audit service to be provided by APS’s registered public accounting firm.  The Audit Committee has delegated to the Chair of the Audit Committee the authority to pre-approve audit and non-audit services to be performed by the independent public accountants if the services are not expected to cost more than $50,000.  The Chair must report any pre-approval decisions to the Audit Committee at its next scheduled meeting.  All of the services performed by Deloitte & Touche LLP for APS in 2016 were pre-approved by the Audit Committee or the Chair of the Audit Committee consistent with the pre-approval policy.

177

PART IV

ITEM 15.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

Financial Statements and Financial Statement Schedules

See the Index to Financial Statements and Financial Statement Schedule in Part II, Item 8.

Exhibits Filed

The documents listed below are being filed or have previously been filed on behalf of Pinnacle West or APS and are incorporated herein by reference from the documents indicated and made a part hereof.  Exhibits not identified as previously filed are filed herewith.

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
3.1	Pinnacle West	Articles of Incorporation, restated as of May 21, 2008	3.1 to Pinnacle West/APS June 30, 2008 Form 10-Q Report, File No. 1-8962	8/7/2008
3.2	Pinnacle West	Pinnacle West Capital Corporation Bylaws, amended as of May 19, 2010	3.1 to Pinnacle West/APS June 30, 2010 Form 10-Q Report, File No. 1-8962	8/3/2010
3.3	APS	Articles of Incorporation, restated as of May 25, 1988	4.2 to APS’s Form 18 Registration Nos. 33-33910 and 33-55248 by means of September 24, 1993 Form 8-K Report, File No. 1-4473	9/29/1993
3.3.1	APS	Amendment to the Articles of Incorporation of Arizona Public Service Company, amended May 16, 2012	3.1 to Pinnacle West/APS May 22, 2012 Form 8-K Report, File Nos. 1-8962 and 1-4473	5/22/2012
3.4	APS	Arizona Public Service Company Bylaws, amended as of December 16, 2008	3.4 to Pinnacle West/APS December 31, 2008 Form 10-K, File No. 1-4473	2/20/2009
4.1	Pinnacle West	Specimen Certificate of Pinnacle West Capital Corporation Common Stock, no par value	4.1 to Pinnacle West June 28, 2011 Form 8-K Report, File No. 1-8962	6/28/2011
4.2	Pinnacle West APS	Indenture dated as of January 1, 1995 among APS and The Bank of New York Mellon, as Trustee	4.6 to APS’s Registration Statement Nos. 33-61228 and 33-55473 by means of January 1, 1995 Form 8-K Report, File No. 1-4473	1/11/1995
4.2a	Pinnacle West APS	First Supplemental Indenture dated as of January 1, 1995	4.4 to APS’s Registration Statement Nos. 33-61228 and 33-55473 by means of January 1, 1995 Form 8-K Report, File No. 1-4473	1/11/1995
4.3	Pinnacle West APS	Indenture dated as of November 15, 1996 between APS and The Bank of New York, as Trustee	4.5 to APS’s Registration Statements Nos. 33-61228, 33-55473, 33-64455 and 333- 15379 by means of November 19, 1996 Form 8-K Report, File No. 1-4473	11/22/1996

178

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
4.3a	Pinnacle West APS	First Supplemental Indenture dated as of November 15, 1996	4.6 to APS’s Registration Statements Nos. 33-61228, 33-55473, 33-64455 and 333-15379 by means of November 19, 1996 Form 8-K Report, File No. 1-4473	11/22/1996
4.3b	Pinnacle West APS	Second Supplemental Indenture dated as of April 1, 1997	4.10 to APS’s Registration Statement Nos. 33-55473, 33-64455 and 333-15379 by means of April 7, 1997 Form 8-K Report, File No. 1-4473	4/9/1997
4.3c	Pinnacle West APS	Third Supplemental Indenture dated as of November 1, 2002	10.2 to Pinnacle West’s March 31, 2003 Form 10-Q Report, File No. 1-8962	5/15/2003
4.4	Pinnacle West	Indenture dated as of December 1, 2000 between the Company and The Bank of New York, as Trustee, relating to Senior Unsecured Debt Securities	4.1 to Pinnacle West’s Registration Statement No. 333-52476	12/21/2000
4.5	Pinnacle West	Indenture dated as of December 1, 2000 between the Company and The Bank of New York, as Trustee, relating to Subordinated Unsecured Debt Securities	4.2 to Pinnacle West’s Registration Statement No. 333-52476	12/21/2000
4.6	Pinnacle West APS	Indenture dated as of January 15, 1998 between APS and The Bank of New York Mellon Trust Company N.A. (successor to JPMorgan Chase Bank, N.A., formerly known as The Chase Manhattan Bank), as Trustee	4.10 to APS’s Registration Statement Nos. 333-15379 and 333-27551 by means of January 13, 1998 Form 8-K Report, File No. 1-4473	1/16/1998
4.6a	Pinnacle West APS	Seventh Supplemental Indenture dated as of May 1, 2003	4.1 to APS’s Registration Statement No. 333-90824 by means of May 7, 2003 Form 8-K Report, File No. 1-4473	5/9/2003
4.6b	Pinnacle West APS	Eighth Supplemental Indenture dated as of June 15, 2004	4.1 to APS’s Registration Statement No. 333-106772 by means of June 24, 2004 Form 8-K Report, File No. 1-4473	6/28/2004
4.6c	Pinnacle West APS	Ninth Supplemental Indenture dated as of August 15, 2005	4.1 to APS’s Registration Statements Nos. 333-106772 and 333-121512 by means of August 17, 2005 Form 8-K Report, File No. 1-4473	8/22/2005
4.6d	APS	Tenth Supplemental Indenture dated as of August 1, 2006	4.1 to APS’s July 31, 2006 Form 8-K Report, File No. 1-4473	8/3/2006
4.6e	Pinnacle West APS	Eleventh Supplemental Indenture dated as of February 26, 2009	4.6e to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
4.6f	Pinnacle West APS	Twelfth Supplemental Indenture dated as of August 25, 2011	4.6f to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
4.6g	Pinnacle West APS	Thirteenth Supplemental Indenture dated as of January 13, 2012	4.6g to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
4.6h	Pinnacle West APS	Fourteenth Supplemental Indenture dated as of January 10, 2014	4.6h to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015

179

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
4.6i	Pinnacle West APS	Fifteenth Supplemental Indenture dated as of June 18, 2014	4.6i to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
4.6j	Pinnacle West APS	Sixteenth Supplemental Indenture dated as of January 12, 2015	4.6j to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
4.6k	Pinnacle West APS	Seventeenth Supplemental Indenture dated as of May 19, 2015	4.1 to Pinnacle West/APS May 14, 2015 Form 8-K Report, File Nos. 1-8962 and 1-4473	5/19/2015
4.6l	Pinnacle West APS	Eighteenth Supplemental Indenture dated as of November 6, 2015	4.1 to Pinnacle West/APS November 3, 2015 Form 8-K Report, File Nos. 1-8962 and 1-4473	11/6/2015
4.6m	Pinnacle West APS	Nineteenth Supplemental Indenture dated as of May 6, 2016	4.1 to Pinnacle West/APS May 3, 2016 Form 8-K Report, File Nos. 1-8962 and 1-4473	5/6/2016
4.6n	Pinnacle West APS	Twentieth Supplemental Indenture dated as of September 20, 2016	4.1 to Pinnacle West/APS September 15, 2016 Form 8-K Report, File Nos. 1-8962 and 1-4473	9/20/2016
4.7	Pinnacle West	Second Amended and Restated Pinnacle West Capital Corporation Investors Advantage Plan dated as of June 23, 2004	4.4 to Pinnacle West’s June 23, 2004 Form 8-K Report, File No. 1-8962	8/9/2004
4.7a	Pinnacle West	Third Amended and Restated Pinnacle West Capital Corporation Investors Advantage Plan dated as of November 25, 2008	4.1 to Pinnacle West’s Form S-3 Registration Statement No. 333-155641, File No. 1-8962	11/25/2008
4.8	Pinnacle West	Agreement, dated March 29, 1988, relating to the filing of instruments defining the rights of holders of long-term debt not in excess of 10% of the Company’s total assets	4.1 to Pinnacle West’s 1987 Form 10-K Report, File No. 1-8962	3/30/1988
4.8a	Pinnacle West APS	Agreement, dated March 21, 1994, relating to the filing of instruments defining the rights of holders of APS long-term debt not in excess of 10% of APS’s total assets	4.1 to APS’s 1993 Form 10-K Report, File No. 1-4473	3/30/1994
10.1.1	Pinnacle West APS	Two separate Decommissioning Trust Agreements (relating to PVNGS Units 1 and 3, respectively), each dated July 1, 1991, between APS and Mellon Bank, N.A., as Decommissioning Trustee	10.2 to APS’s September 30, 1991 Form 10-Q Report, File No. 1-4473	11/14/1991
10.1.1a	Pinnacle West APS	Amendment No. 1 to Decommissioning Trust Agreement (PVNGS Unit 1), dated as of December 1, 1994	10.1 to APS’s 1994 Form 10-K Report, File No. 1-4473	3/30/1995
10.1.1b	Pinnacle West APS	Amendment No. 1 to Decommissioning Trust Agreement (PVNGS Unit 3), dated as of December 1, 1994	10.2 to APS’s 1994 Form 10-K Report, File No. 1-4473	3/30/1995
10.1.1c	Pinnacle West APS	Amendment No. 2 to APS Decommissioning Trust Agreement (PVNGS Unit 1) dated as of July 1, 1991	10.4 to APS’s 1996 Form 10-K Report , File No. 1-4473	3/28/1997

180

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.1.1d	Pinnacle West APS	Amendment No. 2 to APS Decommissioning Trust Agreement (PVNGS Unit 3) dated as of July 1, 1991	10.6 to APS’s 1996 Form 10-K Report, File No. 1-4473	3/28/1997
10.1.1e	Pinnacle West APS	Amendment No. 3 to the Decommissioning Trust Agreement (PVNGS Unit 1), dated as of March 18, 2002	10.2 to Pinnacle West’s March 31, 2002 Form 10-Q Report, File No. 1-8962	5/15/2002
10.1.1f	Pinnacle West APS	Amendment No. 3 to the Decommissioning Trust Agreement (PVNGS Unit 3), dated as of March 18, 2002	10.4 to Pinnacle West’s March 2002 Form 10-Q Report, File No. 1-8962	5/15/2002
10.1.1g	Pinnacle West APS	Amendment No. 4 to the Decommissioning Trust Agreement (PVNGS Unit 1), dated as of December 19, 2003	10.3 to Pinnacle West’s 2003 Form 10-K Report, File No. 1-8962	3/15/2004
10.1.1h	Pinnacle West APS	Amendment No. 4 to the Decommissioning Trust Agreement (PVNGS Unit 3), dated as of December 19, 2003	10.5 to Pinnacle West’s 2003 Form 10-K Report, File No. 1-8962	3/15/2004
10.1.1i	Pinnacle West APS	Amendment No. 5 to the Decommissioning Trust Agreement (PVNGS Unit 1), dated as of May 1, 2007	10.1 to Pinnacle West/APS March 31, 2007 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/9/2007
10.1.1j	Pinnacle West APS	Amendment No. 5 to the Decommissioning Trust Agreement (PVNGS Unit 3), dated as of May 1, 2007	10.2 to Pinnacle West/APS March 31, 2007 Form 10-Q Report, File Nos. 1-8962 and 104473	5/9/2007
10.1.2	Pinnacle West APS	Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2) dated as of January 31, 1992, among APS, Mellon Bank, N.A., as Decommissioning Trustee, and State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee under two separate Trust Agreements, each with a separate Equity Participant, and as Lessor under two separate Facility Leases, each relating to an undivided interest in PVNGS Unit 2	10.1 to Pinnacle West’s 1991 Form 10-K Report, File No. 1-8962	3/26/1992
10.1.2a	Pinnacle West APS	First Amendment to Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of November 1, 1992	10.2 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
10.1.2b	Pinnacle West APS	Amendment No. 2 to Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of November 1, 1994	10.3 to APS’s 1994 Form 10-K Report, File No. 1-4473	3/30/1995
10.1.2c	Pinnacle West APS	Amendment No. 3 to Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of June 20, 1996	10.1 to APS’s June 30, 1996 Form 10-Q Report, File No. 1-4473	8/9/1996

181

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.1.2d	Pinnacle West APS	Amendment No. 4 to Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2) dated as of December 16, 1996	APS 10.5 to APS’s 1996 Form 10-K Report, File No. 1-4473	3/28/1997
10.1.2e	Pinnacle West APS	Amendment No. 5 to the Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of June 30, 2000	10.1 to Pinnacle West’s March 31, 2002 Form 10-Q Report, File No. 1-8962	5/15/2002
10.1.2f	Pinnacle West APS	Amendment No. 6 to the Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of March 18, 2002	10.3 to Pinnacle West’s March 31, 2002 Form 10-Q Report, File No. 1-8962	5/15/2002
10.1.2g	Pinnacle West APS	Amendment No. 7 to the Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of December 19, 2003	10.4 to Pinnacle West’s 2003 Form 10-K Report, File No. 1-8962	3/15/2004
10.1.2h	Pinnacle West APS	Amendment No. 8 to the Amended and Restated Decommissioning Trust Agreement (PVNGS Unit 2), dated as of April 1, 2007	10.1.2h to Pinnacle West’s 2007 Form 10-K Report, File No. 1-8962	2/27/2008
10.2.1b	Pinnacle West APS	Arizona Public Service Company Deferred Compensation Plan, as restated, effective January 1, 1984, and the second and third amendments thereto, dated December 22, 1986, and December 23, 1987, respectively	10.4 to APS’s 1988 Form 10-K Report, File No. 1-4473	3/8/1989
10.2.1ab	Pinnacle West APS	Third Amendment to the Arizona Public Service Company Deferred Compensation Plan, effective as of January 1, 1993	10.3A to APS’s 1993 Form 10-K Report, File No. 1-4473	3/30/1994
10.2.1bb	Pinnacle West APS	Fourth Amendment to the Arizona Public Service Company Deferred Compensation Plan effective as of May 1, 1993	10.2 to APS’s September 30, 1994 Form 10-Q Report, File No. 1-4473	11/10/1994
10.2.1cb	Pinnacle West APS	Fifth Amendment to the Arizona Public Service Company Deferred Compensation Plan effective January 1, 1997	10.3A to APS’s 1996 Form 10-K Report, File No. 1-4473	3/28/1997
10.2.1db	Pinnacle West APS	Sixth Amendment to the Arizona Public Service Company Deferred Compensation Plan effective January 1, 2001	10.8A to Pinnacle West’s 2000 Form 10-K Report, File No. 1-8962	3/14/2001
10.2.2b	Pinnacle West APS	Arizona Public Service Company Directors’ Deferred Compensation Plan, as restated, effective January 1, 1986	10.1 to APS’s June 30, 1986 Form 10-Q Report, File No. 1-4473	8/13/1986
10.2.2ab	Pinnacle West APS	Second Amendment to the Arizona Public Service Company Directors’ Deferred Compensation Plan, effective as of January 1, 1993	10.2A to APS’s 1993 Form 10-K Report, File No. 1-4473	3/30/1994
10.2.2bb	Pinnacle West APS	Third Amendment to the Arizona Public Service Company Directors’ Deferred Compensation Plan, effective as of May 1, 1993	10.1 to APS’s September 30, 1994 Form 10-Q Report, File No. 1-4473	11/10/1994

182

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.2.2cb	Pinnacle West APS	Fourth Amendment to the Arizona Public Service Company Directors Deferred Compensation Plan, effective as of January 1, 1999	10.8A to Pinnacle West’s 1999 Form 10-K Report, File No. 1-8962	3/30/2000
10.2.3b	Pinnacle West APS	Trust for the Pinnacle West Capital Corporation, Arizona Public Service Company and SunCor Development Company Deferred Compensation Plans dated August 1, 1996	10.14A to Pinnacle West’s 1999 Form 10-K Report, File No. 1-8962	3/30/2000
10.2.3ab	Pinnacle West APS	First Amendment dated December 7, 1999 to the Trust for the Pinnacle West Capital Corporation, Arizona Public Service Company and SunCor Development Company Deferred Compensation Plans	10.15A to Pinnacle West’s 1999 Form 10-K Report, File No. 1-8962	3/30/2000
10.2.4b	Pinnacle West APS	Pinnacle West Capital Corporation, Arizona Public Service Company, SunCor Development Company and El Dorado Investment Company Deferred Compensation Plan as amended and restated effective January 1, 1996	10.10A to APS’s 1995 Form  10-K Report, File No. 1-4473	3/29/1996
10.2.4ab	Pinnacle West APS	First Amendment effective as of January 1, 1999, to the Pinnacle West Capital Corporation, Arizona Public Service Company, SunCor Development Company and El Dorado Investment Company Deferred Compensation Plan	10.7A to Pinnacle West’s 1999 Form 10-K Report, File No. 1-8962	3/30/2000
10.2.4bb	Pinnacle West APS	Second Amendment effective January 1, 2000 to the Pinnacle West Capital Corporation, Arizona Public Service Company, SunCor Development Company and El Dorado Investment Company Deferred Compensation Plan	10.10A to Pinnacle West’s 1999 Form 10-K Report, File No. 1-8962	3/30/2000
10.2.4cb	Pinnacle West APS	Third Amendment to the Pinnacle West Capital Corporation, Arizona Public Service Company, SunCor Development Company and El Dorado Investment Company Deferred Compensation Plan, effective as of January 1, 2002	10.3 to Pinnacle West’s March 31, 2003 Form 10-Q Report, File No. 1-8962	5/15/2003
10.2.4db	Pinnacle West APS	Fourth Amendment to the Pinnacle West Capital Corporation, Arizona Public Service Company, SunCor Development Company and El Dorado Investment Company Deferred Compensation Plan, effective January 1, 2003	10.64 to Pinnacle West/APS 2005 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/13/2006
10.2.5b	Pinnacle West APS	Deferred Compensation Plan of 2005 for Employees of Pinnacle West Capital Corporation and Affiliates (as amended and restated effective January 1, 2016)	10.2.5 to Pinnacle West/APS 2015 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/19/2016

183

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.3.1b	Pinnacle West APS	Pinnacle West Capital Corporation Supplemental Excess Benefit Retirement Plan, amended and restated as of January 1, 2003	10.7A to Pinnacle West’s 2003 Form 10-K Report, File No. 1-8962	3/15/2004
10.3.1ab	Pinnacle West APS	Pinnacle West Capital Corporation Supplemental Excess Benefit Retirement Plan, as amended and restated, dated December 18, 2003	10.48b to Pinnacle West/APS 2005 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/13/2006
10.3.2b	Pinnacle West APS	Pinnacle West Capital Corporation Supplemental Excess Benefit Retirement Plan of 2005 (as amended and restated effective January 1, 2016)	10.3.2 to Pinnacle West/APS 2015 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/19/2016
10.3.2ab	Pinnacle West APS	First Amendment to the Pinnacle West Capital Corporation Supplemental Excess Benefit Retirement Plan of 2005 (as amended and restated effective January 1, 2016)
10.4.1b	APS	Letter Agreement dated December 20, 2006 between APS and Randall K. Edington	10.78 to Pinnacle West/APS 2006 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/28/2007
10.4.2b	APS	Letter Agreement dated July 22, 2008 between APS and Randall K. Edington	10.3 to Pinnacle West/APS June 30, 2008 Form 10-Q Report, File No. 1-4473	8/7/2008
10.4.3b	Pinnacle West APS	Letter Agreement dated June 17, 2008 between Pinnacle West/APS and James R. Hatfield	10.1 to Pinnacle West/APS June 30, 2008 Form 10-Q Report, File Nos. 1-8962 and 1-4473	8/7/2008
10.4.4b	APS	Supplemental Agreement dated December 26, 2008 between APS and Randall K. Edington	10.4.10 to Pinnacle West/APS 2008 Form 10-K Report, File No. 1-4473	2/20/2009
10.4.5b	APS	Description of 2010 Palo Verde Specific Compensation Opportunity for Randall K. Edington	10.4.13 to Pinnacle West/APS 2009 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/19/2010
10.4.6b	Pinnacle West	Letter Agreement dated May 21, 2009, between Pinnacle West and David P. Falck	10.4 to Pinnacle West/APS March 31, 2010 Form 10-Q Report, File No. 1-8962	5/6/2010
10.4.7b	APS	Supplemental Agreement dated June 19, 2012 between APS and Randall K. Edington	10.1 to Pinnacle West/APS June 30, 2012 Form 10-Q Report File Nos. 1-8962 and 1-4473	8/2/2012
10.4.8b	APS	Description of 2016 Palo Verde Specific Compensation Opportunity for Randall K. Edington	Pinnacle West/APS December 15, 2015 Form 8-K Report, File No. 1-4473	12/21/2015
10.4.9b	APS	Supplemental Agreement dated December 14, 2014 between APS and Randall K. Edington	10.4.9 to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
10.5.1bd	Pinnacle West APS	Key Executive Employment and Severance Agreement between Pinnacle West and certain executive officers of Pinnacle West and its subsidiaries	10.77 to Pinnacle West/APS 2005 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/13/2006

184

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.5.1abd	Pinnacle West APS	Form of Amended and Restated Key Executive Employment and Severance Agreement between Pinnacle West and certain officers of Pinnacle West and its subsidiaries	10.4 to Pinnacle West/APS September 30, 2007 Form 10-Q Report, File Nos. 1-8962 and 1-4473	11/6/2007
10.5.2bd	Pinnacle West APS	Form of Key Executive Employment and Severance Agreement between Pinnacle West and certain officers of Pinnacle West and its subsidiaries	10.3 to Pinnacle West/APS September 30, 2007 Form 10-Q Report, File Nos. 1-8962 and 1-4473	11/6/2007
10.5.3bd	Pinnacle West APS	Form of Key Executive Employment and Severance Agreement between Pinnacle West and certain officers of Pinnacle West and its subsidiaries	10.5.3 to Pinnacle West/APS 2009 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/19/2010
10.5.4bd	Pinnacle West APS	Form of Key Executive Employment and Severance Agreement between Pinnacle West and certain officers of Pinnacle West and its subsidiaries	10.5.4 to Pinnacle West/APS 2012 Form 10-K, File Nos. 1-8962 and 1-4473	2/22/2013
10.6.1b	Pinnacle West	Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	Appendix B to the Proxy Statement for Pinnacle West’s 2007 Annual Meeting of Shareholders, File No. 1-8962	4/20/2007
10.6.1ab	Pinnacle West	First Amendment to the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	10.2 to Pinnacle West/APS April 18, 2007 Form 8-K Report, File No. 1-8962	4/20/2007
10.6.1bbd	Pinnacle West APS	Performance Share Agreement under the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	10.3 to Pinnacle West/APS March 31, 2009 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/5/2009
10.6.1cbd	Pinnacle West	Form of Performance Share Agreement under the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	10.1 to Pinnacle West/APS June 30, 2010 Form 10-Q Report, File No. 1-8962	8/3/2010
10.6.1dbd	Pinnacle West	Form of Restricted Stock Unit Agreement under the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	10.2 to Pinnacle West/APS June 30, 2010 Form 10-Q Report, File No. 1-8962	8/3/2010
10.6.1ebd	Pinnacle West	Form of Performance Share Agreement under the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	10.4 to Pinnacle West/APS March 31, 2011 Form 10-Q Report, File No. 1-8962	4/29/2011
10.6.1fbd	Pinnacle West	Form of Restricted Stock Unit Agreement under the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan	10.5 to Pinnacle West/APS March 31, 2011 Form 10-Q Report, File No. 1-8962	4/29/2011
10.6.1gbd	Pinnacle West	Form of Restricted Stock Unit Agreement under the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan (Supplemental 2010 Award)	10.6 to Pinnacle West/APS March 31, 2011 Form 10-Q Report, File No. 1-8962	4/29/2011
10.6.2b	Pinnacle West	Description of Annual Stock Grants to Non-Employee Directors	10.1 to Pinnacle West/APS September 30, 2007 Form 10-Q Report, File No. 1-8962	11/6/2007
10.6.3b	Pinnacle West	Description of Annual Stock Grants to Non-Employee Directors	10.2 to Pinnacle West/APS June 30, 2008 Form 10-Q Report, File No. 1-8962	8/7/2008

185

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.6.4bd	Pinnacle West APS	Summary of 2017 CEO Variable Incentive Plan and Officer Variable Incentive Plan
10.6.5	Pinnacle West	Description of Restricted Stock Unit Grant to Donald E. Brandt	Pinnacle West/APS December 24, 2012 Form 8-K Report, File No. 1-8962	12/26/2012
10.6.6b	Pinnacle West APS	Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan	Appendix A to the Proxy Statement for Pinnacle West’s 2012 Annual Meeting of Shareholders, File No. 1-8962	3/29/2012
10.6.6abd	Pinnacle West	Form of Performance Share Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan	10.1 to Pinnacle West/APS March 31, 2012 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/3/2012
10.6.6bbd	Pinnacle West	Form of Restricted Stock Unit Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan	10.2 to Pinnacle West/APS March 31, 2012 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/3/2012
10.6.6cbd	Pinnacle West	Form of Performance Share Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan	10.6.8c to Pinnacle West/APS 2013 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/21/2014
10.6.6dbd	Pinnacle West	Form of Restricted Stock Unit Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan	10.6.8d to Pinnacle West/APS 2013 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/21/2014
10.6.6ebd	Pinnacle West	Form of Performance Share Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan	10.6.6e to Pinnacle West/APS 2015 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/19/2016
10.6.6fbd	Pinnacle West	Form of Restricted Stock Unit Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan
10.6.6gbd	Pinnacle West	Form of Performance Share Award Agreement under the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan
10.6.6hbd	Pinnacle West	Master Amendment to Performance Share Agreements	10.3 to Pinnacle West/APS March 31, 2012 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/3/2012
10.6.6ibd	Pinnacle West	Master Amendment to Restricted Stock Unit Agreements	10.4 to Pinnacle West/APS March 31, 2012 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/3/2012
10.7.1	Pinnacle West APS	Indenture of Lease with Navajo Tribe of Indians, Four Corners Plant	5.01 to APS’s Form S-7 Registration Statement, File No. 2-59644	9/1/1977
10.7.1a	Pinnacle West APS	Supplemental and Additional Indenture of Lease, including amendments and supplements to original lease with Navajo Tribe of Indians, Four Corners Plant	5.02 to APS’s Form S-7 Registration Statement, File No. 2-59644	9/1/1977

186

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.7.1b	Pinnacle West APS	Amendment and Supplement No. 1 to Supplemental and Additional Indenture of Lease Four Corners, dated April 25, 1985	10.36 to Pinnacle West’s Registration Statement on Form  8-B Report, File No. 1-8962	7/25/1985
10.7.1c	Pinnacle West APS	Amendment and Supplement No. 2 to Supplemental and Additional Indenture of Lease with the Navajo Nation dated March 7, 2011	10.1 to Pinnacle West/APS March 31, 2011 Form 10-Q Report, File Nos. 1-8962 and 1-4473	4/29/2011
10.7.1d	Pinnacle West APS	Amendment and Supplement No. 3 to Supplemental and Additional Indenture of Lease with the Navajo Nation dated March 7, 2011	10.2 to Pinnacle West/APS March 31, 2011 Form 10-Q Report, File Nos. 1-8962 and 1-4473	4/29/2011
10.7.2	Pinnacle West APS	Application and Grant of multi-party rights-of-way and easements, Four Corners Plant Site	5.04 to APS’s Form S-7 Registration Statement, File No. 2-59644	9/1/1977
10.7.2a	Pinnacle West APS	Application and Amendment No. 1 to Grant of multi-party rights-of-way and easements, Four Corners Site dated April 25, 1985	10.37 to Pinnacle West’s Registration Statement on Form 8-B, File No. 1-8962	7/25/1985
10.7.3	Pinnacle West APS	Application and Grant of APS rights- of-way and easements, Four Corners Site	5.05 to APS’s Form S-7 Registration Statement, File No. 2-59644	9/1/1977
10.7.3a	Pinnacle West APS	Application and Amendment No. 1 to Grant of APS rights-of-way and easements, Four Corners Site dated April 25, 1985	10.38 to Pinnacle West’s Registration Statement on Form 8-B, File No. 1-8962	7/25/1985
10.7.4a	Pinnacle West APS	Four Corners Project Co-Tenancy Agreement Amendment No. 6	10.7 to Pinnacle West’s 2000 Form 10-K Report, File No. 1-8962	3/14/2001
10.7.4b	Pinnacle West APS	Four Corners Project Co-Tenancy Agreement Amendment No. 7, dated December 30, 2013, among APS, El Paso Electric Company, Public Service Company of New Mexico, SRP, SCE, and Tucson Electric Power Company	10.3 to Pinnacle West/APS March 31, 2014 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/2/2014
10.8.1	Pinnacle West APS	Indenture of Lease, Navajo Units 1, 2, and 3	5(g) to APS’s Form S-7 Registration Statement, File No. 2-36505	3/23/1970
10.8.2	Pinnacle West APS	Application of Grant of rights-of-way and easements, Navajo Plant	5(h) to APS Form S-7 Registration Statement, File No. 2-36505	3/23/1970
10.8.3	Pinnacle West APS	Water Service Contract Assignment with the United States Department of Interior, Bureau of Reclamation, Navajo Plant	5(l) to APS’s Form S-7 Registration Statement, File No. 2-394442	3/16/1971
10.8.4	Pinnacle West APS	Navajo Project Co-Tenancy Agreement dated as of March 23, 1976, and Supplement No. 1 thereto dated as of October 18, 1976, Amendment No. 1 dated as of July 5, 1988, and Amendment No. 2 dated as of June 14, 1996; Amendment No. 3 dated as of February 11, 1997; Amendment No. 4 dated as of January 21, 1997; Amendment No. 5 dated as of January 23, 1998; Amendment No. 6 dated as of July 31, 1998	10.107 to Pinnacle West/APS 2005 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/13/2006

187

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.8.5	Pinnacle West APS	Navajo Project Participation Agreement dated as of September 30, 1969, and Amendment and Supplement No. 1 dated as of January 16, 1970, and Coordinating Committee Agreement No. 1 dated as of September 30, 1971	10.108 to Pinnacle West/APS 2005 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/13/2006
10.9.1	Pinnacle West APS	ANPP Participation Agreement, dated August 23, 1973, among APS, SRP, SCE, Public Service Company of New Mexico, El Paso, Southern California Public Power Authority, and Department of Water and Power of the City of Los Angeles, and amendments 1-12 thereto	10. 1 to APS’s 1988 Form 10-K Report, File No. 1-4473	3/8/1989
10.9.1a	Pinnacle West APS	Amendment No. 13, dated as of April 22, 1991, to ANPP Participation Agreement, dated August 23, 1973, among APS, SRP, SCE, Public Service Company of New Mexico, El Paso, Southern California Public Power Authority, and Department of Water and Power of the City of Los Angeles	10.1 to APS’s March 31, 1991 Form 10-Q Report, File No. 1-4473	5/15/1991
10.9.1b	Pinnacle West APS	Amendment No. 14 to ANPP Participation Agreement, dated August 23, 1973, among APS, SRP, SCE, Public Service Company of New Mexico, El Paso, Southern California Public Power Authority, and Department of Water and Power of the City of Los Angeles	99.1 to Pinnacle West’s June 30, 2000 Form 10-Q Report, File No. 1-8962	8/14/2000
10.9.1c	Pinnacle West APS	Amendment No. 15, dated November 29, 2010, to ANPP Participation Agreement, dated August 23, 1973, among APS, SRP, SCE, Public Service Company of New Mexico, El Paso, Southern California Public Power Authority, and Department of Water and Power of the City of Los Angeles	10.9.1c to Pinnacle West/APS 2010 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/18/2011
10.9.1d	Pinnacle West APS	Amendment No. 16, dated April 28, 2014, to ANPP Participation Agreement, dated August 23, 1973, among APS, SRP, SCE, Public Service Company of New Mexico, El Paso, Southern California Public Power Authority, and Department of Water and Power of the City of Los Angeles	10.2 to Pinnacle West/APS March 31, 2014 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/2/2014
10.10.1	Pinnacle West APS	Asset Purchase and Power Exchange Agreement dated September 21, 1990 between APS and PacifiCorp, as amended as of October 11, 1990 and as of July 18, 1991	10.1 to APS’s June 30, 1991 Form 10-Q Report, File No. 1-4473	8/8/1991

188

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.10.2	Pinnacle West APS	Long-Term Power Transaction Agreement dated September 21, 1990 between APS and PacifiCorp, as amended as of October 11, 1990, and as of July 8, 1991	10.2 to APS’s June 30, 1991 Form 10-Q Report, File No. 1-4473	8/8/1991
10.10.2a	Pinnacle West APS	Amendment No. 1 dated April 5, 1995 to the Long-Term Power Transaction Agreement and Asset Purchase and Power Exchange Agreement between PacifiCorp and APS	10.3 to APS’s 1995 Form 10-K Report, File No. 1-4473	3/29/1996
10.10.3	Pinnacle West APS	Restated Transmission Agreement between PacifiCorp and APS dated April 5, 1995	10.4 to APS’s 1995 Form 10-K Report, File No. 1-4473	3/29/1996
10.10.4	Pinnacle West APS	Contract among PacifiCorp, APS and DOE Western Area Power Administration, Salt Lake Area Integrated Projects for Firm Transmission Service dated May 5, 1995	10.5 to APS’s 1995 Form 10-K Report, File No. 1-4473	3/29/1996
10.10.5	Pinnacle West APS	Reciprocal Transmission Service Agreement between APS and PacifiCorp dated as of March 2, 1994	10.6 to APS’s 1995 Form 10-K Report, File No. 1-4473	3/29/1996
10.11.1	Pinnacle West	Term Loan Agreement dated as of December 31, 2014 among Pinnacle West, as Borrower,  JPMorgan Chase Bank, N.A., as Agent, U.S. Bank Association, as Syndication Agent, TD Bank, N.A., The Bank of Nova Scotia and The Bank of Tokyo-Mitsubishi UFJ, Ltd., as Co-Documentation Agents, and such institutions compromising the lenders party thereto	10.11.2 to Pinnacle West/APS 2014 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/20/2015
10.11.2	Pinnacle West	Five-Year Credit Agreement dated as of May 13, 2016, among Pinnacle West, as Borrower, Barclays Bank PLC, as Agent and Issuing Bank, and the lenders and other parties thereto	10.1 to Pinnacle West/APS June 30, 2016 Form 10-Q Report, File Nos. 1-8962 and 1-4473	8/2/2016
10.11.3	Pinnacle West	364-day Credit Agreement dated as of August 31, 2016, among Pinnacle West, as Borrower, The Bank of Tokyo-Mitsubishi UFJ, Ltd., as Agent and Issuing Bank, and the lenders and other parties thereto	10.1 to Pinnacle West/APS September 30, 2016 Form 10-Q Report, File Nos. 1-8962 and 1-4473	11/3/2016
10.11.4	Pinnacle West APS	Five-Year Credit Agreement dated as of September 2, 2015 among APS, as Borrower, Barclays Bank PLC, as Agent and Issuing Bank, and the lenders and other parties thereto	10.1 to Pinnacle West/APS September 30, 2015 Form 10-Q Report, File Nos. 1-8962 and 1-4473	10/30/2015

189

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.11.5	Pinnacle West APS	Term Loan Agreement dated as of June 26, 2015 among APS, as Borrower, Toronto Dominion (Texas) LLC, as Agent, Citibank, N.A., as Syndication Agent, and such institutions compromising the lenders party thereto	10.1 to Pinnacle West/APS June 30, 2015 Form 10-Q Report, File Nos. 1-8962 and 1-4473	7/30/2015
10.11.6	Pinnacle West APS	Term Loan Agreement dated as of April 22, 2016 among APS, as Borrower, Toronto Dominion (Texas) LLC, as Agent and such institutions compromising the lenders party thereto	10.1 to Pinnacle West/APS March 31, 2016 Form 10-Q Report, File Nos. 1-8962 and 1-4473	4/29/2016
10.11.7	Pinnacle West APS	Five-Year Credit Agreement dated as of May 13, 2016, among APS, as Borrower, Barclays Bank PLC, as Agent and Issuing Bank, and the lenders and other parties thereto	10.2 to Pinnacle West/APS June 30, 2016 Form 10-Q Report, File Nos. 1-8962 and 1-4473	8/2/2016
10.12.1c	Pinnacle West APS	Facility Lease, dated as of August 1, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its capacity as Owner Trustee, as Lessor, and APS, as Lessee	4.3 to APS’s Form 18 Registration Statement, File No. 33-9480	10/24/1986
10.12.1ac	Pinnacle West APS	Amendment No. 1, dated as of November 1, 1986, to Facility Lease, dated as of August 1, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its capacity as Owner Trustee, as Lessor, and APS, as Lessee	10.5 to APS’s September 30, 1986 Form 10-Q Report by means of Amendment No. 1 on December 3, 1986 Form 8, File No. 1-4473	12/4/1986
10.12.1bc	Pinnacle West APS	Amendment No. 2 dated as of June 1, 1987 to Facility Lease dated as of August 1, 1986 between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Lessor, and APS, as Lessee	10.3 to APS’s 1988 Form 10-K Report, File No. 1-4473	3/8/1989
10.12.1cc	Pinnacle West APS	Amendment No. 3, dated as of March 17, 1993, to Facility Lease, dated as of August 1, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Lessor, and APS, as Lessee	10.3 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993

190

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.12.1dc	Pinnacle West APS	Amendment No. 4, dated as of September 30, 2015, to Facility Lease, dated as of August 1, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee under a Trust Agreement with Emerson Finance LLC, as Lessor, and APS, as Lessee	10.2 to Pinnacle West/APS September 30, 2015 Form 10-Q Report, File Nos. 1-8962 and 1-4473	10/30/2015
10.12.1ec	Pinnacle West APS	Amendment No. 3, dated as of September 30, 2015, to Facility Lease, dated as of August 1, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee under a Trust Agreement with Security Pacific Capital Leasing Corporation, as Lessor, and APS, as Lessee	10.3 to Pinnacle West/APS September 30, 2015 Form 10-Q Report, File Nos. 1-8962 and 1-4473	10/30/2015
10.12.2	Pinnacle West APS	Facility Lease, dated as of December 15, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its capacity as Owner Trustee, as Lessor, and APS, as Lessee	10.1 to APS’s November 18, 1986 Form 8-K Report, File No. 1-4473	1/20/1987
10.12.2a	Pinnacle West APS	Amendment No. 1, dated as of August 1, 1987, to Facility Lease, dated as of December 15, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Lessor, and APS, as Lessee	4.13 to APS’s Form 18 Registration Statement No.  33-9480 by means of August 1, 1987 Form 8-K Report, File No. 1-4473	8/24/1987
10.12.2b	Pinnacle West APS	Amendment No. 2, dated as of March 17, 1993, to Facility Lease, dated as of December 15, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Lessor, and APS, as Lessee	10.4 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
10.12.2c	Pinnacle West APS	Amendment No. 3, dated July 10, 2014, to Facility Lease, dated as of December 15, 1986, between U.S. Bank National Association, successor to State Street Bank and Trust Company, as successor to the First National Bank of Boston, as Lessor, and APS, as Lessee	10.2 to Pinnacle West/APS June 30, 2014 Form 10-Q Report, File Nos. 1-8962 and 1-4473	7/31/2014

191

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
10.13.1	Pinnacle West APS	Agreement between Pinnacle West Energy Corporation and APS for Transportation and Treatment of Effluent by and between Pinnacle West Energy Corporation and APS dated as of the 10th day of April, 2001	10.102 to Pinnacle West/APS 2004 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/16/2005
10.13.2	Pinnacle West APS	Agreement for the Transfer and Use of Wastewater and Effluent by and between APS, SRP and PWE dated June 1, 2001	10.103 to Pinnacle West/APS 2004 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/16/2005
10.13.3	Pinnacle West APS	Agreement for the Sale and Purchase of Wastewater Effluent dated November 13, 2000, by and between the City of Tolleson, Arizona, APS and SRP	10.104 to Pinnacle West/APS 2004 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/16/2005
10.13.4	Pinnacle West APS	Operating Agreement for the Co-Ownership of Wastewater Effluent dated November 16, 2000 by and between APS and SRP	10.105 to Pinnacle West/APS 2004 Form 10-K Report, File Nos. 1-8962 and 1-4473	3/16/2005
10.13.5	Pinnacle West APS	Municipal Effluent Purchase and Sale Agreement dated April 29, 2010, by and between City of Phoenix, City of Mesa, City of Tempe, City of Scottsdale, City of Glendale, APS and SRP	10.1 to Pinnacle West/APS March 31, 2010 Form 10-Q Report, File Nos. 1-8962 and 1-4473	5/6/2010
10.14.1	Pinnacle West APS	Contract, dated July 21, 1984, with DOE providing for the disposal of nuclear fuel and/or high-level radioactive waste, ANPP	10.31 to Pinnacle West’s Form S-14 Registration Statement, File No. 2-96386	3/13/1985
10.15.1	Pinnacle West APS	Territorial Agreement between APS and SRP	10.1 to APS’s March 31, 1998 Form 10-Q Report, File No. 1-4473	5/15/1998
10.15.2	Pinnacle West APS	Power Coordination Agreement between APS and SRP	10.2 to APS’s March 31, 1998 Form 10-Q Report, File No. 1-4473	5/15/1998
10.15.3	Pinnacle West APS	Memorandum of Agreement between APS and SRP	10.3 to APS’s March 31, 1998 Form 10-Q Report, File No. 1-4473	5/15/1998
10.15.3a	Pinnacle West APS	Addendum to Memorandum of Agreement between APS and SRP dated as of May 19, 1998	10.2 to APS’s May 19, 1998 Form 8-K Report, File No. 1-4473	6/26/1998
10.16	Pinnacle West APS	Purchase and Sale Agreement dated November 8, 2010 by and between SCE and APS	10.1 to Pinnacle West/APS November 8, 2010 Form 8-K Report, File Nos. 1-8962 and 1-4473	11/8/2010
10.17	Pinnacle West APS	Proposed Settlement Agreement dated January 6, 2012 by and among APS and certain parties to its retail rate case (approved by ACC Order No. 73183)	10.17 to Pinnacle West/APS 2011 Form 10-K Report, File Nos. 1-8962 and 1-4473	2/24/2012
12.1	Pinnacle West	Ratio of Earnings to Fixed Charges
12.2	APS	Ratio of Earnings to Fixed Charges
12.3	Pinnacle West	Ratio of Earnings to Combined Fixed Charges and Preferred Stock Dividend Requirements
21.1	Pinnacle West	Subsidiaries of Pinnacle West

192

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
23.1	Pinnacle West	Consent of Deloitte & Touche LLP
23.2	APS	Consent of Deloitte & Touche LLP
31.1	Pinnacle West	Certificate of Donald E. Brandt, Chief Executive Officer, pursuant to Rule 13a-14(a) and Rule 15d-14(a) of the Securities Exchange Act, as amended
31.2	Pinnacle West	Certificate of James R. Hatfield, Chief Financial Officer, pursuant to Rule 13a-14(a) and Rule 15d-14(a) of the Securities Exchange Act, as amended
31.3	APS	Certificate of Donald E. Brandt, Chief Executive Officer, pursuant to Rule 13a-14(a) and Rule 15d-14(a) of the Securities Exchange Act, as amended
31.4	APS	Certificate of James R. Hatfield, Chief Financial Officer, pursuant to Rule 13a-14(a) and Rule 15d-14(a) of the Securities Exchange Act, as amended
32.1e	Pinnacle West	Certification of Chief Executive Officer and Chief Financial Officer, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2e	APS	Certification of Chief Executive Officer and Chief Financial Officer, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
99.1	Pinnacle West APS	Collateral Trust Indenture among PVNGS II Funding Corp., Inc., APS and Chemical Bank, as Trustee	4.2 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.1a	Pinnacle West APS	Supplemental Indenture to Collateral Trust Indenture among PVNGS II Funding Corp., Inc., APS and Chemical Bank, as Trustee	4.3 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.2c	Pinnacle West APS	Participation Agreement, dated as of August 1, 1986, among PVNGS Funding Corp., Inc., Bank of America National Trust and Savings Association, State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its individual capacity and as Owner Trustee, Chemical Bank, in its individual capacity and as Indenture Trustee, APS, and the Equity Participant named therein	28.1 to APS’s September 30, 1992 Form 10-Q Report, File No. 1-4473	11/9/1992

193

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
99.2ac	Pinnacle West APS	Amendment No. 1 dated as of November 1, 1986, to Participation Agreement, dated as of August 1, 1986, among PVNGS Funding Corp., Inc., Bank of America National Trust and Savings Association, State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its individual capacity and as Owner Trustee, Chemical Bank, in its individual capacity and as Indenture Trustee, APS, and the Equity Participant named therein	10.8 to APS’s September 30, 1986 Form 10-Q Report by means of Amendment No. 1, on December 3, 1986 Form 8, File No. 1-4473	12/4/1986
99.2bc	Pinnacle West APS	Amendment No. 2, dated as of March 17, 1993, to Participation Agreement, dated as of August 1, 1986, among PVNGS Funding Corp., Inc., PVNGS II Funding Corp., Inc., State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its individual capacity and as Owner Trustee, Chemical Bank, in its individual capacity and as Indenture Trustee, APS, and the Equity Participant named therein	28.4 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.3c	Pinnacle West APS	Trust Indenture, Mortgage, Security Agreement and Assignment of Facility Lease, dated as of August 1, 1986, between State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, and Chemical Bank, as Indenture Trustee	4.5 to APS’s Form 18 Registration Statement, File No. 33-9480	10/24/1986
99.3ac	Pinnacle West APS	Supplemental Indenture No. 1, dated as of November 1, 1986 to Trust Indenture, Mortgage, Security Agreement and Assignment of Facility Lease, dated as of August 1, 1986, between State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, and Chemical Bank, as Indenture Trustee	10.6 to APS’s September 30, 1986 Form 10-Q Report by means of Amendment No. 1 on December  3, 1986 Form 8, File No. 1-4473	12/4/1986
99.3bc	Pinnacle West APS	Supplemental Indenture No. 2 to Trust Indenture, Mortgage, Security Agreement and Assignment of Facility Lease, dated as of August 1, 1986, between State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, and Chemical Bank, as Lease Indenture Trustee	4.4 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.4c	Pinnacle West APS	Assignment, Assumption and Further Agreement, dated as of August 1, 1986, between APS and State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee	28.3 to APS’s Form 18 Registration Statement, File No. 33-9480	10/24/1986

194

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
99.4ac	Pinnacle West APS	Amendment No. 1, dated as of November 1, 1986, to Assignment, Assumption and Further Agreement, dated as of August 1, 1986, between APS and State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee	10.10 to APS’s September 30, 1986 Form 10-Q Report by means of Amendment No. l on December  3, 1986 Form 8, File No. 1-4473	12/4/1986
99.4bc	Pinnacle West APS	Amendment No. 2, dated as of March 17, 1993, to Assignment, Assumption and Further Agreement, dated as of August 1, 1986, between APS and State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee	28.6 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.5	Pinnacle West APS	Participation Agreement, dated as of December 15, 1986, among PVNGS Funding Report Corp., Inc., State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its individual capacity and as Owner Trustee, Chemical Bank, in its individual capacity and as Indenture Trustee under a Trust Indenture, APS, and the Owner Participant named therein	28.2 to APS’s September 30, 1992 Form 10-Q Report, File No. 1-4473	11/9/1992
99.5a	Pinnacle West APS	Amendment No. 1, dated as of August 1, 1987, to Participation Agreement, dated as of December 15, 1986, among PVNGS Funding Corp., Inc. as Funding Corporation, State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, Chemical Bank, as Indenture Trustee, APS, and the Owner Participant named therein	28.20 to APS’s Form 18 Registration Statement No. 33-9480 by means of a November 6, 1986 Form 8-K Report, File No. 1-4473	8/10/1987
99.5b	Pinnacle West APS	Amendment No. 2, dated as of March 17, 1993, to Participation Agreement, dated as of December 15, 1986, among PVNGS Funding Corp., Inc., PVNGS II Funding Corp., Inc., State Street Bank and Trust Company, as successor to The First National Bank of Boston, in its individual capacity and as Owner Trustee, Chemical Bank, in its individual capacity and as Indenture Trustee, APS, and the Owner Participant named therein	28.5 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.6	Pinnacle West APS	Trust Indenture, Mortgage Security Agreement and Assignment of Facility Lease, dated as of December 15, 1986, between State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, and Chemical Bank, as Indenture Trustee	10.2 to APS’s November 18, 1986 Form 10-K Report, File No. 1-4473	1/20/1987

195

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
99.6a	Pinnacle West APS	Supplemental Indenture No. 1, dated as of August 1, 1987, to Trust Indenture, Mortgage, Security Agreement and Assignment of Facility Lease, dated as of December 15, 1986, between State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, and Chemical Bank, as Indenture Trustee	4.13 to APS’s Form 18 Registration Statement No. 33-9480 by means of August 1, 1987 Form 8-K Report, File No. 1-4473	8/24/1987
99.6b	Pinnacle West APS	Supplemental Indenture No. 2 to Trust Indenture Mortgage, Security Agreement and Assignment of Facility Lease, dated as of December 15, 1986, between State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee, and Chemical Bank, as Lease Indenture Trustee	4.5 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.7	Pinnacle West APS	Assignment, Assumption and Further Agreement, dated as of December 15, 1986, between APS and State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee	10.5 to APS’s November 18, 1986 Form 8-K Report, File No. 1-4473	1/20/1987
99.7a	Pinnacle West APS	Amendment No. 1, dated as of March 17, 1993, to Assignment, Assumption and Further Agreement, dated as of December 15, 1986, between APS and State Street Bank and Trust Company, as successor to The First National Bank of Boston, as Owner Trustee	28.7 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.8c	Pinnacle West APS	Indemnity Agreement dated as of March 17, 1993 by APS	28.3 to APS’s 1992 Form 10-K Report, File No. 1-4473	3/30/1993
99.9	Pinnacle West APS	Extension Letter, dated as of August 13, 1987, from the signatories of the Participation Agreement to Chemical Bank	28.20 to APS’s Form 18 Registration Statement No. 33-9480 by means of a November 6, 1986 Form 8-K Report, File No. 1-4473	8/10/1987
99.10	Pinnacle West APS	ACC Order, Decision No. 61969, dated September 29, 1999, including the Retail Electric Competition Rules	10.2 to APS’s September 30, 1999 Form 10-Q Report, File No. 1-4473	11/15/1999
99.11	Pinnacle West	Purchase Agreement by and among Pinnacle West Energy Corporation and GenWest, L.L.C. and Nevada Power Company, dated June 21, 2005	99.5 to Pinnacle West/APS June 30, 2005 Form 10-Q Report, File Nos. 1-8962 and 1-4473	8/9/2005
101.INS	Pinnacle West APS	XBRL Instance Document
101.SCH	Pinnacle West APS	XBRL Taxonomy Extension Schema Document
101.CAL	Pinnacle West APS	XBRL Taxonomy Extension Calculation Linkbase Document

196

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit: a	Date Filed
101.LAB	Pinnacle West APS	XBRL Taxonomy Extension Label Linkbase Document
101.PRE	Pinnacle West APS	XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF	Pinnacle West APS	XBRL Taxonomy Definition Linkbase Document

aReports filed under File No. 1-4473 and 1-8962 were filed in the office of the Securities and Exchange Commission located in Washington, D.C.

bManagement contract or compensatory plan or arrangement to be filed as an exhibit pursuant to Item 15(b) of Form 10-K.

cAn additional document, substantially identical in all material respects to this Exhibit, has been entered into, relating to an additional Equity Participant.  Although such additional document may differ in other respects (such as dollar amounts, percentages, tax indemnity matters, and dates of execution), there are no material details in which such document differs from this Exhibit.

dAdditional agreements, substantially identical in all material respects to this Exhibit have been entered into with additional persons.  Although such additional documents may differ in other respects (such as dollar amounts and dates of execution), there are no material details in which such agreements differ from this Exhibit.

eFurnished herewith as an Exhibit.

197

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	PINNACLE WEST CAPITAL CORPORATION
	(Registrant)
Date: February 24, 2017	/s/ Donald E. Brandt
	(Donald E. Brandt, Chairman of the Board of Directors, President and Chief Executive Officer)

Power of Attorney

We, the undersigned directors and executive officers of Pinnacle West Capital Corporation, hereby severally appoint James R. Hatfield and David P. Falck, and each of them, our true and lawful attorneys with full power to them and each of them to sign for us, and in our names in the capacities indicated below, any and all amendments to this Annual Report on Form 10-K filed with the Securities and Exchange Commission.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature	Title	Date
/s/ Donald E. Brandt	Principal Executive Officer	February 24, 2017
(Donald E. Brandt, Chairman	and Director
of the Board of Directors, President
and Chief Executive Officer)
/s/ James R. Hatfield	Principal Financial Officer	February 24, 2017
(James R. Hatfield,
Executive Vice President and
Chief Financial Officer)
/s/ Denise R. Danner	Principal Accounting Officer	February 24, 2017
(Denise R. Danner,
Vice President, Controller and
Chief Accounting Officer)

198

/s/ Denis A. Cortese	Director	February 24, 2017
(Denis A. Cortese, M.D.)
/s/ Richard P. Fox	Director	February 24, 2017
(Richard P. Fox)
/s/ Michael L. Gallagher	Director	February 24, 2017
(Michael L. Gallagher)
/s/ Roy A. Herberger, Jr.	Director	February 24, 2017
(Roy A. Herberger, Jr., Ph.D.)
/s/ Dale E. Klein	Director	February 24, 2017
(Dale E. Klein, Ph.D.)
/s/ Humberto S. Lopez	Director	February 24, 2017
(Humberto S. Lopez)
/s/ Kathryn L. Munro	Director	February 24, 2017
(Kathryn L. Munro)
/s/ Bruce J. Nordstrom	Director	February 24, 2017
(Bruce J. Nordstrom)
/s/ Paula J. Sims	Director	February 24, 2017
(Paula J. Sims)
/s/ David P. Wagener	Director	February 24, 2017
(David P. Wagener)

199

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	ARIZONA PUBLIC SERVICE COMPANY
	(Registrant)
Date: February 24, 2017	/s/ Donald E. Brandt
	(Donald E. Brandt, Chairman of the Board of Directors, President and Chief Executive Officer)

Power of Attorney

We, the undersigned directors and executive officers of Arizona Public Service Company, hereby severally appoint James R. Hatfield and David P. Falck, and each of them, our true and lawful attorneys with full power to them and each of them to sign for us, and in our names in the capacities indicated below, any and all amendments to this Annual Report on Form 10-K filed with the Securities and Exchange Commission.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature	Title	Date
/s/ Donald E. Brandt	Principal Executive Officer	February 24, 2017
(Donald E. Brandt, Chairman	and Director
of the Board of Directors, President and
Chief Executive Officer)
/s/ James R. Hatfield	Principal Financial Officer	February 24, 2017
(James R. Hatfield,
Executive Vice President and
Chief Financial Officer)
/s/ Denise R. Danner	Principal Accounting Officer	February 24, 2017
(Denise R. Danner,
Vice President, Controller and
Chief Accounting Officer)

200

/s/ Denis A. Cortese	Director	February 24, 2017
(Denis A. Cortese, M.D.)
/s/ Richard P. Fox	Director	February 24, 2017
(Richard P. Fox)
/s/ Michael L. Gallagher	Director	February 24, 2017
(Michael L. Gallagher)
/s/ Roy A. Herberger, Jr.	Director	February 24, 2017
(Roy A. Herberger, Jr., Ph.D.)
/s/ Dale E. Klein	Director	February 24, 2017
(Dale E. Klein, Ph.D.)
/s/ Humberto S. Lopez	Director	February 24, 2017
(Humberto S. Lopez)
/s/ Kathryn L. Munro	Director	February 24, 2017
(Kathryn L. Munro)
/s/ Bruce J. Nordstrom	Director	February 24, 2017
(Bruce J. Nordstrom)
/s/ Paula J. Sims	Director	February 24, 2017
(Paula J. Sims)
/s/ David P. Wagener	Director	February 24, 2017
(David P. Wagener)

201

EX-10.3.2A

Exhibit 10.3.2a

FIRST AMENDMENT TO THE
PINNACLE WEST CAPITAL CORPORATION
SUPPLEMENTAL EXCESS BENEFIT RETIREMENT PLAN OF 2005

Effective as of January 1, 2005, Pinnacle West Capital Corporation (the “Company”) adopted the Pinnacle West Capital Corporation Supplemental Excess Benefit Retirement Plan of 2005 (the “Plan”). Effective as of January 1, 2016, the Company amended and restated the Plan. By this instrument, the Company amends the amended and restated Plan as described below. Defined terms used in this First Amendment shall have the meanings specified in the Plan.

1.        This First Amendment shall be effective as of January 1, 2017.

2.        This First Amendment clarifies the provisions of the Plan noted below. This First Amendment also supersedes the other provisions of the Plan to the extent those provisions are inconsistent with the provisions and intent of this First Amendment.

3.    Section 4(a)(1) of the Plan is hereby amended by changing the language that precedes the first comma (“Subject to Article 7”) to read “Subject to Section 4(a)(6) and Article 7.”

4.        Section 4(a)(2) of the Plan is hereby amended by changing the language that precedes the first comma (“Subject to Article 7”) to read “Subject to Section 4(a)(6) and Article 7.”

5.         The caption of Section 4(a)(3A) is hereby amended to read “(3A) Group C Participants – Individuals Becoming Officers on or after January 1, 2011.”

6.        Section 4(a)(6) is hereby amended and restated in its entirety to read as set forth below:

(6)     Promotion or Re-Hire into Officer Status on or after January 1, 2011. The provisions of this Section 4(a)(6), rather than the provisions of Section 4(a)(1) or Section 4(a)(2), shall apply to an individual who is a Group A Participant or a Group B Participant in the Retirement Plan and who becomes an Officer on or after January 1, 2011 either by reason of being promoted to an Officer position or being rehired in an Officer position. Subject to Article 7, the benefit due to such an

individual shall be a monthly benefit equal to the sum of (i) and (ii) reduced by (iii), where

(i)     Equals the benefit, if any, determined pursuant to Section 4(b)(i) (or if the participant is not entitled to a benefit pursuant to Section 4(b)(i), the benefit, if any, determined pursuant to the Retirement Plan), calculated as of the day immediately prior to such promotion or rehire as if the participant terminated employment on that day or was not rehired but reflecting the participant’s Average Monthly Compensation as of the date of determination;

(ii)     Equals the participant’s Supplemental Retirement Account Balance (converted to a monthly annuity using Actuarial Equivalence for Group A participants); and

(iii)     Equals the participant’s benefit determined pursuant to the Retirement Plan.

A participant’s Supplemental Retirement Account Balance shall be a notional account credited with Monthly Retirement Account Balance Credits and Interest Credits. For purposes of this Plan, Monthly Retirement Account Balance Credits shall be determined under the general methodology set forth in the Retirement Plan based on the participant’s Monthly Compensation for the month but using the following chart:

Age at End of Plan Year	Percent of Monthly Compensation Contribution Rate
Less than 35	8%
35-39	9%
40-44	10%
45-49	12%
50-54	15%
55 and over	18%

7.        Except as otherwise amended by this First Amendment, the Plan shall continue in full force and effect.

IN WITNESS WHEREOF, Pinnacle West Capital Corporation has caused this First Amendment to be executed as of this 20th day of December, 2016.

Pinnacle West Capital Corporation

By: /s/ Donald E. Brandt

Its: Chairman of the Board of Directors, President and Chief Executive Officer

EX-10.6.4

Exhibit 10.6.4

Summary of 2017 Incentive Plans

On December 20, 2016, the Human Resources Committee (the “Committee”) of the Pinnacle West Capital Corporation (“Pinnacle West” or the “Company”) Board of Directors (the “Board”) approved the Pinnacle West 2017 CEO Annual Incentive Award Plan (the “PNW Plan”), which provides an incentive award opportunity for Donald E. Brandt, the Chairman of the Board, President, and Chief Executive Officer of Pinnacle West and the Chairman of the Board, President and Chief Executive Officer of Arizona Public Service Company (“APS”).  On December 21, 2016, the Board, acting on the recommendation of the Committee, approved the APS 2017 Annual Incentive Award Plan (the “APS Plan”), which includes an incentive award opportunity for Mark A. Schiavoni, Executive Vice President and Chief Operating Officer, James R. Hatfield, Executive Vice President and Chief Financial Officer, David P. Falck, Executive Vice President and General Counsel and Randall K. Edington, Executive Vice President and Advisor to the Chief Executive Officer.

No incentive payments will be awarded under the PNW Plan or the APS Plan unless Pinnacle West, with respect to Mr. Brandt, or APS, with respect to Messrs. Schiavoni, Hatfield, Falck and Edington, each achieves a specified threshold earnings level.  The Committee will evaluate the impacts of unusual or nonrecurring adjustments to earnings in determining whether any earnings level has been met for purposes of the PNW Plan and may make adjustments to reflect such impacts. Earnings impacts of actions of the Arizona Corporation Commission ("ACC") in the PNW Plan year are excluded.

Mr. Brandt’s incentive award opportunity is based 62.5% on Pinnacle West’s 2017 earnings, and 37.5% on the achievement of performance goals established for all business units of APS. Mr. Brandt has an award opportunity of 50% of his base salary if the threshold earnings level is met. If Pinnacle West earnings exceed the threshold level, Mr. Brandt’s award opportunity increases proportionately by up to an additional 75% of his base salary. To the extent certain business unit performance goals are met, Mr. Brandt has a further award opportunity of up to 75% of base salary. The business unit performance indicators for Mr. Brandt are in the functional areas of customer service, transmission and distribution, fossil generation, corporate resources and performance of the Palo Verde Nuclear Generating Station. In no event may Mr. Brandt’s award exceed 200% of his base salary.

The award opportunities for Messrs. Schiavoni, Hatfield, Falck and Edington under the APS Plan are based on the achievement of specified 2017 APS earnings levels and specified business unit performance goals.  Mr. Schiavoni has a target award opportunity of up to 75% of his base salary, Mr. Hatfield has as a target award opportunity of up to 70% of his base salary and Messrs. Falck and Edington each have a target award opportunity of up to 65% of their base salaries.  Messrs. Schiavoni, Hatfield, Falck and Edington may earn less or more than the target amount, up to a maximum award opportunity of 150% of base salary for Mr. Schiavoni, 140% for Mr. Hatfield and 130% for Messrs. Falck and Edington, depending on the achievement of the earnings and business unit performance goals separately or in combination, and before adjustment for individual performance.  The business unit performance indicators that will be considered for Messrs. Schiavoni, Hatfield, Falck and Edington are derived from the APS critical areas of focus, as provided in its “Core” strategic framework, in the functional areas of employees, operational excellence, customer value and shareholder value.  The Committee may adjust targets under the APS Plan to reflect unanticipated events or unusual or nonrecurring adjustments to earnings that arise in the APS Plan year, including ACC rate-related impacts.

Any awards for Messrs. Brandt, Schiavoni, Hatfield, Falck and Edington will be subject to potential forfeiture or recovery to the extent called for by the Company’s clawback policy.

EX-10.6.6F

Exhibit 10.6.6f

RESTRICTED STOCK UNIT AWARD AGREEMENT

THIS AWARD AGREEMENT is made and entered into as of ____________________ (the "Date of Grant"), by and between Pinnacle West Capital Corporation (the "Company"), and ____________________ ("Employee").

BACKGROUND

A. The Board of Directors of the Company (the “Board of Directors”) has adopted, and the shareholders of the Company have approved, the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan (the “Plan”), pursuant to which Restricted Stock Units and Dividend Equivalents may be granted to employees of the Company and its subsidiaries.

B. The Company desires to grant to Employee Restricted Stock Units and Dividend Equivalents under the terms of the Plan.

C. Pursuant to the Plan, the Company and Employee agree as follows:

AGREEMENT

1. Grant of Award. Pursuant to action of the Committee which was taken on the Date of Grant, the Company grants to Employee ___________ ( ) Restricted Stock Units and related Dividend Equivalents.

2. Award Subject to Plan. This Restricted Stock Unit Award and the related Dividend Equivalent Award are granted under and are expressly subject to all of the terms and provisions of the Plan, which terms are incorporated herein by reference, and this Award Agreement. In the event of any conflict between the terms and conditions of this Award Agreement and the Plan, the provisions of the Plan shall control.

3. Vesting of Restricted Stock Units.

(a) Regular Vesting. The Restricted Stock Units granted pursuant to Section 1 will vest and no longer be subject to the restrictions of and forfeiture under this Award Agreement on the following dates (each a “Vesting Date”) and as otherwise set forth in this Section 3:

i. ____ Restricted Stock Units will vest on _______________;

ii. ____ Restricted Stock Units will vest on _______________;

iii. ____ Restricted Stock Units will vest on _______________; and

iv. The remaining ____ Restricted Stock Units will vest on _______________.

(b) Normal or Early Retirement, Death or Disability.

i. Provided that Employee either qualifies for “Early Retirement” or “Normal Retirement”, as defined in the Pinnacle West Capital Corporation

Retirement Plan (the “Retirement Plan”), or is a Late Career Recipient (as defined below), the Restricted Stock Units will fully vest and no longer be subject to the restrictions of and forfeiture under this Award Agreement upon Employee’s death or Disability.

ii. The Restricted Stock Units will fully vest and no longer be subject to the restrictions of and forfeiture under this Award Agreement upon Employee’s Termination of Employment which constitutes an Early Retirement or a Normal Retirement.

(c) Late Career Recipient. If, at the time of Employee’s death, Disability or retirement, Employee has reached sixty (60) years of age and has been credited with at least five (5) Years of Service, as defined under the Retirement Plan, and does not otherwise meet the criteria for Early Retirement or Normal Retirement under the Retirement Plan, Employee shall be treated for purposes of this Agreement as a “Late Career Recipient.” Upon the date of a Late Career Recipient’s retirement (the “Effective Date”), a portion of Employee’s unvested Restricted Stock Units that would have vested on the next Vesting Date will vest on a straight pro-rata basis based on the number of days elapsed between the last Vesting Date (or, if a Vesting Date has not yet occurred, the Date of Grant) and the Effective Date. Payment will be made on the next Vesting Date following the Effective Date in accordance with Section 4(a). No fractional Stock shall be issued. If the Stock payout results in a fractional share of one-half or greater, such fraction will be increased to provide for the issuance of a full share of Stock.

(d) Termination Without Cause. In the event Employee’s employment is terminated by the Company without cause, the Chief Executive Officer of the Company (the “CEO”) may determine in his discretion if, to what extent, and when, any unvested portion of the Restricted Stock Units granted pursuant to this Award should vest; provided, however, that (i) any vesting of unvested Restricted Stock Units pursuant to this Section 3(d)shall be approved by the Chair of the Committee, and (ii) nothing herein shall obligate the CEO to exercise his discretion to cause any unvested Restricted Stock Units to vest.

(e) Termination For Cause. Notwithstanding any other provision in this Section 3, in the event Employee’s employment is terminated for Cause, then regardless of Employee’s retirement, Early Retirement, Normal Retirement, death or Disability, Employee shall forfeit the right to receive any cash payment or Stock hereunder that Employee would otherwise be entitled to receive following his or her date of termination. For purposes only of this Section 3(e), “Cause” means (A) embezzlement, theft, fraud, deceit and/or dishonesty by the Employee involving the property, business or affairs of the Company or any of its subsidiaries, or (B) an act of moral turpitude which in the sole judgment of the CEO reflects adversely on the business or reputation of the Company or any of its subsidiaries or negatively affects any of the Company’s or any of its subsidiaries’ employees or customers.

(f) Disability. “Disability” has the meaning set forth for such term in the Retirement Plan.

4. Payment.

(a) Time and Form of Payment. When a Restricted Stock Unit vests in accordance with Section 3 above, Employee (or his or her estate) shall receive in exchange

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for each Restricted Stock Unit one unrestricted fully transferrable share of Stock. Employee may elect, pursuant to Section 4(b), to receive payment for the Restricted Stock Units payable on any Vesting Date in the form of (i) fully transferrable shares of Stock, (ii) 50% cash and 50% in fully transferrable shares of Stock or (iii) 100% cash. Except as provided in Section 3(d)above following a Termination of Employment without cause, if a Restricted Stock Unit vests prior to the applicable Vesting Date due to Employee’s status as a Late Career Recipient or Employee’s Early Retirement or Normal Retirement, the payment will be made within 30 days of the Vesting Date applicable to such Restricted Stock Unit. Any cash payment will be based on the Fair Market Value of one share of Stock determined as of the applicable Vesting Date. The payment for a Restricted Stock Unit that vests prior to the applicable Vesting Date due to the death or Disability of Employee, shall be made no later than March 15 of the year following the year in which Employee dies or becomes Disabled. If Employee dies after acquiring a vested interest in the Restricted Stock Units but before receiving payment for the Restricted Stock Units, the payment will be made to Employee’s designated beneficiary in accordance with the elections previously made by Employee.

(b) Election of Form of Payment. No later than ___________, Employee must elect to receive payment for Employee’s vested Restricted Stock Units and Dividend Equivalents in (i) fully transferable shares of Stock, (ii) 50% in cash and 50% in fully transferrable shares of Stock or (iii) 100% in cash by completing and returning to the Company the election form attached to this Agreement. In the absence of a timely election by Employee, Employee will receive payment for the vested Restricted Stock Units and Dividend Equivalents in fully transferable shares of Stock.

(c) Dividend Equivalents. In satisfaction of the Dividend Equivalents Award made pursuant to Section 1, at the time of the Company’s delivery of payment pursuant to Section 3 or Section 4(a), the Company also will deliver to Employee a payment equal to the amount of dividends, if any, that Employee would have received if Employee had directly owned the Stock to which the Restricted Stock Units relate from the Date of Grant to the applicable Vesting Date, plus interest on such amount at the rate of 5percent compounded quarterly. Pursuant to the election filed by the Employee pursuant to Section 4(b), payment for the Dividend Equivalents and interest will be made in (i) fully transferrable shares of Stock, (ii) 50% in cash and 50% in fully transferrable shares of Stock or (iii) 100% in cash. The number of shares of Stock distributed to Employee will be determined by dividing the amount of the Dividend Equivalents and interest by the Fair Market Value of one share of Stock as of the applicable Vesting Date. No fractional Stock shall be issued. If the Stock payout results in a fractional share of one-half or greater, such fraction will be increased to provide for the issuance of a full share of Stock.

(d) Impact on Retirement Plans. The value of the shares of Stock distributed upon payment for the Restricted Stock Units and Dividend Equivalents will be disregarded for purposes of calculating the amount of Employee’s benefit under any Company retirement plans.

5. Termination of Award. Except as otherwise provided in Section 3 above or in Article 15 of the Plan, in the event of the termination of Employee’s employment with the Company or any of its subsidiaries, whether due to voluntary or involuntary termination, retirement, death, Disability or otherwise, Employee’s right to vest in any additional Restricted Stock

3

Units or Dividend Equivalents under the Plan or this Award Agreement, if any, will terminate. Any unvested Restricted Stock Units and the related Dividend Equivalents will be forfeited effective as of the date that Employee terminates active employment with the Company or any of its subsidiaries.

6. Section 409A Compliance. If the Company concludes, in the exercise of its discretion, that this Award is subject to Section 409A of the Code, the Plan and this Award Agreement shall be administered in compliance with Section 409A and each provision of this Award Agreement and the Plan shall be interpreted to comply with Section 409A. If the Company concludes, in the exercise of its discretion, that this Award is not subject to Section 409A, but, instead, is eligible for the short-term deferral exception to the requirements of Section 409A, the Plan and this Award Agreement shall be administered to comply with the requirements of the short-term deferral exception to the requirements of Section 409A and each provision of this Award Agreement and the Plan shall be interpreted to comply with the requirements of such exception. In either event, Employee does not have any right to make any election regarding the time or form of any payment due under this Award Agreement other than the election described in Section 4(b).

7. Tax Withholding. Employee is responsible for any and all federal, state, and local income, payroll or other tax obligations or withholdings (collectively, the “Taxes”) arising out of this Award. Employee shall pay any and all Taxes due prior to the payout of Stock or cash hereunder by check or other arrangement acceptable to the Company. Employee shall pay any and all Taxes due in connection with a payout of Stock or cash hereunder by check or by having the Company withhold cash or shares of Stock from such payout. No later than__________, Employee must elect, on the election form described in Section 4(b), how Employee will satisfy the tax obligations upon a payout. In the absence of a timely election by Employee, Employee’s tax withholding obligation upon a payout will be satisfied through the Company’s withholding of cash or shares of Stock as set forth above.

8. Continued Employment. Nothing in the Plan or this Award Agreement shall be interpreted to interfere with or limit in any way the right of the Company or its subsidiaries to terminate Employee’s employment or services at any time. In addition, nothing in the Plan or this Award Agreement shall be interpreted to confer upon Employee the right to continue in the employ or service of the Company or its subsidiaries.

9. Confidentiality. During Employee’s employment and after termination thereof for any reason, Employee agrees that Employee will not, directly or indirectly, in one or a series of transactions, disclose to any person, or use or otherwise exploit for Employee’s own benefit or for the benefit of anyone other than the Company or any of its Affiliates any Confidential Information (as hereinafter defined), whether prepared by Employee or not; provided, however, that during the term of Employee’s employment, any Confidential Information may be disclosed (i) to officers, representatives, employees and agents of the Company and its Affiliates who need to know such Confidential Information in order to perform the services or conduct the operations required or expected of them in the business, and (ii) in good faith by Employee in connection with the performance of Employee’s job duties to persons who are authorized to receive such information by the Company or its Affiliates. Employee shall have no obligation to keep confidential any Confidential Information, if and to the extent disclosure of any such information is specifically required by law; provided, however, that in the event disclosure is required by applicable law, Employee shall provide the Company with prompt notice of such requirement, prior to making any disclosure, so that it may seek an appropriate protective order.

4

Employee agrees that all Confidential Information of the Company and its Affiliates (whether now or hereafter existing) conceived, discovered or made by him during employment exclusively belongs to the Company or its Affiliates (and not to Employee). Employee will promptly disclose such Confidential Information to the Company and perform all actions reasonably requested by the Company to establish and confirm such exclusive ownership. For purposes of this Section 9, the term “Confidential Information” shall mean and include any information disclosed to Employee any time during Employee’s employment with the Company or its Affiliates or thereafter which is not generally known to the public, including, but not limited to, information concerning the Company’s or its Affiliates’ assets and valuations, business plans, methods of operation, management, information systems, procedures, processes, practices, policies, plans, programs, personnel and/or reports or other information prepared by appraisers, consultants, advisors, bankers or attorneys.

10. Restrictive Covenants.

(a) Non-Competition.  Employee agrees that for a period of 12 months following any Termination of Employment voluntarily by Employee (other than due to Disability),  Employee shall not, without the prior written consent of the Company’s General Counsel, participate, whether as a consultant, employee, contractor, partner, owner (ownership of less than 5% of the outstanding stock of a publicly traded company will not be considered ownership under this provision), co-owner, or otherwise, with any business, corporation, group, entity or individual that is or intends to be engaged in the business activity of supplying electricity in any area of Arizona for which the Company or its Affiliates is authorized to supply electricity.

(b) Employee Non-Solicitation. Employee agrees that for a period of 12 months following Employee’s Termination of Employment for any reason, Employee will not encourage, induce, or otherwise solicit, or actively assist any other person or organization to encourage, induce or otherwise solicit, directly or indirectly, any employee of the Company or any of its Affiliates to terminate his or her employment with the Company or its Affiliates, or otherwise interfere with the advantageous business relationship of the Company and its Affiliates with their employees.

(c) [No Pledging or Hedging.Employee agrees that during his or her term of employment and for a period of 90 days thereafter, Employee will not pledge, margin, hypothecate, hedge, or otherwise grant an economic interest in any shares of Company stock received by Employee pursuant to this Award (net of shares sold or surrendered to meet tax withholding or exercise requirements).  This restriction shall extend to the purchase or creation of any short sales, zero-cost collars, forward sales contracts, puts, calls, options or other derivative securities in respect of any shares of Company stock.]

(d) Remedies. If Employee fails to comply with Sections 9, 10(a), [or] 10(b) [or] [10(c)] in a material respect, the Company may (i) cause any of Employee’s unvested Restricted Stock Units and related Dividend Equivalents to be cancelled and forfeited, (ii) refuse to deliver shares of Stock or cash in exchange for vested Restricted Stock Units or Dividend Equivalents, and/or (iii) pursue any other rights and remedies the Company may have pursuant to this Award Agreement or the Plan at law or in equity including, specifically, injunctive relief.

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11. Non‑Transferability. Neither this Award nor any rights under this Award Agreement may be assigned, transferred, or in any manner encumbered except as provided in the Plan.

12. Definitions: Copy of Plan and Plan Prospectus. To the extent not specifically defined in this Award Agreement, all capitalized terms used in this Award Agreement will have the same meanings ascribed to them in the Plan. By signing this Award Agreement, Employee acknowledges receipt of a copy of the Plan and the related Plan prospectus.

13. Amendment. Except as provided below, any amendments to this Award Agreement must be made by a written agreement executed by the Company and Employee. The Company may amend this Award Agreement unilaterally, without the consent of Employee, if the change (i) is required by law or regulation, (ii) does not adversely affect in any material way the rights of Employee, or (iii) is required to cause the benefits under the Plan to qualify as performance-based compensation within the meaning of Section 162(m) of the Code or to comply with the provisions of Section 409A of the Code and applicable regulations or other interpretive authority. Additional rules relating to amendments to the Plan or any Award Agreement to assure compliance with Section 409A of the Code are set forth in Section 17.15 of the Plan.

IN WITNESS WHEREOF, the Company has caused this Award Agreement to be executed, as of the Date of Grant, by an authorized representative of the Company and this Award Agreement has been executed by Employee.

PINNACLE WEST CAPITAL CORPORATION

By: _______________________

Its: _______________________

Date: _____________________

EMPLOYEE

By: _____________________

Date: __________________________

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Pinnacle West Capital Corporation

RESTRICTED STOCK UNIT AWARD
ELECTION FORM

(applies to Award Agreement dated __/__/____)

INFORMATION ABOUT YOU
Last		First			Middle Initial			Employee ID#
1. PAYMENT ELECTION
	In accordance with the terms of the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan and pursuant to Section 4(b) of the Award Agreement, I hereby elect to receive payment for the Restricted Stock Units and Dividend Equivalents that vest on the dates set forth below in the following form (place an “X” in the “100% Stock” column, in the “50% Cash/50% Stock” column or in the “100% Cash” column for each of the years and types of Awards set forth below):
			Restricted Stock Units and Dividend Equivalents
	Vesting Date		100% Stock	50% Cash/ 50% Stock			100% Cash
	__/__/_____		¨ ¨ ¨ ¨	¨ ¨ ¨ ¨			¨ ¨ ¨ ¨
	__/__/_____
	__/__/_____
	__/__/_____
	2. TAX WITHHOLDING ELECTION
	I hereby elect to satisfy any tax withholding obligation associated with my receipt of Stock, Stock and cash, or cash in exchange for my Restricted Stock Units and Dividend Equivalents in the following form (place an “X” in the “Check” column or in the “Withholding” column):
	Check (I will write a check for my taxes that are due and deliver it to the Company within one (1) day of the release date of my Stock or cash payment) ¨					Withholding (The Company should withhold shares of my Stock or cash payment to cover my taxes) ¨
	__________________________________________ PARTICIPANT NAME (PLEASE PRINT) __________________________________________ PARTICIPANT SIGNATURE					______________________ DATE

IMPORTANT NOTE:    Please complete and return this Election Form to ________ at _______ by _____________

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EX-10.6.6G

Exhibit 10.6.6g

PERFORMANCE SHARE AWARD AGREEMENT

THIS AWARD AGREEMENT is made and entered into as of _________________ (the “Date of Grant”), by and between Pinnacle West Capital Corporation (the “Company”), and _________________ (“Employee”).

BACKGROUND

A. The Board of Directors of the Company (the “Board of Directors”) has adopted, and the Company’s shareholders have approved, the Pinnacle West Capital Corporation 2012 Long-Term Incentive Plan (the “Plan”), pursuant to which Performance Share Awards and Dividend Equivalent Awards may be granted to employees of the Company and its subsidiaries.

B. The Company desires to grant to Employee Performance Shares and Dividend Equivalents under the terms of the Plan.

C. Pursuant to the Plan, the Company and Employee agree as follows:

AGREEMENT

1. Grant of Award. Pursuant to action of the Committee, which was taken on the Date of Grant, the Company grants to Employee ____________ (____) Performance Shares and related Dividend Equivalents. The Performance Shares granted under this Section 1 are referred to in this Award Agreement as the “Base Grant.”

2. Award Subject to Plan. This Performance Share Award and the related Dividend Equivalent Award are granted under and are expressly subject to all of the terms and provisions of the Plan, which terms are incorporated herein by reference, and this Award Agreement. In the event of any conflict between the terms and conditions of this Award Agreement and the Plan, the provisions of the Plan shall control.

3. Performance Period. The Performance Period for this Award begins January 1, _____, and ends December 31, _____.

4. Payment and Vesting.

(a) Performance Shares Payable In Stock. As soon as practicable in the fiscal year immediately following the end of the Performance Period, the Company will determine (i) the Company’s Total Shareholder Return (as defined herein) as compared to the Total Shareholder Return of the companies in the S&P 1500 Super Composite Electric Utility Index (the “Growth Index”) over the Performance Period and (ii) the Company’s Average Performance with respect to the Performance Metrics (as defined herein). The Company then will deliver to Employee one (1) share of the Company’s Stock for each then-outstanding Performance Share under this Award Agreement, subject to adjustment pursuant to Section 5 below. The Company anticipates that the Stock payout, if any, related to the Company’s Total Shareholder Return will be made by _________. The Company anticipates that the Stock payout, if any, related to the Performance Metrics will be made by __________ and in no event will such Stock payout be made later than ___________.

(b) Normal or Early Retirement, Death or Disability; Late Career Recipient.

(i) Provided that Employee either qualifies for “Early Retirement” or “Normal Retirement” under the Pinnacle West Capital Corporation Retirement Plan (the “Retirement Plan”), or is a Late Career Recipient (as defined below), in the case of Employee’s death or Disability,

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Employee shall be deemed to have been employed by the Company through the end of the Performance Period and Employee (or his or her estate) will receive the Stock, if any, to which Employee is entitled at the time specified in Section 4(a).

(ii) In the case of Employee’s Termination of Employment during the Performance Period which constitutes an Early Retirement or a Normal Retirement under the Retirement Plan, Employee shall be deemed to have been employed by the Company through the end of the Performance Period and Employee (or his or her estate) will receive the Stock, if any, to which Employee is entitled at the time specified in Section 4(a).

(iii)If, at the time of Employee’s death, Disability or retirement Employee has reached sixty (60) years of age and has been credited with at least five (5) Years of Service, as defined under the Retirement Plan, and does not otherwise meet the criteria for Early Retirement or Normal Retirement under the Retirement Plan, Employee shall be treated for purposes of this Agreement as a “Late Career Recipient”. Upon a Late Career Recipient’s retirement during the Performance Period, Employee will receive a straight prorated payout of the number of Performance Shares calculated in accordance with Section 5 based on the number of days Employee was employed during the Performance Period. Upon a Late Career Recipient’s retirement following the end of the Performance Period, Employee will receive a payout of the number of Performance Shares calculated in accordance with Section 5. No fractional Stock shall be issued. If the Stock payout results in a fractional share of one-half or greater, such fraction will be increased to provide for the issuance of a full share of Stock. Employee will receive the Stock, if any, to which Employee is entitled at the time specified in Section 4(a).

(c) Termination Without Cause. In the event Employee’s employment is terminated by the Company without cause, the Chief Executive Officer (“CEO”) of the Company may determine in his discretion if, to what extent, and when any unvested portion of the Performance Shares granted under this Agreement should vest; provided, however, that (i) any vesting of unvested Performance Shares granted under this Agreement pursuant to this Section 4(c)shall be approved by the Committee, and (ii) nothing herein shall obligate the CEO to exercise his discretion to cause any unvested Performance Shares to vest.

(d) Termination For Cause. Notwithstanding any other provision in this Section 4, in the event Employee is terminated for Cause, then regardless of Employee’s retirement, Early Retirement, Normal Retirement, death or Disability, Employee shall forfeit the right to receive any Stock hereunder that Employee would otherwise be entitled to receive following his or her date of termination. For purposes only of this Section 4(d), “Cause” means (A) embezzlement, theft, fraud, deceit and/or dishonesty by the Employee involving the property, business or affairs of the Company or any of its subsidiaries, or (B) an act of moral turpitude which in the sole judgment of the CEO reflects adversely on the business or reputation of the Company or any of its subsidiaries or negatively affects any of the Company’s or any of its subsidiaries’ employees or customers.

(e) Disability. “Disability” has the meaning set forth for such term in the Retirement Plan.

(f) Dividend Equivalents. In satisfaction of the Dividend Equivalents Award made pursuant to Section 1, at the time of the Company’s delivery of Stock to Employee pursuant to this Section 4, the Company also will deliver to Employee fully transferrable shares of Stock equal in value to the amount of dividends, if any, that Employee would have received if Employee had directly owned the Stock to which the Performance Shares relate from the Date of Grant to the date of the Stock payout, plus interest on such amount at the rate of 5 percent compounded quarterly, as determined pursuant to the Plan. The number of shares of Stock distributed to Employee will be determined by dividing the amount of the Dividend Equivalents and interest by the Fair Market Value of one share of Stock as of the applicable date of the Stock payout. No fractional Stock shall be issued. If the Stock payout results in

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a fractional share of one-half or greater, such fraction will be increased to provide for the issuance of a full share of Stock.

(g) Impact on Retirement Plans. The value of the shares of Stock distributed upon payment for the Performance Shares and Dividend Equivalents will be disregarded for purposes of calculating the amount of Employee’s benefit under any Company retirement plans.

5. Performance Criteria and Adjustments. Fifty percent (50%) of the Performance Shares awarded under this Award Agreement will be determined pursuant to Section 5(a) and fifty percent (50%) of the Performance Shares awarded under this Award Agreement will be determined pursuant to Section 5(b). In no event will Employee be entitled to receive a number of Performance Shares pursuant to this Award Agreement greater than 2.0 times the Base Grant.

(a) Adjustment of Base Grant for Total Shareholder Return. Fifty percent (50%) of the Base Grant will increase or decrease based upon the Company’s “Total Shareholder Return” as compared to the Total Shareholder Return of the companies in the Growth Index during the Performance Period, as follows:

If the Company’s Total Shareholder Return Over The Performance Period As Compared to the Total Shareholder Return of the Companies in the Growth Index is:	The Number of Performance Shares will be:
90th Percentile or greater	1.0 X Base Grant
75th Percentile	.75 X Base Grant
50th Percentile	0.5 X Base Grant
25th Percentile	0.25 X Base Grant
Less than 25th Percentile	None

If intermediate percentiles are achieved, the number of Performance Shares awarded will be prorated (partial shares will be rounded down to the nearest whole share when applicable). For example, if the Company’s Total Shareholder Return during the Performance Period places the Company’s performance in the 60th percentile, then the number of Performance Shares would be increased to 0.60 (0.5 X 60/50) multiplied by the Base Grant. In no event will Employee be entitled to receive a number of Performance Shares pursuant to this Subsection 5(a) greater than 1.0 times the Base Grant.

(b) Adjustment of Base Grant for Performance Metrics. Fifty percent (50%) of the Base Grant will increase or decrease based upon the Company’s “Average Performance” with respect to the “Performance Metrics,” as follows:

If the Company’s Average Performance is:	The Number of Performance Shares will be:
90th Percentile or greater	1.0 X Base Grant
75th Percentile	.75 X Base Grant
50th Percentile	0.5 X Base Grant
25th Percentile	0.25 X Base Grant
Less than 25th Percentile	None

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If intermediate percentiles are achieved, the number of Performance Shares awarded pursuant to this Subsection 5(b) will be prorated (partial shares will be rounded down to the nearest whole share when applicable). For example, if the Company’s Average Performance during the Performance Period places the Company’s performance in the 60th percentile, then the number of Performance Shares would be increased to .60 (0.5 X 60/50) multiplied by the Base Grant. In no event will Employee be entitled to receive a number of Performance Shares pursuant to this Subsection (b) greater than 1.0 times the Base Grant.

6. Definitions.

(a) Performance Metrics. The “Performance Metrics” for the Performance Period are: (i) the System Average Interruption Frequency Index (Major Events Excluded) (“SAIFI”); (ii) Arizona Public Service Company’s customer to employee improvement ratio; (iii) the OSHA rate (All Incident Injury Rate); (iv) nuclear capacity factor; and (v) coal capacity factor.

(1) With respect to the Performance Metric described in clause (i) of this Subsection 6(a), the Edison Electric Institute (“EEI”) will provide data on an annual basis regarding the SAIFI result of the participating companies; the Company will calculate its SAIFI result for the year in question and determine its percentile ranking based on the information provided by EEI.

(2) With respect to the Performance Metric described in clause (ii) of this Subsection 6(a), SNL, an independent third party data system, will provide data on an annual basis regarding the customer and employee counts; the Company will use its customer and employee counts for the year in question and determine its percentile ranking based on the information provided by SNL. Only those companies whose customers and employees were included in the data provided by SNL in each of the years of the Performance Period will be considered.

(3) With respect to the Performance Metric described in clause (iii) of this Subsection 6(a), EEI will provide data on an annual basis regarding the OSHA rate of the participating companies; the Company will calculate its OSHA rate for the year in question and determine its percentile ranking based on the information provided by EEI.

(4) With respect to the Performance Metric described in clause (iv) of this Subsection 6(a), SNL will provide data on an annual basis regarding the nuclear capacity factors of the participating nuclear plants; the Company will calculate its nuclear capacity factor for the year in question and determine its percentile ranking based on the information provided by SNL. Only those plants that were included in the data provided by SNL in each of the years of the Performance Period will be considered.

(5) With respect to the Performance Metric described in clause (v) of this Subsection 6(a), SNL will provide data on an annual basis regarding the coal capacity factors of the participating coal plants; the Company will calculate its coal capacity factor for the year in question and determine its percentile ranking based on the information provided by SNL. Only those plants that were included in the data provided by SNL in each of the years of the Performance Period will be considered.

(6) The Company’s percentile ranking during the Performance Period for each Performance Metric will be the average of the Company’s percentile ranking for each Performance Metric during each of the three years of the Performance Period (each, an “Average Performance Metric”); provided, however, that if the third year of a Performance Metric is not calculable by December 15 of the following year, the Performance Metric shall consist of the three most recent years for which such

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Performance Metric is calculable. The Company’s “Average Performance,” for purposes of determining any Base Grant adjustments pursuant to Subsection 5(b) above will be the average of the Average Performance Metrics. If only quartile, rather than percentile, rankings are available for a particular Performance Metric, the Average Performance Metric for any such Performance Metric shall be expressed as a percentile. For example, if the Performance Metric was in the top quartile for two Performance Periods and in the lowest quartile in the other Performance Period, the average of these quartiles would be 3 (the average of 4, 4, and 1) and the Average Performance Metric would be the 75^th percentile (3 /4). The calculations in this Subsection 6(a)(6) will be verified by the Company’s internal auditors.

(7) If either EEI or SNL discontinues providing the data specified above, the Committee shall select a data source that, in the Committee’s judgment, will provide data most comparable to the data provided by EEI or SNL, as the case may be.

(b) Total Shareholder Return. “Total Shareholder Return” for the Performance Period is the measure of a company’s stock price appreciation plus any dividends paid during the Performance Period. Only those companies that were included in the Growth Index in each of the years of the Performance Period will be considered. Total Shareholder Return for the Company and the companies in the Growth Index will be determined using the Daily Comparative Return as calculated by Bloomberg (or other independent third party data system). If the Growth Index is discontinued, the Committee shall select the most comparable index then in use for the sector comparison. In addition, if the sector comparison is no longer representative of the Company’s industry or business, the Committee shall replace the Growth Index with the most representative index then in use. Once the Total Shareholder Returns of the Company and all relevant companies in the Growth Index have been determined, the member companies will be ranked from greatest to least. Percentiles will be calculated (interpolated from 0% to 100%) based on a company’s relative ranking. Percentiles will be carried out to one (1) decimal place. If the Company is not in the Growth Index, then its percentile will be interpolated between the companies listed in the relative ranking. These calculations will be verified by the Company’s internal auditors.

7. Termination of Award. This Award Agreement will terminate and be of no further force or effect on the date that Employee is no longer employed by the Company or any of its subsidiaries, whether due to voluntary or involuntary termination, death, retirement, Disability, or otherwise, except as specifically set forth in Section 4 above or in Article 15 of the Plan. Employee will, however, be entitled to receive any Stock and Dividend Equivalents payable under Section 4 of this Award Agreement if Employee’s employment terminates after the end of the Performance Period but before Employee’s receipt of such Stock and Dividend Equivalents.

8. Section 409A Compliance. If the Company concludes, in the exercise of its discretion, that this Award is subject to Section 409A of the Code, the Plan and this Award Agreement shall be administered in compliance with Section 409A and each provision of this Award Agreement and the Plan shall be interpreted to comply with Section 409A. If the Company concludes, in the exercise of its discretion, that this Award is not subject to Section 409A, but, instead, is eligible for the short-term deferral exception to the requirements of Section 409A, the Plan and this Award Agreement shall be administered to comply with the requirements of the short-term deferral exception to the requirements of Section 409A and each provision of this Award Agreement and the Plan shall be interpreted to comply with the requirements of such exception. In either event, Employee does not have any right to make any election regarding the time or form of any payment due under this Award Agreement other than the tax withholding election described in Section 9.

9. Tax Withholding. Employee is responsible for any and all federal, state, and local income, payroll or other tax obligations or withholdings (collectively, the “Taxes”) arising out of this Award. Employee shall pay any and all Taxes due in connection with a payout of Stock hereunder by check

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or by having the Company withhold shares of Stock from such payout. No later than _________, Employee must elect, on the election form attached hereto, how Employee will satisfy the tax obligations upon a payout. In the absence of a timely election by Employee, Employee’s tax withholding obligation will be satisfied through the Company’s withholding of shares of Stock as set forth above.

10. Continued Employment. Nothing in the Plan or this Award Agreement shall be interpreted to interfere with or limit in any way the right of the Company or its subsidiaries to terminate Employee’s employment or services at any time. In addition, nothing in the Plan or this Award Agreement shall be interpreted to confer upon Employee the right to continue in the employ or service of the Company or its subsidiaries.

11. Confidentiality. During Employee’s employment and after termination thereof, for any reason, Employee agrees that Employee will not, directly or indirectly, in one or a series of transactions, disclose to any person, or use or otherwise exploit for Employee’s own benefit or for the benefit of anyone other than the Company or any of its Affiliates any Confidential Information (as hereinafter defined), whether prepared by Employee or not; provided, however, that during the term of Employee’s employment, any Confidential Information may be disclosed (i) to officers, representatives, employees and agents of the Company and its Affiliates who need to know such Confidential Information in order to perform the services or conduct the operations required or expected of them in the business, and (ii) in good faith by Employee in connection with the performance of Employee’s job duties to persons who are authorized to receive such information by the Company or its Affiliates. Employee shall have no obligation to keep confidential any Confidential Information, if and to the extent disclosure of any such information is specifically required by law; provided, however, that in the event disclosure is required by applicable law, Employee shall provide the Company with prompt notice of such requirement, prior to making any disclosure, so that it may seek an appropriate protective order.

Employee agrees that all Confidential Information of the Company and its Affiliates (whether now or hereafter existing) conceived, discovered or made by him during employment exclusively belongs to the Company or its Affiliates (and not to Employee). Employee will promptly disclose such Confidential Information to the Company and perform all actions reasonably requested by the Company to establish and confirm such exclusive ownership. For purposes of this Section 11, the term “Confidential Information” shall mean and include any information disclosed to Employee any time during Employee’s employment with the Company or its Affiliates or thereafter which is not generally known to the public, including, but not limited to, information concerning the Company’s or its Affiliates’ assets and valuations, business plans, methods of operation, management, information systems, procedures, processes, practices, policies, plans, programs, personnel and/or reports or other information prepared by appraisers, consultants, advisors, bankers or attorneys.

12. Restrictive Covenants.

(a) Non-Competition.  Employee agrees that for a period of 12 months following any Termination of Employment voluntarily by Employee (other than due to Disability),  Employee shall not, without the prior written consent of the Company’s General Counsel, participate, whether as a consultant, employee, contractor, partner, owner (ownership of less than 5% of the outstanding stock of a publicly traded company will not be considered ownership under this provision), co-owner, or otherwise, with any business, corporation, group, entity or individual that is or intends to be engaged in the business activity of supplying electricity in any area of Arizona for which the Company or its Affiliates is authorized to supply electricity. 

(b) Employee Non-Solicitation. Employee agrees that for a period of 12 months following Employee’s Termination of Employment for any reason, Employee will not encourage, induce, or otherwise solicit, or actively assist any other person or organization to encourage, induce or otherwise solicit, directly or indirectly, any employee of the Company

6

or any of its Affiliates to terminate his or her employment with the Company or its Affiliates, or otherwise interfere with the advantageous business relationship of the Company and its Affiliates with their employees.

(c) [No Pledging or Hedging. Employee agrees that during his or her term of employment, Employee will not pledge, margin, hypothecate, hedge, or otherwise grant an economic interest in any shares of Company stock received by Employee pursuant to this Award (net of shares sold or surrendered to meet tax withholding or exercise requirements). This restriction shall extend to the purchase or creation of any short sales, zero-cost collars, forward sales contracts, puts, calls, options or other derivative securities in respect of any shares of Company stock.]

(d) Remedies. If Employee fails to comply with Sections 11, 12(a), [or] 12(b), [or 12(c)] in a material respect, the Company may (i) cause any of Employee’s unvested Performance Shares and related Dividend Equivalents to be cancelled and forfeited, (ii) refuse to deliver shares of Stock or cash in exchange for vested Performance Shares or Dividend Equivalents, and/or (iii) pursue any other rights and remedies the Company may have pursuant to this Award Agreement or the Plan at law or in equity including, specifically, injunctive relief.

13. Clawback. The portion of this Award, if any, that is earned based on the Company’s Total Shareholder Return will be subject to potential forfeiture or recovery to the extent called for by the Company’s Clawback Policy, which is intended to be responsive to the final rules to be issued by the Securities and Exchange Commission and the listing standards to be adopted by the New York Stock Exchange pursuant to Section 954 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. The Clawback Policy may include such other provisions as the Human Resources Committee of the Board of Directors determines to be necessary or appropriate either to comply with any applicable law or listing standard or in light of Company ethics or other policies and practices. Specific requirements of the Clawback Policy may be adopted and amended at such times as the Human Resources Committee of the Board of Directors determines in its discretion. By accepting this Award, Employee consents and agrees to abide by such Clawback Policy.

14. Non-Transferability. Neither this Award nor any rights under this Award Agreement may be assigned, transferred, or in any manner encumbered except as provided in the Plan.

15. Definitions:Copy of Plan and Plan Prospectus. To the extent not specifically defined in this Award Agreement, all capitalized terms used in this Award Agreement will have the same meanings ascribed to them in the Plan. By signing this Award Agreement, Employee acknowledges receipt of a copy of the Plan and the related Plan prospectus.

16. Amendment. Except as provided below, any amendments to this Award Agreement must be made by a written agreement executed by the Company and Employee. The Company may amend this Award Agreement unilaterally, without the consent of Employee, if the change (i) is required by law or regulation, (ii) does not adversely affect in any material way the rights of Employee, or (iii) is required to cause the benefits under the Plan to qualify as performance-based compensation within the meaning of Section 162(m) of the Code or to comply with the provisions of Section 409A of the Code and applicable regulations or other interpretive authority. Additional rules relating to amendments to the Plan or any Award Agreement to assure compliance with Section 409A of the Code are set forth in Section 17.15 of the Plan.

17. Performance-Based Award. This Award is intended to be a Performance-Based Award if Employee is considered to be a Covered Employee for the tax year of the Company for which the Company claims a related tax deduction.

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IN WITNESS WHEREOF, the Company has caused this Award Agreement to be executed, as of the Date of Grant, by an authorized representative of the Company and this Award Agreement has been executed by Employee.

PINNACLE WEST CAPITAL CORPORATION

By: _______________________

Its: _______________________

Date: ______________________

EMPLOYEE

By:________________________

Date: ______________________

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Pinnacle West Capital Corporation

PERFORMANCE SHARE AWARD
ELECTION FORM

(applies to Award Agreement dated ___/__/____)

INFORMATION ABOUT YOU
Last	First	Middle Initial		Employee ID#
TAX WITHHOLDING ELECTION
I hereby elect to satisfy any tax withholding obligation associated with my receipt of Stock pursuant to my Performance Share Award in the following form (place an “X” in the “Check” column or in the “Stock” column):
Check (I will write a check for my taxes that are due and deliver it to the Company within one (1) day of the release of the Stock)			Stock (The Company should withhold shares of my Stock to cover my taxes)
__________________________________________ PARTICIPANT NAME (PLEASE PRINT) __________________________________________ PARTICIPANT SIGNATURE			______________________ DATE

IMPORTANT NOTE:    Please complete and return this Election Form to ________ at _______ by __________.

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EX-12.1

Exhibit 12.1

PINNACLE WEST CAPITAL CORPORATION

RATIO OF EARNINGS TO FIXED CHARGES

(dollars in thousands)

	2016		2015		2014		2013		2012
Earnings:
Income from continuing operations attributable to common shareholders	$	442,034	$	437,257	$	397,595	$	406,074	$	387,380
Income taxes	236,411		237,720		220,705		230,591		237,317
Fixed charges	213,973		202,465		208,226		206,089		219,437
Total earnings	$	892,418	$	877,442	$	826,526	$	842,754	$	844,134
Fixed Charges:
Interest expense	$	205,720	$	194,964	$	200,950	201,888		$	214,616
Estimated interest portion of annual rents	8,253		7,501		7,276		4,201		4,821
Total fixed charges	$	213,973	$	202,465	$	208,226	$	206,089	$	219,437
Ratio of Earnings to Fixed Charges (rounded down)	4.17		4.33		3.96		4.08		3.84

EX-12.2

Exhibit 12.2

ARIZONA PUBLIC SERVICE COMPANY
RATIO OF EARNINGS TO FIXED CHARGES
(dollars in thousands)

	2016		2015		2014		2013		2012
Earnings:
Income from continuing operations attributable to common shareholders	$	462,141	$	450,274	$	421,219	$	424,969	$	395,497
Income taxes	245,842		245,841		237,360		245,095		244,396
Fixed charges	210,776		199,458		204,198		202,457		214,227
Total earnings	$	918,759	$	895,573	$	862,777	$	872,521	$	854,120
Fixed Charges:
Interest charges	$	197,811	$	187,499	$	193,119	$	194,616	$	205,533
Amortization of debt discount	4,760		4,793		4,168		4,046		4,215
Estimated interest portion of annual rents	8,205		7,166		6,911		3,795		4,479
Total fixed charges	$	210,776	$	199,458	$	204,198	$	202,457	$	214,227
Ratio of Earnings to Fixed Charges (rounded down)
Earnings:	4.35		4.49		4.22		4.30		3.98

EX-12.3

Exhibit 12.3

PINNACLE WEST CAPITAL CORPORATION
RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED
STOCK DIVIDEND REQUIREMENTS
(dollars in thousands)

	2016		2015		2014		2013		2012
Earnings:
Income from continuing operations attributable to common shareholders	$	442,034	$	437,257	$	397,595	$	406,074	$	387,380
Income taxes	236,411		237,720		220,705		230,591		237,317
Fixed charges	213,973		202,465		208,226		206,089		219,437
Total earnings	$	892,418	$	877,442	$	826,526	$	842,754	$	844,134
Fixed Charges:
Interest expense	$	205,720	$	194,964	$	200,950	$	201,888	$	214,616
Estimated interest portion of annual rents	8,253		7,501		7,276		4,201		4,821
Total fixed charges	$	213,973	$	202,465	$	208,226	$	206,089	$	219,437
Preferred Stock Dividend Requirements:
Income before income taxes attributable to common shareholders	$	678,445	$	674,977	$	618,300	$	636,665	$	624,697
Net income from continuing operations attributable to common shareholders	442,034		437,257		397,595		406,074		387,380
Ratio of income before income taxes to net income	1.53		1.54		1.56		1.57		1.61
Preferred stock dividends	—		—		—		—		—
Preferred stock dividend requirements — ratio (above) times preferred stock dividends	$	—	$	—	$	—	$	—	$	—
Fixed Charges and Preferred Stock Dividend Requirements:
Fixed charges	$	213,973	$	202,465	$	208,226	$	206,089	$	219,437
Preferred stock dividend requirements	—		—		—		—		—
Total	$	213,973	$	202,465	$	208,226	$	206,089	$	219,437
Ratio of Earnings to Fixed Charges (rounded down)	4.17		4.33		3.96		4.08		3.84

EX-21.1

Exhibit 21.1

SUBSIDIARIES LIST

Arizona Public Service Company

*All other subsidiaries of Pinnacle West Capital Corporation and all subsidiaries of Arizona Public Service Company have been omitted as they do not constitute significant subsidiaries within the meaning of Rule 1-02(w) of Regulation S-X.

EX-23.1

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement Nos. 333-203578 and 333-197017 on Form S-3 and in Registration Statement Nos. 333-143432, 333-182427, and 333-157151 on Form S-8 of our report dated February 24, 2017, relating to the consolidated financial statements and financial statement schedules of Pinnacle West Capital Corporation, and the effectiveness of Pinnacle West Capital Corporation's internal control over financial reporting, appearing in this Annual Report on Form 10-K of Pinnacle West Capital Corporation for the year ended December 31, 2016.

/s/ Deloitte & Touche LLP

Phoenix, Arizona

February 24, 2017

EX-23.2

Exhibit 23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement No. 333-203578-01 on Form S-3 and in Registration Statement Nos. 333-46161 and 333-158774 on Form S-8 of our report dated February 24, 2017, relating to the consolidated financial statements and financial statement schedule of Arizona Public Service Company, and the effectiveness of Arizona Public Service Company's internal control over financial reporting, appearing in this Annual Report on Form 10-K of Arizona Public Service Company for the year ended December 31, 2016.

/s/ Deloitte & Touche LLP

Phoenix, Arizona

February 24, 2017

EX-31.1

Exhibit 31.1

CERTIFICATION

I, Donald E. Brandt, certify that:

1. I have reviewed this Annual Report on Form 10-K of Pinnacle West Capital Corporation;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the

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audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: February 24, 2017

/s/ Donald E. Brandt

Donald E. Brandt

Chairman, President and Chief Executive Officer

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EX-31.2

CERTIFICATION

I, James R. Hatfield, certify that:

1. I have reviewed this Annual Report on Form 10-K of Pinnacle West Capital Corporation;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the

1

audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date:    February 24, 2017

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and Chief Financial Officer

2

EX-31.3

CERTIFICATION

I, Donald E. Brandt, certify that:

1. I have reviewed this Annual Report on Form 10-K of Arizona Public Service Company;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the

2

audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date:    February 24, 2017

/s/ Donald E. Brandt

Donald E. Brandt

Chairman, President and Chief Executive Officer

2

EX-31.4

CERTIFICATION

I, James R. Hatfield, certify that:

1. I have reviewed this Annual Report on Form 10-K of Arizona Public Service Company;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the

2

audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date:    February 24, 2017

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and Chief Financial Officer

2

EX-32.1

CERTIFICATIONOFCHIEF EXECUTIVE OFFICERANDCHIEF FINANCIAL OFFICERPURSUANT TO 18 U.S.C. 1350,AS ADOPTED PURSUANT TOSECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, Donald E. Brandt, certify, pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Annual Report on Form 10-K of Pinnacle West Capital Corporation for the year ended December 31, 2016 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Pinnacle West Capital Corporation.

Date:    February 24, 2017

/s/ Donald E. Brandt

Donald E. Brandt

Chairman, President and Chief Executive Officer

I, James R. Hatfield, certify, pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Annual Report on Form 10-K of Pinnacle West Capital Corporation for the year ended December 31, 2016 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Pinnacle West Capital Corporation.

Date:    February 24, 2017

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and Chief Financial Officer

EX-32.2

CERTIFICATIONOFCHIEF EXECUTIVE OFFICERANDCHIEF FINANCIAL OFFICERPURSUANT TO 18 U.S.C. 1350,AS ADOPTED PURSUANT TOSECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, Donald E. Brandt, certify, pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Annual Report on Form 10-K of Arizona Public Service Company for the year ended December 31, 2016 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Arizona Public Service Company.

Date:    February 24, 2017

/s/ Donald E. Brandt

Donald E. Brandt

Chairman, President and Chief Executive Officer

I, James R. Hatfield, certify, pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Annual Report on Form 10-K of Arizona Public Service Company for the year ended December 31, 2016 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Arizona Public Service Company.

Date:    February 24, 2017

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and Chief Financial Officer

XML

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 17, 2017	Jun. 30, 2016
Entity Information [Line Items]
Entity Registrant Name	PINNACLE WEST CAPITAL CORP
Entity Central Index Key	0000764622
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 8,961,361,256
Entity Common Stock, Shares Outstanding		111,340,169
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
ARIZONA PUBLIC SERVICE COMPANY
Entity Information [Line Items]
Entity Registrant Name	ARIZONA PUBLIC SERVICE COMPANY
Entity Central Index Key	0000007286
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		71,264,947
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY

XML

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
OPERATING REVENUES	$ 3,498,682	$ 3,495,443	$ 3,491,632
OPERATING EXPENSES
Fuel and purchased power	1,075,510	1,101,298	1,179,829
Operations and maintenance	911,319	868,377	908,025
Depreciation and amortization	485,829	494,422	417,358
Taxes other than income taxes	166,499	171,812	172,295
Other expenses	3,541	4,932	2,883
Total	2,642,698	2,640,841	2,680,390
OPERATING INCOME	855,984	854,602	811,242
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction (Note 1)	42,140	35,215	30,790
Other income (Note 17)	901	621	9,608
Other expense (Note 17)	(15,337)	(17,823)	(21,746)
Total	27,704	18,013	18,652
INTEREST EXPENSE
Interest charges	205,720	194,964	200,950
Allowance for borrowed funds used during construction (Note 1)	(19,970)	(16,259)	(15,457)
Total	185,750	178,705	185,493
INCOME BEFORE INCOME TAXES	697,938	693,910	644,401
INCOME TAXES (Note 4)	236,411	237,720	220,705
NET INCOME	461,527	456,190	423,696
Less: Net income attributable to noncontrolling interests (Note 18)	19,493	18,933	26,101
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 442,034	$ 437,257	$ 397,595
Weighted Average common shares outstanding — basic (in shares)	111,409	111,026	110,626
Weighted Average common shares outstanding — diluted (in shares)	112,046	111,552	111,178
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 3.97	$ 3.94	$ 3.59
Net income attributable to common shareholders — diluted (in dollars per share)	$ 3.95	$ 3.92	$ 3.58
ARIZONA PUBLIC SERVICE COMPANY
ELECTRIC OPERATING REVENUES	$ 3,489,754	$ 3,492,357	$ 3,488,946
OPERATING EXPENSES
Fuel and purchased power	1,082,625	1,101,298	1,179,829
Operations and maintenance	879,108	853,135	882,442
Depreciation and amortization	484,909	494,298	417,264
Taxes other than income taxes	165,779	171,499	171,583
Income taxes (Note 4)	259,353	260,143	245,036
Total	2,871,774	2,880,373	2,896,154
OPERATING INCOME	617,980	611,984	592,792
OTHER INCOME (DEDUCTIONS)
Income taxes (Note 4)	13,511	14,302	7,676
Allowance for equity funds used during construction (Note 1)	42,140	35,215	30,790
Other income (Note 17)	8,607	2,834	11,295
Other expense (Note 17)	(17,514)	(19,019)	(13,403)
Total	46,744	33,332	36,358
INTEREST EXPENSE
Interest on long-term debt	189,828	180,123	186,323
Interest on short-term borrowings	7,983	7,376	6,796
Debt discount, premium and expense	4,760	4,793	4,168
Allowance for borrowed funds used during construction (Note 1)	(19,481)	(16,183)	(15,457)
Total	183,090	176,109	181,830
INCOME TAXES (Note 4)	245,842	245,841	237,360
NET INCOME	481,634	469,207	447,320
Less: Net income attributable to noncontrolling interests (Note 18)	19,493	18,933	26,101
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 462,141	$ 450,274	$ 421,219

XML

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
NET INCOME	$ 461,527	$ 456,190	$ 423,696
Derivative instruments:
Net unrealized loss, net of tax benefit (expense)	(538)	(957)	(810)
Reclassification of net realized loss, net of tax benefit	2,941	4,187	13,483
Pension and other postretirement benefits activity, net of tax (expense) benefit	(1,477)	20,163	(2,761)
Total other comprehensive income	926	23,393	9,912
COMPREHENSIVE INCOME	462,453	479,583	433,608
Less: Comprehensive income attributable to noncontrolling interests	19,493	18,933	26,101
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	442,960	460,650	407,507
ARIZONA PUBLIC SERVICE COMPANY
NET INCOME	481,634	469,207	447,320
Derivative instruments:
Net unrealized loss, net of tax benefit (expense)	(538)	(957)	(809)
Reclassification of net realized loss, net of tax benefit	2,941	4,187	13,483
Pension and other postretirement benefits activity, net of tax (expense) benefit	(729)	18,006	(7,635)
Total other comprehensive income	1,674	21,236	5,039
COMPREHENSIVE INCOME	483,308	490,443	452,359
Less: Comprehensive income attributable to noncontrolling interests	19,493	18,933	26,101
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 463,815	$ 471,510	$ 426,258

XML

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net unrealized loss, tax (expense)	$ (585)	$ (342)	$ (438)
Reclassification of net realized loss, tax benefit	985	1,801	7,932
Pension and other postretirement benefits activity, tax benefit (expense)	633	(13,302)	1,307
ARIZONA PUBLIC SERVICE COMPANY
Net unrealized loss, tax (expense)	(585)	(342)	(438)
Reclassification of net realized loss, tax benefit	985	1,801	7,932
Pension and other postretirement benefits activity, tax benefit (expense)	$ 293	$ (11,776)	$ 4,655

XML

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
CURRENT ASSETS
Cash and cash equivalents	$ 8,881	$ 39,488
Customer and other receivables	250,491	274,691
Accrued unbilled revenues	107,949	96,240
Allowance for doubtful accounts	(3,037)	(3,125)
Materials and supplies (at average cost)	253,979	234,234
Fossil fuel (at average cost)	28,608	45,697
Income tax receivable (Note 4)	3,751	589
Assets from risk management activities (Note 16)	19,694	15,905
Deferred fuel and purchased power regulatory asset (Note 3)	12,465	0
Other regulatory assets (Note 3)	94,410	149,555
Other current assets	45,028	37,242
Total current assets	822,219	890,516
INVESTMENTS AND OTHER ASSETS
Assets from risk management activities (Note 16)	1	12,106
Nuclear decommissioning trust (Notes 13 and 19)	779,586	735,196
Other assets	69,063	52,518
Total investments and other assets	848,650	799,820
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	17,341,888	16,222,232
Accumulated depreciation and amortization	(5,970,100)	(5,594,094)
Net	11,371,788	10,628,138
Construction work in progress	1,019,947	816,307
Palo Verde sale leaseback, net of accumulated depreciation of $237,535 and $233,665 (Note 18)	113,515	117,385
Intangible assets, net of accumulated amortization of $603,637 and $546,038	90,022	123,975
Nuclear fuel, net of accumulated amortization of $147,202 and $146,228	119,004	123,139
Total property, plant and equipment	12,714,276	11,808,944
DEFERRED DEBITS
Regulatory assets (Notes 1, 3 and 4)	1,313,428	1,214,146
Assets for other postretirement benefits (Note 7)	166,206	185,997
Other	139,474	128,835
Total deferred debits	1,619,108	1,528,978
Total Assets	16,004,253	15,028,258
CURRENT LIABILITIES
Accounts payable	264,631	297,480
Accrued taxes (Note 4)	138,964	138,600
Accrued interest	52,835	56,305
Common dividends payable	72,926	69,363
Short-term borrowings (Note 5)	177,200	0
Current maturities of long-term debt (Note 6)	125,000	357,580
Customer deposits	82,520	73,073
Liabilities from risk management activities (Note 16)	25,836	77,716
Liabilities for asset retirements (Note 11)	9,135	28,573
Deferred fuel and purchased power regulatory liability (Note 3)	0	9,688
Other regulatory liabilities (Note 3)	99,899	136,078
Other current liabilities	244,000	197,861
Total current liabilities	1,292,946	1,442,317
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 6)	4,021,785	3,462,391
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,945,232	2,723,425
Regulatory liabilities (Notes 1, 3, 4 and 7)	948,916	994,152
Liabilities for asset retirements (Note 11)	615,340	415,003
Liabilities for pension benefits (Note 7)	509,310	480,998
Liabilities from risk management activities (Note 16)	47,238	89,973
Customer advances	88,672	115,609
Coal mine reclamation	221,910	201,984
Deferred investment tax credit	210,162	187,080
Unrecognized tax benefits (Note 4)	10,046	9,524
Other	156,784	186,345
Total deferred credits and other	5,753,610	5,404,093
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 111,392,053 and 111,095,402 issued at respective dates	2,596,030	2,541,668
Treasury stock at cost; 55,317 shares at end of 2016 and 115,030 shares at end of 2015	(4,133)	(5,806)
Total common stock	2,591,897	2,535,862
Retained earnings	2,255,547	2,092,803
Accumulated other comprehensive loss:
Pension and other postretirement benefits (Note 7)	(39,070)	(37,593)
Derivative instruments (Note 16)	(4,752)	(7,155)
Total accumulated other comprehensive loss	(43,822)	(44,748)
Total shareholders’ equity	4,803,622	4,583,917
Noncontrolling interests (Note 18)	132,290	135,540
Total equity	4,935,912	4,719,457
Total Liabilities and Equity	16,004,253	15,028,258
ARIZONA PUBLIC SERVICE COMPANY
CURRENT ASSETS
Cash and cash equivalents	8,840	22,056
Customer and other receivables	262,611	274,428
Accrued unbilled revenues	107,949	96,240
Allowance for doubtful accounts	(3,037)	(3,125)
Materials and supplies (at average cost)	252,777	234,234
Fossil fuel (at average cost)	28,608	45,697
Income tax receivable (Note 4)	11,174	0
Assets from risk management activities (Note 16)	19,694	15,905
Deferred fuel and purchased power regulatory asset (Note 3)	12,465	0
Other regulatory assets (Note 3)	94,410	149,555
Other current assets	41,849	35,765
Total current assets	837,340	870,755
INVESTMENTS AND OTHER ASSETS
Assets from risk management activities (Note 16)	1	12,106
Nuclear decommissioning trust (Notes 13 and 19)	779,586	735,196
Other assets	48,320	34,455
Total investments and other assets	827,907	781,757
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	17,228,787	16,218,724
Accumulated depreciation and amortization	(5,881,941)	(5,590,937)
Net	11,346,846	10,627,787
Construction work in progress	989,497	812,845
Palo Verde sale leaseback, net of accumulated depreciation of $237,535 and $233,665 (Note 18)	113,515	117,385
Intangible assets, net of accumulated amortization of $603,637 and $546,038	89,868	123,820
Nuclear fuel, net of accumulated amortization of $147,202 and $146,228	119,004	123,139
Total property, plant and equipment	12,658,730	11,804,976
DEFERRED DEBITS
Regulatory assets (Notes 1, 3 and 4)	1,313,428	1,214,146
Assets for other postretirement benefits (Note 7)	162,911	182,625
Other	130,859	127,923
Total deferred debits	1,607,198	1,524,694
Total Assets	15,931,175	14,982,182
CURRENT LIABILITIES
Accounts payable	259,161	291,574
Accrued taxes (Note 4)	130,576	144,488
Accrued interest	52,525	56,003
Common dividends payable	72,900	69,400
Short-term borrowings (Note 5)	135,500	0
Current maturities of long-term debt (Note 6)	0	357,580
Customer deposits	82,520	73,073
Liabilities from risk management activities (Note 16)	25,836	77,716
Liabilities for asset retirements (Note 11)	8,703	28,573
Deferred fuel and purchased power regulatory liability (Note 3)	0	9,688
Other regulatory liabilities (Note 3)	99,899	136,078
Other current liabilities	226,417	180,535
Total current liabilities	1,094,037	1,424,708
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,999,295	2,764,489
Regulatory liabilities (Notes 1, 3, 4 and 7)	948,916	994,152
Liabilities for asset retirements (Note 11)	607,234	415,003
Liabilities for pension benefits (Note 7)	488,253	459,065
Liabilities from risk management activities (Note 16)	47,238	89,973
Customer advances	88,672	115,609
Coal mine reclamation	206,645	201,984
Deferred investment tax credit	210,162	187,080
Unrecognized tax benefits (Note 4)	37,408	35,251
Other	143,560	142,683
Total deferred credits and other	5,777,383	5,405,289
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
EQUITY
Total common stock	178,162	178,162
Additional paid-in capital	2,421,696	2,379,696
Retained earnings	2,331,245	2,148,493
Accumulated other comprehensive loss:
Pension and other postretirement benefits (Note 7)	(20,671)	(19,942)
Derivative instruments (Note 16)	(4,752)	(7,155)
Total accumulated other comprehensive loss	(25,423)	(27,097)
Total shareholders’ equity	4,905,680	4,679,254
Noncontrolling interests (Note 18)	132,290	135,540
Total equity	5,037,970	4,814,794
Long-term debt less current maturities (Note 6)	4,021,785	3,337,391
Total capitalization	9,059,755	8,152,185
Total Liabilities and Equity	$ 15,931,175	$ 14,982,182

XML

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Accumulated depreciation of Palo Verde sale leaseback	$ 237,535	$ 233,665
Accumulated amortization on intangible assets	603,637	546,038
Accumulated amortization on nuclear fuel	$ 147,202	$ 146,228
EQUITY
Common stock, par value	$ 0	$ 0
Common stock, authorized shares	150,000,000	150,000,000
Common stock, issued shares	111,392,053	111,095,402
Treasury stock at cost, shares	55,317	115,030
ARIZONA PUBLIC SERVICE COMPANY
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Accumulated depreciation of Palo Verde sale leaseback	$ 237,535	$ 233,665
Accumulated amortization on intangible assets	603,637	546,038
Accumulated amortization on nuclear fuel	$ 147,202	$ 146,228

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CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 461,527	$ 456,190	$ 423,696
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	565,011	571,664	496,487
Deferred fuel and purchased power	(60,303)	14,997	(26,927)
Deferred fuel and purchased power amortization	38,152	1,617	40,757
Allowance for equity funds used during construction	(42,140)	(35,215)	(30,790)
Deferred income taxes	206,870	236,819	159,023
Deferred investment tax credit	23,082	8,473	26,246
Change in derivative instruments fair value	(403)	(381)	339
Stock compensation	18,883	18,756	33,059
Change in derivative instruments fair value
Customer and other receivables	(2,489)	(22,219)	(52,672)
Accrued unbilled revenues	(11,709)	4,293	(3,737)
Materials, supplies and fossil fuel	(1,491)	(23,945)	3,724
Income tax receivable	(3,162)	2,509	132,419
Other current assets	(23,324)	3,145	4,384
Accounts payable	(66,917)	(34,266)	(353)
Accrued taxes	447	(2,013)	9,615
Other current liabilities	29,594	603	17,892
Change in margin and collateral accounts — assets	673	(324)	(343)
Change in margin and collateral accounts — liabilities	17,735	22,776	(24,975)
Change in unrecognized tax benefits	1,628	(10,328)	2,778
Change in long-term regulatory liabilities	14,682	(20,535)	59,618
Change in other long-term assets	(60,163)	2,426	(56,561)
Change in other long-term liabilities	(82,793)	(100,715)	(114,052)
Net cash flow provided by operating activities	1,023,390	1,094,327	1,099,627
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,275,472)	(1,076,087)	(910,634)
Contributions in aid of construction	64,296	46,546	20,325
Allowance for borrowed funds used during construction	(19,970)	(16,259)	(15,457)
Proceeds from nuclear decommissioning trust sales	633,410	478,813	356,195
Investment in nuclear decommissioning trust	(635,691)	(496,062)	(373,444)
Other	(18,651)	(3,184)	347
Net cash flow used for investing activities	(1,252,078)	(1,066,233)	(922,668)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	693,151	842,415	731,126
Repayment of long-term debt	(370,430)	(415,570)	(652,578)
Short-term borrowings and payments — net	137,200	(147,400)	(5,725)
Short-term debt borrowings under revolving credit facility	40,000	0	0
Dividends paid on common stock	(274,229)	(260,027)	(246,671)
Common stock equity issuance and purchases - net	(4,867)	19,373	15,288
Distributions to noncontrolling interests	(22,744)	(35,002)	(20,482)
Other	0	1	161
Net cash flow provided by (used for) financing activities	198,081	3,790	(178,881)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(30,607)	31,884	(1,922)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	39,488	7,604	9,526
CASH AND CASH EQUIVALENTS AT END OF YEAR	8,881	39,488	7,604
Supplemental disclosure of cash flow information:
Income taxes, net of refunds	9,956	6,550	(102,154)
Interest, net of amounts capitalized	184,462	170,209	177,074
Significant non-cash investing and financing activities:
Accrued capital expenditures	114,855	83,798	44,712
Dividends declared but not paid	72,926	69,363	65,790
ARIZONA PUBLIC SERVICE COMPANY
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	481,634	469,207	447,320
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	564,091	571,540	496,393
Deferred fuel and purchased power	(60,303)	14,997	(26,927)
Deferred fuel and purchased power amortization	38,152	1,617	40,757
Allowance for equity funds used during construction	(42,140)	(35,215)	(30,790)
Deferred income taxes	221,167	223,069	155,401
Deferred investment tax credit	23,082	8,473	26,246
Change in derivative instruments fair value	(403)	(381)	339
Change in derivative instruments fair value
Customer and other receivables	(1,601)	(21,040)	(52,466)
Accrued unbilled revenues	(11,709)	4,293	(3,737)
Materials, supplies and fossil fuel	(1,454)	(23,945)	3,724
Income tax receivable	(14,567)	0	135,179
Other current assets	(21,640)	4,498	3,766
Accounts payable	(67,543)	(34,891)	(2,355)
Accrued taxes	(13,912)	13,378	8,650
Other current liabilities	5,097	(3,718)	33,970
Change in margin and collateral accounts — assets	673	(324)	(343)
Change in margin and collateral accounts — liabilities	17,735	22,776	(24,975)
Change in unrecognized tax benefits	1,628	(10,328)	2,778
Change in long-term regulatory liabilities	14,682	(20,535)	59,618
Change in other long-term assets	(45,866)	(813)	(62,739)
Change in other long-term liabilities	(76,855)	(82,628)	(85,642)
Net cash flow provided by operating activities	1,009,948	1,100,030	1,124,167
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,248,010)	(1,072,053)	(910,084)
Contributions in aid of construction	64,296	46,546	20,325
Allowance for borrowed funds used during construction	(19,481)	(16,183)	(15,457)
Proceeds from nuclear decommissioning trust sales	633,410	478,813	356,195
Investment in nuclear decommissioning trust	(635,691)	(496,062)	(373,444)
Other	(13,865)	(1,093)	347
Net cash flow used for investing activities	(1,219,341)	(1,060,032)	(922,118)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	693,151	842,415	606,126
Repayment of long-term debt	(370,430)	(415,570)	(527,578)
Short-term borrowings and payments — net	135,500	(147,400)	(5,725)
Dividends paid on common stock	(281,300)	(266,900)	(253,600)
Equity infusion from Pinnacle West	42,000	0	0
Distributions to noncontrolling interests	(22,744)	(35,002)	(20,482)
Net cash flow provided by (used for) financing activities	196,177	(22,457)	(201,259)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(13,216)	17,541	790
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	22,056	4,515	3,725
CASH AND CASH EQUIVALENTS AT END OF YEAR	8,840	22,056	4,515
Supplemental disclosure of cash flow information:
Income taxes, net of refunds	26,864	14,831	(86,054)
Interest, net of amounts capitalized	181,809	167,670	173,436
Significant non-cash investing and financing activities:
Accrued capital expenditures	114,874	83,798	44,712
Dividends declared but not paid	$ 72,900	$ 69,400	$ 65,800

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CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands		Total	Common Stock	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	ARIZONA PUBLIC SERVICE COMPANY	ARIZONA PUBLIC SERVICE COMPANY Common Stock	ARIZONA PUBLIC SERVICE COMPANY Additional Paid-In Capital	ARIZONA PUBLIC SERVICE COMPANY Retained Earnings	ARIZONA PUBLIC SERVICE COMPANY Accumulated Other Comprehensive Income (Loss)	ARIZONA PUBLIC SERVICE COMPANY Noncontrolling Interests
Beginning balance at Dec. 31, 2013		$ 4,340,460	$ 2,491,558	$ (4,308)	$ 1,785,273	$ (78,053)	$ 145,990	$ 4,454,874	$ 178,162	$ 2,379,696	$ 1,804,398	$ (53,372)	$ 145,990
Beginning Balance (in shares) at Dec. 31, 2013			110,280,703	98,944					71,264,947
Increase (Decrease) in Shareholders' Equity
Net income		423,696			397,595		26,101	447,320			421,219		26,101
Other comprehensive income		9,912				9,912		5,039				5,039
Dividends on common stock		(256,803)			(256,803)			(256,900)			(256,900)
Other								1			1
Issuance of common stock		21,412	$ 21,412
Issuance of common stock (in shares)			369,059
Purchase of treasury stock	[1]	(7,893)		$ (7,893)
Purchase of treasury stock (in shares)	[1]			(139,746)
Reissuance of treasury stock for stock-based compensation and other		8,800		$ 8,800
Reissuance of treasury stock for stock-based compensation and other (in shares)				160,290
Net capital activities by noncontrolling interests		(20,482)					(20,482)	(20,482)					(20,482)
Ending balance at Dec. 31, 2014		4,519,102	$ 2,512,970	$ (3,401)	1,926,065	(68,141)	151,609	4,629,852	$ 178,162	2,379,696	1,968,718	(48,333)	151,609
Ending Balance (in shares) at Dec. 31, 2014			110,649,762	78,400					71,264,947
Increase (Decrease) in Shareholders' Equity
Net income		456,190			437,257		18,933	469,207			450,274		18,933
Other comprehensive income		23,393				23,393		21,236				21,236
Dividends on common stock		(270,519)			(270,519)			(270,500)			(270,500)
Other								1			1
Issuance of common stock		28,698	$ 28,698
Issuance of common stock (in shares)			445,640
Purchase of treasury stock	[1]	(10,136)		$ (10,136)
Purchase of treasury stock (in shares)	[1]			(154,751)
Reissuance of treasury stock for stock-based compensation and other		7,731		$ 7,731
Reissuance of treasury stock for stock-based compensation and other (in shares)				118,121
Net capital activities by noncontrolling interests		(35,002)					(35,002)	(35,002)					(35,002)
Ending balance at Dec. 31, 2015		$ 4,719,457	$ 2,541,668	$ (5,806)	2,092,803	(44,748)	135,540	4,814,794	$ 178,162	2,379,696	2,148,493	(27,097)	135,540
Ending Balance (in shares) at Dec. 31, 2015		111,095,402	111,095,402	115,030					71,264,947
Increase (Decrease) in Shareholders' Equity
Stock compensation cumulative effect adjustments		$ 45,855	$ 40,380		5,475			5,411			5,411
Net income		461,527			442,034		19,493	481,634			462,141		19,493
Other comprehensive income		926				926		1,674				1,674
Dividends on common stock		(284,765)			(284,765)			(284,800)			(284,800)
Issuance of common stock		13,982	$ 13,982
Issuance of common stock (in shares)			296,651
Purchase of treasury stock	[1]	(9,087)		$ (9,087)
Purchase of treasury stock (in shares)	[1]			(128,105)
Reissuance of treasury stock for stock-based compensation and other		10,760		$ 10,760
Equity infusion from Pinnacle West								42,000		42,000
Reissuance of treasury stock for stock-based compensation and other (in shares)				187,818
Net capital activities by noncontrolling interests		(22,743)					(22,743)	(22,743)					(22,743)
Ending balance at Dec. 31, 2016		$ 4,935,912	$ 2,596,030	$ (4,133)	$ 2,255,547	$ (43,822)	$ 132,290	$ 5,037,970	$ 178,162	$ 2,421,696	$ 2,331,245	$ (25,423)	$ 132,290
Ending Balance (in shares) at Dec. 31, 2016		111,392,053	111,392,053	55,317					71,264,947

[1] Primarily represents shares of common stock withheld from certain stock awards for tax purposes.

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CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Common stock dividends declared (in dollars per share)	$ 2.56	$ 2.44	$ 2.33

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Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

Description of Business and Basis of Presentation

Pinnacle West is a holding company that conducts business through its subsidiaries, APS, El Dorado, BCE and 4CA. APS, our wholly-owned subsidiary, is a vertically-integrated electric utility that provides either retail or wholesale electric service to substantially all of the state of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona.  APS accounts for essentially all of our revenues and earnings, and is expected to continue to do so.  El Dorado is an investment firm. BCE is a subsidiary that was formed in 2014 that focuses on growth opportunities that leverage the Company's core expertise in the electric energy industry. BCE is currently pursuing transmission opportunities through a joint venture arrangement. 4CA is a subsidiary that was formed in 2016 as a result of the purchase of El Paso's 7% interest in Four Corners.

Pinnacle West’s Consolidated Financial Statements include the accounts of Pinnacle West and our subsidiaries:  APS, El Dorado, BCE and 4CA. APS’s consolidated financial statements include the accounts of APS and certain VIEs relating to the Palo Verde sale leaseback.  Intercompany accounts and transactions between the consolidated companies have been eliminated.

We consolidate VIEs for which we are the primary beneficiary.  We determine whether we are the primary beneficiary of a VIE through a qualitative analysis that identifies which variable interest holder has the controlling financial interest in the VIE.  In performing our primary beneficiary analysis, we consider all relevant facts and circumstances, including the design and activities of the VIE, the terms of the contracts the VIE has entered into, and which parties participated significantly in the design or redesign of the entity.  We continually evaluate our primary beneficiary conclusions to determine if changes have occurred which would impact our primary beneficiary assessments.  We have determined that APS is the primary beneficiary of certain VIE lessor trusts relating to the Palo Verde sale leaseback, and therefore APS consolidates these entities (see Note 18).

Our consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as otherwise disclosed in the notes) that we believe are necessary for the fair presentation of our financial position, results of operations and cash flows for the periods presented.

Certain line items are presented in more detail on the Consolidated Statements of Cash Flows than was presented in the prior years. The prior year amounts were reclassified to conform to the current year presentation. These reclassifications have no impact on net cash flows provided by operating activities. The following tables show the impacts of the reclassifications of the prior years (previously reported) amounts (dollars in thousands):

Statement of Cash Flows for the Year Ended December 31, 2015	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	18,756		$	18,756
Change in other long term liabilities	(81,959		)	(18,756		)	(100,715		)

Statement of Cash Flows for the Year Ended December 31, 2014	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	33,059		$	33,059
Change in other long-term liabilities	(80,993		)	(33,059		)	(114,052		)

Accounting Records and Use of Estimates

Our accounting records are maintained in accordance with GAAP.  The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period.  Actual results could differ from those estimates.

Regulatory Accounting

APS is regulated by the ACC and FERC.  The accompanying financial statements reflect the rate-making policies of these commissions.  As a result, we capitalize certain costs that would be included as expense in the current period by unregulated companies.  Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer rates.  Regulatory liabilities generally represent expected future costs that have already been collected from customers.

Management continually assesses whether our regulatory assets are probable of future recovery by considering factors such as changes in the applicable regulatory environment and recent rate orders applicable to APS or other regulated entities in the same jurisdiction.  This determination reflects the current political and regulatory climate in Arizona and is subject to change in the future.  If future recovery of costs ceases to be probable, the assets would be written off as a charge in current period earnings.

See Note 3 for additional information.

Electric Revenues

We derive electric revenues primarily from sales of electricity to our regulated Native Load customers.  Revenues related to the sale of electricity are generally recorded when service is rendered or electricity is delivered to customers.  The billing of electricity sales to individual Native Load customers is based on the reading of their meters, which occurs on a systematic basis throughout the month.  Unbilled revenues are estimated by applying an average revenue/kWh by customer class to the number of estimated kWhs delivered but not billed.  Differences historically between the actual and estimated unbilled revenues are immaterial.  We exclude sales taxes and franchise fees on electric revenues from both revenue and taxes other than income taxes.

Revenues from our Native Load customers and non-derivative instruments are reported on a gross basis on Pinnacle West’s Consolidated Statements of Income.  In the electricity business, some contracts to purchase energy are netted against other contracts to sell energy.  This is called a “book-out” and usually occurs for contracts that have the same terms (quantities and delivery points) and for which power does not flow.  We net these book-outs, which reduces both revenues and fuel and purchased power costs.

Some of our cost recovery mechanisms are alternative revenue programs.  For alternative revenue programs that meet specified accounting criteria, we recognize revenues when the specific events permitting billing of the additional revenues have been completed.

Allowance for Doubtful Accounts

The allowance for doubtful accounts represents our best estimate of existing accounts receivable that will ultimately be uncollectible.  The allowance is calculated by applying estimated write-off factors to various classes of outstanding receivables, including accrued utility revenues.  The write-off factors used to estimate uncollectible accounts are based upon consideration of both historical collections experience and management’s best estimate of future collections success given the existing collections environment.

Property, Plant and Equipment

Utility plant is the term we use to describe the business property and equipment that supports electric service, consisting primarily of generation, transmission and distribution facilities.  We report utility plant at its original cost, which includes:

• material and labor;

• contractor costs;

• capitalized leases;

• construction overhead costs (where applicable); and

• allowance for funds used during construction.

Pinnacle West’s property, plant and equipment included in the December 31, 2016 and 2015 consolidated balance sheets is composed of the following (dollars in thousands):

Property, Plant and Equipment:	2016			2015
Generation	$	7,874,898		$	7,336,902
Transmission	2,746,508			2,494,744
Distribution	5,738,801			5,543,561
General plant	981,681			847,025
Plant in service and held for future use	17,341,888			16,222,232
Accumulated depreciation and amortization	(5,970,100		)	(5,594,094		)
Net	11,371,788			10,628,138
Construction work in progress	1,019,947			816,307
Palo Verde sale leaseback, net of accumulated depreciation	113,515			117,385
Intangible assets, net of accumulated amortization	90,022			123,975
Nuclear fuel, net of accumulated amortization	119,004			123,139
Total property, plant and equipment	$	12,714,276		$	11,808,944

Property, plant and equipment balances and classes for APS are not materially different than Pinnacle West.

We expense the costs of plant outages, major maintenance and routine maintenance as incurred.  We charge retired utility plant to accumulated depreciation.  Liabilities associated with the retirement of tangible long-lived assets are recognized at fair value as incurred and capitalized as part of the related tangible long-lived assets.  Accretion of the liability due to the passage of time is an operating expense, and the capitalized cost is depreciated over the useful life of the long-lived asset.  See Note 11.

APS records a regulatory liability for the difference between the amount that has been recovered in regulated rates and the amount calculated in accordance with guidance on accounting for asset retirement obligations.  APS believes it can recover in regulated rates the costs calculated in accordance with this accounting guidance.

We record depreciation on utility plant on a straight-line basis over the remaining useful life of the related assets.  The approximate remaining average useful lives of our utility property at December 31, 2016 were as follows:

•Fossil plant — 19 years;

•Nuclear plant — 27 years;

•Other generation — 26 years;

•Transmission — 39 years;

•Distribution — 33 years; and

•General plant — 7 years.

Pursuant to an ACC order, we deferred operating costs in 2013 and 2014 related to APS's acquisition of additional interests in Units 4 and 5 and the related closure of Units 1-3 of Four Corners. See Note 3 for further discussion. These costs were deferred and are now being amortized on the depreciation line of the Consolidated Statements of Income.

Depreciation of utility property, plant and equipment is computed on a straight-line, remaining-life basis. Depreciation expense was $422 million in 2016, $430 million in 2015, and $396 million in 2014. For the years 2014 through 2016, the depreciation rates ranged from a low of 0.30% to a high of 14.12%.  The weighted-average depreciation rate was 2.66% in 2016, 2.74% in 2015, and 2.77% in 2014.

Allowance for Funds Used During Construction

AFUDC represents the approximate net composite interest cost of borrowed funds and an allowed return on the equity funds used for construction of regulated utility plant.  Both the debt and equity components of AFUDC are non-cash amounts within the Consolidated Statements of Income.  Plant construction costs, including AFUDC, are recovered in authorized rates through depreciation when completed projects are placed into commercial operation.

AFUDC was calculated by using a composite rate of 7.17% for 2016, 8.02% for 2015, and 8.47% for 2014.  APS compounds AFUDC semi-annually and ceases to accrue AFUDC when construction work is completed and the property is placed in service.

Materials and Supplies

APS values materials, supplies and fossil fuel inventory using a weighted-average cost method.  APS materials, supplies and fossil fuel inventories are carried at the lower of weighted-average cost or market, unless evidence indicates that the weighted-average cost (even if in excess of market) will be recovered.

Fair Value Measurements

We account for derivative instruments, investments held in our nuclear decommissioning trust, certain cash equivalents and plan assets held in our retirement and other benefit plans at fair value on a recurring basis.  Due to the short-term nature of net accounts receivable, accounts payable, and short-term borrowings, the carrying values of these instruments approximate fair value.  Fair value measurements may also be applied on a nonrecurring basis to other assets and liabilities in certain circumstances such as impairments.  We also disclose fair value information for our long-term debt, which is carried at amortized cost (see Note 6).

Fair value is the price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market which we can access for the asset or liability in an orderly transaction between willing market participants on the measurement date.  Inputs to fair value may include observable and unobservable data.  We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

We determine fair market value using observable inputs such as actively-quoted prices for identical instruments when available.  When actively quoted prices are not available for the identical instruments, we use other observable inputs, such as prices for similar instruments, other corroborative market information, or prices provided by other external sources.  For options, long-term contracts and other contracts for which observable price data are not available, we use models and other valuation methods, which may incorporate unobservable inputs to determine fair market value.

The use of models and other valuation methods to determine fair market value often requires subjective and complex judgment.  Actual results could differ from the results estimated through application of these methods.

See Note 13 for additional information about fair value measurements.

Derivative Accounting

We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal and in interest rates.  We manage risks associated with market volatility by utilizing various physical and financial instruments including futures, forwards, options and swaps.  As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and fuels.  The changes in market value of such contracts have a high correlation to price changes in the hedged transactions.  We also enter into derivative instruments for economic hedging purposes.  Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power expenses in our Consolidated Statements of Income, but does not impact our financial condition, net income or cash flows.

We account for our derivative contracts in accordance with derivatives and hedging guidance, which requires all derivatives not qualifying for a scope exception to be measured at fair value on the balance sheet as either assets or liabilities.  Transactions with counterparties that have master netting arrangements are reported net on the balance sheet.  See Note 16 for additional information about our derivative instruments.

Loss Contingencies and Environmental Liabilities

Pinnacle West and APS are involved in certain legal and environmental matters that arise in the normal course of business.  Contingent losses and environmental liabilities are recorded when it is determined that it is probable that a loss has occurred and the amount of the loss can be reasonably estimated.  When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, Pinnacle West and APS record a loss contingency at the minimum amount in the range.  Unless otherwise required by GAAP, legal fees are expensed as incurred.

Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan for the employees of Pinnacle West and its subsidiaries.  We also sponsor an other postretirement benefit plan for the employees of Pinnacle West and its subsidiaries that provides medical and life insurance benefits to retired employees.  Pension and other postretirement benefit expense are determined by actuarial valuations, based on assumptions that are evaluated annually.  See Note 7 for additional information on pension and other postretirement benefits.

Nuclear Fuel

APS amortizes nuclear fuel by using the unit-of-production method.  The unit-of-production method is based on actual physical usage.  APS divides the cost of the fuel by the estimated number of thermal units it expects to produce with that fuel.  APS then multiplies that rate by the number of thermal units produced within the current period.  This calculation determines the current period nuclear fuel expense.

APS also charges nuclear fuel expense for the interim storage and permanent disposal of spent nuclear fuel.  The DOE is responsible for the permanent disposal of spent nuclear fuel and charged APS $0.001 per kWh of nuclear generation through May 2014, at which point the DOE suspended the fee.  In accordance with a settlement agreement with the DOE in August 2014, we will now accrue a receivable for incurred claims and an offsetting regulatory liability through the settlement period ending December of 2016. See Note 10 for information on spent nuclear fuel disposal costs.

Income Taxes

Income taxes are provided using the asset and liability approach prescribed by guidance relating to accounting for income taxes.  We file our federal income tax return on a consolidated basis, and we file our state income tax returns on a consolidated or unitary basis.  In accordance with our intercompany tax sharing agreement, federal and state income taxes are allocated to each first-tier subsidiary as though each first-tier subsidiary filed a separate income tax return.  Any difference between that method and the consolidated (and unitary) income tax liability is attributed to the parent company.  The income tax accounts reflect the tax and interest associated with management’s estimate of the largest amount of tax benefit that is greater than 50% likely of being realized upon settlement for all known and measurable tax exposures (see Note 4).

Cash and Cash Equivalents

We consider all highly liquid investments with a remaining maturity of three months or less at acquisition to be cash equivalents.

The following table summarizes supplemental Pinnacle West cash flow information for each of the last three years (dollars in thousands):

	Year ended December 31,
	2016		2015		2014
Cash paid (received) during the period for:
Income taxes, net of refunds	$	9,956	$	6,550	$	(102,154	)
Interest, net of amounts capitalized	184,462		170,209		177,074
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	114,855	$	83,798	$	44,712
Dividends declared but not paid	72,926		69,363		65,790

Intangible Assets

We have no goodwill recorded and have separately disclosed other intangible assets, primarily APS's software, on Pinnacle West’s Consolidated Balance Sheets. The intangible assets are amortized over their finite useful lives.  Amortization expense was $58 million in 2016, $58 million in 2015, and $53 million in 2014.  Estimated amortization expense on existing intangible assets over the next five years is $41 million in 2017, $23 million in 2018, $12 million in 2019, $4 million in 2020, and $1 million in 2021.  At December 31, 2016, the weighted-average remaining amortization period for intangible assets was 6 years.

Investments

El Dorado accounts for its investments using either the equity method (if significant influence) or the cost method (if less than 20% ownership and no significant influence).

Our investments in the nuclear decommissioning trust fund are accounted for in accordance with guidance on accounting for certain investments in debt and equity securities. See Note 13 and Note 19 for more information on these investments.

Business Segments

Pinnacle West’s reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electricity service to Native Load customers) and related activities and includes electricity generation, transmission and distribution. All other segment activities are insignificant.

Preferred Stock

At December 31, 2016, Pinnacle West had 10 million shares of serial preferred stock authorized with no par value, none of which was outstanding, and APS had 15,535,000 shares of various types of preferred stock authorized with $25, $50 and $100 par values, none of which was outstanding.

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New Accounting Standards

12 Months Ended

Dec. 31, 2016

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

New Accounting Standards

New Accounting Standards

ASU 2016-09, Stock Compensation: Improvements to Employee Share-Based Payment Accounting

In March 2016, new stock compensation accounting guidance was issued intended to simplify the accounting for employee share-based payments. The new guidance impacts several aspects of the accounting for share-based payments including: modifies the tax withholding threshold that triggers liability classification of an award, requires all excess income tax benefits and deficiencies arising from share-based payments to be recognized in earnings in the period they occur, simplifies the accounting for forfeitures, and clarifies certain cash flow presentation matters. Certain aspects of the standard must be adopted using a prospective approach and other aspects must be adopted using a modified retrospective approach.

During the fourth quarter of 2016, we elected to early adopt this standard, and accordingly have applied the guidance effective as of January 1, 2016. Prior to adoption of the new standard, our stock compensation awards were generally classified as liability awards and accounted for at fair value until settled because employees could withhold at more than the minimum statutory tax withholding rate. In accordance with the new guidance, certain of these stock compensation awards are now classified as equity awards and accounted for at grant date fair value. As a result of adopting the new standard, Pinnacle West recorded a cumulative effect adjustment to retained earnings of $6 million. The other provisions of the standard did not have a material impact on our consolidated financial statements. See Note 15 for additional details of the adoption impacts.

ASU 2015-07, Fair Value Measurement: Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent)

In May 2015, new accounting guidance was issued that removes the requirement to categorize certain investments valued using net asset value, as a practical expedient, within the fair value hierarchy. We retrospectively adopted this guidance during the first quarter of 2016. The adoption of this guidance modifies our fair value disclosures, but does not impact the methodology for valuing these instruments, or our financial statement results.  See Note 7 and Note 13.  

ASU 2014-09, Revenue from Contracts with Customers

In May 2014, a new revenue recognition accounting standard was issued. This standard provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. Since the issuance of the new revenue standard, additional guidance was issued to clarify certain aspects of the new revenue standard, including principal versus agent considerations, identifying performance obligations, and other narrow scope improvements. The new revenue standard, and related amendments, will be effective for us on January 1, 2018. The standard may be adopted using a full retrospective application or a simplified transition method that allows entities to record a cumulative effect adjustment in retained earnings at the date of initial application.

We plan on adopting this standard on January 1, 2018, and are currently evaluating the transition method and the effect on our financial statements. As part of our evaluation we continue to actively monitor certain industry issues being addressed by the American Institute of Certified Public Accountants’ Revenue Recognition Working Group and the Financial Accounting Standards Board’s Transition Resource Group. Conclusions reached by these groups may impact our application of the standard, specifically in regards to the treatment of contributions in aid of construction.

ASU 2016-01, Financial Instruments: Recognition and Measurement

In January 2016, a new accounting standard was issued relating to the recognition and measurement of financial instruments. The new guidance will require certain investments in equity securities to be measured at fair value with changes in fair value recognized in net income, and modifies the impairment assessment of certain equity securities. The new standard is effective for us on January 1, 2018. Certain aspects of the standard may require a cumulative effect adjustment and other aspects of the standard are required to be adopted prospectively. We plan on adopting this standard on January 1, 2018, and continue to evaluate the impacts the new guidance may have on our financial statements.

ASU 2016-02, Leases

In February 2016, a new lease accounting standard was issued. This new standard supersedes the existing lease accounting model, and modifies both lessee and lessor accounting. The new standard will require a lessee to reflect most operating lease arrangements on the balance sheet by recording a right-of-use asset and a lease liability that will initially be measured at the present value of lease payments. Among other changes, the new standard also modifies the definition of a lease, and requires expanded lease disclosures. The new standard will be effective for us on January 1, 2019, with early application permitted. The standard must be adopted using a modified retrospective approach, with various optional practical expedients provided to facilitate transition. We are currently evaluating this new accounting standard and the impacts it may have on our financial statements.

ASU 2016-13, Financial Instruments: Measurement of Credit Losses

In June 2016, a new accounting standard was issued that amends the measurement of credit losses on certain financial instruments. The new standard will require entities to use a current expected credit loss model to measure impairment of certain investments in debt securities, trade accounts receivables, and other financial instruments. The new standard is effective for us on January 1, 2020 and must be adopted using a modified retrospective approach for certain aspects of the standard, and a prospective approach for other aspects of the standard. We are currently evaluating this new accounting standard and the impacts it may have on our financial statements.

ASU 2017-01, Business Combinations: Clarifying the Definition of a Business

                In January 2017, a new accounting standard was issued that clarifies the definition of a business. This standard is intended to assist entities with evaluating whether a transaction should be accounted for as an acquisition (or disposal) of assets or a business.  The definition of a business  affects many areas of accounting including acquisitions, disposals, goodwill, and consolidation. The new standard is effective for us on January 1, 2018 using a prospective approach. We are evaluating the impacts of adopting this new standard, and the impacts it may have on our financial statements.

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Regulatory Matters

12 Months Ended

Dec. 31, 2016

Regulated Operations [Abstract]

Regulatory Matters

Regulatory Matters

Retail Rate Case Filing with the Arizona Corporation Commission

On June 1, 2016, APS filed an application with the ACC for an annual increase in retail base rates of $165.9 million. This amount excludes amounts that are currently collected on customer bills through adjustor mechanisms. The application requests that some of the balances in these adjustor accounts (aggregating to approximately $267.6 million as of December 31, 2015) be transferred into base rates through the ratemaking process. This transfer would not have an incremental effect on average customer bills. The average annual customer bill impact of APS’s request is an increase of 5.74% (the average annual bill impact for a typical APS residential customer is 7.96%).

The principal provisions of the application are:

• a test year ended December 31, 2015, adjusted as described below;

• an original cost rate base of $6.8 billion, which approximates the ACC-jurisdictional portion of the book value of utility assets, net of accumulated depreciation and other credits, as of December 31, 2015;

• the following proposed capital structure and costs of capital:

	Capital Structure		Cost of Capital
Long-term debt	44.20	%	5.13	%
Common stock equity	55.80	%	10.50	%
Weighted-average cost of capital			8.13	%

• a 1% return on the increment of fair value rate base above APS’s original cost rate base, as provided for by Arizona law;

• a base rate for fuel and purchased power costs of $0.029882 per kWh based on estimated 2017 prices (a decrease from the current base fuel rate of $0.03207 per kWh);

• authorization to defer for potential future recovery its share of the construction costs associated with installing selective catalytic reduction equipment at Four Corners (estimated at approximately $400 million in direct costs). APS proposes that the rates established in this rate case be increased through a step mechanism beginning in 2019 to reflect these deferred costs;

• authorization to defer for potential future recovery in the Company’s next general rate case the construction costs APS incurs for its Ocotillo power plant modernization project, once the project reaches commercial operation. APS estimates the direct construction costs at approximately $500 million and that the new facility will be fully in service by early 2019;

• authorization to defer until the Company’s next general rate case the increase or decrease in its Arizona property taxes attributable to tax rate changes after the date the rate application is adjudicated;

• updates and modifications to four of APS’s adjustor mechanisms - the PSA, the LFCR, the TCA and the Environmental Improvement Surcharge (“EIS”);

• a number of proposed rate design changes for residential customers, including:

◦ change the on-peak time of use period from 12 p.m. - 7 p.m. to 3 p.m. - 8 p.m. Monday through Friday, excluding holidays;

◦ reduce the difference in the on- and off-peak energy price and lower all energy charges;

◦ offer four rate plan options, three of which have demand charges and a fourth that is available to non-partial requirements customers using less than 600 kWh on average per month; and

◦ modify the current net metering tariff to provide for a credit at the retail rate for the portion of generation by rooftop solar customers that offsets their own load, and for a credit for excess energy delivered to the grid at an export rate.

• proposed rate design changes for commercial customers, including an aggregation rider that allows certain large customers to qualify for a reduced rate, an extra-high load factor rate schedule for certain customers, and an economic development rate offering for new loads meeting certain criteria.

The Company requested that the increase become effective July 1, 2017.  On July 22, 2016, the ALJ set a procedural schedule for the rate proceeding, which supported completing the case within 12 months.

The ACC staff and intervenors began filing their direct testimony in late December 2016 and additional filings of testimony are ongoing. On January 12, 2017, APS began settlement discussions with all parties.  On January 13, 2017, the ALJ hearing the case before the ACC issued a procedural order delaying hearings on the case from the originally scheduled March 22, 2017 to April 24, 2017, to allow parties to participate in settlement discussions and prepare testimony on the distributed generation rate design issues addressed in the value and cost of DG decision.  According to the procedural order, settlement discussions are to be completed and, if applicable, any related settlement must be filed by March 17, 2017.  The procedural order also extended the rate case completion date as calculated by Commission rule for an additional 33 days. APS cannot predict the outcome of this case.

Prior Rate Case Filing

On June 1, 2011, APS filed an application with the ACC for a net retail base rate increase of $95.5 million.  APS requested that the increase become effective July 1, 2012.  The request would have increased the average retail customer bill by approximately 6.6%.  On January 6, 2012, APS and other parties to the general retail rate case entered into the 2012 Settlement Agreement detailing the terms upon which the parties agreed to settle the rate case.  On May 15, 2012, the ACC approved the 2012 Settlement Agreement without material modifications.

Settlement Agreement

The 2012 Settlement Agreement provides for a zero net change in base rates, consisting of:  (1) a non-fuel base rate increase of $116.3 million; (2) a fuel-related base rate decrease of $153.1 million (to be implemented by a change in the Base Fuel Rate from $0.03757 to $0.03207 per kWh); and (3) the transfer of cost recovery for certain renewable energy projects from the RES surcharge to base rates in an estimated amount of $36.8 million.

Other key provisions of the 2012 Settlement Agreement include the following:

•An authorized return on common equity of 10.0%;

•A capital structure comprised of 46.1% debt and 53.9% common equity;

• A test year ended December 31, 2010, adjusted to include plant that is in service as of March 31, 2012;

• Deferral for future recovery or refund of property taxes above or below a specified 2010 test year level caused by changes to the Arizona property tax rate as follows:

• Deferral of increases in property taxes of 25% in 2012, 50% in 2013 and 75% for 2014 and subsequent years if Arizona property tax rates increase; and

•Deferral of 100% in all years if Arizona property tax rates decrease;

• A procedure to allow APS to request rate adjustments prior to its next general rate case related to APS’s acquisition of additional interests in Units 4 and 5 and the related closure of Units 1-3 of Four Corners (APS made its filing under this provision on December 30, 2013, see "Four Corners" below);

• Implementation of a “Lost Fixed Cost Recovery” rate mechanism to support energy efficiency and distributed renewable generation;

• Modifications to the Environmental Improvement Surcharge to allow for the recovery of carrying costs for capital expenditures associated with government-mandated environmental controls, subject to an existing cents per kWh cap on cost recovery that could produce up to approximately $5 million in revenues annually;

•Modifications to the PSA, including the elimination of the 90/10 sharing provision;

• A limitation on the use of the RES surcharge and the DSMAC to recoup capital expenditures not required under the terms of the settlement agreement for the 2009 retail rate case (the "2009 Settlement Agreement");

• Allowing a negative credit that existed in the PSA rate to continue until February 2013, rather than being reset on the anticipated July 1, 2012 rate effective date;

• Modification of the TCA to streamline the process for future transmission-related rate changes; and

• Implementation of various changes to rate schedules, including the adoption of an experimental “buy-through” rate that could allow certain large commercial and industrial customers to select alternative sources of generation to be supplied by APS.

The 2012 Settlement Agreement was approved by the ACC on May 15, 2012, with new rates effective on July 1, 2012.  This accomplished a goal set by the parties to the 2009 Settlement Agreement to process subsequent rate cases within twelve months of sufficiency findings from the ACC staff, which generally occurs within 30 days after the filing of a rate case.

Cost Recovery Mechanisms

APS has received regulatory decisions that allow for more timely recovery of certain costs through the following recovery mechanisms.

Renewable Energy Standard.  In 2006, the ACC approved the RES.  Under the RES, electric utilities that are regulated by the ACC must supply an increasing percentage of their retail electric energy sales from eligible renewable resources, including solar, wind, biomass, biogas and geothermal technologies.  In order to achieve these requirements, the ACC allows APS to include a RES surcharge as part of customer bills to recover the approved amounts for use on renewable energy projects. Each year APS is required to file a five-year implementation plan with the ACC and seek approval for funding the upcoming year’s RES budget.

In December 2014, the ACC voted that it had no objection to APS implementing an APS-owned rooftop solar research and development program aimed at learning how to efficiently enable the integration of rooftop solar and battery storage with the grid.  The first stage of the program, called the "Solar Partner Program," placed 8 MW of residential rooftop solar on strategically selected distribution feeders in an effort to maximize potential system benefits, as well as made systems available to limited-income customers who could not easily install solar through transactions with third parties. The second stage of the program, which included an additional 2 MW of rooftop solar and energy storage, placed two energy storage systems sized at 2 MW on two different high solar penetration feeders to test various grid-related operation improvements and system interoperability, and was in operation by the end of 2016.  The ACC expressly reserved that any determination of prudency of the residential rooftop solar program for rate making purposes would not be made until the project was fully in service, and APS has requested cost recovery for the project in its currently pending rate case. On September 30, 2016, APS presented its preliminary findings from the residential rooftop solar program in a filing with the ACC.

On July 1, 2015, APS filed its 2016 RES implementation plan and proposed a RES budget of approximately $148 million. On January 12, 2016, the ACC approved APS’s plan and requested budget.

On July 1, 2016, APS filed its 2017 RES Implementation Plan and proposed a budget of approximately $150 million. APS’s budget request included additional funding to process the high volume of residential rooftop solar interconnection requests and also requested a permanent waiver of the residential distributed energy requirement for 2017 contained in the RES rules. The ACC has not yet ruled on the Company’s 2017 RES Implementation Plan.

In September of 2016, the ACC initiated a proceeding which will examine the possible modernization and expansion of the RES.  The ACC noted that many of the provisions of the original rule may no longer be appropriate, and the underlying economic assumptions associated with the rule have changed dramatically.  The proceeding will review such issues as the rapidly declining cost of solar generation, an increased interest in community solar projects, energy storage options, and the decline in fossil fuel generation due to stringent regulations of the EPA.  The proceeding will also examine the feasibility of increasing the standard to 30% of retail sales by 2030, in contrast to the current standard of 15% of retail sales by 2025.  APS cannot predict the outcome of this proceeding.

Demand Side Management Adjustor Charge. The ACC Electric Energy Efficiency Standards require APS to submit a Demand Side Management Implementation Plan ("DSM Plan") for review by and approval of the ACC. In March 2014, the ACC approved a Resource Savings Initiative that allows APS to count towards compliance with the ACC Electric Energy Efficiency Standards, savings from improvements to APS’s transmission and delivery system, generation and facilities that have been approved through a DSM Plan. 

On March 20, 2015, APS filed an application with the ACC requesting a budget of $68.9 million for 2015 and minor modifications to its DSM portfolio going forward, including for the first time three resource savings projects which reflect energy savings on APS's system. The ACC approved APS’s 2015 DSM budget on November 25, 2015. In its decision, the ACC also approved that verified energy savings from APS's resource savings projects could be counted toward compliance with the Electric Energy Efficiency Standard, however, the ACC ruled that APS was not allowed to count savings from systems savings projects toward determination of its achievement tier level for its performance incentive, nor may APS include savings from conservation voltage reduction in the calculation of its LFCR mechanism.

On June 1, 2015, APS filed its 2016 DSM Plan requesting a budget of $68.9 million and minor modifications to its DSM portfolio to increase energy savings and cost effectiveness of the programs. On April 1, 2016, APS filed an amended 2016 DSM Plan that sought minor modifications to its existing DSM Plan and requested to continue the current DSMAC and current budget of $68.9 million. On July 12, 2016, the ACC approved APS’s amended DSM Plan and directed APS to spend up to an additional $4 million on a new residential demand response or load management program that facilitates energy storage technology. On December 5, 2016, APS filed for ACC approval of a $4 million Residential Demand Response, Energy Storage and Load Management Program.

On June 1, 2016, the Company filed its 2017 DSM Implementation Plan, in which APS proposes programs and measures that specifically focus on reducing peak demand, shifting load to off-peak periods and educating customers about strategies to manage their energy and demand.  The requested budget in the 2017 DSM Implementation Plan is $62.6 million. On January 27, 2017, APS filed an updated and modified 2017 DSM Implementation Plan that incorporated the proposed Residential Demand Response, Energy Storage and Load Management Program and the requested budget increased to $66.6 million. The ACC has not yet ruled on the Company’s 2017 DSM Plan.    

Electric Energy Efficiency. On June 27, 2013, the ACC voted to open a new docket investigating whether the Electric Energy Efficiency Standards should be modified. The ACC held a series of three workshops in March and April 2014 to investigate methodologies used to determine cost effective energy efficiency programs, cost recovery mechanisms, incentives, and potential changes to the Electric Energy Efficiency and Resource Planning Rules.

On November 4, 2014, the ACC staff issued a request for informal comment on a draft of possible amendments to Arizona’s Electric Energy Efficiency Standards. The draft proposed substantial changes to the rules and energy efficiency standards. The ACC accepted written comments and took public comment regarding the possible amendments on December 19, 2014. On July 12, 2016, the ACC ordered that ACC staff convene a workshop within 120 days to discuss a number of issues related to the Electric Energy Efficiency Standards, including the process of determining the cost effectiveness of DSM programs and the treatment of peak demand and capacity reductions, among others. ACC staff convened the workshop on November 29, 2016 and sought public comment on potential revisions to the Electric Energy Efficiency Standards. APS cannot predict the outcome of this proceeding.

PSA Mechanism and Balance.  The PSA provides for the adjustment of retail rates to reflect variations in retail fuel and purchased power costs. The PSA is subject to specified parameters and procedures, including the following:

• APS records deferrals for recovery or refund to the extent actual retail fuel and purchased power costs vary from the Base Fuel Rate;

• An adjustment to the PSA rate is made annually each February 1 (unless otherwise approved by the ACC) and goes into effect automatically unless suspended by the ACC;

• The PSA uses a forward-looking estimate of fuel and purchased power costs to set the annual PSA rate, which is reconciled to actual costs experienced for each PSA Year (February 1 through January 31) (see the following bullet point);

• The PSA rate includes (a) a “Forward Component,” under which APS recovers or refunds differences between expected fuel and purchased power costs for the upcoming calendar year and those embedded in the Base Fuel Rate; (b) a “Historical Component,” under which differences between actual fuel and purchased power costs and those recovered through the combination of the Base Fuel Rate and the Forward Component are recovered during the next PSA Year; and (c) a “Transition Component,” under which APS may seek mid-year PSA changes due to large variances between actual fuel and purchased power costs and the combination of the Base Fuel Rate and the Forward Component; and

• The PSA rate may not be increased or decreased more than $0.004 per kWh in a year without permission of the ACC.

The following table shows the changes in the deferred fuel and purchased power regulatory asset (liability) for 2016 and 2015 (dollars in thousands):

	Year Ended December 31,
	2016			2015
Beginning balance	$	(9,688	)	$	6,926
Deferred fuel and purchased power costs - current period	60,303			(14,997		)
Amounts charged to customers	(38,150		)	(1,617		)
Ending balance	$	12,465		$	(9,688	)

The PSA rate for the PSA year beginning February 1, 2017 is $(0.001348) per kWh, as compared to $0.001678 per kWh for the prior year.  This new rate is comprised of a forward component of $(0.001027) per kWh and a historical component of $(0.000321) per kWh. 

Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters.  In July 2008, FERC approved an Open Access Transmission Tariff for APS to move from fixed rates to a formula rate-setting methodology in order to more accurately reflect and recover the costs that APS incurs in providing transmission services.  A large portion of the rate represents charges for transmission services to serve APS’s retail customers ("Retail Transmission Charges").  In order to recover the Retail Transmission Charges, APS was previously required to file an application with, and obtain approval from, the ACC to reflect changes in Retail Transmission Charges through the TCA.  Under the terms of the 2012 Settlement Agreement, however, an adjustment to rates to recover the Retail Transmission Charges will be made annually each June 1 and will go into effect automatically unless suspended by the ACC.

The formula rate is updated each year effective June 1 on the basis of APS’s actual cost of service, as disclosed in APS’s FERC Form 1 report for the previous fiscal year.  Items to be updated include actual capital expenditures made as compared with previous projections, transmission revenue credits and other items.  The resolution of proposed adjustments can result in significant volatility in the revenues to be collected.  APS reviews the proposed formula rate filing amounts with the ACC staff.  Any items or adjustments which are not agreed to by APS and the ACC staff can remain in dispute until settled or litigated at FERC.  Settlement or litigated resolution of disputed issues could require an extended period of time and could have a significant effect on the Retail Transmission Charges because any adjustment, though applied prospectively, may be calculated to account for previously over- or under-collected amounts.

Effective June 1, 2015, APS’s annual wholesale transmission rates for all users of its transmission system decreased by approximately $17.6 million for the twelve-month period beginning June 1, 2015 in accordance with the FERC-approved formula.  An adjustment to APS’s retail rates to recover FERC-approved transmission charges went into effect automatically on June 1, 2015.

Effective June 1, 2016, APS's annual wholesale transmission rates for all users of its transmission system increased by approximately $24.9 million for the twelve-month period beginning June 1, 2016 in accordance with the FERC-approved formula.  An adjustment to APS’s retail rates to recover FERC approved transmission charges went into effect automatically on June 1, 2016.

APS's formula rate protocols have been in effect since 2008. Recent FERC orders suggest that FERC is examining the structure of formula rate protocols and may require companies to make changes to their protocols in the future. As a result, APS is evaluating how its formula rate protocols compare with more recently approved formula rate protocols and anticipates that it will make a filing to update its formula rate protocols in the first quarter of 2017.

Lost Fixed Cost Recovery Mechanism. The LFCR mechanism permits APS to recover on an after-the-fact basis a portion of its fixed costs that would otherwise have been collected by APS in the kWh sales lost due to APS energy efficiency programs and to distributed generation such as rooftop solar arrays.  The fixed costs recoverable by the LFCR mechanism were established in the 2012 Settlement Agreement and amount to approximately 3.1 cents per residential kWh lost and 2.3 cents per non-residential kWh lost.  The LFCR adjustment has a year-over-year cap of 1% of retail revenues.  Any amounts left unrecovered in a particular year because of this cap can be carried over for recovery in a future year.  The kWh’s lost from energy efficiency are based on a third-party evaluation of APS’s energy efficiency programs.  Distributed generation sales losses are determined from the metered output from the distributed generation units.

APS files for a LFCR adjustment every January.  APS filed its 2015 annual LFCR adjustment on January 15, 2015, requesting an LFCR adjustment of $38.5 million, which was approved on March 2, 2015, effective for the first billing cycle of March. APS filed its 2016 annual LFCR adjustment on January 15, 2016, requesting an LFCR adjustment of $46.4 million (a $7.9 million annual increase), to be effective for the first billing cycle of March 2016. The ACC approved the 2016 annual LFCR to be effective in May 2016. Because the LFCR mechanism has a balancing account that trues up any under or over recoveries, the two month delay in implementation did not have an adverse effect on APS. APS filed its 2017 LFCR adjustment on January 13, 2017. APS requested an adjustment of $63.7 million (a $17.3 million per year increase over 2016 levels), to be effective the first billing cycle of March 2017.

Net Metering

In 2015, the ACC voted to conduct a generic evidentiary hearing on the value and cost of distributed generation to gather information that will inform the ACC on net metering issues and cost of service studies in upcoming utility rate cases.  A hearing was held in April 2016. On October 7, 2016, the ALJ issued a recommendation in the docket concerning the value and cost of DG solar installations. On December 20, 2016, the ACC completed its open meeting to consider the recommended decision by the ALJ. After making several amendments, the ACC approved the recommended decision by a 4-1 vote. As a result of the ACC’s action, effective following APS’s pending rate case, the current net metering tariff that governs payments for energy exported to the grid from rooftop solar systems will be replaced by a more formula-driven approach that will utilize inputs from historical wholesale solar power costs and eventually an avoided cost methodology.

As amended, the decision provides that payments by utilities for energy exported to the grid from DG solar facilities will be determined using a resource comparison proxy methodology, a method that is based on the price that APS pays for utility-scale solar projects on a five year rolling average, while a forecasted avoided cost methodology is being developed.  The price established by this resource comparison proxy method will be updated annually (between rate cases) but will not be decreased by more than 10% per year. Once the avoided cost methodology is developed, the ACC will determine in APS's subsequent rate cases which method (or a combination of methods) is appropriate to determine the actual price to be paid by that utility for exported distributed energy.

In addition, the ACC made the following determinations:

• Customers who have interconnected a DG system or submitted an application for interconnection for DG systems prior to the date new rates are effective based on APS' pending rate case will be grandfathered for a period of 20 years from the date of interconnection;

• Customers with DG solar systems are to be considered a separate class of customers for ratemaking purposes; and

• Once an export price is set for APS, no netting or banking of retail credits will be available for new DG customers, and the then-applicable export price will be guaranteed for new customers for a period of 10 years.

This decision of the ACC addresses policy determinations only. The decision states that its principles will be applied in future rate cases, and the policy determinations themselves may be subject to future change as are all ACC policies. The determination of the initial export energy price to be paid by APS will be made in APS’s currently pending rate case, which is scheduled for hearing by the ACC in April 2017.  APS cannot predict the outcome of this determination.

The ACC’s decision did not make any policy determinations as to any specific costs to be charged to DG solar system customers for their use of the grid. The determination of any such costs will be made in APS's future rate cases.

On January 23, 2017, The Alliance for Solar Choice ("TASC") sought rehearing of the ACC's decision regarding the value and cost of DG. TASC asserts that the ACC improperly ignored the Administrative Procedure Act, failed to give adequate notice regarding the scope of the proceedings, and relied on information that was not submitted as evidence, among other alleged defects. TASC's request for rehearing is required for TASC to challenge this decision in court. To date, the ACC has taken no action on the rehearing request. The ACC's decision is expected to remain in effect during any legal challenge.

Appellate Review of Third-Party Regulatory Decision ("System Improvement Benefits" or "SIB")

In a recent appellate challenge to an ACC rate decision involving a water company, the Arizona Court of Appeals considered the question of how the ACC should determine the “fair value” of a utility’s property, as specified in the Arizona Constitution, in connection with authorizing the recovery of costs through rate adjustors outside of a rate case.  The Court of Appeals reversed the ACC’s method of finding fair value in that case, and raised questions concerning the relationship between the need for fair value findings and the recovery of capital and certain other utility costs through adjustors. The ACC sought review by the Arizona Supreme Court of this decision, and APS filed a brief supporting the ACC’s petition to the Arizona Supreme Court for review of the Court of Appeals’ decision.  On February 9, 2016, the Arizona Supreme Court granted review of the decision and on August 8, 2016, the Arizona Supreme Court vacated the Court of Appeals opinion and affirmed the ACC’s orders approving the water company’s SIB adjustor.

System Benefits Charge

The 2012 Settlement Agreement  provided that once APS achieved full funding of its decommissioning obligation under the sale leaseback agreements covering Unit 2 of Palo Verde, APS was required to implement a reduced System Benefits charge effective January 1, 2016.  Beginning on January 1, 2016, APS began implementing a reduced System Benefits charge.  The impact on APS retail revenues from the new System Benefits charge is an overall reduction of approximately $14.6 million per year with a corresponding reduction in depreciation and amortization expense.

Subpoena from Arizona Corporation Commissioner Robert Burns

On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, filed subpoenas in APS’s current retail rate proceeding to APS and Pinnacle West for the production of records and information relating to a range of expenditures from 2011 through 2016. The subpoenas requested information concerning marketing and advertising expenditures, charitable donations, lobbying expenses, contributions to 501(c)(3) and (c)(4) nonprofits and political contributions. The return date for the production of information was set as September 15, 2016. The subpoenas also sought testimony from Company personnel having knowledge of the material, including the Chief Executive Officer.

On September 9, 2016, APS filed with the ACC a motion to quash the subpoenas or, alternatively to stay APS's obligations to comply with the subpoenas and decline to decide APS's motion pending court proceedings. Contemporaneously with the filing of this motion, APS and Pinnacle West filed a complaint for special action and declaratory judgment in the Superior Court of Arizona for Maricopa County, seeking a declaratory judgment that Commissioner Burns’ subpoenas are contrary to law. On September 15, 2016, APS produced all non-confidential and responsive documents and offered to produce any remaining responsive documents that are confidential after an appropriate confidentiality agreement is signed.

On February 7, 2017, Commissioner Burns opened a new ACC docket and indicated that its purpose is to study and rectify problems with transparency and disclosure regarding financial contributions from regulated monopolies or other stakeholders who may appear before the ACC that may directly or indirectly benefit an ACC Commissioner, a candidate for ACC Commissioner, or key ACC staff.  As part of this docket, Commissioner Burns set March 24, 2017 as a deadline for APS to produce all information previously requested through the subpoenas.  Commissioner Burns has also scheduled a workshop in this matter for March 17, 2017.  APS and Pinnacle West cannot predict the outcome of this matter.

Four Corners

On December 30, 2013, APS purchased SCE’s 48% ownership interest in each of Units 4 and 5 of Four Corners.  The 2012 Settlement Agreement includes a procedure to allow APS to request rate adjustments prior to its next general rate case related to APS’s acquisition of the additional interests in Units 4 and 5 and the related closure of Units 1-3 of Four Corners.  APS made its filing under this provision on December 30, 2013.  On December 23, 2014, the ACC approved rate adjustments resulting in a revenue increase of $57.1 million on an annual basis.  This includes the deferral for future recovery of all non-fuel operating costs for the acquired SCE interest in Four Corners, net of the non-fuel operating costs savings resulting from the closure of Units 1-3 from the date of closing of the purchase through its inclusion in rates.  The 2012 Settlement Agreement also provides for deferral for future recovery of all unrecovered costs incurred in connection with the closure of Units 1-3.  The deferral balance related to the acquisition of SCE’s interest in Units 4 and 5 and the closure of Units 1-3 was $64 million as of December 31, 2016 and is being amortized in rates over a total of 10 years. On February 23, 2015, the Arizona School Boards Association and the Association of Business Officials filed a notice of appeal in Division 1 of the Arizona Court of Appeals of the ACC decision approving the rate adjustments. APS has intervened and is actively participating in the proceeding. The Arizona Court of Appeals suspended the appeal pending the Arizona Supreme Court's decision in the SIB matter discussed above. On August 8, 2016, the Arizona Supreme Court issued its opinion in the SIB matter, and the Arizona Court of Appeals has now ordered supplemental briefing on how that SIB decision should affect the challenge to the Four Corners rate adjustment. We cannot predict when or how this matter will be resolved.

As part of APS’s acquisition of SCE’s interest in Units 4 and 5, APS and SCE agreed, via a “Transmission Termination Agreement” that, upon closing of the acquisition, the companies would terminate an existing transmission agreement (“Transmission Agreement”) between the parties that provides transmission capacity on a system (the “Arizona Transmission System”) for SCE to transmit its portion of the output from Four Corners to California.  APS previously submitted a request to FERC related to this termination, which resulted in a FERC order denying rate recovery of $40 million that APS agreed to pay SCE associated with the termination.   On December 22, 2015, APS and SCE agreed to terminate the Transmission Termination Agreement and allow for the Transmission Agreement to expire according to its terms, which includes settling obligations in accordance with the terms of the Transmission Agreement. APS established a regulatory asset of $12 million in 2015 in connection with the payment required under the terms of the Transmission Agreement. On July 1, 2016, FERC issued an order denying APS’s request to recover the regulatory asset through its FERC-jurisdictional rates.  APS and SCE completed the termination of the Transmission Agreement on July 6, 2016. APS made the required payment to SCE and wrote-off the $12 million regulatory asset and charged operating revenues to reflect the effects of this order in the second quarter of 2016.  On July 29, 2016, APS filed a request for rehearing with FERC. In its order denying recovery, FERC also referred to its enforcement division a question of whether the agreement between APS and SCE relating to the settlement of obligations under the Transmission Agreement was a jurisdictional contract that should have been filed with FERC. APS cannot predict the outcome of either matter.

Cholla

On September 11, 2014, APS announced that it would close Cholla Unit 2 and cease burning coal at the other APS-owned units (Units 1 and 3) at the plant by the mid-2020s, if EPA approves a compromise proposal offered by APS to meet required environmental and emissions standards and rules. On April 14, 2015, the ACC approved APS's plan to retire Unit 2, without expressing any view on the future recoverability of APS's remaining investment in the Unit. APS closed Unit 2 on October 1, 2015. On January 13, 2017, EPA approved a final rule incorporating APS's compromise proposal. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

Previously, APS estimated Cholla Unit 2’s end of life to be 2033. APS is currently recovering a return on and of the net book value of the unit in base rates and is seeking recovery of the unit’s decommissioning and other retirement-related costs over the previously estimated remaining life of the plant in its current retail rate case. APS believes it will be allowed recovery of the remaining net book value of Unit 2 ($116 million as of December 31, 2016), in addition to a return on its investment. In accordance with GAAP, in the third quarter of 2014, Unit 2’s remaining net book value was reclassified from property, plant and equipment to a regulatory asset. If the ACC does not allow full recovery of the remaining net book value of Cholla Unit 2, all or a portion of the regulatory asset will be written off and APS’s net income, cash flows, and financial position will be negatively impacted.

Navajo Plant

On February 13, 2017, the co-owners of the Navajo Plant voted not to pursue continued operation of the plant beyond December 2019, the expiration of the current lease term, and to pursue a new lease or lease extension with the Navajo Nation that would allow decommissioning activities to begin after December 2019 instead of later this year. Various stakeholders including regulators, tribal representatives and others interested in the continued operation of the plant intend to meet to determine if an alternate solution can be reached that would permit continued operation of the plant beyond 2019. We cannot predict whether any alternate solutions will be found that would be acceptable to all of the stakeholders and feasible to implement. APS is currently recovering depreciation and a return on the net book value of its interest in the Navajo Plant. APS will seek continued recovery in rates for the book value of its remaining investment in the plant ($108 million as of December 31, 2016, see Note 9 for additional details) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and which may be material. We cannot predict whether APS would obtain such recovery.

On February 14, 2017, the ACC opened a docket titled "ACC Investigation Concerning the Future of the Navajo Generating Station" with the stated goal of engaging stakeholders and negotiating a sustainable pathway for the Navajo Plant to continue operating in some form after December 2019. APS cannot predict the outcome of this proceeding.

Regulatory Assets and Liabilities

The detail of regulatory assets is as follows (dollars in thousands):

S	Amortization Through	December 31, 2016				December 31, 2015
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	711,059	$	—	$	619,223
Retired power plant costs	2033	9,913		117,591		9,913		127,518
Income taxes - AFUDC equity	2046	6,305		152,118		5,495		133,712
Deferred fuel and purchased power — mark-to-market (Note 16)	2020	—		42,963		71,852		69,697
Four Corners cost deferral	2024	6,689		56,894		6,689		63,582
Income taxes — investment tax credit basis adjustment	2046	2,120		54,356		1,766		48,462
Lost fixed cost recovery	2017	61,307		—		45,507		—
Palo Verde VIEs (Note 18)	2046	—		18,775		—		18,143
Deferred compensation	2036	—		35,595		—		34,751
Deferred property taxes	(d)	—		73,200		—		50,453
Loss on reacquired debt	2038	1,637		16,942		1,515		16,375
AG-1 deferral	2018	—		5,868		—		—
Demand side management (b)	2017	3,744		—		—		—
Tax expense of Medicare subsidy	2024	1,513		10,589		1,520		12,163
Transmission vegetation management	2016	—		—		4,543		—
Mead-Phoenix transmission line CIAC	2050	332		10,708		332		11,040
Deferred fuel and purchased power (b) (c)	2017	12,465		—		—		—
Coal reclamation	2026	418		5,182		418		6,085
Other	Various	432		1,588		5		2,942
Total regulatory assets (e)		$	106,875	$	1,313,428	$	149,555	$	1,214,146

(a) This asset represents the future recovery of pension benefit obligations through retail rates.  If these costs are disallowed by the ACC, this regulatory asset would be charged to OCI and result in lower future revenues.  See Note 7 for further discussion.

(b) See “Cost Recovery Mechanisms” discussion above.

(c) Subject to a carrying charge.

(d) Per the provision of the 2012 Settlement Agreement.

(e) There are no regulatory assets for which the ACC has allowed recovery of costs, but not allowed a return by exclusion from rate base.  FERC rates are set using a formula rate as described in “Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters.”

The detail of regulatory liabilities is as follows (dollars in thousands):

	Amortization Through	December 31, 2016				December 31, 2015
		Current		Non-Current		Current		Non-Current
Asset retirement obligations	2057	$	—	$	279,976	$	—	$	277,554
Removal costs	(a)	29,899		223,145		39,746		240,367
Other postretirement benefits	(d)	32,662		123,913		34,100		179,521
Income taxes — deferred investment tax credit	2046	4,368		108,827		3,604		97,175
Income taxes - change in rates	2045	1,771		70,898		1,113		72,454
Spent nuclear fuel	2047	—		71,726		3,051		67,437
Renewable energy standard (b)	2017	26,809		—		43,773		4,365
Demand side management (b)	2019	—		20,472		6,079		19,115
Sundance maintenance	2030	—		15,287		—		13,678
Deferred fuel and purchased power (b) (c)	2016	—		—		9,688		—
Deferred gains on utility property	2018	2,063		8,895		2,062		6,001
Four Corners coal reclamation	2031	—		18,248		—		8,920
Other	Various	2,327		7,529		2,550		7,565
Total regulatory liabilities		$	99,899	$	948,916	$	145,766	$	994,152

(a) In accordance with regulatory accounting guidance, APS accrues for removal costs for its regulated assets, even if there is no legal obligation for removal (see Note 11).

(b) See “Cost Recovery Mechanisms” discussion above.

(c) Subject to a carrying charge.

(d) See Note 7.

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Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

Certain assets and liabilities are reported differently for income tax purposes than they are for financial statement purposes.  The tax effect of these differences is recorded as deferred taxes.  We calculate deferred taxes using currently enacted income tax rates.

APS has recorded regulatory assets and regulatory liabilities related to income taxes on its Balance Sheets in accordance with accounting guidance for regulated operations.  The regulatory assets are for certain temporary differences, primarily the allowance for equity funds used during construction, investment tax credit basis adjustment and tax expense of Medicare subsidy.  The regulatory liabilities primarily relate to deferred taxes resulting from investment tax credits (“ITC”) and the change in income tax rates.

In accordance with regulatory requirements, APS ITCs are deferred and are amortized over the life of the related property with such amortization applied as a credit to reduce current income tax expense in the statement of income.

Net income associated with the Palo Verde sale leaseback VIEs is not subject to tax (see Note 18).  As a result, there is no income tax expense associated with the VIEs recorded on the Pinnacle West Consolidated and APS Consolidated Statements of Income.

The following is a tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year that are included in accrued taxes and unrecognized tax benefits (dollars in thousands):

	Pinnacle West Consolidated									APS Consolidated
	2016			2015			2014			2016			2015			2014
Total unrecognized tax benefits, January 1	$	34,447		$	44,775		$	41,997		$	34,447		$	44,775		$	41,997
Additions for tax positions of the current year	2,695			2,175			4,309			2,695			2,175			4,309
Additions for tax positions of prior years	886			—			751			886			—			751
Reductions for tax positions of prior years for:
Changes in judgment	(1,953		)	(10,244		)	(2,282		)	(1,953		)	(10,244		)	(2,282		)
Settlements with taxing authorities	—			—			—			—			—			—
Lapses of applicable statute of limitations	—			(2,259		)	—			—			(2,259		)	—
Total unrecognized tax benefits, December 31	$	36,075		$	34,447		$	44,775		$	36,075		$	34,447		$	44,775

Included in the balances of unrecognized tax benefits are the following tax positions that, if recognized, would decrease our effective tax rate (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	2016		2015		2014		2016		2015		2014
Tax positions, that if recognized, would decrease our effective tax rate	$	11,313	$	9,523	$	11,207	$	11,313	$	9,523	$	11,207

As of the balance sheet date, the tax year ended December 31, 2013 and all subsequent tax years remain subject to examination by the IRS.  With a few exceptions, we are no longer subject to state income tax examinations by tax authorities for years before 2012.

We reflect interest and penalties, if any, on unrecognized tax benefits in the Pinnacle West Consolidated and APS Consolidated Statements of Income as income tax expense.  The amount of interest expense or benefit recognized related to unrecognized tax benefits are as follows (dollars in thousands): 

	Pinnacle West Consolidated							APS Consolidated
	2016		2015			2014		2016		2015			2014
Unrecognized tax benefit interest expense/(benefit) recognized	$	529	$	(161	)	$	752	$	529	$	(161	)	$	752

Following are the total amount of accrued liabilities for interest recognized related to unrecognized benefits that could reverse and decrease our effective tax rate to the extent matters are settled favorably (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	2016		2015		2014		2016		2015		2014
Unrecognized tax benefit interest accrued	$	1,333	$	804	$	965	$	1,333	$	804	$	965

Additionally, as of December 31, 2016, we have recognized less than $1 million of interest expense to be paid on the underpayment of income taxes for certain adjustments that we have filed, or will file, with the IRS.

The components of income tax expense are as follows (dollars in thousands):

	Pinnacle West Consolidated							APS Consolidated
	Year Ended December 31,							Year Ended December 31,
	2016		2015			2014		2016		2015		2014
Current:
Federal	$	8,630	$	(12,335	)	$	25,054	$	711	$	6,485	$	40,115
State	1,259		4,763			10,382		4,276		7,813		15,598
Total current	9,889		(7,572		)	35,436		4,987		14,298		55,713
Deferred:
Federal	201,743		221,505			167,365		215,178		208,326		165,027
State	24,779		23,787			17,904		25,677		23,217		16,620
Total deferred	226,522		245,292			185,269		240,855		231,543		181,647
Income tax expense	$	236,411	$	237,720		$	220,705	$	245,842	$	245,841	$	237,360

On the APS Consolidated Statements of Income, federal and state income taxes are allocated between operating income and other income.

The following chart compares pretax income at the 35% federal income tax rate to income tax expense (dollars in thousands):

	Pinnacle West Consolidated									APS Consolidated
	Year Ended December 31,									Year Ended December 31,
	2016			2015			2014			2016			2015			2014
Federal income tax expense at 35% statutory rate	$	244,278		$	242,869		$	225,540		$	254,617		$	250,267		$	239,638
Increases (reductions) in tax expense resulting from:
State income tax net of federal income tax benefit	16,311			18,265			18,149			18,750			20,433			21,148
Credits and favorable adjustments related to prior years resolved in current year	—			(2,169		)	—			—			(1,892		)	—
Medicare Subsidy Part-D	844			837			830			844			837			830
Allowance for equity funds used during construction (see Note 1)	(11,724		)	(9,711		)	(8,523		)	(11,724		)	(9,711		)	(8,523		)
Palo Verde VIE noncontrolling interest (see Note 18)	(6,823		)	(6,626		)	(9,135		)	(6,823		)	(6,626		)	(9,135		)
Investment tax credit amortization	(5,887		)	(5,527		)	(4,928		)	(5,887		)	(5,527		)	(4,928		)
Other	(588		)	(218		)	(1,228		)	(3,935		)	(1,940		)	(1,670		)
Income tax expense	$	236,411		$	237,720		$	220,705		$	245,842		$	245,841		$	237,360

    On February 17, 2011, Arizona enacted legislation (H.B. 2001) that included a four-year phase-in of corporate income tax rate reductions beginning in 2014.  As a result of these tax rate reductions, Pinnacle West has revised the tax rate applicable to reversing temporary items in Arizona.  In accordance with accounting for regulated companies, the benefit of this rate reduction is substantially offset by a regulatory liability.  As of December 31, 2016, APS has recorded a regulatory liability of $74 million, with a corresponding decrease in accumulated deferred income tax liabilities, to reflect the impact of this change in tax law.

On April 4, 2013, New Mexico enacted legislation (H.B. 641) that included a five-year phase-in of corporate income tax rate reductions beginning in 2014.  As a result of these tax rate reductions, Pinnacle West has revised the tax rate applicable to reversing temporary items in New Mexico. In accordance with accounting for regulated companies, the benefit of this rate reduction is substantially offset by a regulatory liability.  As of December 31, 2016, APS has recorded a regulatory liability of $2 million, with a corresponding decrease in accumulated deferred income tax liabilities, to reflect the impact of this change in tax law.

The components of the net deferred income tax liability were as follows (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	December 31,						December 31,
	2016			2015			2016			2015
DEFERRED TAX ASSETS
Risk management activities	$	26,614		$	70,498		$	26,614		$	70,498
Regulatory liabilities:
Asset retirement obligation and removal costs	200,140			216,765			200,140			216,765
Unamortized investment tax credits	113,195			100,779			113,195			100,779
Other postretirement benefits	60,375			83,034			60,375			83,034
Other	63,311			60,707			63,311			60,707
Pension liabilities	204,436			191,028			194,981			181,787
Renewable energy incentives	56,379			60,956			56,379			60,956
Credit and loss carryforwards	75,944			59,557			1,645			—
Other	158,421			149,033			187,453			176,016
Total deferred tax assets	958,815			992,357			904,093			950,542
DEFERRED TAX LIABILITIES
Plant-related	(3,297,989		)	(3,116,752		)	(3,297,989		)	(3,116,752		)
Risk management activities	(7,594		)	(10,626		)	(7,594		)	(10,626		)
Other postretirement assets	(63,477		)	(71,737		)	(62,819		)	(70,986		)
Regulatory assets:
Allowance for equity funds used during construction	(61,088		)	(54,110		)	(61,088		)	(54,110		)
Deferred fuel and purchased power — mark-to-market	(21,396		)	(55,020		)	(21,396		)	(55,020		)
Pension benefits	(274,184		)	(240,692		)	(274,184		)	(240,692		)
Retired power plant costs (see Note 3)	(49,166		)	(53,420		)	(49,166		)	(53,420		)
Other	(123,987		)	(108,441		)	(123,987		)	(108,441		)
Other	(5,166		)	(4,984		)	(5,165		)	(4,984		)
Total deferred tax liabilities	(3,904,047		)	(3,715,782		)	(3,903,388		)	(3,715,031		)
Deferred income taxes — net	$	(2,945,232	)	$	(2,723,425	)	$	(2,999,295	)	$	(2,764,489	)

As of December 31, 2016, the deferred tax assets for credit and loss carryforwards relate primarily to federal general business credits of approximately $98 million, which first begin to expire in 2031, and other federal and state loss carryforwards of $5 million, which first begin to expire in 2019. The credit and loss carryforwards amount above has been reduced by $27 million of unrecognized tax benefits.

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Lines of Credit and Short-Term Borrowings

12 Months Ended

Dec. 31, 2016

Lines of Credit and Short-Term Borrowings

Lines of Credit and Short-Term Borrowings

Lines of Credit and Short-Term Borrowings

Pinnacle West and APS maintain committed revolving credit facilities in order to enhance liquidity and provide credit support for their commercial paper programs, to refinance indebtedness, and for other general corporate purposes.

The table below presents the consolidated credit facilities and the amounts available and outstanding as of December 31, 2016 and 2015 (dollars in thousands):

	December 31, 2016									December 31, 2015
	Pinnacle West			APS			Total			Pinnacle West		APS		Total
Commitments under Credit Facilities	$	275,000		$	1,000,000		$	1,275,000		$	200,000	$	1,000,000	$	1,200,000
Outstanding Commercial Paper and Revolving Credit Facility Borrowings	(41,700		)	(135,500		)	(177,200		)	—		—		—
Amount of Credit Facilities Available	$	233,300		$	864,500		$	1,097,800		$	200,000	$	1,000,000	$	1,200,000
Weighted-Average Commitment Fees	0.125%			0.100%						0.125%		0.100%

Pinnacle West

On May 13, 2016, Pinnacle West replaced its $200 million revolving credit facility that would have matured in May 2019, with a new $200 million facility that matures in May 2021. Pinnacle West has the option to increase the amount of the facility up to a maximum of $300 million upon the satisfaction of certain conditions and with the consent of the lenders.  At December 31, 2016, Pinnacle West had no outstanding borrowings under its credit facility, no letters of credit outstanding and $1.7 million commercial paper borrowings.

On August 31, 2016, PNW entered into a $75 million364-day unsecured revolving credit facility that matures in August 2017. PNW will use the new facility to fund or otherwise support obligations related to 4CA, and borrowings under the facility will bear interest at LIBOR plus 0.80% per annum. At December 31, 2016, Pinnacle West had $40 million outstanding under the facility.

APS

During the first quarter of 2016, APS increased its commercial paper program from $250 million to $500 million.

On May 13, 2016, APS replaced its $500 million revolving credit facility that would have matured in May 2019, with a new $500 million facility that matures in May 2021.

At December 31, 2016, APS had two revolving credit facilities totaling $1 billion, including a $500 million credit facility that matures in September 2020 and the $500 million facility that matures in May 2021. APS may increase the amount of each facility up to a maximum of $700 million, for a total of $1.4 billion, upon the satisfaction of certain conditions and with the consent of the lenders. Interest rates are based on APS’s senior unsecured debt credit ratings. These facilities are available to support APS’s $500 million commercial paper program, for bank borrowings or for issuances of letters of credit. At December 31, 2016, APS had $135.5 million of commercial paper outstanding and no outstanding borrowings or letters of credit under its revolving credit facilities. See "Financial Assurances" in Note 10 for a discussion of APS's other outstanding letters of credit.

Debt Provisions

On February 6, 2013, the ACC issued a financing order in which, subject to specified parameters and procedures, it approved APS’s short-term debt authorization equal to a sum of 7% of APS’s capitalization, and $500 million (which is required to be used for costs relating to purchases of natural gas and power). This financing order is set to expire on December 31, 2017. See Note 6 for additional long-term debt provisions.

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Long-Term Debt and Liquidity Matters

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Long-Term Debt and Liquidity Matters

Long-Term Debt and Liquidity Matters

All of Pinnacle West’s and APS’s debt is unsecured.  The following table presents the components of long-term debt on the Consolidated Balance Sheets outstanding at December 31, 2016 and 2015 (dollars in thousands):

	Maturity	Interest	December 31,
	Dates (a)	Rates	2016			2015
APS
Pollution control bonds:
Variable	2029	(b)	$	35,975		$	92,405
Fixed	2024-2029	1.75%-4.70%	147,150			211,150
Total pollution control bonds			183,125			303,555
Senior unsecured notes	2019-2046	2.20%-8.75%	3,725,000			3,375,000
Term loans	2018-2019	(c)	150,000			50,000
Unamortized discount			(11,816		)	(10,374		)
Unamortized premium			4,506			4,686
Unamortized debt issuance cost			(29,030		)	(27,896		)
Total APS long-term debt			4,021,785			3,694,971
Less current maturities			—			357,580
Total APS long-term debt less current maturities			4,021,785			3,337,391
Pinnacle West
Term loan	2017	(d)	125,000			125,000
Less current maturities			125,000			—
Total PNW long-term debt less current maturities			—			125,000
TOTAL LONG-TERM DEBTLESS CURRENT MATURITIES			$	4,021,785		$	3,462,391

(a) This schedule does not reflect the timing of redemptions that may occur prior to maturities.

(b) The weighted-average rate for the variable rate pollution control bonds was 0.81% at December 31, 2016 and 0.01%-0.24% at December 31, 2015.

(c) The weighted-average interest rate was 1.427% at December 31, 2016, and 1.024% at December 31, 2015.

(d) The interest rate was 1.520% at December 31, 2016 and 1.174% at December 31, 2015.

The following table shows principal payments due on Pinnacle West’s and APS’s total long-term debt (dollars in thousands):

Year	Consolidated Pinnacle West		Consolidated APS
2017	$	125,000	$	—
2018	82,000		82,000
2019	600,000		600,000
2020	250,000		250,000
2021	—		—
Thereafter	3,126,125		3,126,125
Total	$	4,183,125	$	4,058,125

Debt Fair Value

Our long-term debt fair value estimates are based on quoted market prices for the same or similar issues, and are classified within Level 2 of the fair value hierarchy.  Certain of our debt instruments contain third-party credit enhancements and, in accordance with GAAP, we do not consider the effect of these credit enhancements when determining fair value.  The following table represents the estimated fair value of our long-term debt, including current maturities (dollars in thousands):

	As of December 31, 2016				As of December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Pinnacle West	$	125,000	$	125,000	$	125,000	$	125,000
APS	4,021,785		4,300,789		3,694,971		3,981,367
Total	$	4,146,785	$	4,425,789	$	3,819,971	$	4,106,367

Credit Facilities and Debt Issuances

APS

On April 22, 2016, APS entered into a $100 million term loan facility that matures April 22, 2019. Interest rates are based on APS's senior unsecured debt credit ratings. APS used the proceeds to repay and refinance existing short-term indebtedness.

On May 6, 2016, APS issued $350 million of 3.75% unsecured senior notes that mature on May 15, 2046. The net proceeds from the sale were used to redeem and cancel pollution control bonds (see details below), and to repay commercial paper borrowings and replenish cash temporarily used to fund capital expenditures.

On June 1, 2016, APS redeemed at par and canceled all $64 million of the Navajo County, Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Cholla Project), 2009 Series D and E.

On June 1, 2016, APS redeemed at par and canceled all $13 million of the Coconino County, Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Navajo Project), 2009 Series A.

On August 1, 2016, APS repaid at maturity APS's $250 million aggregate principal amount of 6.25% senior notes due August 1, 2016.

On September 20, 2016, APS issued $250 million of 2.55% unsecured senior notes that mature on September 15, 2026. The net proceeds from the sale were used to repay commercial paper borrowings and replenish cash temporarily used in connection with the payment at maturity of our $250 million aggregate principal amount of 6.25% Notes due August 1, 2016.

On September 20, 2016, APS redeemed at par and canceled all $27 million of the Coconino County Arizona Pollution Control Corporation Revenue Refunding Bonds (Arizona Public Service Company Navajo Project), 2009 Series B.

On December 6, 2016, APS redeemed at par and canceled all $17 million of the Coconino County Arizona Pollution Control Corporation Revenue Bonds (Arizona Public Service Company Project), Series 1998.

See “Lines of Credit and Short-Term Borrowings” in Note 5 and “Financial Assurances” in Note 10 for discussion of APS’s separate outstanding letters of credit.

Debt Provisions

Pinnacle West’s and APS’s debt covenants related to their respective bank financing arrangements include maximum debt to capitalization ratios. Pinnacle West and APS comply with this covenant.  For both Pinnacle West and APS, this covenant requires that the ratio of consolidated debt to total consolidated capitalization not exceed 65%.  At December 31, 2016, the ratio was approximately 48% for Pinnacle West and 47% for APS.  Failure to comply with such covenant levels would result in an event of default which, generally speaking, would require the immediate repayment of the debt subject to the covenants and could cross-default other debt.  See further discussion of “cross-default” provisions below.

Neither Pinnacle West’s nor APS’s financing agreements contain “rating triggers” that would result in an acceleration of the required interest and principal payments in the event of a rating downgrade.  However, our bank credit agreements contain a pricing grid in which the interest rates we pay for borrowings thereunder are determined by our current credit ratings.

All of Pinnacle West’s loan agreements contain “cross-default” provisions that would result in defaults and the potential acceleration of payment under these loan agreements if Pinnacle West or APS were to default under certain other material agreements.  All of APS’s bank agreements contain "cross-default" provisions that would result in defaults and the potential acceleration of payment under these bank agreements if APS were to default under certain other material agreements.  Pinnacle West and APS do not have a material adverse change restriction for credit facility borrowings.

An existing ACC order requires APS to maintain a common equity ratio of at least 40%.  As defined in the ACC order, the common equity ratio is total shareholder equity divided by the sum of total shareholder equity and long-term debt, including current maturities of long-term debt.  At December 31, 2016, APS was in compliance with this common equity ratio requirement.  Its total shareholder equity was approximately $4.9 billion, and total capitalization was approximately $9.1 billion.  APS would be prohibited from paying dividends if the payment would reduce its total shareholder equity below approximately $3.6 billion, assuming APS’s total capitalization remains the same. APS was in compliance with this common equity ratio requirement as of December 31, 2016.

Although provisions in APS’s articles of incorporation and ACC financing orders establish maximum amounts of preferred stock and debt that APS may issue, APS does not expect any of these provisions to limit its ability to meet its capital requirements. On February 6, 2013, the ACC issued a financing order in which, subject to specified parameters and procedures, it approved an increase in APS’s long-term debt authorization from $4.2 billion to $5.1 billion in light of the projected growth of APS and its customer base and the resulting projected financing needs, and authorized APS to enter into derivative financial instruments for the purpose of managing interest rate risk associated with its long- and short-term debt. This financing order is set to expire on December 31, 2017. See Note 5 for additional short-term debt provisions.

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Retirement Plans and Other Benefits

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Retirement Plans and Other Benefits

Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan (The Pinnacle West Capital Corporation Retirement Plan) and a non-qualified supplemental excess benefit retirement plan for the employees of Pinnacle West and its subsidiaries.  All new employees participate in the account balance plan.  Defined benefit plans specify the amount of benefits a plan participant is to receive using information about the participant.  The pension plan covers nearly all employees.  The supplemental excess benefit retirement plan covers officers of the Company and highly compensated employees designated for participation by the Board of Directors.  Our employees do not contribute to the plans.  We calculate the benefits based on age, years of service and pay.

Pinnacle West also sponsors other postretirement benefit plans (Pinnacle West Capital Corporation Group Life and Medical Plan and Pinnacle West Capital Corporation Post-65 Retiree Health Reimbursement Arrangement) for the employees of Pinnacle West and its subsidiaries.  These plans provide medical and life insurance benefits to retired employees.  Employees must retire to become eligible for these retirement benefits, which are based on years of service and age.  For the medical insurance plan, retirees make contributions to cover a portion of the plan costs.  For the life insurance plan, retirees do not make contributions.  We retain the right to change or eliminate these benefits.

On September 30, 2014, Pinnacle West announced plan design changes to the other postretirement benefit plan, which required an interim remeasurement of the benefit obligation for the plan. Effective January 1, 2015, those eligible retirees and dependents over age 65 and on Medicare can choose to be enrolled in a Health Reimbursement Arrangement (HRA). The Company is providing a subsidy allowing post-65 retirees to purchase a Medicare supplement plan on a private exchange network. The remeasurement of the benefit obligation included updating the assumptions. The remeasurement reduced net periodic benefit costs in 2014 by $10 million ($5 million of which reduced expense). The remeasurement also resulted in a decrease in Pinnacle West’s other postretirement benefit obligation of $316 million, which was offset by the related regulatory asset and accumulated other comprehensive income.

Because of the plan changes, the Company is currently in the process of seeking IRS approval to move up to $140 million of the other postretirement benefit trust assets into a new trust account to pay for active union employee medical costs. In December 2016, FERC approved a methodology for determining the amount of other postretirement benefit trust assets to move into a new account to pay for active union employee medical costs. As of December 31, 2016, such methodology would result in an amount of approximately $140 million being transferred to the new account.

Pinnacle West uses a December 31 measurement date each year for its pension and other postretirement benefit plans.  The market-related value of our plan assets is their fair value at the measurement date.  See Note 13 for further discussion of how fair values are determined.  Due to subjective and complex judgments, which may be required in determining fair values, actual results could differ from the results estimated through the application of these methods.

A significant portion of the changes in the actuarial gains and losses of our pension and postretirement plans is attributable to APS and therefore is recoverable in rates.  Accordingly, these changes are recorded as a regulatory asset or regulatory liability.  In its 2009 retail rate case settlement, APS received approval to defer a portion of pension and other postretirement benefit cost increases incurred in 2011 and 2012.  We deferred pension and other postretirement benefit costs of approximately $14 million in 2012 and $11 million in 2011.  Pursuant to an ACC regulatory order, we began amortizing the regulatory asset over three years beginning in July 2012.  We amortized approximately $5 million in 2015, $8 million in 2014, $8 million in 2013 and $4 million in 2012.

The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged to the regulatory asset or liability) (dollars in thousands):

	Pension									Other Benefits
	2016			2015			2014			2016			2015			2014
Service cost-benefits earned during the period	$	53,792		$	59,627		$	53,080		$	14,993		$	16,827		$	18,139
Interest cost on benefit obligation	131,647			123,983			129,194			29,721			28,102			41,243
Expected return on plan assets	(173,906		)	(179,231		)	(158,998		)	(36,495		)	(36,855		)	(46,400		)
Amortization of:
Prior service cost (credit)	527			594			869			(37,883		)	(37,968		)	(9,626		)
Net actuarial loss	40,717			31,056			10,963			4,589			4,881			1,175
Net periodic benefit cost	$	52,777		$	36,029		$	35,108		$	(25,075	)	$	(25,013	)	$	4,531
Portion of cost charged to expense	$	26,172		$	20,036		$	21,985		$	(12,435	)	$	(10,391	)	$	6,000

The following table shows the plans’ changes in the benefit obligations and funded status for the years 2016 and 2015 (dollars in thousands):

	Pension						Other Benefits
	2016			2015			2016			2015
Change in Benefit Obligation
Benefit obligation at January 1	$	3,033,803		$	3,078,648		$	647,020		$	682,335
Service cost	53,792			59,627			14,993			16,827
Interest cost	131,647			123,983			29,721			28,102
Benefit payments	(142,247		)	(137,115		)	(26,231		)	(24,988		)
Actuarial (gain) loss	127,467			(91,340		)	50,942			(55,256		)
Benefit obligation at December 31	3,204,462			3,033,803			716,445			647,020
Change in Plan Assets
Fair value of plan assets at January 1	2,542,774			2,615,404			833,017			834,625
Actual return on plan assets	166,408			(44,690		)	63,463			(2,399		)
Employer contributions	100,000			100,000			819			791
Benefit payments	(133,825		)	(127,940		)	(14,648		)	—
Fair value of plan assets at December 31	2,675,357			2,542,774			882,651			833,017
Funded Status at December 31	$	(529,105	)	$	(491,029	)	$	166,206		$	185,997

The following table shows the projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets as of December 31, 2016 and 2015 (dollars in thousands):

	2016		2015
Projected benefit obligation	$	3,204,462	$	3,033,803
Accumulated benefit obligation	3,049,406		2,873,467
Fair value of plan assets	2,675,357		2,542,774

The following table shows the amounts recognized on the Consolidated Balance Sheets as of December 31, 2016 and 2015 (dollars in thousands):

	Pension						Other Benefits
	2016			2015			2016		2015
Noncurrent asset	$	—		$	—		$	166,206	$	185,997
Current liability	(19,795		)	(10,031		)	—		—
Noncurrent liability	(509,310		)	(480,998		)	—		—
Net amount recognized	$	(529,105	)	$	(491,029	)	$	166,206	$	185,997

The following table shows the details related to accumulated other comprehensive loss as of December 31, 2016 and 2015 (dollars in thousands): 

	Pension						Other Benefits
	2016			2015			2016			2015
Net actuarial loss	$	773,750		$	679,501		$	146,509		$	127,124
Prior service cost (credit)	81			609			(303,417		)	(341,301		)
APS’s portion recorded as a regulatory (asset) liability	(711,059		)	(619,223		)	156,575			213,621
Income tax expense (benefit)	(24,202		)	(23,663		)	833			925
Accumulated other comprehensive loss	$	38,570		$	37,224		$	500		$	369

The following table shows the estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets and liabilities into net periodic benefit cost in 2017 (dollars in thousands):

	Pension		Other Benefits
Net actuarial loss	$	46,971	$	5,181
Prior service cost (credit)	81		(37,842		)
Total amounts estimated to be amortized from accumulated other comprehensive loss (gain) and regulatory assets (liabilities) in 2017	$	47,052	$	(32,661	)

The following table shows the weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs:

	Benefit Obligations As of December 31,				Benefit Costs For the Years Ended December 31,
	2016		2015		2016		2015		2014
									January - September		October - December
Discount rate – pension	4.08	%	4.37	%	4.37	%	4.02	%	4.88	%	4.88	%
Discount rate – other benefits	4.17	%	4.52	%	4.52	%	4.14	%	5.10	%	4.41	%
Rate of compensation increase	4.00	%	4.00	%	4.00	%	4.00	%	4.00	%	4.00	%
Expected long-term return on plan assets - pension	N/A		N/A		6.90	%	6.90	%	6.90	%	6.90	%
Expected long-term return on plan assets - other benefits	N/A		N/A		4.45	%	4.45	%	6.80	%	4.25	%
Initial healthcare cost trend rate (pre-65 participants)	7.00	%	7.00	%	7.00	%	7.00	%	7.50	%	7.50	%
Initial healthcare cost trend rate (post-65 participants)	5.00	%	5.00	%	5.00	%	5.00	%	7.50	%	5.00	%
Ultimate healthcare cost trend rate	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%
Number of years to ultimate trend rate (pre-65 participants)	4		4		4		4		4		4
Number of years to ultimate trend rate (post-65 participants)	0		0		0		0		4		0

In selecting the pretax expected long-term rate of return on plan assets, we consider past performance and economic forecasts for the types of investments held by the plan.  For 2017, we are assuming a 6.55% long-term rate of return for pension assets and 6.37% (before tax) for other benefit assets, which we believe is reasonable given our asset allocation in relation to historical and expected performance.

In October 2014, the Society of Actuaries’ Retirement Plans Experience Committee issued its final reports on its recommended mortality basis (“RP-2014 Mortality Tables Report” and "Mortality Improvement Scale MP-2014 Report").  At December 31, 2014, we updated our mortality assumptions using the recommended basis with modifications to better reflect our plan experience and additional data regarding mortality trends.  The updated mortality assumptions resulted in a $67 million increase in Pinnacle West’s pension and other postretirement obligations, which was offset by the related regulatory asset, regulatory liability and accumulated other comprehensive income.

In selecting our healthcare trend rates, we consider past performance and forecasts of healthcare costs.  A one percentage point change in the assumed initial and ultimate healthcare cost trend rates would have the following effects (dollars in thousands): 

	1% Increase		1% Decrease
Effect on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants	$	8,430	$	(5,455	)
Effect on service and interest cost components of net periodic other postretirement benefit costs	8,440		(6,527		)
Effect on the accumulated other postretirement benefit obligation	108,046		(86,651		)

Plan Assets

The Board of Directors has delegated oversight of the pension and other postretirement benefit plans’ assets to an Investment Management Committee (“Committee”).  The Committee has adopted investment policy statements (“IPS”) for the pension and the other postretirement benefit plans’ assets. The investment strategies for these plans include external management of plan assets, and prohibition of investments in Pinnacle West securities.

The overall strategy of the pension plan’s IPS is to achieve an adequate level of trust assets relative to the benefit obligations.  To achieve this objective, the plan’s investment policy provides for mixes of investments including long-term fixed income assets and return-generating assets.  The target allocation between return-generating and long-term fixed income assets is defined in the IPS and is a function of the plan’s funded status.  The plan’s funded status is reviewed on at least a monthly basis.

Changes in the value of long-term fixed income assets, also known as liability-hedging assets, are intended to offset changes in the benefit obligations due to changes in interest rates.  Long-term fixed income assets consist primarily of fixed income debt securities issued by the U.S. Treasury and other government agencies, U.S Treasury Futures Contracts, and fixed income debt securities issued by corporations.  Long-term fixed income assets may also include interest rate swaps, and other instruments.

Return-generating assets are intended to provide a reasonable long-term rate of investment return with a prudent level of volatility.  Return-generating assets are composed of U.S. equities, international equities, and alternative investments.  International equities include investments in both developed and emerging markets.  Alternative investments include investments in real estate, private equity and various other strategies.  The plan may also hold investments in return-generating assets by holding securities in partnerships, common and collective trusts and mutual funds.

Based on the IPS, and given the pension plan’s funded status at year-end 2016, the long-term fixed income assets had a target allocation of 58% with a permissible range of 55% to 61% and the return-generating assets had a target allocation of 42% with a permissible range of 39% to 45%.  The return-generating assets have additional target allocations, as a percent of total plan assets, of 22% equities in U.S. and other developed markets, 6% equities in emerging markets, and 14% in alternative investments.  The pension plan IPS does not provide for a specific mix of long-term fixed income assets, but does expect the average credit quality of such assets to be investment grade.  As of December 31, 2016, long-term fixed income assets represented 57% of total pension plan assets, and return-generating assets represented 43% of total pension plan assets.

As of December 31, 2016, the asset allocation for other postretirement benefit plan assets is governed by the IPS for those plans, which provides for different asset allocation target mixes depending on the characteristics of the liability.  Some of these asset allocation target mixes vary with the plan’s funded status.  As of December 31, 2016, investment in fixed income assets represented 51% of the other postretirement benefit plan total assets, and non-fixed income assets represented 49% of the other postretirement benefit plan’s assets. 

See Note 13 for a discussion on the fair value hierarchy and how fair value methodologies are applied.  The plans invest directly in fixed income, U.S Treasury Futures Contracts, and equity securities, in addition to investing indirectly in fixed income securities, equity securities and real estate through the use of mutual funds, partnerships and common and collective trusts.  Equity securities held directly by the plans are valued using quoted active market prices from the published exchange on which the equity security trades, and are classified as Level 1.  U.S Treasury Future Contracts are valued using the quoted active market prices from the exchange on which they trade, and are classified as Level 1. Fixed income securities issued by the U.S. Treasury held directly by the plans are valued using quoted active market prices, and are classified as Level 1.  Fixed income securities issued by corporations, municipalities, and other agencies are primarily valued using quoted inactive market prices, or quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield, maturity and credit quality.  These instruments are classified as Level 2.

Mutual funds, partnerships, and common and collective trusts are valued utilizing a net asset value (NAV) concept or its equivalent. Mutual funds, classified as Level 1, are valued using a NAV that is observable and based on the active market in which the fund trades.

Common and collective trusts, are maintained by banks or investment companies and hold certain investments in accordance with a stated set of objectives (such as tracking the performance of the S&P 500 Index).  The trust's shares are offered to a limited group of investors, and are not traded in an active market. Investments in common and collective trusts are valued using NAV, as a practical expedient and accordingly are not classified in the fair value hierarchy. The NAV for trusts investing in exchange traded equities is derived from the quoted active market prices of the underlying securities held by the trusts. The NAV for trusts investing in real estate is derived from the appraised values of the trust's underlying real estate assets.  As of December 31, 2016, the plans were able to transact in the common and collective trusts at NAV.

Investments in partnerships are also valued using the concept of NAV, as a practical expedient and accordingly are not classified in the fair value hierarchy. The NAV for these investments is derived from the value of the partnerships' underlying assets. The plan's partnerships holdings relate to investments in high-yield fixed income instruments and assets of privately held portfolio companies. Certain partnerships also include funding commitments that may require the plan to contribute up to $75 million to these partnerships; as of December 31, 2016, approximately $54 million of these commitments have been funded.

The plans’ trustee provides valuation of our plan assets by using pricing services that utilize methodologies described to determine fair market value.  We have internal control procedures to ensure this information is consistent with fair value accounting guidance.  These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustee’s internal operating controls and valuation processes.

The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2016, by asset category, are as follows (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Other (a)		Balance at December 31, 2016
Pension Plan:
Cash and cash equivalents	$	13,995	$	—	$	—	$	13,995
Fixed income securities:
Corporate	—		1,210,453		—		1,210,453
U.S. Treasury	112,583		—		—		112,583
Other (b)	—		102,170		—		102,170
Common stock equities (c)	235,109		—		—		235,109
Mutual funds (d)	251,506		—		—		251,506
Common and collective trusts:
Equities	—		—		266,840		266,840
Real estate	—		—		161,449		161,449
Partnerships	—		—		208,915		208,915
Short-term investments and other (e)	—		—		112,337		112,337
Total	$	613,193	$	1,312,623	$	749,541	$	2,675,357
Other Benefits:
Cash and cash equivalents	$	304	$	—	$	—	$	304
Fixed income securities:
Corporate	—		268,193		—		268,193
U.S. Treasury	145,255		—		—		145,255
Other (b)	—		34,506		—		34,506
Common stock equities (c)	243,741		—		—		243,741
Mutual funds (d)	67,418		—		—		67,418
Common and collective trusts:
Equities	—		—		95,814		95,814
Real estate	—		—		14,509		14,509
Partnerships	—		—		3,060		3,060
Short-term investments and other (e)	—		—		9,851		9,851
Total	$	456,718	$	302,699	$	123,234	$	882,651

(a) These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.

(b) This category consists primarily of debt securities issued by municipalities.

(c) This category primarily consists of US common stock equities.

(d) These funds invest in US and international common stock equities.

(e) This category includes plan receivables and payables.

The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2015, by asset category, are as follows (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Other (a)		Balance at December 31, 2015
Pension Plan:
Cash and cash equivalents	$	1,893	$	—	$	—	$	1,893
Fixed Income Securities:
Corporate	—		1,108,736		—		1,108,736
U.S. Treasury	274,778		—		—		274,778
Other (b)	—		113,008		—		113,008
Common stock equities (c)	247,701		—		—		247,701
Mutual funds - International equities	116,307		—		—		116,307
Common and collective trusts:
Equities	—		—		315,989		315,989
Real Estate	—		—		150,359		150,359
Partnerships	—		—		169,937		169,937
Short-term investments and other (d)	—		—		44,066		44,066
Total	$	640,679	$	1,221,744	$	680,351	$	2,542,774
Other Benefits:
Cash and cash equivalents	$	240	$	—	$	—	$	240
Fixed Income Securities:
Corporate	—		217,026		—		217,026
U.S. Treasury	131,435		—		—		131,435
Other (b)	—		31,106		—		31,106
Common stock equities (c)	265,583		—		—		265,583
Mutual funds - International equities	52,568		—		—		52,568
Common and collective trusts:
Equities	—		—		110,055		110,055
Real Estate	—		—		13,512		13,512
Short-term investments and other (d)	—		—		11,492		11,492
Total	$	449,826	$	248,132	$	135,059	$	833,017

(a) These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.

(b) This category consists primarily of debt securities issued by municipalities.

(c) This category primarily consists of US common stock equities.

(d) This category includes plan receivables and payables.

Contributions

Future year contribution amounts are dependent on plan asset performance and plan actuarial assumptions.  We made contributions to our pension plan totaling $100 million in 2016, $100 million in 2015, and $175 million in 2014.  The minimum required contributions for the pension plan are zero for the next three years.  We expect to make voluntary contributions up to a total of $300 million during the 2017-2019 period.  With regard to contributions to our other postretirement benefit plans, we made a contribution of approximately $1 million in each of 2016, 2015 and 2014.  We expect to make contributions of less than $1 million in total for the next three years to our other postretirement benefit plans. APS funds its share of the contributions.  APS’s share of the pension plan contribution was approximately $100 million in 2016, $100 million in 2015 and $175 million in 2014.  APS’s share of the contributions to the other postretirement benefit plan was approximately $1 million in 2016, 2015 and 2014.

Estimated Future Benefit Payments

Benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter, are estimated to be as follows (dollars in thousands):

Year	Pension		Other Benefits
2017	$	172,859	$	31,126
2018	173,232		33,795
2019	182,944		36,195
2020	191,037		37,998
2021	196,292		39,368
Years 2022-2026	1,049,149		201,944

Electric plant participants contribute to the above amounts in accordance with their respective participation agreements.

Employee Savings Plan Benefits

Pinnacle West sponsors a defined contribution savings plan for eligible employees of Pinnacle West and its subsidiaries.  In 2016, costs related to APS’s employees represented 99% of the total cost of this plan.  In a defined contribution savings plan, the benefits a participant receives result from regular contributions participants make to their own individual account, the Company’s matching contributions and earnings or losses on their investments.  Under this plan, the Company matches a percentage of the participants’ contributions in cash which is then invested in the same investment mix as participants elect to invest their own future contributions.  Pinnacle West recorded expenses for this plan of approximately $10 million for 2016, $9 million for 2015, and $9 million for 2014.

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Leases

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Leases

Leases

We lease certain vehicles, land, buildings, equipment and miscellaneous other items through operating rental agreements with varying terms, provisions and expiration dates. See Note 2 for a discussion of the new lease accounting standard.

Total lease expense recognized in the Consolidated Statements of Income was $16 million in 2016, $17 million in 2015, and $18 million in 2014.  APS’s lease expense was $15 million in 2016, $14 million in 2015, and $15 million in 2014.

Estimated future minimum lease payments for Pinnacle West’s and APS’s operating leases, excluding purchased power agreements, are approximately as follows (dollars in thousands):

Year	Pinnacle West Consolidated		APS
2017	$	12,330	$	11,919
2018	10,987		10,690
2019	9,019		8,767
2020	7,688		7,439
2021	5,266		5,020
Thereafter	59,647		57,207
Total future lease commitments	$	104,937	$	101,042

In 1986, APS entered into agreements with three separate lessor trust entities in order to sell and lease back interests in Palo Verde Unit 2 and related common facilities.  These lessor trust entities have been deemed VIEs for which APS is the primary beneficiary.  As the primary beneficiary, APS consolidated these lessor trust entities.  The impacts of these sale leaseback transactions are excluded from our lease disclosures as lease accounting is eliminated upon consolidation.  See Note 18 for a discussion of VIEs.

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Jointly-Owned Facilities

12 Months Ended

Dec. 31, 2016

Jointly Owned Utility Plant, Net Ownership Amount [Abstract]

Jointly-Owned Facilities

Jointly-Owned Facilities

APS shares ownership of some of its generating and transmission facilities with other companies.  We are responsible for our share of operating costs which are included in the corresponding operating expenses on our Consolidated Statements of Income. We are also responsible for providing our own financing.  Our share of operating expenses and utility plant costs related to these facilities is accounted for using proportional consolidation.  The following table shows APS’s interests in those jointly-owned facilities recorded on the Consolidated Balance Sheets at December 31, 2016 (dollars in thousands):

	Percent Owned			Plant in Service		Accumulated Depreciation		Construction Work in Progress
Generating facilities:
Palo Verde Units 1 and 3	29.1	%		$	1,770,324	$	1,080,072	$	17,615
Palo Verde Unit 2 (a)	16.8	%		581,572		360,757		9,717
Palo Verde Common	28.0	%	(b)	672,799		242,649		62,479
Palo Verde Sale Leaseback			(a)	351,050		237,535		—
Four Corners Generating Station	63.0	%		934,837		578,924		248,072
Navajo Generating Station Units 1, 2 and 3	14.0	%		279,629		176,931		5,761
Cholla common facilities (c)	63.3	%	(b)	159,707		58,276		806		(d)
Transmission facilities:
ANPP 500kV System	33.6	%	(b)	127,970		38,610		2,291
Navajo Southern System	22.5	%	(b)	62,135		20,491		334
Palo Verde — Yuma 500kV System	19.0	%	(b)	13,699		5,368		408
Four Corners Switchyards	51.3	%	(b)	39,850		10,474		1,044
Phoenix — Mead System	17.1	%	(b)	39,330		13,725		85
Palo Verde — Rudd 500kV System	50.0	%	(b)	91,904		19,818		227
Morgan — Pinnacle Peak System	65.2	%	(b)	140,374		13,557		—
Round Valley System	50.0	%	(b)	515		127		—
Palo Verde — Morgan System	85.8	%	(b)	125,908		1,326		28,949
Hassayampa — North Gila System	80.0	%	(b)	142,541		3,231		—
Cholla 500kV Switchyard	85.7	%	(b)	5,078		1,201		—
Saguaro 500kV Switchyard	75.0	%	(b)	20,456		12,426		2

(a) See Note 18.

(b) Weighted-average of interests.

(c) PacifiCorp owns Cholla Unit 4 and APS operates the unit for PacifiCorp.  The common facilities at Cholla are jointly-owned.

(d) Due to the closure of Cholla Unit 2 in 2015, all new Cholla common facilities construction is owned by APS at 50.5%

4CA is a subsidiary that was formed in 2016 as a result of the purchase of El Paso's 7% interest in Four Corners. At December 31, 2016, 4CA had plant in service of $110 million, accumulated depreciation of $79 million and construction work in progress of $30 million.

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Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments and Contingencies

Palo Verde Nuclear Generating Station

Spent Nuclear Fuel and Waste Disposal

On December 19, 2012, APS, acting on behalf of itself and the participant owners of Palo Verde, filed a second breach of contract lawsuit against the DOE in the Court of Federal Claims.  The lawsuit sought to recover damages incurred due to DOE’s breach of the Standard Contract for failing to accept Palo Verde's spent nuclear fuel and high level waste from January 1, 2007 through June 30, 2011, as it was required to do pursuant to the terms of the Standard Contract and the Nuclear Waste Policy Act.  On August 18, 2014, APS and DOE entered into a settlement agreement, stipulating to a dismissal of the lawsuit and payment of $57.4 million by DOE to the Palo Verde owners for certain specified costs incurred by Palo Verde during the period January 1, 2007 through June 30, 2011. APS’s share of this amount is $16.7 million. Amounts recovered in the lawsuit and settlement were recorded as adjustments to a regulatory liability and had no impact on the amount of reported net income. In addition, the settlement agreement provides APS with a method for submitting claims and getting recovery for costs incurred through December 31, 2016, which has been extended to December 31, 2019.

APS has submitted two claims pursuant to the terms of the August 18, 2014 settlement agreement, for two separate time periods during July 1, 2011 through June 30, 2015. The DOE has approved and paid $53.9 million for these claims (APS’s share is $15.7 million). The amounts recovered were primarily recorded as adjustments to a regulatory liability and had no impact on reported net income. APS’s next claim pursuant to the terms of the August 18, 2014 settlement agreement was submitted to the DOE on October 31, 2016, and approved on February 1, 2017, in the amount of $11.3 million (APS’s share is $3.3 million). Payment for the claim is expected in the second quarter of 2017.

Nuclear Insurance

Public liability for incidents at nuclear power plants is governed by the Price-Anderson Nuclear Industries Indemnity Act ("Price-Anderson Act"), which limits the liability of nuclear reactor owners to the amount of insurance available from both commercial sources and an industry-wide retrospective payment plan.  In accordance with the Price-Anderson Act, the Palo Verde participants are insured against public liability for a nuclear incident up to approximately $13.4 billion per occurrence.  Palo Verde maintains the maximum available nuclear liability insurance in the amount of $375 million (on January 1, 2017 this coverage was increased to $450 million), which is provided by American Nuclear Insurers ("ANI").  The remaining balance of approximately $13.1 billion (on January 1, 2017 this balance was decreased to $13.0 billion) of liability coverage is provided through a mandatory industry-wide retrospective premium program.  If losses at any nuclear power plant covered by the program exceed the accumulated funds, APS could be responsible for retrospective premiums.  The maximum retrospective premium per reactor under the program for each nuclear liability incident is approximately $127.3 million, subject to a maximum annual premium of $18.9 million per incident.  Based on APS’s ownership interest in the three Palo Verde units, APS’s maximum retrospective premium per incident for all three units is approximately $111.1 million, with a maximum annual retrospective premium of approximately $16.6 million.

The Palo Verde participants maintain insurance for property damage to, and decontamination of, property at Palo Verde in the aggregate amount of $2.8 billion.  APS has also secured accidental outage insurance for a sudden and unforeseen accidental outage of any of the three units. The property damage, decontamination, and accidental outage insurance are provided by Nuclear Electric Insurance Limited ("NEIL").  APS is subject to retrospective premium adjustments under all NEIL policies if NEIL’s losses in any policy year exceed accumulated funds.  The maximum amount APS could incur under the current NEIL policies totals approximately $23.8 million for each retrospective premium assessment declared by NEIL’s Board of Directors due to losses.  In addition, NEIL policies contain rating triggers that would result in APS providing approximately $64 million of collateral assurance within 20 business days of a rating downgrade to non-investment grade.  The insurance coverage discussed in this and the previous paragraph is subject to certain policy conditions, sublimits and exclusions.

Fuel and Purchased Power Commitments and Purchase Obligations

APS is party to various fuel and purchased power contracts and purchase obligations with terms expiring between 2017 and 2043 that include required purchase provisions.  APS estimates the contract requirements to be approximately $977 million in 2017; $737 million in 2018; $598 million in 2019; $525 million in 2020; $524 million in 2021; and $7.3 billion thereafter.  However, these amounts may vary significantly pursuant to certain provisions in such contracts that permit us to decrease required purchases under certain circumstances.

Of the various fuel and purchased power contracts mentioned above, some of those contracts for coal supply include take-or-pay provisions.  The current coal contracts with take-or-pay provisions have terms expiring through 2031.

The following table summarizes our estimated coal take-or-pay commitments (dollars in thousands):

	Years Ended December 31,
	2017		2018		2019		2020		2021		Thereafter
Coal take-or-pay commitments (a)	$	195,428	$	189,588	$	193,818	$	198,160	$	202,619	$	2,068,355

(a) Total take-or-pay commitments are approximately $3.0 billion.  The total net present value of these commitments is approximately $2.1 billion.

APS may spend more to meet its actual fuel requirements than the minimum purchase obligations in our coal take-or-pay contracts. The following table summarizes actual amounts purchased under the coal contracts which include take-or-pay provisions for each of the last three years (dollars in thousands):

	Year Ended December 31,
	2016		2015		2014
Total purchases	$	160,066	$	211,327	$	236,773

Renewable Energy Credits

APS has entered into contracts to purchase renewable energy credits to comply with the RES.  APS estimates the contract requirements to be approximately $40 million in 2017; $40 million in 2018; $40 million in 2019; $40 million in 2020; $40 million in 2021; and $420 million thereafter.  These amounts do not include purchases of renewable energy credits that are bundled with energy.

Coal Mine Reclamation Obligations

APS and 4CA must reimburse certain coal providers for amounts incurred for final and contemporaneous coal mine reclamation.  We account for contemporaneous reclamation costs as part of the cost of the delivered coal.  We utilize site-specific studies of costs expected to be incurred in the future to estimate our final reclamation obligation.  These studies utilize various assumptions to estimate the future costs.  Based on the most recent reclamation studies, APS recorded an obligation for the coal mine final reclamation of approximately $207 million at December 31, 2016 and $202 million at December 31, 2015. 4CA recorded an obligation for the coal mine final reclamation of approximately $15 million at December 31, 2016. Under our current coal supply agreements, APS expects to make payments for the final mine reclamation as follows:  $17 million in 2017; $18 million in 2018; $19 million in 2019; $21 million in 2020; $22 million in 2021; and $241 million thereafter.  4CA expects to make payments for the final mine reclamation as follows: $1 million in 2017; $1 million in 2018; $1 million in 2019; $1 million in 2020; $2 million in 2021; and $17 million thereafter. Any amendments to current coal supply agreements may change the timing of the contribution. Portions of these funds will be held in an escrow account and distributed to certain coal providers under the terms of the applicable coal supply agreements.

Superfund-Related Matters

Superfund establishes liability for the cleanup of hazardous substances found contaminating the soil, water or air.  Those who generated, transported or disposed of hazardous substances at a contaminated site are among those who are PRPs.  PRPs may be strictly, and often are jointly and severally, liable for clean-up.  On September 3, 2003, EPA advised APS that EPA considers APS to be a PRP in the Motorola 52^nd Street Superfund Site, OU3 in Phoenix, Arizona.  APS has facilities that are within this Superfund site.  APS and Pinnacle West have agreed with EPA to perform certain investigative activities of the APS facilities within OU3.  In addition, on September 23, 2009, APS agreed with EPA and one other PRP to voluntarily assist with the funding and management of the site-wide groundwater RI/FS work plan.  The OU3 working group parties have agreed to a schedule with EPA that calls for the submission of a revised draft RI/FS by June 2017. We estimate that our costs related to this investigation and study will be approximately $2 million.  We anticipate incurring additional expenditures in the future, but because the overall investigation is not complete and ultimate remediation requirements are not yet finalized, at the present time expenditures related to this matter cannot be reasonably estimated.

On August 6, 2013, RID filed a lawsuit in Arizona District Court against APS and 24 other defendants, alleging that RID’s groundwater wells were contaminated by the release of hazardous substances from facilities owned or operated by the defendants.  The lawsuit also alleges that, under Superfund laws, the defendants are jointly and severally liable to RID.  The allegations against APS arise out of APS’s current and former ownership of facilities in and around OU3.  As part of a state governmental investigation into groundwater contamination in this area, on January 25, 2015, ADEQ sent a letter to APS seeking information concerning the degree to which, if any, APS’s current and former ownership of these facilities may have contributed to groundwater contamination in this area.  APS responded to ADEQ on May 4, 2015. On December 16, 2016, two RID contractors filed ancillary lawsuits for recovery of costs against APS and the other defendants. We are unable to predict the outcome of these matters; however, we do not expect the outcome to have a material impact on our financial position, results of operations or cash flows.

Southwest Power Outage

On September 8, 2011 at approximately 3:30 PM, a 500 kV transmission line running between the Hassayampa and North Gila substations in southwestern Arizona tripped out of service due to a fault that occurred at a switchyard operated by APS.  Approximately ten minutes after the transmission line went off-line, generation and transmission resources for the Yuma area were lost, resulting in approximately 69,700 APS customers losing service.

On September 6, 2013, a purported consumer class action complaint was filed in Federal District Court in San Diego, California, naming APS and Pinnacle West as defendants and seeking damages for loss of perishable inventory and sales as a result of interruption of electrical service.  APS and Pinnacle West filed a motion to dismiss, which the court granted on December 9, 2013.  On January 13, 2014, the plaintiffs appealed the lower court’s decision.  On March 2, 2016, the United States Court of Appeals for the Ninth Circuit unanimously affirmed the District Court's decision. The plaintiffs filed a Petition for Rehearing En Banc, which was denied on April 11, 2016.

Environmental Matters

APS is subject to numerous environmental laws and regulations affecting many aspects of its present and future operations, including air emissions of both conventional pollutants and greenhouse gases, water quality, wastewater discharges, solid waste, hazardous waste, and CCRs.  These laws and regulations can change from time to time, imposing new obligations on APS resulting in increased capital, operating, and other costs.  Associated capital expenditures or operating costs could be material.  APS intends to seek recovery of any such environmental compliance costs through our rates, but cannot predict whether it will obtain such recovery.  The following proposed and final rules involve material compliance costs to APS.

Regional Haze Rules.  APS has received the final rulemaking imposing new requirements on Four Corners and the Navajo Plant. EPA will require these plants to install pollution control equipment that constitutes BART to lessen the impacts of emissions on visibility surrounding the plants. EPA recently approved a proposed rule for Regional Haze compliance at Cholla that does not involve the installation of new pollution controls and that will replace an earlier BART determination for this facility. See below for details of the recent Cholla rule approval.

Four Corners. Based on EPA’s final standards, APS estimates that its 63% share of the cost of required controls for Four Corners Units 4 and 5 would be approximately $400 million.  In addition, APS and El Paso entered into an asset purchase agreement providing for the purchase by APS, or an affiliate of APS, of El Paso's 7% interest in Four Corners Units 4 and 5. 4CA purchased the El Paso interest on July 6, 2016. NTEC has the option to purchase the interest within a certain timeframe pursuant to an option granted to NTEC. In December 2015, NTEC notified APS of its intent to exercise the option. The cost of the pollution controls related to the 7% interest is approximately $45 million, which will be assumed by the ultimate owner of the 7% interest.

Navajo Plant. APS estimates that its share of costs for upgrades at the Navajo Plant, based on EPA’s FIP, could be up to approximately $200 million.  In October 2014, a coalition of environmental groups, an Indian tribe and others filed petitions for review in the United States Court of Appeals for the Ninth Circuit asking the Court to review EPA's final BART rule for the Navajo Plant. We cannot predict the outcome of this review process. See "Navajo Plant" in Note 3 for information regarding future plans for the Navajo Plant.

Cholla. APS believes that EPA’s original 2012 final rule establishing controls constituting BART for Cholla, which would require installation of SCR controls with a cost to APS of approximately $100 million is unsupported and that EPA had no basis for disapproving Arizona’s SIP and promulgating a FIP that is inconsistent with the state’s considered BART determinations under the regional haze program.  Accordingly, on February 1, 2013, APS filed a Petition for Review of the final BART rule in the United States Court of Appeals for the Ninth Circuit.  Briefing in the case was completed in February 2014.

In September 2014, APS met with EPA to propose a compromise BART strategy. Pending certain regulatory approvals, APS would permanently close Cholla Unit 2 and cease burning coal at Units 1 and 3 by the mid-2020s. (See Note 3 for details related to the resulting regulatory asset.) APS made the proposal with the understanding that additional emission control equipment is unlikely to be required in the future because retiring and/or converting the units as contemplated in the proposal is more cost effective than, and will result in increased visibility improvement over, the current BART requirements for NOx imposed on the Cholla units under EPA's BART FIP. APS’s proposal involves state and federal rulemaking processes. In light of these ongoing administrative proceedings, on February 19, 2015, APS, PacifiCorp (owner of Cholla Unit 4), and EPA jointly moved the court to sever and hold in abeyance those claims in the litigation pertaining to Cholla pending regulatory actions by the state and EPA. The court granted the parties' unopposed motion on February 20, 2015.

On October 16, 2015, ADEQ issued a revised operating permit for Cholla, which incorporates APS's proposal, and subsequently submitted a proposed revision to the SIP to the EPA, which would incorporate the new permit terms.  On June 30, 2016, EPA issued a proposed rule approving a revision to the Arizona SIP that incorporates APS’s compromise approach for compliance with the Regional Haze program.  EPA signed the final rule approving the Agency's proposal on January 13, 2017. Once the final rule is published in the Federal Register, parties have 60 days to file a petition for review in the Ninth Circuit Court of Appeals. APS cannot predict at this time whether such petitions will be filed or if they will be successful. In addition, under the terms of an executive memorandum issued on January 20, 2017, this final rule will not be published in the Federal Register until after it has been reviewed by an appointee of the President. We cannot predict when such review will occur and what may result from the additional review.

Mercury and Air Toxic Standards ("MATS"). In 2011, EPA issued rules establishing maximum achievable control technology standards to regulate emissions of mercury and other hazardous air pollutants from fossil-fired plants.  APS estimates that the cost for the remaining equipment necessary to meet these standards is approximately $8 million for Cholla. No additional equipment is needed for Four Corners Units 4 and 5 to comply with these rules.  SRP, the operating agent for the Navajo Plant, estimates that APS's share of costs for equipment necessary to comply with the rules is approximately $1 million, the majority of which has already been incurred. Litigation concerning the rules, including supplemental analyses EPA has prepared in support of the MATS regulation, is ongoing. These proceedings do not materially impact APS.  Regardless of the results from further judicial or administrative proceedings concerning the MATS rulemaking, the Arizona State Mercury Rule, the stringency of which is roughly equivalent to that of MATS, would still apply to Cholla.

Coal Combustion Waste.On December 19, 2014, EPA issued its final regulations governing the handling and disposal of CCR, such as fly ash and bottom ash. The rule regulates CCR as a non-hazardous waste under Subtitle D of RCRA and establishes national minimum criteria for existing and new CCR landfills and surface impoundments and all lateral expansions consisting of location restrictions, design and operating criteria, groundwater monitoring and corrective action, closure requirements and post closure care, and recordkeeping, notification, and Internet posting requirements. The rule generally requires any existing unlined CCR surface impoundment that is contaminating groundwater above a regulated constituent’s groundwater protection standard to stop receiving CCR and either retrofit or close, and further requires the closure of any CCR landfill or surface impoundment that cannot meet the applicable performance criteria for location restrictions or structural integrity. While EPA has chosen to regulate the disposal of CCR in landfills and surface impoundments as non-hazardous waste under the final rule, the agency makes clear that it will continue to evaluate any risks associated with CCR disposal and leaves open the possibility that it may regulate CCR as a hazardous waste under RCRA Subtitle C in the future.

On December 16, 2016, President Obama signed the WIIN Act into law, which contains a number of provisions requiring EPA to modify the self-implementing provisions of the Agency's current CCR rules under Subtitle D. Such modifications include new EPA authority to directly enforce the CCR rules through the use of administrative orders and providing states, like Arizona, where the Cholla facility is located, the option of developing CCR disposal unit permitting programs, subject to EPA approval. For facilities in states that do not develop state-specific permitting programs, EPA is required to develop a federal permit program, pending the availability of congressional appropriations. By contrast, for facilities located within the boundaries of Native American tribal reservations, such as the Navajo Nation, where the Navajo Plant and Four Corners facilities are located, EPA is required to develop a federal permit program regardless of appropriated funds. Because EPA has yet to undertake rulemaking proceedings to implement the CCR provisions of the WIIN Act, and Arizona has yet to determine whether it will develop a state-specific permitting program, it is unclear what effects the CCR provisions of the WIIN Act will have on APS's management of CCR.

APS currently disposes of CCR in ash ponds and dry storage areas at Cholla and Four Corners. APS estimates that its share of incremental costs to comply with the CCR rule for Four Corners is approximately $15 million. APS is currently evaluating compliance alternatives for Cholla and estimates that its share of incremental costs to comply with the CCR rule for this plant is in the range of $5 million to $40 million based upon which compliance alternatives are ultimately selected. The Navajo Plant currently disposes of CCR in a dry landfill storage area. APS estimates that its share of incremental costs to comply with the CCR rule for the Navajo Plant is approximately $1 million, the majority of which has already been incurred. Additionally, the CCR rule requires ongoing groundwater monitoring. Depending upon the results of such monitoring at each of Cholla, Four Corners and the Navajo Plant, we may be required to take corrective actions, the costs of which we are unable to reasonably estimate at this time.

Pursuant to a June 24, 2016 order by the D.C. Circuit Court of Appeals in the litigation by industry- and environmental-groups challenging EPA’s CCR regulations, within the next 3 years EPA is required to complete a rulemaking proceeding concerning whether or not boron must be included on the list of groundwater constituents that might trigger corrective action under EPA’s CCR rules.  EPA is not required to take final action approving the inclusion of boron, but EPA must propose and consider its inclusion.  Should EPA take final action adding boron to the list of groundwater constituents that might trigger corrective action, any resulting corrective action measures may increase APS's costs of compliance with the CCR rule at our coal-fired generating facilities.  At this time, though, APS cannot predict when EPA will commence its rulemaking concerning boron or the eventual results of those proceedings.

Clean Power Plan. On August 3, 2015, EPA finalized carbon pollution standards for existing, new, modified, and reconstructed EGUs. EPA’s final rules require newly built fossil fuel-fired EGUs, along with those undergoing modification or reconstruction, to meet CO₂ performance standards based on a combination of best operating practices and equipment upgrades. EPA established separate performance standards for two types of EGUs: stationary combustion turbines, typically natural gas; and electric utility steam generating units, typically coal.

With respect to existing power plants, EPA’s recently finalized “Clean Power Plan” imposes state-specific goals or targets to achieve reductions in CO₂ emission rates from existing EGUs measured from a 2012 baseline. In a significant change from the proposed rule, EPA’s final performance standards apply directly to specific units based upon their fuel-type and configuration (i.e., coal- or oil-fired steam plants versus combined cycle natural gas plants). As such, each state’s goal is an emissions performance standard that reflects the fuel mix employed by the EGUs in operation in those states. The final rule provides guidelines to states to help develop their plans for meeting the interim (2022-2029) and final (2030 and beyond) emission performance standards, with three distinct compliance periods within that timeframe. States were originally required to submit their plans to EPA by September 2016, with an optional two-year extension provided to states establishing a need for additional time; however, this timing will be impacted by the court-imposed stay described below.

Prior to the court-imposed stay described below, ADEQ, with input from a technical working group comprised of Arizona utilities and other stakeholders, was working to develop a compliance plan for submittal to EPA. Since the imposition of the stay, ADEQ is continuing to assess alternatives while completing outreach and soliciting feedback from stakeholders. In addition to these ongoing state proceedings, EPA has taken public comments on proposed model rules and a proposed federal compliance plan, which included consideration as to how the Clean Power Plan will apply to EGUs on tribal land such as the Navajo Nation.

The legality of the Clean Power Plan is being challenged in the U.S. Court of Appeals for the D.C. Circuit; the parties raising this challenge include, among others, the ACC. On February 9, 2016, the U.S. Supreme Court granted a stay of the Clean Power Plan pending judicial review of the rule, which temporarily delays compliance obligations under the Clean Power Plan. We cannot predict the extent of such a delay.

With respect to our Arizona generating units, we are currently evaluating the range of compliance options available to ADEQ, including whether Arizona deploys a rate- or mass-based compliance plan. Based on the fuel-mix and location of our Arizona EGUs, and the significant investments we have made in renewable generation and demand-side energy efficiency, if ADEQ selects a rate-based compliance plan, we believe that we will be able to comply with the Clean Power Plan for our Arizona generating units in a manner that will not have material financial or operational impacts to the Company. On the other hand, if ADEQ selects a mass-based approach to compliance with the Clean Power Plan, our annual cost of compliance could be material. These costs could include costs to acquire mass-based compliance allowances.

As to our facilities on the Navajo Nation, EPA has yet to determine whether or to what extent EGUs on the Navajo Nation will be required to comply with the Clean Power Plan. EPA has proposed to determine that it is necessary or appropriate to impose a federal plan on the Navajo Nation for compliance with the Clean Power Plan. In response, we filed comments with EPA advocating that such a federal plan is neither necessary nor appropriate to protect air quality on the Navajo Nation. If EPA reaches a determination that is consistent with our preferred approach for the Navajo Nation, we believe the Clean Power Plan will not have material financial or operational impacts on our operations within the Navajo Nation.

Alternatively, if EPA determines that a federal plan is necessary or appropriate for the Navajo Nation, and depending on our need for future operations at our EGUs located there, we may be unable to comply with the federal plan unless we acquire mass-based allowances or emission rate credits within established carbon trading markets, or curtail our operations. Subject to the uncertainties set forth below, and assuming that EPA establishes a federal plan for the Navajo Nation that requires carbon allowances or credits to be surrendered for plan compliance, it is possible we will be required to purchase some quantity of credits or allowances, the cost of which could be material.

Because ADEQ has not issued its plan for Arizona, and because we do not know whether EPA will decide to impose a plan or, if so, what that plan will require, there are a number of uncertainties associated with our potential cost exposure. These uncertainties include: whether judicial review will result in the Clean Power Plan being vacated in whole or in part or, if not, the extent of any resulting compliance deadline delays; whether any plan will be imposed for EGUs on the Navajo Nation; the future existence and liquidity of allowance or credit compliance trading markets; the applicability of existing contractual obligations with current and former owners of our participant-owned coal-fired EGUs; the type of federal or state compliance plan (either rate- or mass-based); whether or not the trading of allowances or credits will be authorized mechanisms for compliance with any final EPA or ADEQ plan; and how units that have been closed will be treated for allowance or credit allocation purposes.

In the event that the incurrence of compliance costs is not economically viable or prudent for our operations in Arizona or on the Navajo Nation, or if we do not have the option of acquiring allowances to account for the emissions from our operations, we may explore other options, including reduced levels of output or potential plant closures, as alternatives to purchasing allowances. Given these uncertainties, our analysis of the available compliance options remains ongoing, and additional information or considerations may arise that change our expectations.

Other environmental rules that could involve material compliance costs include those related to effluent limitations, the ozone national ambient air quality standard and other rules or matters involving the Clean Air Act, Clean Water Act, Endangered Species Act, RCRA, Superfund, the Navajo Nation, and water supplies for our power plants.  The financial impact of complying with current and future environmental rules could jeopardize the economic viability of our coal plants or the willingness or ability of power plant participants to fund any required equipment upgrades or continue their participation in these plants.  The economics of continuing to own certain resources, particularly our coal plants, may deteriorate, warranting early retirement of those plants, which may result in asset impairments.  APS would seek recovery in rates for the book value of any remaining investments in the plants as well as other costs related to early retirement, but cannot predict whether it would obtain such recovery.

Federal Agency Environmental Lawsuit Related to Four Corners

On April 20, 2016, several environmental groups filed a lawsuit against OSM and other federal agencies in the District of Arizona in connection with their issuance of the approvals that extended the life of Four Corners and the adjacent mine.  The lawsuit alleges that these federal agencies violated both the ESA and NEPA in providing the federal approvals necessary to extend operations at the Four Corners Power Plant and the adjacent Navajo Mine past July 6, 2016.  APS filed a motion to intervene in the proceedings, which was granted on August 3, 2016. Briefing on the merits of this litigation is expected to extend through May 2017. On September 15, 2016, NTEC, the company that owns the adjacent mine, filed a motion to intervene for the purpose of dismissing the lawsuit based on NTEC's tribal sovereign immunity. Because the court has placed a stay on all litigation deadlines pending its decision regarding NTEC's motion to dismiss, the schedule for briefing and the anticipated timeline for completion of this litigation will likely be extended. We cannot predict the outcome of this matter or its potential effect on Four Corners.

New Mexico Tax Matter

On May 23, 2013, the New Mexico Taxation and Revenue Department ("NMTRD") issued a notice of assessment for coal severance surtax, penalty, and interest totaling approximately $30 million related to coal supplied under the coal supply agreement for Four Corners (the “Assessment”).  APS’s share of the Assessment is approximately $12 million.  For procedural reasons, on behalf of the Four Corners co-owners, including APS, the coal supplier made a partial payment of the Assessment in the amount of $0.8 million and immediately filed a refund claim with respect to that partial payment in August 2013.  The NMTRD denied the refund claim.  On December 19, 2013, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, filed a complaint with the New Mexico District Court contesting both the validity of the Assessment and the refund claim denial.  On June 30, 2015, the court ruled that the Assessment was not valid and further ruled that APS and the other Four Corners co-owners receive a refund of all of the contested amounts previously paid under the applicable tax statute. The NMTRD filed an appeal of the decision on August 31, 2015.

On March 16, 2016, APS and the coal supplier entered into a final settlement agreement with the NMTRD with respect to the Assessment. Pursuant to the final settlement agreement, the NMTRD agreed to release the Assessment, dismiss its filed appeal, and release its rights to any other surtax claims with respect to the coal supply agreement. APS and the other Four Corners co-owners agreed to forgo refund rights with respect to all of the contested amounts previously paid under the applicable tax statute, as well as pay $1 million. APS's share of this settlement payment, together with its share of the partial payment described above, is approximately $0.8 million.

Peabody Bankruptcy

On April 13, 2016, Peabody Energy Corporation and certain affiliated entities filed a petition for relief under chapter 11 of the Bankruptcy Code in the United States Bankruptcy Court for the Eastern District of Missouri.  Under a Coal Supply Agreement, dated December 21, 2005, Peabody supplied coal to APS and PacifiCorp (collectively, the “Buyers”) for use at the Cholla power plant in Arizona.  APS believes that the Coal Supply Agreement terminated automatically on April 13, 2016 as a result of Peabody's bankruptcy filing. The Buyers filed a motion requesting that the Bankruptcy Court enter an order determining that the Buyers are authorized to enforce the termination provisions in the Coal Supply Agreement.  

On May 13, 2016, Peabody filed a complaint against the Buyers in the bankruptcy court in which Peabody alleged that the Buyers breached the Agreement. On January 27, 2017, the bankruptcy court approved a settlement between the parties, and on February 6, 2017 the parties executed an amendment to the Coal Supply Agreement that allows for continuation of the agreement with modified terms and conditions acceptable to the parties.

Financial Assurances

In the normal course of business, we obtain standby letters of credit and surety bonds from financial institutions and other third parties. These instruments guarantee our own future performance and provide third parties with financial and performance assurance in the event we do not perform. These instruments support certain commodity contract collateral obligations and other transactions. As of December 31, 2016, standby letters of credit totaled $35 million and will expire in 2017. As of December 31, 2016, surety bonds expiring through 2019 totaled $53 million. The underlying liabilities insured by these instruments are reflected on our balance sheets, where applicable. Therefore, no additional liability is reflected for the letters of credit and surety bonds themselves.

We enter into agreements that include indemnification provisions relating to liabilities arising from or related to certain of our agreements.  Most significantly, APS has agreed to indemnify the equity participants and other parties in the Palo Verde sale leaseback transactions with respect to certain tax matters.  Generally, a maximum obligation is not explicitly stated in the indemnification provisions and, therefore, the overall maximum amount of the obligation under such indemnification provisions cannot be reasonably estimated.  Based on historical experience and evaluation of the specific indemnities, we do not believe that any material loss related to such indemnification provisions is likely.

Pinnacle West has issued parental guarantees and has provided indemnification under certain surety bonds for APS which were not material at December 31, 2016. Effective July 6, 2016, Pinnacle West has issued two parental guarantees for 4CArelating to payment obligations arising from 4CA’s acquisition of El Paso’s 7% interest in Four Corners, and pursuant to the Four Corners participation agreement payment obligations arising from 4CA’s ownership interest in Four Corners.

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Asset Retirement Obligations

12 Months Ended

Dec. 31, 2016

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligations

Asset Retirement Obligations

APS has asset retirement obligations for its Palo Verde nuclear facilities and certain other generation assets. 

The Palo Verde asset retirement obligation primarily relates to final plant decommissioning.  This obligation is based on the NRC’s requirements for disposal of radiated property or plant and agreements APS reached with the ACC for final decommissioning of the plant.  The non-nuclear generation asset retirement obligations primarily relate to requirements for removing portions of those plants at the end of the plant life or lease term and coal ash pond closures. Some of APS’s transmission and distribution assets have asset retirement obligations because they are subject to right of way and easement agreements that require final removal.  These agreements have a history of uninterrupted renewal that APS expects to continue.  As a result, APS cannot reasonably estimate the fair value of the asset retirement obligation related to such transmission and distribution assets. Additionally, APS has aquifer protection permits for some of its generation sites that require the closure of certain facilities at those sites.

In 2016, APS recognized an ARO for the Ocotillo steam units as a condition of the air permit (issued in 2016) to allow the construction and operation of five new turbine units. This resulted in an increase to the ARO in the amount of $10 million. In addition, 4CA acquired El Paso's share of Four Corners Units 4 & 5 and the associated ARO. This resulted in an increase to the ARO in the amount of $9 million. In addition, Four Corners spent $16 million in actual decommissioning costs. Finally, in 2016, APS received a new decommissioning study for the Palo Verde Nuclear Generating Station. This resulted in an increase to the ARO in the amount of $151 million, an increase in plant in service of $131 million, and a reduction of the regulatory liability of $20 million.

In 2015, a revision to the estimated cash flows for the decommissioning study was completed for the Four Corners coal-fired plant, which resulted in an increase to the ARO in the amount of $24 million. Also in 2015, Four Corners spent $32 million in actual decommissioning costs. In addition, APS recognized an ARO for Cholla as a result of new CCR environmental rules that were published in the Federal Register in the second quarter of 2015. See Note 10 for additional information related to the CCR environmental rules. This resulted in an increase to the ARO in the amount of $39 million, an increase in plant in service of $23 million and a reduction of the regulatory liability of $16 million. Finally, in 2015 there was a revision in estimated cash flows for the Cholla decommissioning, which resulted in a decrease of the ARO in the amount of $3 million.

The following table shows the change in our asset retirement obligations for 2016 and 2015 (dollars in thousands):

	2016			2015
Asset retirement obligations at the beginning of year	$	443,576		$	390,750
Changes attributable to:
Accretion expense	26,656			25,163
Settlements	(15,732		)	(32,048		)
Estimated cash flow revisions	151,046			17,556
Newly incurred or acquired obligations	18,929			42,155
Asset retirement obligations at the end of year	$	624,475		$	443,576

Decommissioning activities for Four Corners Units 1-3 began in January 2014. Thus, $9 million of the total ARO of $624 million at December 31, 2016, is classified as a current liability on the balance sheet. At December 31, 2015, $29 million of the total ARO of $444 million was classified as a current liability on the balance sheet.

In accordance with regulatory accounting, APS accrues removal costs for its regulated utility assets, even if there is no legal obligation for removal.  See detail of regulatory liabilities in Note 3.

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Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Information [Line Items]

Selected Quarterly Financial Data (Unaudited)

Selected Quarterly Financial Data (Unaudited)

Consolidated quarterly financial information for 2016 and 2015 is provided in the tables below (dollars in thousands, except per share amounts).  Weather conditions cause significant seasonal fluctuations in our revenues; therefore, results for interim periods do not necessarily represent results expected for the year.

	2016 Quarter Ended								2016
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	677,167	$	915,394	$	1,166,922	$	739,199	$	3,498,682
Operations and maintenance	243,195		242,279		217,568		208,277		911,319
Operating income	50,162		231,748		451,258		122,816		855,984
Income taxes	1,914		65,742		141,446		27,309		236,411
Net income	9,326		126,182		267,900		58,119		461,527
Net income attributable to common shareholders	4,453		121,308		263,027		53,246		442,034
Earnings Per Share:
Net income attributable to common shareholders — Basic	$	0.04	$	1.09	$	2.36	$	0.48	$	3.97
Net income attributable to common shareholders — Diluted	0.04		1.08		2.35		0.47		3.95

	2015 Quarter Ended								2015
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	671,219	$	890,648	$	1,199,146	$	734,430	$	3,495,443
Operations and maintenance	214,944		210,965		220,449		222,019		868,377
Operating income	67,684		231,973		445,111		109,834		854,602
Income taxes	7,947		67,371		139,555		22,847		237,720
Net income	20,727		127,507		261,978		45,978		456,190
Net income attributable to common shareholders	16,122		122,902		257,116		41,117		437,257
Earnings Per Share:
Net income attributable to common shareholders — Basic	$	0.15	$	1.11	$	2.32	$	0.37	$	3.94
Net income attributable to common shareholders — Diluted	0.14		1.10		2.30		0.37		3.92

ARIZONA PUBLIC SERVICE COMPANY

Selected Quarterly Financial Information [Line Items]

Selected Quarterly Financial Data (Unaudited)

Selected Quarterly Financial Data (Unaudited) - APS

APS's quarterly financial information for 2016 and 2015 is as follows (dollars in thousands):

	2016 Quarter Ended,								2016
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	676,632	$	909,757	$	1,166,359	$	737,006	$	3,489,754
Operations and maintenance	238,711		233,712		209,366		197,319		879,108
Operating income	48,930		165,684		307,601		95,765		617,980
Net income attributable to common shareholder	7,253		127,188		269,220		58,480		462,141

	2015 Quarter Ended,								2015
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	670,668	$	889,723	$	1,198,380	$	733,586	$	3,492,357
Operations and maintenance	209,947		208,031		216,011		219,146		853,135
Operating income	61,333		162,704		301,238		86,709		611,984
Net income attributable to common shareholder	19,868		125,362		261,187		43,857		450,274

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Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

We classify our assets and liabilities that are carried at fair value within the fair value hierarchy.  This hierarchy ranks the quality and reliability of the inputs used to determine fair values, which are then classified and disclosed in one of three categories.  The three levels of the fair value hierarchy are:

Level 1 — Unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date.  Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide information on an ongoing basis.  This category includes exchange traded equities, exchange traded derivative instruments, exchange traded mutual funds, cash equivalents, and investments in U.S. Treasury securities.

Level 2 — Utilizes quoted prices in active markets for similar assets or liabilities; quoted prices in markets that are not active; and model-derived valuations whose inputs are observable (such as yield curves).  This category includes non-exchange traded contracts such as forwards, options, swaps and certain investments in fixed income securities.

Level 3 — Valuation models with significant unobservable inputs that are supported by little or no market activity.  Instruments in this category include long-dated derivative transactions where valuations are unobservable due to the length of the transaction, options, and transactions in locations where observable market data does not exist.  The valuation models we employ utilize spot prices, forward prices, historical market data and other factors to forecast future prices.

Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.  Thus, a valuation may be classified in Level 3 even though the valuation may include significant inputs that are readily observable.  We maximize the use of observable inputs and minimize the use of unobservable inputs.  We rely primarily on the market approach of using prices and other market information for identical and/or comparable assets and liabilities.  If market data is not readily available, inputs may reflect our own assumptions about the inputs market participants would use.  Our assessment of the inputs and the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities as well as their placement within the fair value hierarchy levels.  We assess whether a market is active by obtaining observable broker quotes, reviewing actual market activity, and assessing the volume of transactions.  We consider broker quotes observable inputs when the quote is binding on the broker, we can validate the quote with market activity, or we can determine that the inputs the broker used to arrive at the quoted price are observable.

Certain instruments have been valued using the concept of Net Asset Value (“NAV”), as a practical expedient. These instruments are typically structured as investment companies offering shares or units to multiple investors for the purpose of providing a return. These instruments are similar to mutual funds; however, they are not traded on an exchange. During the first quarter of 2016 we retrospectively adopted new accounting guidance that requires certain instruments valued using NAV to no longer be classified within the fair value hierarchy. As such, certain instruments valued using NAV are included in our fair value disclosures and tables in a separate column; however, these investments are not classified within any of the fair value hierarchy levels. Prior to the adoption of this guidance these instruments were typically reported within Level 2 or Level 3. The adoption of this guidance changes our fair value disclosures, but does not impact the methodology for valuing these instruments, or our financial statement results.

Recurring Fair Value Measurements

We apply recurring fair value measurements to certain cash equivalents, derivative instruments, investments held in our nuclear decommissioning trust, plan assets held in our retirement and other benefit plans and coal reclamation trust investments.  See Note 7 for the fair value discussion of plan assets held in our retirement and other benefit plans.

Cash Equivalents

Cash equivalents represent short-term investments with original maturities of three months or less in exchange traded money market funds that are valued using quoted prices in active markets.

Coal Reclamation Trust Investments

The coal reclamation trust holds cash equivalent investments in money market funds that are valued using quoted prices in active markets, and are reported within Level 1.

Risk Management Activities — Derivative Instruments

Exchange traded commodity contracts are valued using unadjusted quoted prices.  For non-exchange traded commodity contracts, we calculate fair value based on the average of the bid and offer price, discounted to reflect net present value.  We maintain certain valuation adjustments for a number of risks associated with the valuation of future commitments.  These include valuation adjustments for liquidity and credit risks.  The liquidity valuation adjustment represents the cost that would be incurred if all unmatched positions were closed out or hedged.  The credit valuation adjustment represents estimated credit losses on our net exposure to counterparties, taking into account netting agreements, expected default experience for the credit rating of the counterparties and the overall diversification of the portfolio.  We maintain credit policies that management believes minimize overall credit risk.

Certain non-exchange traded commodity contracts are valued based on unobservable inputs due to the long-term nature of contracts, characteristics of the product, or the unique location of the transactions.  Our long-dated energy transactions consist of observable valuations for the near-term portion and unobservable valuations for the long-term portions of the transaction.  We rely primarily on broker quotes to value these instruments.  When our valuations utilize broker quotes, we perform various control procedures to ensure the quote has been developed consistent with fair value accounting guidance.  These controls include assessing the quote for reasonableness by comparison against other broker quotes, reviewing historical price relationships, and assessing market activity.  When broker quotes are not available, the primary valuation technique used to calculate the fair value is the extrapolation of forward pricing curves using observable market data for more liquid delivery points in the same region and actual transactions at more illiquid delivery points.

Option contracts are primarily valued using a Black-Scholes option valuation model, which utilizes both observable and unobservable inputs such as broker quotes, interest rates and price volatilities.

When the unobservable portion is significant to the overall valuation of the transaction, the entire transaction is classified as Level 3.  Our classification of instruments as Level 3 is primarily reflective of the long-term nature of our energy transactions and the use of option valuation models with significant unobservable inputs.

Our energy risk management committee, consisting of officers and key management personnel, oversees our energy risk management activities to ensure compliance with our stated energy risk management policies.  We have a risk control function that is responsible for valuing our derivative commodity instruments in accordance with established policies and procedures.  The risk control function reports to the chief financial officer’s organization.

Investments Held in our Nuclear Decommissioning Trust

The nuclear decommissioning trust invests in fixed income securities and equity securities. Equity securities are held indirectly through commingled funds.  The commingled funds are valued using the funds' NAV as a practical expedient. The funds' NAV is primarily derived from the quoted active market prices of the underlying equity securities held by the funds. We may transact in these commingled funds on a semi-monthly basis at the NAV.  The commingled funds are maintained by a bank and hold investments in accordance with the stated objective of tracking the performance of the S&P 500 Index.  Because the commingled funds' shares are offered to a limited group of investors, they are not considered to be traded in an active market. As these instruments are valued using NAV, as a practical expedient, they have not been classified within the fair value hierarchy.

Cash equivalents reported within Level 1 represent investments held in a short-term investment exchange-traded mutual fund, which invests in certificates of deposit, variable rate notes, time deposit accounts, U.S. Treasury and Agency obligations, U.S. Treasury repurchase agreements, and commercial paper.

Fixed income securities issued by the U.S. Treasury held directly by the nuclear decommissioning trust are valued using quoted active market prices and are typically classified as Level 1.  Fixed income securities issued by corporations, municipalities, and other agencies, including mortgage-backed instruments, are valued using quoted inactive market prices, quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield curves and spreads relative to such yield curves.  These instruments are classified as Level 2.  Whenever possible, multiple market quotes are obtained which enables a cross-check validation.  A primary price source is identified based on asset type, class, or issue of securities.

We price securities using information provided by our trustee for our nuclear decommissioning trust assets. Our trustee uses pricing services that utilize the valuation methodologies described to determine fair market value. We have internal control procedures designed to ensure this information is consistent with fair value accounting guidance. These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustee’s internal operating controls and valuation processes.  See Note 19 for additional discussion about our nuclear decommissioning trust.

Fair Value Tables

The following table presents the fair value at December 31, 2016 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other				Balance at December 31, 2016
Assets
Coal reclamation trust - cash equivalents (b)	$	14,521	$	—		$	—		$	—			$	14,521
Risk management activities — derivative instruments:
Commodity contracts	—		43,722			11,076			(35,103		)	(c)	19,695
Nuclear decommissioning trust:
U.S. commingled equity funds	—		—			—			353,261			(d)	353,261
Fixed income securities:
Cash and cash equivalent funds	—		—			—			795			(e)	795
U.S. Treasury	95,441		—			—			—				95,441
Corporate debt	—		111,623			—			—				111,623
Mortgage-backed securities	—		115,337			—			—				115,337
Municipal bonds	—		80,997			—			—				80,997
Other	—		22,132			—			—				22,132
Subtotal nuclear decommissioning trust	95,441		330,089			—			354,056				779,586
Total	$	109,962	$	373,811		$	11,076		$	318,953			$	813,802
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(45,641	)	$	(58,482	)	$	31,049		(c)	$	(73,074	)

(a) Primarily consists of long-dated electricity contracts.

(b) Represents investments restricted for coal mine reclamation funding related to Four Corners. These assets are included in the Other Assets line item, reported under the Investments and Other Assets section of our Consolidated Balance Sheets.

(c) Represents counterparty netting, margin and collateral.  See Note 16.

(d) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

(e) Represents nuclear decommissioning trust net pending securities sales and purchases.

The following table presents the fair value at December 31, 2015 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other				Balance at December 31, 2015
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	22,992		$	30,364		$	(25,345	)	(b)	$	28,011
Nuclear decommissioning trust:
U.S. commingled equity funds	—		—			—			314,957			(c)	314,957
Fixed income securities:
Cash and cash equivalent funds	12,260		—			—			(335		)	(d)	11,925
U.S. Treasury	117,245		—			—			—				117,245
Corporate debt	—		96,243			—			—				96,243
Mortgage-backed securities	—		99,065			—			—				99,065
Municipal bonds	—		72,206			—			—				72,206
Other	—		23,555			—			—				23,555
Subtotal nuclear decommissioning trust	129,505		291,069			—			314,622				735,196
Total	$	129,505	$	314,061		$	30,364		$	289,277			$	763,207
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(144,044	)	$	(63,343	)	$	39,698		(b)	$	(167,689	)

(a) Primarily consists of heat rate options and other long-dated electricity contracts.

(b) Represents counterparty netting, margin and collateral.  See Note 16.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

(d) Represents nuclear decommissioning trust net pending securities sales and purchases.

Fair Value Measurements Classified as Level 3

The significant unobservable inputs used in the fair value measurement of our energy derivative contracts include broker quotes that cannot be validated as an observable input primarily due to the long-term nature of the quote and option model inputs.  Significant changes in these inputs in isolation would result in significantly higher or lower fair value measurements.  Changes in our derivative contract fair values, including changes relating to unobservable inputs, typically will not impact net income due to regulatory accounting treatment (see Note 3).

Because our forward commodity contracts classified as Level 3 are currently in a net purchase position, we would expect price increases of the underlying commodity to result in increases in the net fair value of the related contracts.  Conversely, if the price of the underlying commodity decreases, the net fair value of the related contracts would likely decrease.

Our option contracts classified as Level 3 primarily relate to purchase heat rate options.  The remaining option contract expired on October 1, 2016. The significant unobservable inputs at December 31, 2015 for these instruments include electricity prices, and volatilities.  If electricity prices and electricity price volatilities increase, we would expect the fair value of these options to increase, and if these valuation inputs decrease, we would expect the fair value of these options to decrease.  If natural gas prices and natural gas price volatilities increase, we would expect the fair value of these options to decrease, and if these inputs decrease, we would expect the fair value of the options to increase.  The commodity prices and volatilities do not always move in corresponding directions.  The options’ fair values are impacted by the net changes of these various inputs.

Other unobservable valuation inputs include credit and liquidity reserves which do not have a material impact on our valuations; however, significant changes in these inputs could also result in higher or lower fair value measurements.

The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at December 31, 2016 and December 31, 2015:

	December 31, 2016 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	10,648	$	32,042	Discounted cash flows	Electricity forward price (per MWh)	$16.43 - $41.07	$	29.86
Natural Gas:
Forward Contracts (a)	428		26,440		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.32 - $3.60	$	2.81
Total	$	11,076	$	58,482

(a) Includes swaps and physical and financial contracts.

	December 31, 2015 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	24,543	$	54,679	Discounted cash flows	Electricity forward price (per MWh)	$15.92 - $40.73	$	26.86
Option Contracts (b)	—		5,628		Option model	Electricity forward price (per MWh)	$23.87 - $44.13	$	33.91
						Electricity price volatilities	40% - 59%	52		%
						Natural gas price volatilities	32% - 40%	35		%
Natural Gas:
Forward Contracts (a)	5,821		3,036		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.18 - $3.14	$	2.61
Total	$	30,364	$	63,343

(a) Includes swaps and physical and financial contracts.

(b) Electricity and natural gas price volatilities are estimated based on historical forward price movements due to lack of market quotes for implied volatilities.

The following table shows the changes in fair value for our risk management activities’ assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs for the years ended December 31, 2016 and 2015 (dollars in thousands):

	Year Ended December 31,
Commodity Contracts	2016			2015
Net derivative balance at beginning of period	$	(32,979	)	$	(41,386	)
Total net gains (losses) realized/unrealized:
Included in earnings	—			—
Included in OCI	88			(452		)
Deferred as a regulatory asset or liability	(37,543		)	(4,009		)
Settlements	15,146			14,809
Transfers into Level 3 from Level 2	1,900			(6,256		)
Transfers from Level 3 into Level 2	5,982			4,315
Net derivative balance at end of period	$	(47,406	)	$	(32,979	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—

Amounts included in earnings are recorded in either operating revenues or fuel and purchased power depending on the nature of the underlying contract.

Transfers reflect the fair market value at the beginning of the period and are triggered by a change in the lowest significant input as of the end of the period.  We had no significant Level 1 transfers to or from any other hierarchy level.  Transfers in or out of Level 3 are typically related to our long-dated energy transactions that extend beyond available quoted periods.

Financial Instruments Not Carried at Fair Value

The carrying value of our net accounts receivable, accounts payable and short-term borrowings approximate fair value.  Our short-term borrowings are classified within Level 2 of the fair value hierarchy.  See Note 6 for our long-term debt fair values.

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Earnings Per Share

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Earnings Per Share

Earnings Per Share

The following table presents the calculation of Pinnacle West’s basic and diluted earnings per share for continuing operations attributable to common shareholders for the years ended December 31, 2016, 2015 and 2014 (in thousands, except per share amounts):

	2016		2015		2014
Net income attributable to common shareholders	$	442,034	$	437,257	$	397,595
Weighted average common shares outstanding — basic	111,409		111,026		110,626
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units	637		526		552
Weighted average common shares outstanding — diluted	112,046		111,552		111,178
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic	$	3.97	$	3.94	$	3.59
Net Income attributable to common shareholders - diluted	$	3.95	$	3.92	$	3.58

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Stock-Based Compensation

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Stock-Based Compensation

Pinnacle West has incentive compensation plans under which stock-based compensation is granted to officers, key-employees, and non-officer members of the Board of Directors. Awards granted under the 2012 Long-Term Incentive Plan (“2012 Plan”) may be in the form of stock grants, restricted stock units, stock units, performance shares, restricted stock, dividend equivalents, performance share units, performance cash, incentive and non-qualified stock options, and stock appreciation rights.  The 2012 Plan authorizes up to 4.6 million common shares to be available for grant.  As of December 31, 2016, 2.5 million common shares were available for issuance under the 2012 Plan. During 2016, 2015, and 2014, the Company granted awards in the form of restricted stock units, stock units, stock grants, and performance shares. Awards granted from 2007 to 2011 were issued under the 2007 Long-Term Incentive Plan (“2007 Plan”), and no new awards may be granted under the 2007 Plan.

Stock-Based Compensation Expense and Activity

During the fourth quarter of 2016, we adopted new stock-based compensation accounting guidance prescribed by ASU 2016-09, see Note 2. Prior to the adoption of this guidance we had certain awards that were accounted for as liability awards due to the ability of the employee to withhold taxes beyond the minimum statutory tax withholding rate. Under the new standard, the tax withholding terms of our awards no longer trigger liability treatment. Accordingly, effective, January 1, 2016 certain awards that were previously classified as liability awards are now accounted for as equity awards. The impacts of this accounting change relating to prior years have been applied using a modified retrospective approach, resulting in a $6 million cumulative-effect adjustment, net of income tax expense of $3 million, to increase Retained Earnings as of January 1, 2016. The impacts of this accounting change relating to the current year, resulted in a pre-tax $12 million adjustment to decrease operations and maintenance expense that was recognized during the fourth quarter of 2016. Due to this transition approach, the following discussion reflects this change in the 2016 expense and activity; however, expense and activities relating to 2015 and 2014 reflect the historical treatment. The new standard also requires excess income tax benefits and deficiencies arising from stock based compensation to now be recognized in the period incurred, simplifies accounting for forfeitures, and clarifies certain cash flow presentation matters. These other provisions of the standard did not have a material impact on our consolidated financial statements.

Compensation cost included in net income for stock-based compensation plans was $19 million in 2016, $19 million in 2015, and $33 million in 2014.  The compensation cost capitalized is immaterial for all years. Income tax benefits related to stock-based compensation arrangements were $10 million in 2016, $7 million in 2015, and $13 million in 2014.

As of December 31, 2016, there were approximately $13 million of unrecognized compensation costs related to nonvested stock-based compensation arrangements. We expect to recognize these costs over a weighted-average period of 2 years. 

The total fair value of shares vested was $22 million in 2016, $21 million in 2015 and $22 million in 2014.

The following table is a summary of awards granted and the weighted-average grant date fair value for the three years ended 2016, 2015 and 2014.

	Restricted Stock Units, Stock Grants, and Stock Units (a)						Performance Shares (b)
	2016		2015		2014		2016		2015		2014
Units granted	141,811		152,651		179,291		166,666		151,430		166,244
Weighted-average grant date fair value	$	67.34	$	64.12	$	54.89	$	66.60	$	64.97	$	54.86

(a) Units granted includes awards that will be cash settled of 43,952 in 2016, 45,104 in 2015, and 49,018 in 2014.

(b) Reflects the target payout level.

The following table is a summary of the status of non-vested awards as of December 31, 2016 and changes during the year.

	Restricted Stock Units, Stock Grants, and Stock Units					Performance Shares
	Shares			Weighted-Average Grant Date Fair Value		Shares (b)		Weighted-Average Grant Date Fair Value
Nonvested at January 1, 2016	428,287			$	56.69	305,832		$	58.86
Granted	141,811			67.34		166,666		66.60
Change in performance factor	—			—		15,573		54.09
Vested	(230,881	)		55.07		(171,303	)	54.09
Forfeited (c)	(3,958	)		62.86		(4,044	)	62.34
Nonvested at December 31, 2016	335,259		(a)	62.04		312,724		65.32
Vested Awards Outstanding at December 31, 2016	174,201					171,303

(a) Includes 112,554 of awards that will be cash settled.

(b) The nonvested performance shares are reflected at target payout level.  The performance metric component increase or decrease in the number of shares from the target level to the estimated actual payout level is included in the increase for performance factor amounts in the year the award vests.

(c) We account for forfeitures as they occur.

Share-based liabilities paid relating to restricted stock units were $3 million, $10 million and $9 million in 2016, 2015 and 2014, respectively. This includes cash used to settle restricted stock units of $3 million for each of the years 2016, 2015 and 2014. Restricted stock units that are cash settled are classified as liability awards. Share-based liabilities paid relating to performance shares were $16 million in 2015 and $12 million in 2014. In 2016, performance shares were classified as equity awards.

Restricted Stock Units, Stock Grants, and Stock Units

Restricted stock units are granted to officers and key employees.  Restricted stock units typically vest and settle in equal annual installments over a 4-year period after the grant date.  Vesting is typically dependent upon continuous service during the vesting period; however, awards granted to retirement-eligible employees will vest upon the employee's retirement. Awardees elect to receive payment in either 100% stock, or 50% in cash and 50% in stock. Restricted stock unit awards typically include a dividend equivalent feature. This feature allows each award to accrue dividend rights equal to the dividends they would have received had they directly owned the stock. Interest on dividend rights compounds quarterly. If the award is forfeited the employee is not entitled to the dividends on those shares.

In December 2012, the Company granted a retention award of 50,617 performance-linked restricted stock units to the Chairman of the Board and Chief Executive Officer of Pinnacle West.  This award vested on December 31, 2016, because he remained employed with the Company through that date.  The Board can increase the number of awards that vest, up to an additional 33,745 restricted stock units, payable in stock, if certain performance requirements are met.

Compensation cost for restricted stock unit awards is based on the fair value of the award, with the fair value being the market price of our stock on the measurement date. Restricted stock unit awards that will be settled in cash are accounted for as liability awards, with compensation cost initially calculated on the date of grant using the Company’s closing stock price, and remeasured at each balance sheet date. Restricted stock unit awards that will be settled in shares are accounted for as equity awards, with compensation cost calculated using the Company's closing stock price on the date of grant. Compensation cost is recognized over the requisite service period based on the fair value of the award.

Stock grants are issued to non-officer members of the Board of Directors. They may elect to receive the stock grant, or to defer receipt until a later date and receive stock units in lieu of the stock grant.  The members of the Board of Directors who elect to defer may elect to receive payment in either 100% stock, or 50% in cash and 50% in stock.  Each stock unit is convertible to one share of stock. The stock units accrue dividend rights, equal to the amount of dividends the Directors would have received had they directly owned stock equal to the number of vested restricted stock units or stock units from the date of grant to the date of payment, plus interest compounded quarterly.  The dividends and interest are paid, based on the Director’s election, in either stock, or 50% in cash and 50% in stock.

Performance Share Awards

Performance share awards are granted to officers and key employees.  The awards contain two separate performance criteria that affect the number of shares that may be received if after the end of a 3-year performance period the performance criteria are met. For the first criteria, the number of shares that will vest is based upon six non-financial separate performance metrics (i.e., the metric component). The other criteria is based upon Pinnacle West's total shareholder return (TSR) in relation to the TSR of other companies in a specified utility index (i.e., the TSR component). The exact number of shares issued will vary from 0% to 200% of the target award.  Shares received include dividend rights paid in stock equal to the amount of dividends that they would have received had they directly owned stock, equal to the number of vested performance shares from the date of grant to the date of payment plus interest compounded quarterly. If the award is forfeited or if the performance criteria are not achieved the employee is not entitled to the dividends on those shares.

Performance share awards are accounted for as equity awards, with compensation cost based on the fair value of the award on grant date. Compensation cost relating to the metric component of the award is based on the Company’s closing stock price on the date of grant, with compensation cost recognized over the requisite service period based on the number of shares expected to vest. Management evaluates the probability of meeting the metric component at each balance sheet date. If the metric component criteria are not ultimately achieved, no compensation cost is recognized relating to the metric component, and any previously recognized compensation cost is reversed. Compensation cost relating to the TSR component of the award is determined using a Monte Carlo simulation valuation model, with compensation cost recognized ratably over the requisite service period, regardless of the number of shares that actually vest.

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Derivative Accounting

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Accounting

Derivative Accounting

We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal, emissions allowances and in interest rates.  We manage risks associated with market volatility by utilizing various physical and financial derivative instruments, including futures, forwards, options and swaps.  As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and fuels.  Derivative instruments that meet certain hedge accounting criteria may be designated as cash flow hedges and are used to limit our exposure to cash flow variability on forecasted transactions.  The changes in market value of such instruments have a high correlation to price changes in the hedged transactions.  We also enter into derivative instruments for economic hedging purposes.  While we believe the economic hedges mitigate exposure to fluctuations in commodity prices, these instruments have not been designated as accounting hedges.  Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power costs in our Consolidated Statements of Income, but does not impact our financial condition, net income or cash flows.

Our derivative instruments, excluding those qualifying for a scope exception, are recorded on the balance sheet as an asset or liability and are measured at fair value.  See Note 13 for a discussion of fair value measurements.  Derivative instruments may qualify for the normal purchases and normal sales scope exception if they require physical delivery and the quantities represent those transacted in the normal course of business.  Derivative instruments qualifying for the normal purchases and sales scope exception are accounted for under the accrual method of accounting and excluded from our derivative instrument discussion and disclosures below.

Hedge effectiveness is the degree to which the derivative instrument contract and the hedged item are correlated and is measured based on the relative changes in fair value of the derivative instrument contract and the hedged item over time.  We assess hedge effectiveness both at inception and on a continuing basis.  These assessments exclude the time value of certain options.  For accounting hedges that are deemed an effective hedge, the effective portion of the gain or loss on the derivative instrument is reported as a component of OCI and reclassified into earnings in the same period during which the hedged transaction affects earnings.  We recognize in current earnings, subject to the PSA, the gains and losses representing hedge ineffectiveness, and the gains and losses on any hedge components which are excluded from our effectiveness assessment.  As cash flow hedge accounting has been discontinued for the significant majority of our contracts, after May 31, 2012, effectiveness testing is no longer being performed for these contracts.

For its regulated operations, APS defers for future rate treatment 100% of the unrealized gains and losses on derivatives pursuant to the PSA mechanism that would otherwise be recognized in income.  Realized gains and losses on derivatives are deferred in accordance with the PSA to the extent the amounts are above or below the Base Fuel Rate (see Note 3).  Gains and losses from derivatives in the following tables represent the amounts reflected in income before the effect of PSA deferrals.

As of December 31, 2016, we had the following outstanding gross notional volume of derivatives, which represent both purchases and sales (does not reflect net position):

Commodity	Quantity
Power	1,314	GWh
Gas	194	Billion cubic feet

Gains and Losses from Derivative Instruments

The following table provides information about gains and losses from derivative instruments in designated cash flow accounting hedging relationships during the years ended December 31, 2016, 2015 and 2014 (dollars in thousands):

	Financial Statement	Year Ended December 31,
Commodity Contracts	Location	2016			2015			2014
Gain (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	OCI — derivative instruments	$	47		$	(615	)	$	(372	)
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized) (a)	Fuel and purchased power (b)	(3,926		)	(5,988		)	(21,415		)

(a) During the years ended December 31, 2016, 2015, and 2014, we had no losses reclassified from accumulated OCI to earnings related to discontinued cash flow hedges.

(b) Amounts are before the effect of PSA deferrals.

During the next twelve months, we estimate that a net loss of $3 million before income taxes will be reclassified from accumulated OCI as an offset to the effect of market price changes for the related hedged transactions.  In accordance with the PSA, most of these amounts will be recorded as either a regulatory asset or liability and have no immediate effect on earnings.

The following table provides information about gains and losses from derivative instruments not designated as accounting hedging instruments during the years ended December 31, 2016, 2015 and 2014 (dollars in thousands):

	Financial Statement	Year Ended December 31,
Commodity Contracts	Location	2016		2015			2014
Net Gain Recognized in Income	Operating revenues	$	771	$	574		$	324
Net Gain (Loss) Recognized in Income	Fuel and purchased power (a)	25,711		(108,973		)	(66,367		)
Total		$	26,482	$	(108,399	)	$	(66,043	)

(a) Amounts are before the effect of PSA deferrals.

Derivative Instruments in the Consolidated Balance Sheets

Our derivative transactions are typically executed under standardized or customized agreements, which include collateral requirements and, in the event of a default, would allow for the netting of positive and negative exposures associated with a single counterparty.  Agreements that allow for the offsetting of positive and negative exposures associated with a single counterparty are considered master netting arrangements.  Transactions with counterparties that have master netting arrangements are offset and reported net on the Consolidated Balance Sheets.  Transactions that do not allow for offsetting of positive and negative positions are reported gross on the Consolidated Balance Sheets.

We do not offset a counterparty’s current derivative contracts with the counterparty’s non-current derivative contracts, although our master netting arrangements would allow current and non-current positions to be offset in the event of a default.  Additionally, in the event of a default, our master netting arrangements would allow for the offsetting of all transactions executed under the master netting arrangement.  These types of transactions may include non-derivative instruments, derivatives qualifying for scope exceptions, trade receivables and trade payables arising from settled positions, and other forms of non-cash collateral (such as letters of credit).  These types of transactions are excluded from the offsetting tables presented below.

The significant majority of our derivative instruments are not currently designated as hedging instruments.  The Consolidated Balance Sheets as of December 31, 2016 and December 31, 2015, include gross liabilities of $2 million and $3 million, respectively, of derivative instruments designated as hedging instruments.

The following tables provide information about the fair value of our risk management activities reported on a gross basis, and the impacts of offsetting as of December 31, 2016 and 2015.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Consolidated Balance Sheets.

As of December 31, 2016: (dollars in thousands)	Gross  Recognized  Derivatives (a)			Amounts  Offset (b)			Net Recognized Derivatives			Other (c)			Amount  Reported on  Balance Sheet
Current assets	$	48,094		$	(28,400	)	$	19,694		$	—		$	19,694
Investments and other assets	6,704			(6,703		)	1			—			1
Total assets	54,798			(35,103		)	19,695			—			19,695
Current liabilities	(50,182		)	28,400			(21,782		)	(4,054		)	(25,836		)
Deferred credits and other	(53,941		)	6,703			(47,238		)	—			(47,238		)
Total liabilities	(104,123		)	35,103			(69,020		)	(4,054		)	(73,074		)
Total	$	(49,325	)	$	—		$	(49,325	)	$	(4,054	)	$	(53,379	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting.

(c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,054.

As of December 31, 2015: (dollars in thousands)	Gross Recognized Derivatives (a)			Amounts Offset  (b)			Net Recognized Derivatives			Other (c)			Amount Reported on Balance Sheet
Current assets	$	37,396		$	(22,163	)	$	15,233		$	672		$	15,905
Investments and other assets	15,960			(3,854		)	12,106			—			12,106
Total assets	53,356			(26,017		)	27,339			672			28,011
Current liabilities	(113,560		)	40,223			(73,337		)	(4,379		)	(77,716		)
Deferred credits and other	(93,827		)	3,854			(89,973		)	—			(89,973		)
Total liabilities	(207,387		)	44,077			(163,310		)	(4,379		)	(167,689		)
Total	$	(154,031	)	$	18,060		$	(135,971	)	$	(3,707	)	$	(139,678	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) Includes cash collateral provided to counterparties of $18,060.

(c) Represents cash collateral and cash margin that is not subject to offsetting.  Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,379, and cash margin provided to counterparties of $672. 

Credit Risk and Credit Related Contingent Features

We are exposed to losses in the event of nonperformance or nonpayment by counterparties and have risk management contracts with many counterparties. As of December 31, 2016, we have no counterparties with positive exposures of greater than 10% of risk management assets. Our risk management process assesses and monitors the financial exposure of all counterparties.  Despite the fact that the great majority of trading counterparties' debt is rated as investment grade by the credit rating agencies, there is still a possibility that one or more of these companies could default, resulting in a material impact on consolidated earnings for a given period. Counterparties in the portfolio consist principally of financial institutions, major energy companies, municipalities and local distribution companies.  We maintain credit policies that we believe minimize overall credit risk to within acceptable limits.  Determination of the credit quality of our counterparties is based upon a number of factors, including credit ratings and our evaluation of their financial condition.  To manage credit risk, we employ collateral requirements and standardized agreements that allow for the netting of positive and negative exposures associated with a single counterparty.  Valuation adjustments are established representing our estimated credit losses on our overall exposure to counterparties.

Certain of our derivative instrument contracts contain credit-risk-related contingent features including, among other things, investment grade credit rating provisions, credit-related cross-default provisions, and adequate assurance provisions.  Adequate assurance provisions allow a counterparty with reasonable grounds for uncertainty to demand additional collateral based on subjective events and/or conditions.  For those derivative instruments in a net liability position, with investment grade credit contingencies, the counterparties could demand additional collateral if our debt credit rating were to fall below investment grade (below BBB- for Standard & Poor’s or Fitch or Baa3 for Moody’s).

The following table provides information about our derivative instruments that have credit-risk-related contingent features at December 31, 2016 (dollars in thousands):

	December 31, 2016
Aggregate fair value of derivative instruments in a net liability position	$	104,123
Cash collateral posted	—
Additional cash collateral in the event credit-risk related contingent features were fully triggered (a)	23,914

(a) This amount is after counterparty netting and includes those contracts which qualify for scope exceptions, which are excluded from the derivative details above.

We also have energy related non-derivative instrument contracts with investment grade credit-related contingent features, which could also require us to post additional collateral of approximately $144 million if our debt credit ratings were to fall below investment grade.

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Other Income and Other Expense

12 Months Ended

Dec. 31, 2016

Component of Other Income and Other Expense Nonoperating [Line Items]

Other Income and Other Expense

Other Income and Other Expense

The following table provides detail of Pinnacle West's Consolidated other income and other expense for 2016, 2015 and 2014 (dollars in thousands):

	2016			2015			2014
Other income:
Interest income	$	884		$	493		$	1,010
Debt return on the purchase of Four Corners units 4 & 5	—			—			8,386
Miscellaneous	17			128			212
Total other income	$	901		$	621		$	9,608
Other expense:
Non-operating costs	$	(9,235	)	$	(11,292	)	$	(9,657	)
Investment losses — net	(1,747		)	(2,080		)	(9,426		)
Miscellaneous	(4,355		)	(4,451		)	(2,663		)
Total other expense	$	(15,337	)	$	(17,823	)	$	(21,746	)

ARIZONA PUBLIC SERVICE COMPANY

Component of Other Income and Other Expense Nonoperating [Line Items]

Other Income and Other Expense

Other Income and Other Expense - APS

The following table provides detail of APS’s other income and other expense for 2016, 2015 and 2014 (dollars in thousands):

	2016			2015			2014
Other income:
Interest income	$	261		$	163		$	689
Debt return on the purchase of Four Corners units 4 & 5	—			—			8,386
Gain on disposition of property	5,745			716			1,197
Miscellaneous	2,601			1,955			1,023
Total other income	$	8,607		$	2,834		$	11,295
Other expense:
Non-operating costs (a)	$	(11,034	)	$	(11,648	)	$	(10,397	)
Loss on disposition of property	(1,246		)	(2,219		)	(615		)
Miscellaneous	(5,234		)	(5,152		)	(2,391		)
Total other expense	$	(17,514	)	$	(19,019	)	$	(13,403	)

(a)As defined by FERC, includes non-operating utility income and expense (items excluded from utility rate recovery).

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Palo Verde Sale Leaseback Variable Interest Entities

12 Months Ended

Dec. 31, 2016

Variable Interest Entities [Abstract]

Palo Verde Sale Leaseback Variable Interest Entities

Palo Verde Sale Leaseback Variable Interest Entities

In 1986, APS entered into agreements with three separate VIE lessor trust entities in order to sell and lease back interests in Palo Verde Unit 2 and related common facilities.  APS will retain the assets through 2023 under one lease and 2033 under the other two leases. APS will be required to make payments relating to these leases of approximately $23 million annually for the period 2017 through 2023, and about $16 million annually for the period 2024 through 2033. At the end of the lease period, APS will have the option to purchase the leased assets at their fair market value, extend the leases for up to two years, or return the assets to the lessors.

The leases' terms give APS the ability to utilize the assets for a significant portion of the assets' economic life, and therefore provide APS with the power to direct activities of the VIEs that most significantly impact the VIEs' economic performance. Predominantly due to the lease terms, APS has been deemed the primary beneficiary of these VIEs and therefore consolidates the VIEs.

As a result of consolidation, we eliminate lease accounting and instead recognize depreciation expense, resulting in an increase in net income for 2016, 2015 and 2014 of $19 million, $19 million and $26 million, respectively, entirely attributable to the noncontrolling interests.  Income attributable to Pinnacle West shareholders is not impacted by the consolidation.

Our Consolidated Balance Sheets at December 31, 2016 and December 31, 2015 include the following amounts relating to the VIEs (dollars in thousands):

	December 31, 2016		December 31, 2015
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	$	113,515	$	117,385
Equity-Noncontrolling interests	132,290		135,540

Assets of the VIEs are restricted and may only be used for payment to the noncontrolling interest holders.  These assets are reported on our consolidated financial statements.

APS is exposed to losses relating to these VIEs upon the occurrence of certain events that APS does not consider reasonably likely to occur.  Under certain circumstances (for example, the NRC issuing specified violation orders with respect to Palo Verde or the occurrence of specified nuclear events), APS would be required to make specified payments to the VIEs’ noncontrolling equity participants and take title to the leased Unit 2 interests, which, if appropriate, may be required to be written down in value.  If such an event were to occur during the lease periods, APS may be required to pay the noncontrolling equity participants approximately $291 million beginning in 2017, and up to $456 million over the lease extension term.

For regulatory ratemaking purposes, the agreements continue to be treated as operating leases and, as a result, we have recorded a regulatory asset relating to the arrangements.

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Nuclear Decommissioning Trusts

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Nuclear Decommissioning Trusts

Nuclear Decommissioning Trusts

To fund the costs APS expects to incur to decommission Palo Verde, APS established external decommissioning trusts in accordance with NRC regulations.  Third-party investment managers are authorized to buy and sell securities per stated investment guidelines.  The trust funds are invested in fixed income securities and equity securities.  APS classifies investments in decommissioning trust funds as available for sale.  As a result, we record the decommissioning trust funds at their fair value on our Consolidated Balance Sheets.  See Note 13 for a discussion of how fair value is determined and the classification of the nuclear decommissioning trust investments within the fair value hierarchy.  Because of the ability of APS to recover decommissioning costs in rates and in accordance with the regulatory treatment for decommissioning trust funds, we have deferred realized and unrealized gains and losses (including other-than-temporary impairments on investment securities) in other regulatory liabilities.  The following table includes the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS’s nuclear decommissioning trust fund assets at December 31, 2016 and December 31, 2015 (dollars in thousands):

	Fair Value		Total  Unrealized  Gains		Total  Unrealized  Losses
December 31, 2016
Equity securities	$	353,261	$	188,091	$	—
Fixed income securities	425,530		9,820		(4,962		)
Net receivables (a)	795		—		—
Total	$	779,586	$	197,911	$	(4,962	)

	Fair Value			Total  Unrealized  Gains		Total  Unrealized  Losses
December 31, 2015
Equity securities	$	314,957		$	157,098	$	(115	)
Fixed income securities	420,574			11,955		(2,645		)
Net payables (a)	(335		)	—		—
Total	$	735,196		$	169,053	$	(2,760	)

(a) Net receivables/(payables) relate to pending purchases and sales of securities.

The costs of securities sold are determined on the basis of specific identification.  The following table sets forth approximate gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds (dollars in thousands):

	Year Ended December 31,
	2016			2015			2014
Realized gains	$	11,213		$	5,189		$	4,725
Realized losses	(10,106		)	(6,225		)	(4,525		)
Proceeds from the sale of securities (a)	633,410			478,813			356,195

(a) Proceeds are reinvested in the trust.

The fair value of fixed income securities, summarized by contractual maturities, at December 31, 2016 is as follows (dollars in thousands):

	Fair Value
Less than one year	$	13,063
1 year – 5 years	119,292
5 years – 10 years	105,612
Greater than 10 years	187,563
Total	$	425,530

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Changes in Accumulated Other Comprehensive Loss

12 Months Ended

Dec. 31, 2016

Changes in accumulated other comprehensive income (loss) including reclassification adjustments, by component:

Changes in Accumulated Other Comprehensive Loss

Changes in Accumulated Other Comprehensive Loss

The following table shows the changes in Pinnacle West's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2016 and 2015 (dollars in thousands): 

	Year Ended December 31,
	2016			2015
Balance at beginning of period	$	(44,748	)	$	(68,141	)
Derivative Instruments
OCI (loss) before reclassifications	(538		)	(957		)
Amounts reclassified from accumulated other comprehensive loss (a)	2,941			4,187
Net current period OCI (loss)	2,403			3,230
Pension and Other Postretirement Benefits
OCI (loss) before reclassifications	(4,509		)	16,980
Amounts reclassified from accumulated other comprehensive loss (b)	3,032			3,183
Net current period OCI (loss)	(1,477		)	20,163
Balance at end of period	$	(43,822	)	$	(44,748	)

(a) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA.  See Note 16.

(b) These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost.  See Note 7.

ARIZONA PUBLIC SERVICE COMPANY

Changes in accumulated other comprehensive income (loss) including reclassification adjustments, by component:

Changes in Accumulated Other Comprehensive Loss

Changes in Accumulated Other Comprehensive Loss - APS

The following table shows the changes in APS's accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2016 and 2015 (dollars in thousands): 

	Year Ended December 31,
	2016			2015
Balance at beginning of period	$	(27,097	)	$	(48,333	)
Derivative Instruments
OCI (loss) before reclassifications	(538		)	(957		)
Amounts reclassified from accumulated other comprehensive loss (a)	2,941			4,187
Net current period OCI (loss)	2,403			3,230
Pension and Other Postretirement Benefits
OCI (loss) before reclassifications	(3,821		)	14,726
Amounts reclassified from accumulated other comprehensive loss (b)	3,092			3,280
Net current period OCI (loss)	(729		)	18,006
Balance at end of period	$	(25,423	)	$	(27,097	)

(a) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA.  See Note 16.

(b) These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost.  See Note 7.

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SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT

12 Months Ended

Dec. 31, 2016

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

CONDENSED FINANCIAL INFORMATION OF REGISTRANT

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED STATEMENTS OF COMPREHENSIVE INCOME

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
Operating revenues	$	370		$	550		$	642
Operating expenses	26,424			12,733			23,507
Operating loss	(26,054		)	(12,183		)	(22,865		)
Other
Equity in earnings of subsidiaries	462,027			446,508			411,528
Other expense	(1,771		)	(3,302		)	(3,276		)
Total	460,256			443,206			408,252
Interest expense	3,151			2,672			3,663
Income before income taxes	431,051			428,351			381,724
Income tax benefit	(10,983		)	(8,906		)	(15,871		)
Net income attributable to common shareholders	442,034			437,257			397,595
Other comprehensive income — attributable to common shareholders	926			23,393			9,912
Total comprehensive income — attributable to common shareholders	$	442,960		$	460,650		$	407,507

See Combined Notes to Consolidated Financial Statements.

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED BALANCE SHEETS

(dollars in thousands)

	December 31,
	2016			2015
ASSETS
Current assets
Cash and cash equivalents	$	41		$	17,432
Accounts receivable	81,751			93,093
Income tax receivable	—			14,895
Other current assets	340			197
Total current assets	82,132			125,617
Investments and other assets
Investments in subsidiaries	5,084,035			4,815,236
Deferred income taxes	53,805			41,065
Other assets	38,500			43,422
Total investments and other assets	5,176,340			4,899,723
Total Assets	$	5,258,472		$	5,025,340
LIABILITIES AND EQUITY
Current liabilities
Accounts payable	$	5,421		$	5,901
Accrued taxes	12,050			6,904
Common dividends payable	72,926			69,363
Short-term borrowings	41,700			—
Current maturities of long-term debt	125,000			—
Other current liabilities	31,182			33,120
Total current liabilities	288,279			115,288
Long-term debt less current maturities	—			125,000
Pension liabilities	21,057			21,933
Other	13,224			43,662
Total deferred credits and other	34,281			65,595
Common stock equity
Common stock	2,591,897			2,535,862
Accumulated other comprehensive loss	(43,822		)	(44,748		)
Retained earnings	2,255,547			2,092,803
Total Pinnacle West Shareholders’ equity	4,803,622			4,583,917
Noncontrolling interests	132,290			135,540
Total Equity	4,935,912			4,719,457
Total Liabilities and Equity	$	5,258,472		$	5,025,340

See Combined Notes to Consolidated Financial Statements.

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED STATEMENTS OF CASH FLOWS

(dollars in thousands)

	Year Ended December 31,
	2016			2015			2014
Cash flows from operating activities
Net income	$	442,034		$	437,257		$	397,595
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in earnings of subsidiaries — net	(462,027		)	(446,508		)	(411,528		)
Depreciation and amortization	85			92			94
Deferred income taxes	(12,402		)	12,967			4,406
Accounts receivable	15,823			11,336			(22,945		)
Accounts payable	10,402			637			2,017
Accrued taxes and income tax receivables — net	20,041			(12,882		)	(1,795		)
Dividends received from subsidiaries	239,300			266,900			253,600
Other	5,514			(6,995		)	18,432
Net cash flow provided by operating activities	258,770			262,804			239,876
Cash flows from investing activities
Construction work in progress	(18,457		)	(3,462		)	—
Investments in subsidiaries	(19,242		)	(3,491		)	(10,236		)
Repayments of loans from subsidiaries	1,026			157			322
Advances of loans to subsidiaries	(2,092		)	(1,010		)	(1,450		)
Net cash flow used for investing activities	(38,765		)	(7,806		)	(11,364		)
Cash flows from financing activities
Issuance of long-term debt	—			—			125,000
Short-term debt borrowings under revolving credit facility	40,000			—			—
Commercial Paper - net	1,700			—			—
Dividends paid on common stock	(274,229		)	(260,027		)	(246,671		)
Repayment of long-term debt	—			—			(125,000		)
Common stock equity issuance - net of purchases	(4,867		)	19,373			15,288
Other	—			—			161
Net cash flow used for financing activities	(237,396		)	(240,654		)	(231,222		)
Net increase (decrease) in cash and cash equivalents	(17,391		)	14,344			(2,710		)
Cash and cash equivalents at beginning of year	17,432			3,088			5,798
Cash and cash equivalents at end of year	$	41		$	17,432		$	3,088

     See Combined Notes to Consolidated Financial Statements.

PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY

NOTES TO FINANCIAL STATEMENTS OF HOLDING COMPANY

The Combined Notes to Consolidated Financial Statements in Part II, Item 8 should be read in conjunction with the Pinnacle West Capital Corporation Holding Company Financial Statements.

The Pinnacle West Capital Corporation Holding Company Financial Statements have been prepared to present the financial position, results of operations and cash flows of the Pinnacle West Capital Corporation on a stand-alone basis as a holding company. Investments in subsidiaries are accounted for using the equity method.

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SCHEDULE II - RESERVE FOR UNCOLLECTIBLES

12 Months Ended

Dec. 31, 2016

Reserve for uncollectibles

SCHEDULE II - RESERVE FOR UNCOLLECTIBLES

SCHEDULE II — RESERVE FOR UNCOLLECTIBLES

(dollars in thousands)

Column A	Column B		Column C				Column D		Column E
			Additions
Description	Balance at beginning of period		Charged to cost and expenses		Charged to other accounts		Deductions		Balance at end of period
Reserve for uncollectibles:
2016	$	3,125	$	4,025	$	—	$	4,113	$	3,037
2015	3,094		4,073		—		4,042		3,125
2014	3,203		3,942		—		4,051		3,094

ARIZONA PUBLIC SERVICE COMPANY

Reserve for uncollectibles

SCHEDULE II - RESERVE FOR UNCOLLECTIBLES

ARIZONA PUBLIC SERVICE COMPANY

SCHEDULE II — RESERVE FOR UNCOLLECTIBLES

(dollars in thousands)

Column A	Column B		Column C				Column D		Column E
			Additions
Description	Balance at beginning of period		Charged to cost and expenses		Charged to other accounts		Deductions		Balance at end of period
Reserve for uncollectibles:
2016	$	3,125	$	4,025	$	—	$	4,113	$	3,037
2015	3,094		4,073		—		4,042		3,125
2014	3,203		3,942		—		4,051		3,094

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Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Description of Business and Basis of Presentation

Description of Business and Basis of Presentation

Pinnacle West is a holding company that conducts business through its subsidiaries, APS, El Dorado, BCE and 4CA. APS, our wholly-owned subsidiary, is a vertically-integrated electric utility that provides either retail or wholesale electric service to substantially all of the state of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona.  APS accounts for essentially all of our revenues and earnings, and is expected to continue to do so.  El Dorado is an investment firm. BCE is a subsidiary that was formed in 2014 that focuses on growth opportunities that leverage the Company's core expertise in the electric energy industry. BCE is currently pursuing transmission opportunities through a joint venture arrangement. 4CA is a subsidiary that was formed in 2016 as a result of the purchase of El Paso's 7% interest in Four Corners.

Pinnacle West’s Consolidated Financial Statements include the accounts of Pinnacle West and our subsidiaries:  APS, El Dorado, BCE and 4CA. APS’s consolidated financial statements include the accounts of APS and certain VIEs relating to the Palo Verde sale leaseback.  Intercompany accounts and transactions between the consolidated companies have been eliminated.

We consolidate VIEs for which we are the primary beneficiary.  We determine whether we are the primary beneficiary of a VIE through a qualitative analysis that identifies which variable interest holder has the controlling financial interest in the VIE.  In performing our primary beneficiary analysis, we consider all relevant facts and circumstances, including the design and activities of the VIE, the terms of the contracts the VIE has entered into, and which parties participated significantly in the design or redesign of the entity.  We continually evaluate our primary beneficiary conclusions to determine if changes have occurred which would impact our primary beneficiary assessments.  We have determined that APS is the primary beneficiary of certain VIE lessor trusts relating to the Palo Verde sale leaseback, and therefore APS consolidates these entities (see Note 18).

Our consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as otherwise disclosed in the notes) that we believe are necessary for the fair presentation of our financial position, results of operations and cash flows for the periods presented.

Certain line items are presented in more detail on the Consolidated Statements of Cash Flows than was presented in the prior years. The prior year amounts were reclassified to conform to the current year presentation. These reclassifications have no impact on net cash flows provided by operating activities. The following tables show the impacts of the reclassifications of the prior years (previously reported) amounts (dollars in thousands):

Statement of Cash Flows for the Year Ended December 31, 2015	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	18,756		$	18,756
Change in other long term liabilities	(81,959		)	(18,756		)	(100,715		)

Statement of Cash Flows for the Year Ended December 31, 2014	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	33,059		$	33,059
Change in other long-term liabilities	(80,993		)	(33,059		)	(114,052		)

Accounting Records and Use of Estimates

Accounting Records and Use of Estimates

Our accounting records are maintained in accordance with GAAP.  The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period.  Actual results could differ from those estimates.

Regulatory Accounting

Regulatory Accounting

APS is regulated by the ACC and FERC.  The accompanying financial statements reflect the rate-making policies of these commissions.  As a result, we capitalize certain costs that would be included as expense in the current period by unregulated companies.  Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer rates.  Regulatory liabilities generally represent expected future costs that have already been collected from customers.

Management continually assesses whether our regulatory assets are probable of future recovery by considering factors such as changes in the applicable regulatory environment and recent rate orders applicable to APS or other regulated entities in the same jurisdiction.  This determination reflects the current political and regulatory climate in Arizona and is subject to change in the future.  If future recovery of costs ceases to be probable, the assets would be written off as a charge in current period earnings.

Electric Revenues

Electric Revenues

We derive electric revenues primarily from sales of electricity to our regulated Native Load customers.  Revenues related to the sale of electricity are generally recorded when service is rendered or electricity is delivered to customers.  The billing of electricity sales to individual Native Load customers is based on the reading of their meters, which occurs on a systematic basis throughout the month.  Unbilled revenues are estimated by applying an average revenue/kWh by customer class to the number of estimated kWhs delivered but not billed.  Differences historically between the actual and estimated unbilled revenues are immaterial.  We exclude sales taxes and franchise fees on electric revenues from both revenue and taxes other than income taxes.

Revenues from our Native Load customers and non-derivative instruments are reported on a gross basis on Pinnacle West’s Consolidated Statements of Income.  In the electricity business, some contracts to purchase energy are netted against other contracts to sell energy.  This is called a “book-out” and usually occurs for contracts that have the same terms (quantities and delivery points) and for which power does not flow.  We net these book-outs, which reduces both revenues and fuel and purchased power costs.

Some of our cost recovery mechanisms are alternative revenue programs.  For alternative revenue programs that meet specified accounting criteria, we recognize revenues when the specific events permitting billing of the additional revenues have been completed.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts

The allowance for doubtful accounts represents our best estimate of existing accounts receivable that will ultimately be uncollectible.  The allowance is calculated by applying estimated write-off factors to various classes of outstanding receivables, including accrued utility revenues.  The write-off factors used to estimate uncollectible accounts are based upon consideration of both historical collections experience and management’s best estimate of future collections success given the existing collections environment.

Property, Plant and Equipment

Property, Plant and Equipment

Utility plant is the term we use to describe the business property and equipment that supports electric service, consisting primarily of generation, transmission and distribution facilities.  We report utility plant at its original cost, which includes:

• material and labor;

• contractor costs;

• capitalized leases;

• construction overhead costs (where applicable); and

• allowance for funds used during construction.

Property, plant and equipment balances and classes for APS are not materially different than Pinnacle West.

We expense the costs of plant outages, major maintenance and routine maintenance as incurred.  We charge retired utility plant to accumulated depreciation.  Liabilities associated with the retirement of tangible long-lived assets are recognized at fair value as incurred and capitalized as part of the related tangible long-lived assets.  Accretion of the liability due to the passage of time is an operating expense, and the capitalized cost is depreciated over the useful life of the long-lived asset.  See Note 11.

APS records a regulatory liability for the difference between the amount that has been recovered in regulated rates and the amount calculated in accordance with guidance on accounting for asset retirement obligations.  APS believes it can recover in regulated rates the costs calculated in accordance with this accounting guidance.

We record depreciation on utility plant on a straight-line basis over the remaining useful life of the related assets.

Allowance for Funds Used During Construction

Allowance for Funds Used During Construction

AFUDC represents the approximate net composite interest cost of borrowed funds and an allowed return on the equity funds used for construction of regulated utility plant.  Both the debt and equity components of AFUDC are non-cash amounts within the Consolidated Statements of Income.  Plant construction costs, including AFUDC, are recovered in authorized rates through depreciation when completed projects are placed into commercial operation.

AFUDC was calculated by using a composite rate of 7.17% for 2016, 8.02% for 2015, and 8.47% for 2014.  APS compounds AFUDC semi-annually and ceases to accrue AFUDC when construction work is completed and the property is placed in service.

Materials and Supplies

Materials and Supplies

APS values materials, supplies and fossil fuel inventory using a weighted-average cost method.  APS materials, supplies and fossil fuel inventories are carried at the lower of weighted-average cost or market, unless evidence indicates that the weighted-average cost (even if in excess of market) will be recovered.

Fair Value Measurements

Fair Value Measurements

We account for derivative instruments, investments held in our nuclear decommissioning trust, certain cash equivalents and plan assets held in our retirement and other benefit plans at fair value on a recurring basis.  Due to the short-term nature of net accounts receivable, accounts payable, and short-term borrowings, the carrying values of these instruments approximate fair value.  Fair value measurements may also be applied on a nonrecurring basis to other assets and liabilities in certain circumstances such as impairments.  We also disclose fair value information for our long-term debt, which is carried at amortized cost (see Note 6).

Fair value is the price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market which we can access for the asset or liability in an orderly transaction between willing market participants on the measurement date.  Inputs to fair value may include observable and unobservable data.  We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

We determine fair market value using observable inputs such as actively-quoted prices for identical instruments when available.  When actively quoted prices are not available for the identical instruments, we use other observable inputs, such as prices for similar instruments, other corroborative market information, or prices provided by other external sources.  For options, long-term contracts and other contracts for which observable price data are not available, we use models and other valuation methods, which may incorporate unobservable inputs to determine fair market value.

The use of models and other valuation methods to determine fair market value often requires subjective and complex judgment.  Actual results could differ from the results estimated through application of these methods.

Derivative Accounting

Derivative Accounting

We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal and in interest rates.  We manage risks associated with market volatility by utilizing various physical and financial instruments including futures, forwards, options and swaps.  As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and fuels.  The changes in market value of such contracts have a high correlation to price changes in the hedged transactions.  We also enter into derivative instruments for economic hedging purposes.  Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power expenses in our Consolidated Statements of Income, but does not impact our financial condition, net income or cash flows.

We account for our derivative contracts in accordance with derivatives and hedging guidance, which requires all derivatives not qualifying for a scope exception to be measured at fair value on the balance sheet as either assets or liabilities.  Transactions with counterparties that have master netting arrangements are reported net on the balance sheet.

Loss Contingencies and Environmental Liabilities

Loss Contingencies and Environmental Liabilities

Pinnacle West and APS are involved in certain legal and environmental matters that arise in the normal course of business.  Contingent losses and environmental liabilities are recorded when it is determined that it is probable that a loss has occurred and the amount of the loss can be reasonably estimated.  When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, Pinnacle West and APS record a loss contingency at the minimum amount in the range.  Unless otherwise required by GAAP, legal fees are expensed as incurred.

Retirement Plans and Other Postretirement Benefits

Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan for the employees of Pinnacle West and its subsidiaries.  We also sponsor an other postretirement benefit plan for the employees of Pinnacle West and its subsidiaries that provides medical and life insurance benefits to retired employees.  Pension and other postretirement benefit expense are determined by actuarial valuations, based on assumptions that are evaluated annually.

Nuclear Fuel

Nuclear Fuel

APS amortizes nuclear fuel by using the unit-of-production method.  The unit-of-production method is based on actual physical usage.  APS divides the cost of the fuel by the estimated number of thermal units it expects to produce with that fuel.  APS then multiplies that rate by the number of thermal units produced within the current period.  This calculation determines the current period nuclear fuel expense.

APS also charges nuclear fuel expense for the interim storage and permanent disposal of spent nuclear fuel.  The DOE is responsible for the permanent disposal of spent nuclear fuel and charged APS $0.001 per kWh of nuclear generation through May 2014, at which point the DOE suspended the fee.  In accordance with a settlement agreement with the DOE in August 2014, we will now accrue a receivable for incurred claims and an offsetting regulatory liability through the settlement period ending December of 2016.

Income Taxes

Income Taxes

Income taxes are provided using the asset and liability approach prescribed by guidance relating to accounting for income taxes.  We file our federal income tax return on a consolidated basis, and we file our state income tax returns on a consolidated or unitary basis.  In accordance with our intercompany tax sharing agreement, federal and state income taxes are allocated to each first-tier subsidiary as though each first-tier subsidiary filed a separate income tax return.  Any difference between that method and the consolidated (and unitary) income tax liability is attributed to the parent company.  The income tax accounts reflect the tax and interest associated with management’s estimate of the largest amount of tax benefit that is greater than 50% likely of being realized upon settlement for all known and measurable tax exposures (see Note 4).

Cash and Cash Equivalents

Cash and Cash Equivalents

We consider all highly liquid investments with a remaining maturity of three months or less at acquisition to be cash equivalents.

Intangible Assets

Intangible Assets

We have no goodwill recorded and have separately disclosed other intangible assets, primarily APS's software, on Pinnacle West’s Consolidated Balance Sheets. The intangible assets are amortized over their finite useful lives.

Investments

Investments

El Dorado accounts for its investments using either the equity method (if significant influence) or the cost method (if less than 20% ownership and no significant influence).

Our investments in the nuclear decommissioning trust fund are accounted for in accordance with guidance on accounting for certain investments in debt and equity securities.

Business Segments

Business Segments

Pinnacle West’s reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electricity service to Native Load customers) and related activities and includes electricity generation, transmission and distribution. All other segment activities are insignificant.

New Accounting Standards

New Accounting Standards

ASU 2016-09, Stock Compensation: Improvements to Employee Share-Based Payment Accounting

In March 2016, new stock compensation accounting guidance was issued intended to simplify the accounting for employee share-based payments. The new guidance impacts several aspects of the accounting for share-based payments including: modifies the tax withholding threshold that triggers liability classification of an award, requires all excess income tax benefits and deficiencies arising from share-based payments to be recognized in earnings in the period they occur, simplifies the accounting for forfeitures, and clarifies certain cash flow presentation matters. Certain aspects of the standard must be adopted using a prospective approach and other aspects must be adopted using a modified retrospective approach.

During the fourth quarter of 2016, we elected to early adopt this standard, and accordingly have applied the guidance effective as of January 1, 2016. Prior to adoption of the new standard, our stock compensation awards were generally classified as liability awards and accounted for at fair value until settled because employees could withhold at more than the minimum statutory tax withholding rate. In accordance with the new guidance, certain of these stock compensation awards are now classified as equity awards and accounted for at grant date fair value. As a result of adopting the new standard, Pinnacle West recorded a cumulative effect adjustment to retained earnings of $6 million. The other provisions of the standard did not have a material impact on our consolidated financial statements. See Note 15 for additional details of the adoption impacts.

ASU 2015-07, Fair Value Measurement: Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent)

In May 2015, new accounting guidance was issued that removes the requirement to categorize certain investments valued using net asset value, as a practical expedient, within the fair value hierarchy. We retrospectively adopted this guidance during the first quarter of 2016. The adoption of this guidance modifies our fair value disclosures, but does not impact the methodology for valuing these instruments, or our financial statement results.  See Note 7 and Note 13.  

ASU 2014-09, Revenue from Contracts with Customers

In May 2014, a new revenue recognition accounting standard was issued. This standard provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. Since the issuance of the new revenue standard, additional guidance was issued to clarify certain aspects of the new revenue standard, including principal versus agent considerations, identifying performance obligations, and other narrow scope improvements. The new revenue standard, and related amendments, will be effective for us on January 1, 2018. The standard may be adopted using a full retrospective application or a simplified transition method that allows entities to record a cumulative effect adjustment in retained earnings at the date of initial application.

We plan on adopting this standard on January 1, 2018, and are currently evaluating the transition method and the effect on our financial statements. As part of our evaluation we continue to actively monitor certain industry issues being addressed by the American Institute of Certified Public Accountants’ Revenue Recognition Working Group and the Financial Accounting Standards Board’s Transition Resource Group. Conclusions reached by these groups may impact our application of the standard, specifically in regards to the treatment of contributions in aid of construction.

ASU 2016-01, Financial Instruments: Recognition and Measurement

In January 2016, a new accounting standard was issued relating to the recognition and measurement of financial instruments. The new guidance will require certain investments in equity securities to be measured at fair value with changes in fair value recognized in net income, and modifies the impairment assessment of certain equity securities. The new standard is effective for us on January 1, 2018. Certain aspects of the standard may require a cumulative effect adjustment and other aspects of the standard are required to be adopted prospectively. We plan on adopting this standard on January 1, 2018, and continue to evaluate the impacts the new guidance may have on our financial statements.

ASU 2016-02, Leases

In February 2016, a new lease accounting standard was issued. This new standard supersedes the existing lease accounting model, and modifies both lessee and lessor accounting. The new standard will require a lessee to reflect most operating lease arrangements on the balance sheet by recording a right-of-use asset and a lease liability that will initially be measured at the present value of lease payments. Among other changes, the new standard also modifies the definition of a lease, and requires expanded lease disclosures. The new standard will be effective for us on January 1, 2019, with early application permitted. The standard must be adopted using a modified retrospective approach, with various optional practical expedients provided to facilitate transition. We are currently evaluating this new accounting standard and the impacts it may have on our financial statements.

ASU 2016-13, Financial Instruments: Measurement of Credit Losses

In June 2016, a new accounting standard was issued that amends the measurement of credit losses on certain financial instruments. The new standard will require entities to use a current expected credit loss model to measure impairment of certain investments in debt securities, trade accounts receivables, and other financial instruments. The new standard is effective for us on January 1, 2020 and must be adopted using a modified retrospective approach for certain aspects of the standard, and a prospective approach for other aspects of the standard. We are currently evaluating this new accounting standard and the impacts it may have on our financial statements.

ASU 2017-01, Business Combinations: Clarifying the Definition of a Business

                In January 2017, a new accounting standard was issued that clarifies the definition of a business. This standard is intended to assist entities with evaluating whether a transaction should be accounted for as an acquisition (or disposal) of assets or a business.  The definition of a business  affects many areas of accounting including acquisitions, disposals, goodwill, and consolidation. The new standard is effective for us on January 1, 2018 using a prospective approach. We are evaluating the impacts of adopting this new standard, and the impacts it may have on our financial statements.  

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Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Schedule of reclassifications of the prior year

The following tables show the impacts of the reclassifications of the prior years (previously reported) amounts (dollars in thousands):

Statement of Cash Flows for the Year Ended December 31, 2015	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	18,756		$	18,756
Change in other long term liabilities	(81,959		)	(18,756		)	(100,715		)

Statement of Cash Flows for the Year Ended December 31, 2014	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Cash Flows from Operating Activities
Stock compensation	$	—		$	33,059		$	33,059
Change in other long-term liabilities	(80,993		)	(33,059		)	(114,052		)

Schedule of property, plant and equipment

Pinnacle West’s property, plant and equipment included in the December 31, 2016 and 2015 consolidated balance sheets is composed of the following (dollars in thousands):

Property, Plant and Equipment:	2016			2015
Generation	$	7,874,898		$	7,336,902
Transmission	2,746,508			2,494,744
Distribution	5,738,801			5,543,561
General plant	981,681			847,025
Plant in service and held for future use	17,341,888			16,222,232
Accumulated depreciation and amortization	(5,970,100		)	(5,594,094		)
Net	11,371,788			10,628,138
Construction work in progress	1,019,947			816,307
Palo Verde sale leaseback, net of accumulated depreciation	113,515			117,385
Intangible assets, net of accumulated amortization	90,022			123,975
Nuclear fuel, net of accumulated amortization	119,004			123,139
Total property, plant and equipment	$	12,714,276		$	11,808,944

Summary of supplemental cash flow information

The following table summarizes supplemental Pinnacle West cash flow information for each of the last three years (dollars in thousands):

	Year ended December 31,
	2016		2015		2014
Cash paid (received) during the period for:
Income taxes, net of refunds	$	9,956	$	6,550	$	(102,154	)
Interest, net of amounts capitalized	184,462		170,209		177,074
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	114,855	$	83,798	$	44,712
Dividends declared but not paid	72,926		69,363		65,790

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Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2016

Regulated Operations [Abstract]

Schedule of changes in the deferred fuel and purchased power regulatory asset

The following table shows the changes in the deferred fuel and purchased power regulatory asset (liability) for 2016 and 2015 (dollars in thousands):

	Year Ended December 31,
	2016			2015
Beginning balance	$	(9,688	)	$	6,926
Deferred fuel and purchased power costs - current period	60,303			(14,997		)
Amounts charged to customers	(38,150		)	(1,617		)
Ending balance	$	12,465		$	(9,688	)

Schedule of regulatory assets

The detail of regulatory assets is as follows (dollars in thousands):

S	Amortization Through	December 31, 2016				December 31, 2015
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	711,059	$	—	$	619,223
Retired power plant costs	2033	9,913		117,591		9,913		127,518
Income taxes - AFUDC equity	2046	6,305		152,118		5,495		133,712
Deferred fuel and purchased power — mark-to-market (Note 16)	2020	—		42,963		71,852		69,697
Four Corners cost deferral	2024	6,689		56,894		6,689		63,582
Income taxes — investment tax credit basis adjustment	2046	2,120		54,356		1,766		48,462
Lost fixed cost recovery	2017	61,307		—		45,507		—
Palo Verde VIEs (Note 18)	2046	—		18,775		—		18,143
Deferred compensation	2036	—		35,595		—		34,751
Deferred property taxes	(d)	—		73,200		—		50,453
Loss on reacquired debt	2038	1,637		16,942		1,515		16,375
AG-1 deferral	2018	—		5,868		—		—
Demand side management (b)	2017	3,744		—		—		—
Tax expense of Medicare subsidy	2024	1,513		10,589		1,520		12,163
Transmission vegetation management	2016	—		—		4,543		—
Mead-Phoenix transmission line CIAC	2050	332		10,708		332		11,040
Deferred fuel and purchased power (b) (c)	2017	12,465		—		—		—
Coal reclamation	2026	418		5,182		418		6,085
Other	Various	432		1,588		5		2,942
Total regulatory assets (e)		$	106,875	$	1,313,428	$	149,555	$	1,214,146

(a) This asset represents the future recovery of pension benefit obligations through retail rates.  If these costs are disallowed by the ACC, this regulatory asset would be charged to OCI and result in lower future revenues.  See Note 7 for further discussion.

(b) See “Cost Recovery Mechanisms” discussion above.

(c) Subject to a carrying charge.

(d) Per the provision of the 2012 Settlement Agreement.

(e) There are no regulatory assets for which the ACC has allowed recovery of costs, but not allowed a return by exclusion from rate base.  FERC rates are set using a formula rate as described in “Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters.”

Schedule of regulatory liabilities

The detail of regulatory liabilities is as follows (dollars in thousands):

	Amortization Through	December 31, 2016				December 31, 2015
		Current		Non-Current		Current		Non-Current
Asset retirement obligations	2057	$	—	$	279,976	$	—	$	277,554
Removal costs	(a)	29,899		223,145		39,746		240,367
Other postretirement benefits	(d)	32,662		123,913		34,100		179,521
Income taxes — deferred investment tax credit	2046	4,368		108,827		3,604		97,175
Income taxes - change in rates	2045	1,771		70,898		1,113		72,454
Spent nuclear fuel	2047	—		71,726		3,051		67,437
Renewable energy standard (b)	2017	26,809		—		43,773		4,365
Demand side management (b)	2019	—		20,472		6,079		19,115
Sundance maintenance	2030	—		15,287		—		13,678
Deferred fuel and purchased power (b) (c)	2016	—		—		9,688		—
Deferred gains on utility property	2018	2,063		8,895		2,062		6,001
Four Corners coal reclamation	2031	—		18,248		—		8,920
Other	Various	2,327		7,529		2,550		7,565
Total regulatory liabilities		$	99,899	$	948,916	$	145,766	$	994,152

(a) In accordance with regulatory accounting guidance, APS accrues for removal costs for its regulated assets, even if there is no legal obligation for removal (see Note 11).

(b) See “Cost Recovery Mechanisms” discussion above.

(c) Subject to a carrying charge.

(d) See Note 7.

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Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of unrecognized tax benefits roll forward

The following is a tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year that are included in accrued taxes and unrecognized tax benefits (dollars in thousands):

	Pinnacle West Consolidated									APS Consolidated
	2016			2015			2014			2016			2015			2014
Total unrecognized tax benefits, January 1	$	34,447		$	44,775		$	41,997		$	34,447		$	44,775		$	41,997
Additions for tax positions of the current year	2,695			2,175			4,309			2,695			2,175			4,309
Additions for tax positions of prior years	886			—			751			886			—			751
Reductions for tax positions of prior years for:
Changes in judgment	(1,953		)	(10,244		)	(2,282		)	(1,953		)	(10,244		)	(2,282		)
Settlements with taxing authorities	—			—			—			—			—			—
Lapses of applicable statute of limitations	—			(2,259		)	—			—			(2,259		)	—
Total unrecognized tax benefits, December 31	$	36,075		$	34,447		$	44,775		$	36,075		$	34,447		$	44,775

Summary of unrecognized tax benefits

Included in the balances of unrecognized tax benefits are the following tax positions that, if recognized, would decrease our effective tax rate (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	2016		2015		2014		2016		2015		2014
Tax positions, that if recognized, would decrease our effective tax rate	$	11,313	$	9,523	$	11,207	$	11,313	$	9,523	$	11,207

The amount of interest expense or benefit recognized related to unrecognized tax benefits are as follows (dollars in thousands): 

	Pinnacle West Consolidated							APS Consolidated
	2016		2015			2014		2016		2015			2014
Unrecognized tax benefit interest expense/(benefit) recognized	$	529	$	(161	)	$	752	$	529	$	(161	)	$	752

Following are the total amount of accrued liabilities for interest recognized related to unrecognized benefits that could reverse and decrease our effective tax rate to the extent matters are settled favorably (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	2016		2015		2014		2016		2015		2014
Unrecognized tax benefit interest accrued	$	1,333	$	804	$	965	$	1,333	$	804	$	965

Components of income tax expense

The components of income tax expense are as follows (dollars in thousands):

	Pinnacle West Consolidated							APS Consolidated
	Year Ended December 31,							Year Ended December 31,
	2016		2015			2014		2016		2015		2014
Current:
Federal	$	8,630	$	(12,335	)	$	25,054	$	711	$	6,485	$	40,115
State	1,259		4,763			10,382		4,276		7,813		15,598
Total current	9,889		(7,572		)	35,436		4,987		14,298		55,713
Deferred:
Federal	201,743		221,505			167,365		215,178		208,326		165,027
State	24,779		23,787			17,904		25,677		23,217		16,620
Total deferred	226,522		245,292			185,269		240,855		231,543		181,647
Income tax expense	$	236,411	$	237,720		$	220,705	$	245,842	$	245,841	$	237,360

Comparison of pretax income from continuing operations at the federal income tax rate to income tax expense - continuing operations

The following chart compares pretax income at the 35% federal income tax rate to income tax expense (dollars in thousands):

	Pinnacle West Consolidated									APS Consolidated
	Year Ended December 31,									Year Ended December 31,
	2016			2015			2014			2016			2015			2014
Federal income tax expense at 35% statutory rate	$	244,278		$	242,869		$	225,540		$	254,617		$	250,267		$	239,638
Increases (reductions) in tax expense resulting from:
State income tax net of federal income tax benefit	16,311			18,265			18,149			18,750			20,433			21,148
Credits and favorable adjustments related to prior years resolved in current year	—			(2,169		)	—			—			(1,892		)	—
Medicare Subsidy Part-D	844			837			830			844			837			830
Allowance for equity funds used during construction (see Note 1)	(11,724		)	(9,711		)	(8,523		)	(11,724		)	(9,711		)	(8,523		)
Palo Verde VIE noncontrolling interest (see Note 18)	(6,823		)	(6,626		)	(9,135		)	(6,823		)	(6,626		)	(9,135		)
Investment tax credit amortization	(5,887		)	(5,527		)	(4,928		)	(5,887		)	(5,527		)	(4,928		)
Other	(588		)	(218		)	(1,228		)	(3,935		)	(1,940		)	(1,670		)
Income tax expense	$	236,411		$	237,720		$	220,705		$	245,842		$	245,841		$	237,360

Components of the net deferred income tax liability

The components of the net deferred income tax liability were as follows (dollars in thousands):

	Pinnacle West Consolidated						APS Consolidated
	December 31,						December 31,
	2016			2015			2016			2015
DEFERRED TAX ASSETS
Risk management activities	$	26,614		$	70,498		$	26,614		$	70,498
Regulatory liabilities:
Asset retirement obligation and removal costs	200,140			216,765			200,140			216,765
Unamortized investment tax credits	113,195			100,779			113,195			100,779
Other postretirement benefits	60,375			83,034			60,375			83,034
Other	63,311			60,707			63,311			60,707
Pension liabilities	204,436			191,028			194,981			181,787
Renewable energy incentives	56,379			60,956			56,379			60,956
Credit and loss carryforwards	75,944			59,557			1,645			—
Other	158,421			149,033			187,453			176,016
Total deferred tax assets	958,815			992,357			904,093			950,542
DEFERRED TAX LIABILITIES
Plant-related	(3,297,989		)	(3,116,752		)	(3,297,989		)	(3,116,752		)
Risk management activities	(7,594		)	(10,626		)	(7,594		)	(10,626		)
Other postretirement assets	(63,477		)	(71,737		)	(62,819		)	(70,986		)
Regulatory assets:
Allowance for equity funds used during construction	(61,088		)	(54,110		)	(61,088		)	(54,110		)
Deferred fuel and purchased power — mark-to-market	(21,396		)	(55,020		)	(21,396		)	(55,020		)
Pension benefits	(274,184		)	(240,692		)	(274,184		)	(240,692		)
Retired power plant costs (see Note 3)	(49,166		)	(53,420		)	(49,166		)	(53,420		)
Other	(123,987		)	(108,441		)	(123,987		)	(108,441		)
Other	(5,166		)	(4,984		)	(5,165		)	(4,984		)
Total deferred tax liabilities	(3,904,047		)	(3,715,782		)	(3,903,388		)	(3,715,031		)
Deferred income taxes — net	$	(2,945,232	)	$	(2,723,425	)	$	(2,999,295	)	$	(2,764,489	)

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Lines of Credit and Short-Term Borrowings (Tables)

12 Months Ended

Dec. 31, 2016

Lines of Credit and Short-Term Borrowings

Schedule of consolidated credit facilities and amounts available and outstanding

The table below presents the consolidated credit facilities and the amounts available and outstanding as of December 31, 2016 and 2015 (dollars in thousands):

	December 31, 2016									December 31, 2015
	Pinnacle West			APS			Total			Pinnacle West		APS		Total
Commitments under Credit Facilities	$	275,000		$	1,000,000		$	1,275,000		$	200,000	$	1,000,000	$	1,200,000
Outstanding Commercial Paper and Revolving Credit Facility Borrowings	(41,700		)	(135,500		)	(177,200		)	—		—		—
Amount of Credit Facilities Available	$	233,300		$	864,500		$	1,097,800		$	200,000	$	1,000,000	$	1,200,000
Weighted-Average Commitment Fees	0.125%			0.100%						0.125%		0.100%

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Long-Term Debt and Liquidity Matters (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Components of long-term debt on the Consolidated Balance Sheets

The following table presents the components of long-term debt on the Consolidated Balance Sheets outstanding at December 31, 2016 and 2015 (dollars in thousands):

	Maturity	Interest	December 31,
	Dates (a)	Rates	2016			2015
APS
Pollution control bonds:
Variable	2029	(b)	$	35,975		$	92,405
Fixed	2024-2029	1.75%-4.70%	147,150			211,150
Total pollution control bonds			183,125			303,555
Senior unsecured notes	2019-2046	2.20%-8.75%	3,725,000			3,375,000
Term loans	2018-2019	(c)	150,000			50,000
Unamortized discount			(11,816		)	(10,374		)
Unamortized premium			4,506			4,686
Unamortized debt issuance cost			(29,030		)	(27,896		)
Total APS long-term debt			4,021,785			3,694,971
Less current maturities			—			357,580
Total APS long-term debt less current maturities			4,021,785			3,337,391
Pinnacle West
Term loan	2017	(d)	125,000			125,000
Less current maturities			125,000			—
Total PNW long-term debt less current maturities			—			125,000
TOTAL LONG-TERM DEBTLESS CURRENT MATURITIES			$	4,021,785		$	3,462,391

(a) This schedule does not reflect the timing of redemptions that may occur prior to maturities.

(b) The weighted-average rate for the variable rate pollution control bonds was 0.81% at December 31, 2016 and 0.01%-0.24% at December 31, 2015.

(c) The weighted-average interest rate was 1.427% at December 31, 2016, and 1.024% at December 31, 2015.

(d) The interest rate was 1.520% at December 31, 2016 and 1.174% at December 31, 2015.

Principal payments due on Pinnacle West's and APS's total long-term debt

The following table shows principal payments due on Pinnacle West’s and APS’s total long-term debt (dollars in thousands):

Year	Consolidated Pinnacle West		Consolidated APS
2017	$	125,000	$	—
2018	82,000		82,000
2019	600,000		600,000
2020	250,000		250,000
2021	—		—
Thereafter	3,126,125		3,126,125
Total	$	4,183,125	$	4,058,125

Schedule of estimated fair value of long-term debt, including current maturities

The following table represents the estimated fair value of our long-term debt, including current maturities (dollars in thousands):

	As of December 31, 2016				As of December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Pinnacle West	$	125,000	$	125,000	$	125,000	$	125,000
APS	4,021,785		4,300,789		3,694,971		3,981,367
Total	$	4,146,785	$	4,425,789	$	3,819,971	$	4,106,367

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Retirement Plans and Other Benefits (Tables)

12 Months Ended

Dec. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Schedule of net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged or amortized to the regulatory asset)

The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction, billed to electric plant participants or charged to the regulatory asset or liability) (dollars in thousands):

	Pension									Other Benefits
	2016			2015			2014			2016			2015			2014
Service cost-benefits earned during the period	$	53,792		$	59,627		$	53,080		$	14,993		$	16,827		$	18,139
Interest cost on benefit obligation	131,647			123,983			129,194			29,721			28,102			41,243
Expected return on plan assets	(173,906		)	(179,231		)	(158,998		)	(36,495		)	(36,855		)	(46,400		)
Amortization of:
Prior service cost (credit)	527			594			869			(37,883		)	(37,968		)	(9,626		)
Net actuarial loss	40,717			31,056			10,963			4,589			4,881			1,175
Net periodic benefit cost	$	52,777		$	36,029		$	35,108		$	(25,075	)	$	(25,013	)	$	4,531
Portion of cost charged to expense	$	26,172		$	20,036		$	21,985		$	(12,435	)	$	(10,391	)	$	6,000

Schedule of changes in the benefit obligations and funded status

The following table shows the plans’ changes in the benefit obligations and funded status for the years 2016 and 2015 (dollars in thousands):

	Pension						Other Benefits
	2016			2015			2016			2015
Change in Benefit Obligation
Benefit obligation at January 1	$	3,033,803		$	3,078,648		$	647,020		$	682,335
Service cost	53,792			59,627			14,993			16,827
Interest cost	131,647			123,983			29,721			28,102
Benefit payments	(142,247		)	(137,115		)	(26,231		)	(24,988		)
Actuarial (gain) loss	127,467			(91,340		)	50,942			(55,256		)
Benefit obligation at December 31	3,204,462			3,033,803			716,445			647,020
Change in Plan Assets
Fair value of plan assets at January 1	2,542,774			2,615,404			833,017			834,625
Actual return on plan assets	166,408			(44,690		)	63,463			(2,399		)
Employer contributions	100,000			100,000			819			791
Benefit payments	(133,825		)	(127,940		)	(14,648		)	—
Fair value of plan assets at December 31	2,675,357			2,542,774			882,651			833,017
Funded Status at December 31	$	(529,105	)	$	(491,029	)	$	166,206		$	185,997

Schedule of projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets

The following table shows the projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets as of December 31, 2016 and 2015 (dollars in thousands):

	2016		2015
Projected benefit obligation	$	3,204,462	$	3,033,803
Accumulated benefit obligation	3,049,406		2,873,467
Fair value of plan assets	2,675,357		2,542,774

Schedule of amounts recognized on the Consolidated Balance Sheets

The following table shows the amounts recognized on the Consolidated Balance Sheets as of December 31, 2016 and 2015 (dollars in thousands):

	Pension						Other Benefits
	2016			2015			2016		2015
Noncurrent asset	$	—		$	—		$	166,206	$	185,997
Current liability	(19,795		)	(10,031		)	—		—
Noncurrent liability	(509,310		)	(480,998		)	—		—
Net amount recognized	$	(529,105	)	$	(491,029	)	$	166,206	$	185,997

Schedule of accumulated other comprehensive loss

The following table shows the details related to accumulated other comprehensive loss as of December 31, 2016 and 2015 (dollars in thousands): 

	Pension						Other Benefits
	2016			2015			2016			2015
Net actuarial loss	$	773,750		$	679,501		$	146,509		$	127,124
Prior service cost (credit)	81			609			(303,417		)	(341,301		)
APS’s portion recorded as a regulatory (asset) liability	(711,059		)	(619,223		)	156,575			213,621
Income tax expense (benefit)	(24,202		)	(23,663		)	833			925
Accumulated other comprehensive loss	$	38,570		$	37,224		$	500		$	369

Schedule of estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets into net periodic benefit cost

The following table shows the estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets and liabilities into net periodic benefit cost in 2017 (dollars in thousands):

	Pension		Other Benefits
Net actuarial loss	$	46,971	$	5,181
Prior service cost (credit)	81		(37,842		)
Total amounts estimated to be amortized from accumulated other comprehensive loss (gain) and regulatory assets (liabilities) in 2017	$	47,052	$	(32,661	)

Schedule of weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs

The following table shows the weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs:

	Benefit Obligations As of December 31,				Benefit Costs For the Years Ended December 31,
	2016		2015		2016		2015		2014
									January - September		October - December
Discount rate – pension	4.08	%	4.37	%	4.37	%	4.02	%	4.88	%	4.88	%
Discount rate – other benefits	4.17	%	4.52	%	4.52	%	4.14	%	5.10	%	4.41	%
Rate of compensation increase	4.00	%	4.00	%	4.00	%	4.00	%	4.00	%	4.00	%
Expected long-term return on plan assets - pension	N/A		N/A		6.90	%	6.90	%	6.90	%	6.90	%
Expected long-term return on plan assets - other benefits	N/A		N/A		4.45	%	4.45	%	6.80	%	4.25	%
Initial healthcare cost trend rate (pre-65 participants)	7.00	%	7.00	%	7.00	%	7.00	%	7.50	%	7.50	%
Initial healthcare cost trend rate (post-65 participants)	5.00	%	5.00	%	5.00	%	5.00	%	7.50	%	5.00	%
Ultimate healthcare cost trend rate	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%
Number of years to ultimate trend rate (pre-65 participants)	4		4		4		4		4		4
Number of years to ultimate trend rate (post-65 participants)	0		0		0		0		4		0

Schedule of effects of one percentage point change in the assumed initial and ultimate health care cost trend rates

A one percentage point change in the assumed initial and ultimate healthcare cost trend rates would have the following effects (dollars in thousands): 

	1% Increase		1% Decrease
Effect on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants	$	8,430	$	(5,455	)
Effect on service and interest cost components of net periodic other postretirement benefit costs	8,440		(6,527		)
Effect on the accumulated other postretirement benefit obligation	108,046		(86,651		)

Schedule of fair value of pension plan and other postretirement benefit plan assets, by asset category

The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2015, by asset category, are as follows (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Other (a)		Balance at December 31, 2015
Pension Plan:
Cash and cash equivalents	$	1,893	$	—	$	—	$	1,893
Fixed Income Securities:
Corporate	—		1,108,736		—		1,108,736
U.S. Treasury	274,778		—		—		274,778
Other (b)	—		113,008		—		113,008
Common stock equities (c)	247,701		—		—		247,701
Mutual funds - International equities	116,307		—		—		116,307
Common and collective trusts:
Equities	—		—		315,989		315,989
Real Estate	—		—		150,359		150,359
Partnerships	—		—		169,937		169,937
Short-term investments and other (d)	—		—		44,066		44,066
Total	$	640,679	$	1,221,744	$	680,351	$	2,542,774
Other Benefits:
Cash and cash equivalents	$	240	$	—	$	—	$	240
Fixed Income Securities:
Corporate	—		217,026		—		217,026
U.S. Treasury	131,435		—		—		131,435
Other (b)	—		31,106		—		31,106
Common stock equities (c)	265,583		—		—		265,583
Mutual funds - International equities	52,568		—		—		52,568
Common and collective trusts:
Equities	—		—		110,055		110,055
Real Estate	—		—		13,512		13,512
Short-term investments and other (d)	—		—		11,492		11,492
Total	$	449,826	$	248,132	$	135,059	$	833,017

(a) These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.

(b) This category consists primarily of debt securities issued by municipalities.

(c) This category primarily consists of US common stock equities.

(d) This category includes plan receivables and payables.

The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2016, by asset category, are as follows (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Other (a)		Balance at December 31, 2016
Pension Plan:
Cash and cash equivalents	$	13,995	$	—	$	—	$	13,995
Fixed income securities:
Corporate	—		1,210,453		—		1,210,453
U.S. Treasury	112,583		—		—		112,583
Other (b)	—		102,170		—		102,170
Common stock equities (c)	235,109		—		—		235,109
Mutual funds (d)	251,506		—		—		251,506
Common and collective trusts:
Equities	—		—		266,840		266,840
Real estate	—		—		161,449		161,449
Partnerships	—		—		208,915		208,915
Short-term investments and other (e)	—		—		112,337		112,337
Total	$	613,193	$	1,312,623	$	749,541	$	2,675,357
Other Benefits:
Cash and cash equivalents	$	304	$	—	$	—	$	304
Fixed income securities:
Corporate	—		268,193		—		268,193
U.S. Treasury	145,255		—		—		145,255
Other (b)	—		34,506		—		34,506
Common stock equities (c)	243,741		—		—		243,741
Mutual funds (d)	67,418		—		—		67,418
Common and collective trusts:
Equities	—		—		95,814		95,814
Real estate	—		—		14,509		14,509
Partnerships	—		—		3,060		3,060
Short-term investments and other (e)	—		—		9,851		9,851
Total	$	456,718	$	302,699	$	123,234	$	882,651

(a) These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.

(b) This category consists primarily of debt securities issued by municipalities.

(c) This category primarily consists of US common stock equities.

(d) These funds invest in US and international common stock equities.

(e) This category includes plan receivables and payables.

Schedule of estimated future benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter

Benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter, are estimated to be as follows (dollars in thousands):

Year	Pension		Other Benefits
2017	$	172,859	$	31,126
2018	173,232		33,795
2019	182,944		36,195
2020	191,037		37,998
2021	196,292		39,368
Years 2022-2026	1,049,149		201,944

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Leases (Tables)

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Estimated future minimum lease payments for Pinnacle West's and APS's operating leases, excluding purchased power agreements

Estimated future minimum lease payments for Pinnacle West’s and APS’s operating leases, excluding purchased power agreements, are approximately as follows (dollars in thousands):

Year	Pinnacle West Consolidated		APS
2017	$	12,330	$	11,919
2018	10,987		10,690
2019	9,019		8,767
2020	7,688		7,439
2021	5,266		5,020
Thereafter	59,647		57,207
Total future lease commitments	$	104,937	$	101,042

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Jointly-Owned Facilities (Tables)

12 Months Ended

Dec. 31, 2016

Jointly Owned Utility Plant, Net Ownership Amount [Abstract]

APS's interests in jointly-owned facilities recorded on the Consolidated Balance Sheets

The following table shows APS’s interests in those jointly-owned facilities recorded on the Consolidated Balance Sheets at December 31, 2016 (dollars in thousands):

	Percent Owned			Plant in Service		Accumulated Depreciation		Construction Work in Progress
Generating facilities:
Palo Verde Units 1 and 3	29.1	%		$	1,770,324	$	1,080,072	$	17,615
Palo Verde Unit 2 (a)	16.8	%		581,572		360,757		9,717
Palo Verde Common	28.0	%	(b)	672,799		242,649		62,479
Palo Verde Sale Leaseback			(a)	351,050		237,535		—
Four Corners Generating Station	63.0	%		934,837		578,924		248,072
Navajo Generating Station Units 1, 2 and 3	14.0	%		279,629		176,931		5,761
Cholla common facilities (c)	63.3	%	(b)	159,707		58,276		806		(d)
Transmission facilities:
ANPP 500kV System	33.6	%	(b)	127,970		38,610		2,291
Navajo Southern System	22.5	%	(b)	62,135		20,491		334
Palo Verde — Yuma 500kV System	19.0	%	(b)	13,699		5,368		408
Four Corners Switchyards	51.3	%	(b)	39,850		10,474		1,044
Phoenix — Mead System	17.1	%	(b)	39,330		13,725		85
Palo Verde — Rudd 500kV System	50.0	%	(b)	91,904		19,818		227
Morgan — Pinnacle Peak System	65.2	%	(b)	140,374		13,557		—
Round Valley System	50.0	%	(b)	515		127		—
Palo Verde — Morgan System	85.8	%	(b)	125,908		1,326		28,949
Hassayampa — North Gila System	80.0	%	(b)	142,541		3,231		—
Cholla 500kV Switchyard	85.7	%	(b)	5,078		1,201		—
Saguaro 500kV Switchyard	75.0	%	(b)	20,456		12,426		2

(a) See Note 18.

(b) Weighted-average of interests.

(c) PacifiCorp owns Cholla Unit 4 and APS operates the unit for PacifiCorp.  The common facilities at Cholla are jointly-owned.

(d) Due to the closure of Cholla Unit 2 in 2015, all new Cholla common facilities construction is owned by APS at 50.5%

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Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Summary of estimated coal take-or-pay commitments

The following table summarizes our estimated coal take-or-pay commitments (dollars in thousands):

	Years Ended December 31,
	2017		2018		2019		2020		2021		Thereafter
Coal take-or-pay commitments (a)	$	195,428	$	189,588	$	193,818	$	198,160	$	202,619	$	2,068,355

(a) Total take-or-pay commitments are approximately $3.0 billion.  The total net present value of these commitments is approximately $2.1 billion.

Summary of actual take-or-pay commitments

	Year Ended December 31,
	2016		2015		2014
Total purchases	$	160,066	$	211,327	$	236,773

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Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2016

Asset Retirement Obligation Disclosure [Abstract]

Change in asset retirement obligations

The following table shows the change in our asset retirement obligations for 2016 and 2015 (dollars in thousands):

	2016			2015
Asset retirement obligations at the beginning of year	$	443,576		$	390,750
Changes attributable to:
Accretion expense	26,656			25,163
Settlements	(15,732		)	(32,048		)
Estimated cash flow revisions	151,046			17,556
Newly incurred or acquired obligations	18,929			42,155
Asset retirement obligations at the end of year	$	624,475		$	443,576

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Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Information [Line Items]

Schedule of quarterly financial information

Consolidated quarterly financial information for 2016 and 2015 is provided in the tables below (dollars in thousands, except per share amounts).  Weather conditions cause significant seasonal fluctuations in our revenues; therefore, results for interim periods do not necessarily represent results expected for the year.

	2016 Quarter Ended								2016
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	677,167	$	915,394	$	1,166,922	$	739,199	$	3,498,682
Operations and maintenance	243,195		242,279		217,568		208,277		911,319
Operating income	50,162		231,748		451,258		122,816		855,984
Income taxes	1,914		65,742		141,446		27,309		236,411
Net income	9,326		126,182		267,900		58,119		461,527
Net income attributable to common shareholders	4,453		121,308		263,027		53,246		442,034
Earnings Per Share:
Net income attributable to common shareholders — Basic	$	0.04	$	1.09	$	2.36	$	0.48	$	3.97
Net income attributable to common shareholders — Diluted	0.04		1.08		2.35		0.47		3.95

	2015 Quarter Ended								2015
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	671,219	$	890,648	$	1,199,146	$	734,430	$	3,495,443
Operations and maintenance	214,944		210,965		220,449		222,019		868,377
Operating income	67,684		231,973		445,111		109,834		854,602
Income taxes	7,947		67,371		139,555		22,847		237,720
Net income	20,727		127,507		261,978		45,978		456,190
Net income attributable to common shareholders	16,122		122,902		257,116		41,117		437,257
Earnings Per Share:
Net income attributable to common shareholders — Basic	$	0.15	$	1.11	$	2.32	$	0.37	$	3.94
Net income attributable to common shareholders — Diluted	0.14		1.10		2.30		0.37		3.92

ARIZONA PUBLIC SERVICE COMPANY

Selected Quarterly Financial Information [Line Items]

Schedule of quarterly financial information

APS's quarterly financial information for 2016 and 2015 is as follows (dollars in thousands):

	2016 Quarter Ended,								2016
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	676,632	$	909,757	$	1,166,359	$	737,006	$	3,489,754
Operations and maintenance	238,711		233,712		209,366		197,319		879,108
Operating income	48,930		165,684		307,601		95,765		617,980
Net income attributable to common shareholder	7,253		127,188		269,220		58,480		462,141

	2015 Quarter Ended,								2015
	March 31,		June 30,		September 30,		December 31,		Total
Operating revenues	$	670,668	$	889,723	$	1,198,380	$	733,586	$	3,492,357
Operations and maintenance	209,947		208,031		216,011		219,146		853,135
Operating income	61,333		162,704		301,238		86,709		611,984
Net income attributable to common shareholder	19,868		125,362		261,187		43,857		450,274

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Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair value of assets and liabilities that are measured at fair value on a recurring basis

The following table presents the fair value at December 31, 2016 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other				Balance at December 31, 2016
Assets
Coal reclamation trust - cash equivalents (b)	$	14,521	$	—		$	—		$	—			$	14,521
Risk management activities — derivative instruments:
Commodity contracts	—		43,722			11,076			(35,103		)	(c)	19,695
Nuclear decommissioning trust:
U.S. commingled equity funds	—		—			—			353,261			(d)	353,261
Fixed income securities:
Cash and cash equivalent funds	—		—			—			795			(e)	795
U.S. Treasury	95,441		—			—			—				95,441
Corporate debt	—		111,623			—			—				111,623
Mortgage-backed securities	—		115,337			—			—				115,337
Municipal bonds	—		80,997			—			—				80,997
Other	—		22,132			—			—				22,132
Subtotal nuclear decommissioning trust	95,441		330,089			—			354,056				779,586
Total	$	109,962	$	373,811		$	11,076		$	318,953			$	813,802
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(45,641	)	$	(58,482	)	$	31,049		(c)	$	(73,074	)

(a) Primarily consists of long-dated electricity contracts.

(b) Represents investments restricted for coal mine reclamation funding related to Four Corners. These assets are included in the Other Assets line item, reported under the Investments and Other Assets section of our Consolidated Balance Sheets.

(c) Represents counterparty netting, margin and collateral.  See Note 16.

(d) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

(e) Represents nuclear decommissioning trust net pending securities sales and purchases.

The following table presents the fair value at December 31, 2015 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other				Balance at December 31, 2015
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	22,992		$	30,364		$	(25,345	)	(b)	$	28,011
Nuclear decommissioning trust:
U.S. commingled equity funds	—		—			—			314,957			(c)	314,957
Fixed income securities:
Cash and cash equivalent funds	12,260		—			—			(335		)	(d)	11,925
U.S. Treasury	117,245		—			—			—				117,245
Corporate debt	—		96,243			—			—				96,243
Mortgage-backed securities	—		99,065			—			—				99,065
Municipal bonds	—		72,206			—			—				72,206
Other	—		23,555			—			—				23,555
Subtotal nuclear decommissioning trust	129,505		291,069			—			314,622				735,196
Total	$	129,505	$	314,061		$	30,364		$	289,277			$	763,207
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(144,044	)	$	(63,343	)	$	39,698		(b)	$	(167,689	)

(a) Primarily consists of heat rate options and other long-dated electricity contracts.

(b) Represents counterparty netting, margin and collateral.  See Note 16.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

(d) Represents nuclear decommissioning trust net pending securities sales and purchases.

Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments

s.

The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at December 31, 2016 and December 31, 2015:

	December 31, 2016 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	10,648	$	32,042	Discounted cash flows	Electricity forward price (per MWh)	$16.43 - $41.07	$	29.86
Natural Gas:
Forward Contracts (a)	428		26,440		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.32 - $3.60	$	2.81
Total	$	11,076	$	58,482

(a) Includes swaps and physical and financial contracts.

	December 31, 2015 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	24,543	$	54,679	Discounted cash flows	Electricity forward price (per MWh)	$15.92 - $40.73	$	26.86
Option Contracts (b)	—		5,628		Option model	Electricity forward price (per MWh)	$23.87 - $44.13	$	33.91
						Electricity price volatilities	40% - 59%	52		%
						Natural gas price volatilities	32% - 40%	35		%
Natural Gas:
Forward Contracts (a)	5,821		3,036		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.18 - $3.14	$	2.61
Total	$	30,364	$	63,343

(a) Includes swaps and physical and financial contracts.

(b) Electricity and natural gas price volatilities are estimated based on historical forward price movements due to lack of market quotes for implied volatili

Changes in fair value for assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs

The following table shows the changes in fair value for our risk management activities’ assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs for the years ended December 31, 2016 and 2015 (dollars in thousands):

	Year Ended December 31,
Commodity Contracts	2016			2015
Net derivative balance at beginning of period	$	(32,979	)	$	(41,386	)
Total net gains (losses) realized/unrealized:
Included in earnings	—			—
Included in OCI	88			(452		)
Deferred as a regulatory asset or liability	(37,543		)	(4,009		)
Settlements	15,146			14,809
Transfers into Level 3 from Level 2	1,900			(6,256		)
Transfers from Level 3 into Level 2	5,982			4,315
Net derivative balance at end of period	$	(47,406	)	$	(32,979	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—

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Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Schedule of earnings per weighted average common share outstanding

The following table presents the calculation of Pinnacle West’s basic and diluted earnings per share for continuing operations attributable to common shareholders for the years ended December 31, 2016, 2015 and 2014 (in thousands, except per share amounts):

	2016		2015		2014
Net income attributable to common shareholders	$	442,034	$	437,257	$	397,595
Weighted average common shares outstanding — basic	111,409		111,026		110,626
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units	637		526		552
Weighted average common shares outstanding — diluted	112,046		111,552		111,178
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic	$	3.97	$	3.94	$	3.59
Net Income attributable to common shareholders - diluted	$	3.95	$	3.92	$	3.58

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Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Nonvested Restricted Stock, Stock Grants and Stock Units

The following table is a summary of awards granted and the weighted-average grant date fair value for the three years ended 2016, 2015 and 2014.

	Restricted Stock Units, Stock Grants, and Stock Units (a)						Performance Shares (b)
	2016		2015		2014		2016		2015		2014
Units granted	141,811		152,651		179,291		166,666		151,430		166,244
Weighted-average grant date fair value	$	67.34	$	64.12	$	54.89	$	66.60	$	64.97	$	54.86

(a) Units granted includes awards that will be cash settled of 43,952 in 2016, 45,104 in 2015, and 49,018 in 2014.

(b) Reflects the target payout level.

The following table is a summary of the status of non-vested awards as of December 31, 2016 and changes during the year.

	Restricted Stock Units, Stock Grants, and Stock Units					Performance Shares
	Shares			Weighted-Average Grant Date Fair Value		Shares (b)		Weighted-Average Grant Date Fair Value
Nonvested at January 1, 2016	428,287			$	56.69	305,832		$	58.86
Granted	141,811			67.34		166,666		66.60
Change in performance factor	—			—		15,573		54.09
Vested	(230,881	)		55.07		(171,303	)	54.09
Forfeited (c)	(3,958	)		62.86		(4,044	)	62.34
Nonvested at December 31, 2016	335,259		(a)	62.04		312,724		65.32
Vested Awards Outstanding at December 31, 2016	174,201					171,303

(a) Includes 112,554 of awards that will be cash settled.

(b) The nonvested performance shares are reflected at target payout level.  The performance metric component increase or decrease in the number of shares from the target level to the estimated actual payout level is included in the increase for performance factor amounts in the year the award vests.

(c) We account for forfeitures as they occur.

Summary of Nonvested Performance Shares

The following table is a summary of the status of non-vested awards as of December 31, 2016 and changes during the year.

	Restricted Stock Units, Stock Grants, and Stock Units					Performance Shares
	Shares			Weighted-Average Grant Date Fair Value		Shares (b)		Weighted-Average Grant Date Fair Value
Nonvested at January 1, 2016	428,287			$	56.69	305,832		$	58.86
Granted	141,811			67.34		166,666		66.60
Change in performance factor	—			—		15,573		54.09
Vested	(230,881	)		55.07		(171,303	)	54.09
Forfeited (c)	(3,958	)		62.86		(4,044	)	62.34
Nonvested at December 31, 2016	335,259		(a)	62.04		312,724		65.32
Vested Awards Outstanding at December 31, 2016	174,201					171,303

(a) Includes 112,554 of awards that will be cash settled.

(b) The nonvested performance shares are reflected at target payout level.  The performance metric component increase or decrease in the number of shares from the target level to the estimated actual payout level is included in the increase for performance factor amounts in the year the award vests.

(c) We account for forfeitures as they occur.

The following table is a summary of awards granted and the weighted-average grant date fair value for the three years ended 2016, 2015 and 2014.

	Restricted Stock Units, Stock Grants, and Stock Units (a)						Performance Shares (b)
	2016		2015		2014		2016		2015		2014
Units granted	141,811		152,651		179,291		166,666		151,430		166,244
Weighted-average grant date fair value	$	67.34	$	64.12	$	54.89	$	66.60	$	64.97	$	54.86

(a) Units granted includes awards that will be cash settled of 43,952 in 2016, 45,104 in 2015, and 49,018 in 2014.

(b) Reflects the target payout level.

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Derivative Accounting (Tables)

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Outstanding gross notional amount of derivatives, which represents both purchases and sales (does not reflect net position)

As of December 31, 2016, we had the following outstanding gross notional volume of derivatives, which represent both purchases and sales (does not reflect net position):

Commodity	Quantity
Power	1,314	GWh
Gas	194	Billion cubic feet

Gains and losses from derivative instruments in designated cash flow accounting hedges relationships

The following table provides information about gains and losses from derivative instruments in designated cash flow accounting hedging relationships during the years ended December 31, 2016, 2015 and 2014 (dollars in thousands):

	Financial Statement	Year Ended December 31,
Commodity Contracts	Location	2016			2015			2014
Gain (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	OCI — derivative instruments	$	47		$	(615	)	$	(372	)
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized) (a)	Fuel and purchased power (b)	(3,926		)	(5,988		)	(21,415		)

(a) During the years ended December 31, 2016, 2015, and 2014, we had no losses reclassified from accumulated OCI to earnings related to discontinued cash flow hedges.

(b) Amounts are before the effect of PSA deferrals.

Gains and losses from derivative instruments not designated as accounting hedges instruments

The following table provides information about gains and losses from derivative instruments not designated as accounting hedging instruments during the years ended December 31, 2016, 2015 and 2014 (dollars in thousands):

	Financial Statement	Year Ended December 31,
Commodity Contracts	Location	2016		2015			2014
Net Gain Recognized in Income	Operating revenues	$	771	$	574		$	324
Net Gain (Loss) Recognized in Income	Fuel and purchased power (a)	25,711		(108,973		)	(66,367		)
Total		$	26,482	$	(108,399	)	$	(66,043	)

(a) Amounts are before the effect of PSA deferrals.

Schedule of the entity's fair value of risk management activities reported on a gross basis and the impacts on offsetting liabilities

The following tables provide information about the fair value of our risk management activities reported on a gross basis, and the impacts of offsetting as of December 31, 2016 and 2015.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Consolidated Balance Sheets.

As of December 31, 2016: (dollars in thousands)	Gross  Recognized  Derivatives (a)			Amounts  Offset (b)			Net Recognized Derivatives			Other (c)			Amount  Reported on  Balance Sheet
Current assets	$	48,094		$	(28,400	)	$	19,694		$	—		$	19,694
Investments and other assets	6,704			(6,703		)	1			—			1
Total assets	54,798			(35,103		)	19,695			—			19,695
Current liabilities	(50,182		)	28,400			(21,782		)	(4,054		)	(25,836		)
Deferred credits and other	(53,941		)	6,703			(47,238		)	—			(47,238		)
Total liabilities	(104,123		)	35,103			(69,020		)	(4,054		)	(73,074		)
Total	$	(49,325	)	$	—		$	(49,325	)	$	(4,054	)	$	(53,379	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting.

(c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,054.

As of December 31, 2015: (dollars in thousands)	Gross Recognized Derivatives (a)			Amounts Offset  (b)			Net Recognized Derivatives			Other (c)			Amount Reported on Balance Sheet
Current assets	$	37,396		$	(22,163	)	$	15,233		$	672		$	15,905
Investments and other assets	15,960			(3,854		)	12,106			—			12,106
Total assets	53,356			(26,017		)	27,339			672			28,011
Current liabilities	(113,560		)	40,223			(73,337		)	(4,379		)	(77,716		)
Deferred credits and other	(93,827		)	3,854			(89,973		)	—			(89,973		)
Total liabilities	(207,387		)	44,077			(163,310		)	(4,379		)	(167,689		)
Total	$	(154,031	)	$	18,060		$	(135,971	)	$	(3,707	)	$	(139,678	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) Includes cash collateral provided to counterparties of $18,060.

(c) Represents cash collateral and cash margin that is not subject to offsetting.  Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,379, and cash margin provided to counterparties of $672.

Schedule of the entity's fair value of risk management activities reported on a gross basis and the impacts on offsetting assets

The following tables provide information about the fair value of our risk management activities reported on a gross basis, and the impacts of offsetting as of December 31, 2016 and 2015.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Consolidated Balance Sheets.

As of December 31, 2016: (dollars in thousands)	Gross  Recognized  Derivatives (a)			Amounts  Offset (b)			Net Recognized Derivatives			Other (c)			Amount  Reported on  Balance Sheet
Current assets	$	48,094		$	(28,400	)	$	19,694		$	—		$	19,694
Investments and other assets	6,704			(6,703		)	1			—			1
Total assets	54,798			(35,103		)	19,695			—			19,695
Current liabilities	(50,182		)	28,400			(21,782		)	(4,054		)	(25,836		)
Deferred credits and other	(53,941		)	6,703			(47,238		)	—			(47,238		)
Total liabilities	(104,123		)	35,103			(69,020		)	(4,054		)	(73,074		)
Total	$	(49,325	)	$	—		$	(49,325	)	$	(4,054	)	$	(53,379	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting.

(c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,054.

As of December 31, 2015: (dollars in thousands)	Gross Recognized Derivatives (a)			Amounts Offset  (b)			Net Recognized Derivatives			Other (c)			Amount Reported on Balance Sheet
Current assets	$	37,396		$	(22,163	)	$	15,233		$	672		$	15,905
Investments and other assets	15,960			(3,854		)	12,106			—			12,106
Total assets	53,356			(26,017		)	27,339			672			28,011
Current liabilities	(113,560		)	40,223			(73,337		)	(4,379		)	(77,716		)
Deferred credits and other	(93,827		)	3,854			(89,973		)	—			(89,973		)
Total liabilities	(207,387		)	44,077			(163,310		)	(4,379		)	(167,689		)
Total	$	(154,031	)	$	18,060		$	(135,971	)	$	(3,707	)	$	(139,678	)

(a) All of our gross recognized derivative instruments were subject to master netting arrangements.

(b) Includes cash collateral provided to counterparties of $18,060.

(c) Represents cash collateral and cash margin that is not subject to offsetting.  Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument.  Includes cash collateral received from counterparties of $4,379, and cash margin provided to counterparties of $672.

Information about derivative instruments that have credit-risk-related contingent features

The following table provides information about our derivative instruments that have credit-risk-related contingent features at December 31, 2016 (dollars in thousands):

	December 31, 2016
Aggregate fair value of derivative instruments in a net liability position	$	104,123
Cash collateral posted	—
Additional cash collateral in the event credit-risk related contingent features were fully triggered (a)	23,914

(a) This amount is after counterparty netting and includes those contracts which qualify for scope exceptions, which are excluded from the derivative details above.

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Other Income and Other Expense (Tables)

12 Months Ended

Dec. 31, 2016

Component of Other Income and Other Expense Nonoperating [Line Items]

Detail of other income and other expense

The following table provides detail of Pinnacle West's Consolidated other income and other expense for 2016, 2015 and 2014 (dollars in thousands):

	2016			2015			2014
Other income:
Interest income	$	884		$	493		$	1,010
Debt return on the purchase of Four Corners units 4 & 5	—			—			8,386
Miscellaneous	17			128			212
Total other income	$	901		$	621		$	9,608
Other expense:
Non-operating costs	$	(9,235	)	$	(11,292	)	$	(9,657	)
Investment losses — net	(1,747		)	(2,080		)	(9,426		)
Miscellaneous	(4,355		)	(4,451		)	(2,663		)
Total other expense	$	(15,337	)	$	(17,823	)	$	(21,746	)

ARIZONA PUBLIC SERVICE COMPANY

Component of Other Income and Other Expense Nonoperating [Line Items]

Detail of other income and other expense

The following table provides detail of APS’s other income and other expense for 2016, 2015 and 2014 (dollars in thousands):

	2016			2015			2014
Other income:
Interest income	$	261		$	163		$	689
Debt return on the purchase of Four Corners units 4 & 5	—			—			8,386
Gain on disposition of property	5,745			716			1,197
Miscellaneous	2,601			1,955			1,023
Total other income	$	8,607		$	2,834		$	11,295
Other expense:
Non-operating costs (a)	$	(11,034	)	$	(11,648	)	$	(10,397	)
Loss on disposition of property	(1,246		)	(2,219		)	(615		)
Miscellaneous	(5,234		)	(5,152		)	(2,391		)
Total other expense	$	(17,514	)	$	(19,019	)	$	(13,403	)

(a)As defined by FERC, includes non-operating utility income and expense (items excluded from utility rate recovery).

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Palo Verde Sale Leaseback Variable Interest Entities (Tables)

12 Months Ended

Dec. 31, 2016

Variable Interest Entities [Abstract]

Amounts relating to the VIEs included in Consolidated Balance Sheets

Our Consolidated Balance Sheets at December 31, 2016 and December 31, 2015 include the following amounts relating to the VIEs (dollars in thousands):

	December 31, 2016		December 31, 2015
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	$	113,515	$	117,385
Equity-Noncontrolling interests	132,290		135,540

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Nuclear Decommissioning Trusts (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Fair value of APS's nuclear decommissioning trust fund assets

The following table includes the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS’s nuclear decommissioning trust fund assets at December 31, 2016 and December 31, 2015 (dollars in thousands):

	Fair Value		Total  Unrealized  Gains		Total  Unrealized  Losses
December 31, 2016
Equity securities	$	353,261	$	188,091	$	—
Fixed income securities	425,530		9,820		(4,962		)
Net receivables (a)	795		—		—
Total	$	779,586	$	197,911	$	(4,962	)

	Fair Value			Total  Unrealized  Gains		Total  Unrealized  Losses
December 31, 2015
Equity securities	$	314,957		$	157,098	$	(115	)
Fixed income securities	420,574			11,955		(2,645		)
Net payables (a)	(335		)	—		—
Total	$	735,196		$	169,053	$	(2,760	)

(a) Net receivables/(payables) relate to pending purchases and sales of securities.

Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds

The following table sets forth approximate gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds (dollars in thousands):

	Year Ended December 31,
	2016			2015			2014
Realized gains	$	11,213		$	5,189		$	4,725
Realized losses	(10,106		)	(6,225		)	(4,525		)
Proceeds from the sale of securities (a)	633,410			478,813			356,195

(a) Proceeds are reinvested in the trust.

Fair value of fixed income securities, summarized by contractual maturities

The fair value of fixed income securities, summarized by contractual maturities, at December 31, 2016 is as follows (dollars in thousands):

	Fair Value
Less than one year	$	13,063
1 year – 5 years	119,292
5 years – 10 years	105,612
Greater than 10 years	187,563
Total	$	425,530

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Changes in Accumulated Other Comprehensive Loss (Tables)

12 Months Ended

Dec. 31, 2016

Changes in accumulated other comprehensive income (loss) including reclassification adjustments, by component:

Schedule of changes in accumulated other comprehensive loss including reclassification adjustments, by component

The following table shows the changes in Pinnacle West's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2016 and 2015 (dollars in thousands): 

	Year Ended December 31,
	2016			2015
Balance at beginning of period	$	(44,748	)	$	(68,141	)
Derivative Instruments
OCI (loss) before reclassifications	(538		)	(957		)
Amounts reclassified from accumulated other comprehensive loss (a)	2,941			4,187
Net current period OCI (loss)	2,403			3,230
Pension and Other Postretirement Benefits
OCI (loss) before reclassifications	(4,509		)	16,980
Amounts reclassified from accumulated other comprehensive loss (b)	3,032			3,183
Net current period OCI (loss)	(1,477		)	20,163
Balance at end of period	$	(43,822	)	$	(44,748	)

(a) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA.  See Note 16.

(b) These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost.  See Note 7.

ARIZONA PUBLIC SERVICE COMPANY

Changes in accumulated other comprehensive income (loss) including reclassification adjustments, by component:

Schedule of changes in accumulated other comprehensive loss including reclassification adjustments, by component

The following table shows the changes in APS's accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2016 and 2015 (dollars in thousands): 

	Year Ended December 31,
	2016			2015
Balance at beginning of period	$	(27,097	)	$	(48,333	)
Derivative Instruments
OCI (loss) before reclassifications	(538		)	(957		)
Amounts reclassified from accumulated other comprehensive loss (a)	2,941			4,187
Net current period OCI (loss)	2,403			3,230
Pension and Other Postretirement Benefits
OCI (loss) before reclassifications	(3,821		)	14,726
Amounts reclassified from accumulated other comprehensive loss (b)	3,092			3,280
Net current period OCI (loss)	(729		)	18,006
Balance at end of period	$	(25,423	)	$	(27,097	)

(a) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA.  See Note 16.

(b) These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost.  See Note 7.

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Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended			36 Months Ended
	May 31, 2014 $ / kWh	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Jul. 06, 2016
Approximate remaining average useful lives of utility property
Cost of services, depreciation		$ 422	$ 430	$ 396
Depreciation rates (as a percent)		2.66%	2.74%	2.77%
Allowance for Funds Used During Construction
Composite rate used to calculate AFUDC (as a percent)		7.17%	8.02%	8.47%
Income Taxes
Percent likelihood largest tax benefit amount is realized (greater than)		50.00%
Intangible Assets
Amortization expense		$ 58	$ 58	$ 53
Estimated amortization expense on existing intangible assets over the next five years
2017		41			$ 41
2018		23			23
2019		12			12
2020		4			4
2021		$ 1			$ 1
Remaining amortization period for intangible assets		6 years
ARIZONA PUBLIC SERVICE COMPANY
Nuclear Fuel
Charges for the permanent disposal of spent nuclear fuel (in dollars per kWh) | $ / kWh	0.001
Preferred Stock
Preferred stock, shares authorized (in shares) | shares		15,535,000			15,535,000
Preferred stock par or stated value per share 1 (in dollars per share) | $ / shares		$ 25			$ 25
Preferred stock par or stated value per share 2 (in dollars per share) | $ / shares		50			50
Preferred stock par or stated value per share 3 (in dollars per share) | $ / shares		$ 100			$ 100
Pinnacle West
Preferred Stock
Preferred stock, shares authorized (in shares) | shares		10,000,000			10,000,000
Minimum
Approximate remaining average useful lives of utility property
Depreciation rates (as a percent)					0.30%
Maximum
Approximate remaining average useful lives of utility property
Depreciation rates (as a percent)					14.12%
Investments
Ownership percentage for classification as cost method investments by El Dorado		20.00%
Fossil plant
Approximate remaining average useful lives of utility property
Average useful life		19 years
Nuclear plant
Approximate remaining average useful lives of utility property
Average useful life		27 years
Other generation
Approximate remaining average useful lives of utility property
Average useful life		26 years
Transmission
Approximate remaining average useful lives of utility property
Average useful life		39 years
Distribution
Approximate remaining average useful lives of utility property
Average useful life		33 years
General plant
Approximate remaining average useful lives of utility property
Average useful life		7 years
El Paso's Interest in Four Corners | 4CA
Utility Plant and Depreciation [Line Items]
Ownership interest acquired		7.00%			7.00%	7.00%

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Summary of Significant Accounting Policies - Schedule of Reclassification of Prior Period Adjustments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stock compensation	$ 18,883	$ 18,756	$ 33,059
Change in other long-term liabilities	$ (82,793)	(100,715)	(114,052)
As previously reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stock compensation		0	0
Change in other long-term liabilities		(81,959)	(80,993)
Reclassifications to conform to current year presentation
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Stock compensation		18,756	33,059
Change in other long-term liabilities		$ (18,756)	$ (33,059)

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Summary of Significant Accounting Policies - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Utility Plant and Depreciation [Line Items]
Net	$ 11,371,788	$ 10,628,138
Construction work in progress	1,019,947	816,307
Palo Verde sale leaseback, net of accumulated depreciation	113,515	117,385
Intangible assets, net of accumulated amortization	90,022	123,975
Nuclear fuel, net of accumulated amortization	119,004	123,139
Total property, plant and equipment	12,714,276	11,808,944
Electric Service
Utility Plant and Depreciation [Line Items]
Generation	7,874,898	7,336,902
Transmission	2,746,508	2,494,744
Distribution	5,738,801	5,543,561
General plant	981,681	847,025
Plant in service and held for future use	17,341,888	16,222,232
Accumulated depreciation and amortization	(5,970,100)	(5,594,094)
Net	11,371,788	10,628,138
Construction work in progress	1,019,947	816,307
Palo Verde sale leaseback, net of accumulated depreciation	113,515	117,385
Intangible assets, net of accumulated amortization	90,022	123,975
Nuclear fuel, net of accumulated amortization	119,004	123,139
Total property, plant and equipment	$ 12,714,276	$ 11,808,944

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Summary of Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Income tax (benefit), net of refunds	$ 9,956	$ 6,550	$ (102,154)
Interest, net of amounts capitalized	184,462	170,209	177,074
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Accrued capital expenditures	114,855	83,798	44,712
Dividends declared but not paid	$ 72,926	$ 69,363	$ 65,790

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New Accounting Standards - Narrative (Details) $ in Thousands	Dec. 31, 2015 USD ($)
New Accounting Pronouncement, Early Adoption [Line Items]
Stock compensation cumulative effect adjustments	$ 45,855
Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Stock compensation cumulative effect adjustments	5,475
Retained Earnings | Accountings Standards Update 2016-09 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncement, Early Adoption [Line Items]
Stock compensation cumulative effect adjustments	$ 6,000

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Regulatory Matters (Details) - APS															1 Months Ended		2 Months Ended	12 Months Ended
	Feb. 01, 2017 $ / kWh	Jan. 13, 2017 USD ($)	Dec. 20, 2016	Jul. 12, 2016 USD ($)	Jun. 01, 2016 USD ($) kWh $ / kWh	Feb. 01, 2016 $ / kWh	Jan. 15, 2016 USD ($)	Jan. 01, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 01, 2015 USD ($)	Mar. 02, 2015 USD ($)	Feb. 01, 2015 $ / kWh	Jan. 06, 2012 USD ($) $ / kWh	Jun. 01, 2011 USD ($)	Sep. 30, 2016	Dec. 31, 2014 storage_system penetration_feeder MW	Apr. 30, 2014 workshop	Dec. 31, 2016 $ / kWh	Jan. 27, 2017 USD ($)	Dec. 05, 2016 USD ($)	Jul. 01, 2016 USD ($)	Apr. 01, 2016 USD ($)	Jul. 01, 2015 USD ($)	Mar. 20, 2015 USD ($) project
Lost Fixed Cost Recovery Mechanism
Settlement Agreement
Rate matter cap percentage of retail revenue																		1.00%
ACC | 2016 DSMAC
Settlement Agreement
Amount of approved budget										$ 68,900,000												$ 68,900,000
Additional approved budget				$ 4,000,000
ACC | 2017 DSMAC
Settlement Agreement
Amount of proposed budget					$ 62,600,000
ACC | Residential demand response, energy storage and load management program
Settlement Agreement
Additional approved budget																				$ 4,000,000
ACC | Electric Energy Efficiency Standard
Settlement Agreement
Public utilities, cost effective energy efficiency programs, number of workshops | workshop																	3
Public utilities, cost effective efficiency programs, number of days to convene a workshop				120 days
ACC | Modernization and Expansion of the Renewal Energy Standard
Settlement Agreement
Proposed renewal energy standard, percent of retail sales															30.00%
Current renewal energy standard, percent of retail sales															15.00%
ACC | Net Metering
Settlement Agreement
Cost of service, resource comparison proxy method, maximum annual percentage decrease			10.00%
Cost of service for interconnected DG system customers, grandfathered period			20 years
Rate matters, cost of service for new customers, guaranteed export price period			10 years
ACC | Retail Rate Case Filing with Arizona Corporation Commission
Regulatory Matters [Line Items]
Net retail rate increase					$ 165,900,000
Adjuster account balance transferred into base rates									$ 267,600,000
Approximate percentage of increase in average customer bill					5.74%
Approximate percentage of increase in average residential customer bill					7.96%
original cost rate base					$ 6,800,000,000
Required return on incremental fair value rate base above original cost rate base					1.00%
Base rate for fuel and purchased power costs | $ / kWh					0.029882
Decrease in base rate for fuel and purchased power costs | $ / kWh					0.03207
Plan option, non-partial requirements customers, maximum average monthly energy usage | kWh					600
Case completion term					12 months
Settlement Agreement
Reduced system benefits charge, amount								$ 14,600,000
FERC | Transmission rates, transmission cost adjustor and other transmission matters
Settlement Agreement
Increase (decrease) in annual wholesale transmission rates					$ 24,900,000
Filing with the Arizona Corporation Commission | ACC | Retail rate case filing
Regulatory Matters [Line Items]
Net retail rate increase														$ 95,500,000
Approximate percentage of increase in the average retail customer bill														6.60%
Settlement Agreement
Net change in base rates													$ 0
Non-fuel base rate increase													116,300,000
Fuel-related base rate decrease													$ 153,100,000
Current base fuel rate (in dollars per kWh) | $ / kWh													0.03757
Approved base fuel rate (in dollars per kWh) | $ / kWh													0.03207
Estimated amount of transfer of cost recovery for certain renewable energy projects from the RES surcharge to base rates													$ 36,800,000
Authorized return on common equity (as a percent)													10.00%
Percentage of debt in capital structure													46.10%
Percentage of common equity in capital structure													53.90%
Deferral of property taxes in 2012, if Arizona property tax rates increase (as a percent)													25.00%
Deferral of property taxes in 2013, if Arizona property tax rates increase (as a percent)													50.00%
Deferral of property taxes for 2014 and subsequent years, if Arizona property tax rates increase (as a percent)													75.00%
Deferral of property taxes in all years, if Arizona property tax rates decrease (as a percent)													100.00%
Elimination of the sharing provision of fuel and purchased power costs													9
Period to process the subsequent rate cases													12 months
ACC staff sufficiency findings, general period of time													30 days
Filing with the Arizona Corporation Commission | ACC | Retail rate case filing | Maximum
Settlement Agreement
Annual cost recovery due to modifications to the Environmental Improvement Surcharge													$ 5,000,000
Cost Recovery Mechanisms | Lost Fixed Cost Recovery Mechanism
Settlement Agreement
Fixed costs recoverable per residential power lost (in dollars per kWh) | $ / kWh																		0.031
Fixed costs recoverable per non-residential power lost (in dollars per kWh) | $ / kWh																		0.023
Amount of adjustment approved representing prorated sales losses											$ 38,500,000
Amount of adjustment representing prorated sales losses pending approval							$ 46,400,000
Increase in amount of adjustment representing prorated sales losses							$ 7,900,000
Cost Recovery Mechanisms | ACC | 2015 DSMAC
Settlement Agreement
Amount of proposed budget																								$ 68,900,000
Rate matter number of resource savings projects | project																								3
Cost Recovery Mechanisms | ACC | RES
Settlement Agreement
Plan term																		5 years
Cost Recovery Mechanisms | ACC | Arizona Renewable Energy Standard and Tariff 2016
Settlement Agreement
Amount of proposed budget																							$ 148,000,000
Cost Recovery Mechanisms | ACC | Arizona Renewable Energy Standard and Tariff 2017
Settlement Agreement
Amount of proposed budget																					$ 150,000,000
Cost Recovery Mechanisms | ACC | Power Supply Adjustor (PSA)
Settlement Agreement
Maximum increase (decrease) in PSA rate (in dollars per kWh) | $ / kWh												0.004
PSA rate (in dollars per kWh) | $ / kWh						0.001678
Cost Recovery Mechanisms | FERC | Transmission rates, transmission cost adjustor and other transmission matters
Settlement Agreement
Increase (decrease) in annual wholesale transmission rates										$ (17,600,000)
Subsequent Event | ACC | 2017 DSMAC
Settlement Agreement
Amount of proposed budget																			$ 66,600,000
Subsequent Event | ACC | Power Supply Adjustor (PSA)
Settlement Agreement
PSA rate (in dollars per kWh) | $ / kWh	(0.001348)
Forward component of PSA rate (in dollars per kWh) | $ / kWh	(0.001027)
Historical component of PSA rate (in dollars per kWh) | $ / kWh	(0.000321)
Subsequent Event | ACC | Retail Rate Case Filing with Arizona Corporation Commission
Regulatory Matters [Line Items]
Case completion extension term		33 days
Subsequent Event | Cost Recovery Mechanisms | Lost Fixed Cost Recovery Mechanism
Settlement Agreement
Amount of adjustment representing prorated sales losses pending approval		$ 63,700,000
Increase in amount of adjustment representing prorated sales losses		$ 17,300,000
Four Corners Power Plant | ACC | Retail Rate Case Filing with Arizona Corporation Commission
Regulatory Matters [Line Items]
Authorization to defer for potential future recovery of construction costs					400,000,000
Ocotillo Plant | ACC | Retail Rate Case Filing with Arizona Corporation Commission
Regulatory Matters [Line Items]
Authorization to defer for potential future recovery of construction costs					$ 500,000,000
Alternative to AZ Sun Program, Phase 1 | Arizona Renewable Energy Standard and Tariff 2014
Settlement Agreement
Rate matter additional capacity from AZ Sun projects | MW																8
Alternative to AZ Sun Program Phase 2 | Arizona Renewable Energy Standard and Tariff 2014
Settlement Agreement
Rate matter additional capacity from AZ Sun projects | MW																2
Number of energy storage systems | storage_system																2
Number of high solar penetration feeders | penetration_feeder																2

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Regulatory Matters Regulatory Matters - Retail Rate Case Filing (Details) - Retail Rate Case Filing with Arizona Corporation Commission - ACC - ARIZONA PUBLIC SERVICE COMPANY	Jun. 01, 2016
Proposed Capital Structure and Costs of Capital
Requested debt capital structure (as a percent)	44.20%
Requested debt cost of capital (as a percent)	5.13%
Requested equity capital structure (as a percent)	55.80%
Requested equity cost of capital (as a percent)	10.50%
Requested weighted-average cost of capital (as a percent)	8.13%

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Regulatory Matters Regulatory Matters - Deferred Fuel and Purchased Power Regulatory Asset (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in regulatory asset
Deferred fuel and purchased power	$ (60,303)	$ 14,997	$ (26,927)
Deferred fuel and purchased power amortization	38,152	1,617	40,757
ARIZONA PUBLIC SERVICE COMPANY
Change in regulatory asset
Deferred fuel and purchased power	(60,303)	14,997	(26,927)
Deferred fuel and purchased power amortization	38,152	1,617	40,757
ACC | ARIZONA PUBLIC SERVICE COMPANY | Power Supply Adjustor (PSA) | Cost Recovery Mechanisms
Change in regulatory asset
Beginning balance	(9,688)	6,926
Deferred fuel and purchased power	60,303	(14,997)
Deferred fuel and purchased power amortization	(38,150)	(1,617)
Ending balance	$ 12,465	$ (9,688)	$ 6,926

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Regulatory Matters - Four Corners, Cholla and Navajo Plant (Details) - USD ($) $ in Millions				1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 13, 2017	Dec. 23, 2014	Dec. 30, 2013	Jul. 31, 2012	Jun. 30, 2016	Dec. 31, 2016	Feb. 13, 2017	Dec. 31, 2015
Acquisition
Regulatory asset amortization period				3 years
Retired power plant costs | APS
Acquisition
Regulatory asset, net book value						$ 116.0
SCE | Four Corners | APS
Acquisition
Regulatory assets								$ 12.0
Transmission termination agreement net receipt due to negotiation of alternate arrangement			$ 40.0
Regulatory assets, write of amount					$ 12.0
Four Corners Units 4 and 5 | SCE | APS
Acquisition
Ownership interest acquired			48.00%
Settlement agreement, ACC approved rate adjustment, annualized customer impact		$ 57.1
Four Corners Units 4 and 5 | SCE | Four Corners cost deferral | APS
Acquisition
Regulatory assets						$ 64.0
Regulatory asset amortization period						10 years
Subsequent Event | Navajo Plant | APS
Acquisition
Asset net book value							$ 108.0
Subsequent Event | Compromise Proposal to meet Environmental and Emissions Standards and Rules | ACC | APS
Acquisition
Number of days to file a petition	60 days

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Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Detail of regulatory assets
Regulatory assets, current	$ 106,875	$ 149,555
Regulatory assets, non-current	1,313,428	1,214,146
Pension
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	711,059	619,223
Retired power plant costs
Detail of regulatory assets
Regulatory assets, current	9,913	9,913
Regulatory assets, non-current	117,591	127,518
Income taxes - AFUDC equity
Detail of regulatory assets
Regulatory assets, current	6,305	5,495
Regulatory assets, non-current	152,118	133,712
Deferred fuel and purchased power - mark-to-market
Detail of regulatory assets
Regulatory assets, current	0	71,852
Regulatory assets, non-current	42,963	69,697
Four Corners cost deferral
Detail of regulatory assets
Regulatory assets, current	6,689	6,689
Regulatory assets, non-current	56,894	63,582
Income taxes — investment tax credit basis adjustment
Detail of regulatory assets
Regulatory assets, current	2,120	1,766
Regulatory assets, non-current	54,356	48,462
Lost fixed cost recovery
Detail of regulatory assets
Regulatory assets, current	61,307	45,507
Regulatory assets, non-current	0	0
Palo Verde VIE
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	18,775	18,143
Deferred compensation
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	35,595	34,751
Deferred property taxes
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	73,200	50,453
Loss on reacquired debt
Detail of regulatory assets
Regulatory assets, current	1,637	1,515
Regulatory assets, non-current	16,942	16,375
AG-1 deferral
Detail of regulatory assets
Regulatory assets, current	0	0
Regulatory assets, non-current	5,868	0
Demand side management (b)
Detail of regulatory assets
Regulatory assets, current	3,744	0
Regulatory assets, non-current	0	0
Tax expense of Medicare subsidy
Detail of regulatory assets
Regulatory assets, current	1,513	1,520
Regulatory assets, non-current	10,589	12,163
Transmission vegetation management
Detail of regulatory assets
Regulatory assets, current	0	4,543
Regulatory assets, non-current	0	0
Mead-Phoenix transmission line CIAC
Detail of regulatory assets
Regulatory assets, current	332	332
Regulatory assets, non-current	10,708	11,040
Deferred fuel and purchased power
Detail of regulatory assets
Regulatory assets, current	12,465	0
Regulatory assets, non-current	0	0
Coal reclamation
Detail of regulatory assets
Regulatory assets, current	418	418
Regulatory assets, non-current	5,182	6,085
Other
Detail of regulatory assets
Regulatory assets, current	432	5
Regulatory assets, non-current	$ 1,588	$ 2,942

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Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Detail of regulatory liabilities
Regulatory liabilities, current	$ 99,899	$ 145,766
Regulatory liabilities, non-current	948,916	994,152
Asset retirement obligations
Detail of regulatory liabilities
Regulatory liabilities, current	0	0
Regulatory liabilities, non-current	279,976	277,554
Removal costs
Detail of regulatory liabilities
Regulatory liabilities, current	29,899	39,746
Regulatory liabilities, non-current	223,145	240,367
Other postretirement benefits
Detail of regulatory liabilities
Regulatory liabilities, current	32,662	34,100
Regulatory liabilities, non-current	123,913	179,521
Income taxes — deferred investment tax credit
Detail of regulatory liabilities
Regulatory liabilities, current	4,368	3,604
Regulatory liabilities, non-current	108,827	97,175
Income taxes - change in rates
Detail of regulatory liabilities
Regulatory liabilities, current	1,771	1,113
Regulatory liabilities, non-current	70,898	72,454
Spent nuclear fuel
Detail of regulatory liabilities
Regulatory liabilities, current	0	3,051
Regulatory liabilities, non-current	71,726	67,437
Renewable energy standard (b)
Detail of regulatory liabilities
Regulatory liabilities, current	26,809	43,773
Regulatory liabilities, non-current	0	4,365
Demand side management (b)
Detail of regulatory liabilities
Regulatory liabilities, current	0	6,079
Regulatory liabilities, non-current	20,472	19,115
Sundance maintenance
Detail of regulatory liabilities
Regulatory liabilities, current	0	0
Regulatory liabilities, non-current	15,287	13,678
Deferred fuel and purchased power (b) (c)
Detail of regulatory liabilities
Regulatory liabilities, current	0	9,688
Regulatory liabilities, non-current	0	0
Deferred gains on utility property
Detail of regulatory liabilities
Regulatory liabilities, current	2,063	2,062
Regulatory liabilities, non-current	8,895	6,001
Four Corners coal reclamation
Detail of regulatory liabilities
Regulatory liabilities, current	0	0
Regulatory liabilities, non-current	18,248	8,920
Other
Detail of regulatory liabilities
Regulatory liabilities, current	2,327	2,550
Regulatory liabilities, non-current	$ 7,529	$ 7,565

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Income Taxes (Details) - USD ($)			12 Months Ended
	Apr. 04, 2013	Feb. 17, 2011	Dec. 31, 2016
Income Taxes
Interest income to be received on the overpayment of income taxes for certain adjustments that we have filed, or will file, with the IRS (less than)			$ 1,000,000
General business tax credit carryforwards that will begin to expire in 2031			98,000,000
Amount of federal and state loss carryforwards which will begin to expire in 2019			5,000,000
increase (decrease) in deferred income taxes due to regulation adoption			27,000,000
ARIZONA | State Jurisdiction | ARIZONA PUBLIC SERVICE COMPANY
Income Taxes
Phase-in period of corporate income tax rate reductions beginning in 2014		4 years
Decrease in long term deferred tax liability due to rate changes			74,000,000
NEW MEXICO | State Jurisdiction | ARIZONA PUBLIC SERVICE COMPANY
Income Taxes
Phase-in period of corporate income tax rate reductions beginning in 2014	5 years
Decrease in long term deferred tax liability due to rate changes			2,000,000
Palo Verde VIE
Income Taxes
Income tax expense benefit attributable to non controlling interests			$ 0

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Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year
Total unrecognized tax benefits, beginning of the year	$ 34,447	$ 44,775	$ 41,997
Additions for tax positions of the current year	2,695	2,175	4,309
Additions for tax positions of prior years	886	0	751
Reductions for tax positions of prior years for:
Changes in judgment	(1,953)	(10,244)	(2,282)
Settlements with taxing authorities	0	0	0
Lapses of applicable statute of limitations	0	(2,259)	0
Total unrecognized tax benefits, end of the year	36,075	34,447	44,775
ARIZONA PUBLIC SERVICE COMPANY
Tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year
Total unrecognized tax benefits, beginning of the year	34,447	44,775	41,997
Additions for tax positions of the current year	2,695	2,175	4,309
Additions for tax positions of prior years	886	0	751
Reductions for tax positions of prior years for:
Changes in judgment	(1,953)	(10,244)	(2,282)
Settlements with taxing authorities	0	0	0
Lapses of applicable statute of limitations	0	(2,259)	0
Total unrecognized tax benefits, end of the year	$ 36,075	$ 34,447	$ 44,775

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Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax [Line Items]
Tax positions, that if recognized, would decrease our effective tax rate	$ 11,313	$ 9,523	$ 11,207
Unrecognized tax benefit interest expense/(benefit) recognized	529	(161)	752
Unrecognized tax benefit interest accrued	1,333	804	965
ARIZONA PUBLIC SERVICE COMPANY
Income Tax [Line Items]
Tax positions, that if recognized, would decrease our effective tax rate	11,313	9,523	11,207
Unrecognized tax benefit interest expense/(benefit) recognized	529	(161)	752
Unrecognized tax benefit interest accrued	$ 1,333	$ 804	$ 965

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Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal									$ 8,630	$ (12,335)	$ 25,054
State									1,259	4,763	10,382
Total current									9,889	(7,572)	35,436
Deferred:
Federal									201,743	221,505	167,365
State									24,779	23,787	17,904
Total deferred									226,522	245,292	185,269
Income tax expense	$ 27,309	$ 141,446	$ 65,742	$ 1,914	$ 22,847	$ 139,555	$ 67,371	$ 7,947	236,411	237,720	220,705
ARIZONA PUBLIC SERVICE COMPANY
Current:
Federal									711	6,485	40,115
State									4,276	7,813	15,598
Total current									4,987	14,298	55,713
Deferred:
Federal									215,178	208,326	165,027
State									25,677	23,217	16,620
Total deferred									240,855	231,543	181,647
Income tax expense									$ 245,842	$ 245,841	$ 237,360

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Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Comparison of pretax income from continuing operations at the federal income tax rate to income tax expense - continuing operations
Federal income tax rate (as a percent)									35.00%	35.00%	35.00%
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at 35% statutory rate									$ 244,278	$ 242,869	$ 225,540
State income tax net of federal income tax benefit									16,311	18,265	18,149
Credits and favorable adjustments related to prior years resolved in current year									0	(2,169)	0
Medicare Subsidy Part-D									844	837	830
Allowance for equity funds used during construction (see Note 1)									(11,724)	(9,711)	(8,523)
Palo Verde VIE noncontrolling interest (see Note 18)									(6,823)	(6,626)	(9,135)
Investment tax credit amortization									(5,887)	(5,527)	(4,928)
Other									(588)	(218)	(1,228)
Income tax expense	$ 27,309	$ 141,446	$ 65,742	$ 1,914	$ 22,847	$ 139,555	$ 67,371	$ 7,947	$ 236,411	$ 237,720	$ 220,705
ARIZONA PUBLIC SERVICE COMPANY
Comparison of pretax income from continuing operations at the federal income tax rate to income tax expense - continuing operations
Federal income tax rate (as a percent)									35.00%	35.00%	35.00%
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at 35% statutory rate									$ 254,617	$ 250,267	$ 239,638
State income tax net of federal income tax benefit									18,750	20,433	21,148
Credits and favorable adjustments related to prior years resolved in current year									0	(1,892)	0
Medicare Subsidy Part-D									844	837	830
Allowance for equity funds used during construction (see Note 1)									(11,724)	(9,711)	(8,523)
Palo Verde VIE noncontrolling interest (see Note 18)									(6,823)	(6,626)	(9,135)
Investment tax credit amortization									(5,887)	(5,527)	(4,928)
Other									(3,935)	(1,940)	(1,670)
Income tax expense									$ 245,842	$ 245,841	$ 237,360

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Income Taxes - Components of Deferred Income Tax Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
DEFERRED TAX ASSETS
Risk management activities	$ 26,614	$ 70,498
Regulatory liabilities:
Asset retirement obligation and removal costs	200,140	216,765
Unamortized investment tax credits	113,195	100,779
Other postretirement liabilities	60,375	83,034
Other	63,311	60,707
Pension liabilities	204,436	191,028
Renewable energy incentives	56,379	60,956
Credit and loss carryforwards	75,944	59,557
Other	158,421	149,033
Total deferred tax assets	958,815	992,357
DEFERRED TAX LIABILITIES
Plant-related	(3,297,989)	(3,116,752)
Risk management activities	(7,594)	(10,626)
Other postretirement assets	(63,477)	(71,737)
Regulatory assets:
Allowance for equity funds used during construction	(61,088)	(54,110)
Deferred fuel and purchased power — mark-to-market	(21,396)	(55,020)
Pension benefits	(274,184)	(240,692)
Retired power plant costs (see Note 3)	(49,166)	(53,420)
Other	(123,987)	(108,441)
Other	(5,166)	(4,984)
Total deferred tax liabilities	(3,904,047)	(3,715,782)
Deferred income taxes — net	(2,945,232)	(2,723,425)
ARIZONA PUBLIC SERVICE COMPANY
DEFERRED TAX ASSETS
Risk management activities	26,614	70,498
Regulatory liabilities:
Asset retirement obligation and removal costs	200,140	216,765
Unamortized investment tax credits	113,195	100,779
Other postretirement liabilities	60,375	83,034
Other	63,311	60,707
Pension liabilities	194,981	181,787
Renewable energy incentives	56,379	60,956
Credit and loss carryforwards	1,645	0
Other	187,453	176,016
Total deferred tax assets	904,093	950,542
DEFERRED TAX LIABILITIES
Plant-related	(3,297,989)	(3,116,752)
Risk management activities	(7,594)	(10,626)
Other postretirement assets	(62,819)	(70,986)
Regulatory assets:
Allowance for equity funds used during construction	(61,088)	(54,110)
Deferred fuel and purchased power — mark-to-market	(21,396)	(55,020)
Pension benefits	(274,184)	(240,692)
Retired power plant costs (see Note 3)	(49,166)	(53,420)
Other	(123,987)	(108,441)
Other	(5,165)	(4,984)
Total deferred tax liabilities	(3,903,388)	(3,715,031)
Deferred income taxes — net	$ (2,999,295)	$ (2,764,489)

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Lines of Credit and Short-Term Borrowings - Schedule of Credit Facilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Pinnacle West
Lines of Credit and Short-Term Borrowings
Commitment fees (as a percent)	0.125%	0.125%
ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Commitment fees (as a percent)	0.10%	0.10%
Revolving credit facility
Lines of Credit and Short-Term Borrowings
Amount committed	$ 1,275,000	$ 1,200,000
Commercial paper	(177,200)	0
Unused amount	1,097,800	1,200,000
Revolving credit facility | Pinnacle West
Lines of Credit and Short-Term Borrowings
Amount committed	275,000	200,000
Commercial paper	(41,700)	0
Unused amount	233,300	200,000
Revolving credit facility | ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Amount committed	1,000,000	1,000,000
Commercial paper	(135,500)	0
Unused amount	$ 864,500	$ 1,000,000

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Lines of Credit and Short-Term Borrowings (Details)	Aug. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) Facility	May 13, 2016 USD ($)	May 12, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 02, 2015 USD ($)	Feb. 06, 2013 USD ($)
Lines of Credit and Short-Term Borrowings
Short-term borrowings		$ 177,200,000				$ 0
Pinnacle West
Lines of Credit and Short-Term Borrowings
Short-term borrowings		41,700,000				0
ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Short-term borrowings		135,500,000				0
ARIZONA PUBLIC SERVICE COMPANY | ACC
Debt Provisions
Percentage of APS's capitalization used in calculation of short-term debt authorization								7.00%
Required amount to be used in purchases of natural gas and power which is used in calculation of short-term debt authorization								$ 500,000,000
Revolving credit facility
Lines of Credit and Short-Term Borrowings
Amount committed		1,275,000,000				1,200,000,000
Long-term line of credit		177,200,000				0
Revolving credit facility | Pinnacle West
Lines of Credit and Short-Term Borrowings
Amount committed		275,000,000				200,000,000
Long-term line of credit		41,700,000				0
Revolving credit facility | Pinnacle West | Revolving credit facility maturing August 2017
Lines of Credit and Short-Term Borrowings
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders	$ 75,000,000
Debt instrument, term	364 days
Short-term borrowings		40,000,000
Revolving credit facility | Pinnacle West | Revolving credit facility maturing in May 2019
Lines of Credit and Short-Term Borrowings
Amount committed				$ 200,000,000
Revolving credit facility | Pinnacle West | Revolving credit facility maturing May 2021
Lines of Credit and Short-Term Borrowings
Amount committed			$ 200,000,000
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders		300,000,000
Long-term line of credit		0
Revolving credit facility | ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Amount committed		1,000,000,000				1,000,000,000
Long-term line of credit		135,500,000				0
Revolving credit facility | ARIZONA PUBLIC SERVICE COMPANY | Revolving credit facility maturing September 2020
Lines of Credit and Short-Term Borrowings
Amount committed		500,000,000
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders		700,000,000
Revolving credit facility | ARIZONA PUBLIC SERVICE COMPANY | Revolving credit facility maturing in May 2019
Lines of Credit and Short-Term Borrowings
Amount committed							$ 500,000,000
Revolving credit facility | ARIZONA PUBLIC SERVICE COMPANY | Revolving credit facility maturing May 2021
Lines of Credit and Short-Term Borrowings
Amount committed		500,000,000	$ 500,000,000
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders		700,000,000
Revolving credit facility | ARIZONA PUBLIC SERVICE COMPANY | Revolving credit facilities maturing in 2020 and 2021
Lines of Credit and Short-Term Borrowings
Amount committed		1,000,000,000
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders		1,400,000,000
Long-term line of credit		$ 0
Number of credit facilities | Facility		2
Letter of credit | Pinnacle West | Revolving credit facility maturing May 2021
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit		$ 0
Letter of credit | ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit		35,000,000
Letter of credit | ARIZONA PUBLIC SERVICE COMPANY | Revolving credit facilities maturing in 2020 and 2021
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit		0
Commercial paper | Pinnacle West | Revolving credit facility maturing May 2021
Lines of Credit and Short-Term Borrowings
Commercial paper		1,700,000
Commercial paper | ARIZONA PUBLIC SERVICE COMPANY
Lines of Credit and Short-Term Borrowings
Maximum commercial paper support available under credit facility		500,000,000			$ 500,000,000	$ 250,000,000
Commercial paper | ARIZONA PUBLIC SERVICE COMPANY | Revolving credit facilities maturing in 2020 and 2021
Lines of Credit and Short-Term Borrowings
Long-term line of credit		$ 135,500,000
London Interbank Offered Rate (LIBOR) [Member] | Revolving credit facility | Pinnacle West | Revolving credit facility maturing August 2017
Lines of Credit and Short-Term Borrowings
Debt instrument, basis spread on variable rate	0.80%

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Long-Term Debt and Liquidity Matters (Details) - USD ($)	Aug. 01, 2016	Dec. 31, 2016	Dec. 06, 2016	Sep. 20, 2016	Jun. 01, 2016	May 06, 2016	Apr. 22, 2016	Dec. 31, 2015	Feb. 06, 2013	Feb. 05, 2013
Debt Provisions
Total shareholder equity		$ 4,803,622,000						$ 4,583,917,000
Maximum
Debt Provisions
Ratio of consolidated debt to consolidated capitalization (as a percent)		65.00%
ARIZONA PUBLIC SERVICE COMPANY
Debt Provisions
Actual ratio of consolidated debt to total consolidated capitalization required to be maintained as per the debt covenant (as a percent)		47.00%
Total shareholder equity		$ 4,905,680,000						4,679,254,000
ARIZONA PUBLIC SERVICE COMPANY | ACC
Debt Provisions
Total shareholder equity		4,900,000,000
Total capitalization		9,100,000,000
Dividend restrictions, shareholder equity required		$ 3,600,000,000
Long term debt authorization									$ 5,100,000,000.0	$ 4,200,000,000.0
ARIZONA PUBLIC SERVICE COMPANY | Minimum | ACC
Debt Provisions
Required common equity ratio ordered by ACC (as a percent) (at least)		40.00%
Pinnacle West
Debt Provisions
Actual ratio of consolidated debt to total consolidated capitalization required to be maintained as per the debt covenant (as a percent)		48.00%
Total shareholder equity		$ 4,803,622,000						$ 4,583,917,000
Term Loan Facility Maturing April 22, 2019 | ARIZONA PUBLIC SERVICE COMPANY | Term loan
Long-Term Debt and Liquidity Matters [Line Items]
Notes issued							$ 100,000,000
Unsecured Senior Notes 3.75 Percent Mature on 15 May, 2046 | ARIZONA PUBLIC SERVICE COMPANY | Senior notes
Long-Term Debt and Liquidity Matters [Line Items]
Notes issued						$ 350,000,000
Interest rate (as a percent)						3.75%
Arizona Pollution Control Corporation Revenue Refunding Bonds, 2009 Series D and E | ARIZONA PUBLIC SERVICE COMPANY | Current maturities of long-term debt
Long-Term Debt and Liquidity Matters [Line Items]
Principal balance repaid					$ 64,000,000
Arizona pollution control corporation revenue refunding bonds, 2009 series A | ARIZONA PUBLIC SERVICE COMPANY
Long-Term Debt and Liquidity Matters [Line Items]
Principal balance repaid					$ 13,000,000
Unsecured Senior Notes 6.25 Percent Mature on 01 August, 2016 | ARIZONA PUBLIC SERVICE COMPANY | Senior notes
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	6.25%
Repayments of debt	$ 250,000,000
Unsecured Senior Notes 2.55 Percent Mature on 15 September, 2026 | ARIZONA PUBLIC SERVICE COMPANY | Senior notes
Long-Term Debt and Liquidity Matters [Line Items]
Notes issued				$ 250,000,000
Interest rate (as a percent)				2.55%
Arizona Pollution Control Corporation Revenue Refunding Bond, 2009 Series B | ARIZONA PUBLIC SERVICE COMPANY | Current maturities of long-term debt
Long-Term Debt and Liquidity Matters [Line Items]
Principal balance repaid				$ 27,000,000
Coconino County Arizona Pollution Control Corporation Revenue Refunding Bonds | ARIZONA PUBLIC SERVICE COMPANY | Current maturities of long-term debt
Long-Term Debt and Liquidity Matters [Line Items]
Principal balance repaid			$ 17,000,000

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Long-Term Debt and Liquidity Matters - Components of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Long-Term Debt and Liquidity Matters [Line Items]
Total long-term debt	$ 4,146,785	$ 3,819,971
Long-term debt less current maturities	4,021,785	3,462,391
APS
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	4,058,125
Unamortized discount	(11,816)	(10,374)
Unamortized premium	4,506	4,686
Unamortized debt issue costs	(29,030)	(27,896)
Total long-term debt	4,021,785	3,694,971
Less current maturities	0	(357,580)
Total long-term debt less current maturities	4,021,785	3,337,391
Pinnacle West
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	4,183,125
Total long-term debt	125,000	125,000
Long-term debt less current maturities	0	125,000
Pollution Control Bonds - Variable | APS
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 35,975	$ 92,405
Pollution Control Bonds - Variable | APS | Minimum
Long-Term Debt and Liquidity Matters [Line Items]
Weighted-average interest rate (as a percent)	0.81%	0.01%
Pollution Control Bonds - Variable | APS | Maximum
Long-Term Debt and Liquidity Matters [Line Items]
Weighted-average interest rate (as a percent)		0.24%
Pollution Control Bonds - Fixed | APS
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 147,150	$ 211,150
Pollution Control Bonds - Fixed | APS | Minimum
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	1.75%	1.75%
Pollution Control Bonds - Fixed | APS | Maximum
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	4.70%	4.70%
Total Pollution Control Bonds | APS
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 183,125	$ 303,555
Senior unsecured notes | APS
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 3,725,000	$ 3,375,000
Senior unsecured notes | APS | Minimum
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	2.20%	2.20%
Senior unsecured notes | APS | Maximum
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	8.75%	8.75%
Term loan facility | Pinnacle West
Long-Term Debt and Liquidity Matters [Line Items]
Total long-term debt	$ 125,000	$ 125,000
Less current maturities	(125,000)	0
Total long-term debt less current maturities	$ 0	$ 125,000
Weighted-average interest rate (as a percent)	1.52%	1.174%
Term loan | APS
Long-Term Debt and Liquidity Matters [Line Items]
Weighted-average interest rate (as a percent)	1.427%	1.024%
Term loan | Term loan facility maturing June 26, 2018 | APS
Long-Term Debt and Liquidity Matters [Line Items]
Term loans	$ 150,000	$ 50,000

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Long-Term Debt and Liquidity Matters - Future Principal Payments (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Pinnacle West
Principal payments due on long-term debt
2017	$ 125,000
2018	82,000
2019	600,000
2020	250,000
2021	0
Thereafter	3,126,125
Total	4,183,125
ARIZONA PUBLIC SERVICE COMPANY
Principal payments due on long-term debt
2017	0
2018	82,000
2019	600,000
2020	250,000
2021	0
Thereafter	3,126,125
Total	$ 4,058,125

XML

Long-Term Debt and Liquidity Matters - Fair Value of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Estimated fair value of long-term debt, including current maturities
Carrying Amount	$ 4,146,785	$ 3,819,971
Fair Value	4,425,789	4,106,367
Pinnacle West
Estimated fair value of long-term debt, including current maturities
Carrying Amount	125,000	125,000
Fair Value	125,000	125,000
ARIZONA PUBLIC SERVICE COMPANY
Estimated fair value of long-term debt, including current maturities
Carrying Amount	4,021,785	3,694,971
Fair Value	$ 4,300,789	$ 3,981,367

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Retirement Plans and Other Benefits Retirement Plans and Other Benefits (Details)	1 Months Ended	12 Months Ended
	Jul. 31, 2012	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Jan. 01, 2015 Age
Plan Design Changes [Abstract]
Noncurrent asset		$ 166,206,000	$ 185,997,000
Amount of other postretirement benefit trust assets for union employee medical costs		140,000,000
Amount of pension and other postretirement benefit costs deferred						$ 14,000,000	$ 11,000,000
Regulatory asset amortization period	3 years
Amortization of regulatory assets			5,000,000	$ 8,000,000	$ 8,000,000	$ 4,000,000
Change in mortality assumptions impact on pension and other postretirement obligations			67,000,000
Partnership funding commitments, contribution amount (up to)		75,000,000
Partnership funding commitments, funded amount		54,000,000
Pension Benefits
Plan Design Changes [Abstract]
Noncurrent asset		$ 0	0
Expected long-term return on plan assets for next fiscal year (as a percent)		6.55%
Contributions
Employer's contributions under the plan		$ 100,000,000	100,000,000	175,000,000
Minimum contributions under MAP-21
Minimum contributions under MAP-21		0
Voluntary employer contributions over next three years (up to)		$ 300,000,000
Pension Benefits | Fixed income securities
Target asset allocation
Target allocation (as a percent)		58.00%
Target allocation, minimum (as a percent)		55.00%
Target allocation, maximum (as a percent)		61.00%
Actual asset allocation (as a percent)		57.00%
Pension Benefits | Return-generating assets
Target asset allocation
Target allocation (as a percent)		42.00%
Target allocation, minimum (as a percent)		39.00%
Target allocation, maximum (as a percent)		45.00%
Actual asset allocation (as a percent)		43.00%
Pension Benefits | Developed equities
Target asset allocation
Target allocation (as a percent)		22.00%
Pension Benefits | Emerging equities
Target asset allocation
Target allocation (as a percent)		6.00%
Pension Benefits | Alternative investments
Target asset allocation
Target allocation (as a percent)		14.00%
Other postretirement benefits
Plan Design Changes [Abstract]
Age eligible for benefit | Age								65
Effect of plan amendment on net periodic benefit cost				10,000,000
Effect of plan amendment on expense				5,000,000
Effect of plan amendment on accumulated benefit obligation				316,000,000
Noncurrent asset		$ 166,206,000	185,997,000
Expected long-term return on plan assets for next fiscal year (as a percent)		6.37%
Contributions
Employer's contributions under the plan		$ 819,000	791,000	1,000,000
Expected employer contributions
2017 (less than)		1,000,000
2018 (less than)		1,000,000
2019 (less than)		$ 1,000,000
Other postretirement benefits | Fixed income
Target asset allocation
Actual asset allocation (as a percent)		51.00%
Other postretirement benefits | Non-fixed income
Target asset allocation
Actual asset allocation (as a percent)		49.00%
Pinnacle West
Employee savings plan benefits
Expenses recorded for the defined contribution savings plan		$ 10,000,000	9,000,000	9,000,000
ARIZONA PUBLIC SERVICE COMPANY
Plan Design Changes [Abstract]
Noncurrent asset		$ 162,911,000	182,625,000
Employee savings plan benefits
APS's employees share of total cost of the plans (as a percent)		99.00%
ARIZONA PUBLIC SERVICE COMPANY | Pension Benefits
Contributions
Employer's contributions under the plan		$ 100,000,000	100,000,000	175,000,000
ARIZONA PUBLIC SERVICE COMPANY | Other postretirement benefits
Contributions
Employer's contributions under the plan		$ 1,000,000	$ 1,000,000	$ 1,000,000

XML

Retirement Plans and Other Benefits - Net Periodic Benefit Costs and Portion including Portion Charged to Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Net periodic benefit costs and the portion of these costs charged to expense
Service cost-benefits earned during the period	$ 53,792	$ 59,627	$ 53,080
Interest cost on benefit obligation	131,647	123,983	129,194
Expected return on plan assets	(173,906)	(179,231)	(158,998)
Amortization of prior service cost (credit)	527	594	869
Amortization of net actuarial loss	40,717	31,056	10,963
Net periodic benefit cost	52,777	36,029	35,108
Portion of cost charged to expense	26,172	20,036	21,985
Other Benefits
Net periodic benefit costs and the portion of these costs charged to expense
Service cost-benefits earned during the period	14,993	16,827	18,139
Interest cost on benefit obligation	29,721	28,102	41,243
Expected return on plan assets	(36,495)	(36,855)	(46,400)
Amortization of prior service cost (credit)	(37,883)	(37,968)	(9,626)
Amortization of net actuarial loss	4,589	4,881	1,175
Net periodic benefit cost	(25,075)	(25,013)	4,531
Portion of cost charged to expense	$ (12,435)	$ (10,391)	$ 6,000

XML

Retirement Plans and Other Benefits - Changes Benefit Obligations and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Change in Benefit Obligation
Benefit obligation at the beginning of the period	$ 3,033,803	$ 3,078,648
Service cost	53,792	59,627	$ 53,080
Interest cost	131,647	123,983	129,194
Benefit payments	(142,247)	(137,115)
Actuarial (gain) loss	127,467	(91,340)
Benefit obligation at the end of the period	3,204,462	3,033,803	3,078,648
Change in Plan Assets
Balance at the beginning of the period	2,542,774	2,615,404
Actual return on plan assets	166,408	(44,690)
Employer's contributions under the plan	100,000	100,000	175,000
Benefit payments	(133,825)	(127,940)
Balance at the end of the period	2,675,357	2,542,774	2,615,404
Funded Status at the end of the period	(529,105)	(491,029)
Other Benefits
Change in Benefit Obligation
Benefit obligation at the beginning of the period	647,020	682,335
Service cost	14,993	16,827	18,139
Interest cost	29,721	28,102	41,243
Benefit payments	(26,231)	(24,988)
Actuarial (gain) loss	50,942	(55,256)
Benefit obligation at the end of the period	716,445	647,020	682,335
Change in Plan Assets
Balance at the beginning of the period	833,017	834,625
Actual return on plan assets	63,463	(2,399)
Employer's contributions under the plan	819	791	1,000
Benefit payments	(14,648)	0
Balance at the end of the period	882,651	833,017	$ 834,625
Funded Status at the end of the period	$ 166,206	$ 185,997

XML

Retirement Plans and Other Benefits - Projected Benefit Obligation for Pension Plans (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets
Projected benefit obligation	$ 3,204,462	$ 3,033,803
Accumulated benefit obligation	3,049,406	2,873,467
Fair value of plan assets	$ 2,675,357	$ 2,542,774

XML

Retirement Plans and Other Benefits - Amounts Recognized on the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized on the Consolidated Balance Sheets
Noncurrent asset	$ 166,206	$ 185,997
Pension Benefits
Amounts recognized on the Consolidated Balance Sheets
Noncurrent asset	0	0
Current liability	(19,795)	(10,031)
Noncurrent liability	(509,310)	(480,998)
Net amount recognized	(529,105)	(491,029)
Other Benefits
Amounts recognized on the Consolidated Balance Sheets
Noncurrent asset	166,206	185,997
Current liability	0	0
Noncurrent liability	0	0
Net amount recognized	$ 166,206	$ 185,997

XML

Retirement Plans and Other Benefits - Impact to Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Details related to accumulated other comprehensive loss
Accumulated other comprehensive loss	$ 39,070	$ 37,593
Other Benefits
Details related to accumulated other comprehensive loss
Net actuarial loss	146,509	127,124
Prior service cost (credit)	(303,417)	(341,301)
APS’s portion recorded as a regulatory (asset) liability	156,575	213,621
Income tax expense (benefit)	833	925
Accumulated other comprehensive loss	500	369
Estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets into net periodic benefit cost in 2014
Net actuarial loss	5,181
Prior service cost (credit)	(37,842)
Total amounts estimated to be amortized from accumulated other comprehensive loss (gain) and regulatory assets (liabilities) in 2017	(32,661)
Pension Benefits
Details related to accumulated other comprehensive loss
Net actuarial loss	773,750	679,501
Prior service cost (credit)	81	609
APS’s portion recorded as a regulatory (asset) liability	(711,059)	(619,223)
Income tax expense (benefit)	(24,202)	(23,663)
Accumulated other comprehensive loss	38,570	$ 37,224
Estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets into net periodic benefit cost in 2014
Net actuarial loss	46,971
Prior service cost (credit)	81
Total amounts estimated to be amortized from accumulated other comprehensive loss (gain) and regulatory assets (liabilities) in 2017	$ 47,052

XML

Retirement Plans and Other Benefits - Weighted-Average Assumptions for Pensions and Other Benefits (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015
Weighted-average assumptions used to determine benefit obligations
Rate of compensation increase (as a percent)			4.00%	4.00%
Initial pre-65 healthcare cost trend rate (as a percent)			7.00%	7.00%
Initial post-65 healthcare cost trend rate (as a percent)			5.00%	5.00%
Ultimate health care cost trend rate (as a percent)			5.00%	5.00%
Number of years to ultimate trend rate (pre-65 participants)			4 years	4 years
Number of years to ultimate trend rate (post-65 participants)			0 years	0 years
Weighted-average assumptions used to determine net periodic benefit costs
Initial pre-65 health care cost trend rate (as a percent)	7.50%	7.50%	7.00%	7.00%
Initial post-65 health care cost trend rate (as a percent)	5.00%	7.50%	5.00%	5.00%
Ultimate healthcare cost trend rate (as a percent)	5.00%	5.00%	5.00%	5.00%
Number of years to ultimate trend rate (pre-65 participants)	4 years	4 years	4 years	4 years
Number of years to ultimate trend rate (post-65 participants)	0 years	4 years	0 years	0 years
Pension Benefits
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)			4.08%	4.37%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.88%	4.88%	4.37%	4.02%
Rate of compensation increase (as a percent)	4.00%	4.00%	4.00%	4.00%
Expected long-term return on plan assets (as a percent)	6.90%	6.90%	6.90%	6.90%
Other Benefits
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)			4.17%	4.52%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.41%	5.10%	4.52%	4.14%
Expected long-term return on plan assets (as a percent)	4.25%	6.80%	4.45%	4.45%
Effects of one percentage point change in the assumed initial and ultimate health care cost trend rates
Effect of 1% increase on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants			$ 8,430
Effect of 1% decrease on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants			(5,455)
Effect of 1% increase on service and interest cost components of net periodic other postretirement benefit costs			8,440
Effect of 1% decrease on service and interest cost components of net periodic other postretirement benefit costs			(6,527)
Effect of 1% increase on the accumulated other postretirement benefit obligation			108,046
Effect of 1% decrease on the accumulated other postretirement benefit obligation			$ (86,651)

XML

Retirement Plans and Other Benefits - Fair Value of Pinnacle West's Pension Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	$ 2,675,357	$ 2,542,774	$ 2,615,404
Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	749,541	680,351
Fair value of plan assets	2,675,357	2,542,774
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	613,193	640,679
Pension Benefits | Significant Other Observable Inputs (Level 2) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	1,312,623	1,221,744
Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	882,651	833,017	$ 834,625
Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	123,234	135,059
Fair value of plan assets	882,651	833,017
Other Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	456,718	449,826
Other Benefits | Significant Other Observable Inputs (Level 2) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	302,699	248,132
Cash and cash equivalents | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	13,995	1,893
Cash and cash equivalents | Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	13,995	1,893
Cash and cash equivalents | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	304	240
Cash and cash equivalents | Other Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	304	240
Corporate | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	1,210,453	1,108,736
Corporate | Pension Benefits | Significant Other Observable Inputs (Level 2) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	1,210,453	1,108,736
Corporate | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	268,193	217,026
Corporate | Other Benefits | Significant Other Observable Inputs (Level 2) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	268,193	217,026
U.S. Treasury | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	112,583	274,778
U.S. Treasury | Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	112,583	274,778
U.S. Treasury | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	145,255	131,435
U.S. Treasury | Other Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	145,255	131,435
Other | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	102,170	113,008
Other | Pension Benefits | Significant Other Observable Inputs (Level 2) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	102,170	113,008
Other | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	34,506	31,106
Other | Other Benefits | Significant Other Observable Inputs (Level 2) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	34,506	31,106
Common stock equities | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	235,109	247,701
Common stock equities | Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	235,109	247,701
Common stock equities | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	243,741	265,583
Common stock equities | Other Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	243,741	265,583
Mutual fund | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	251,506
Mutual fund | Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	251,506
Mutual fund | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	67,418
Mutual fund | Other Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	67,418
Equities | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	266,840	315,989
Fair value of plan assets	266,840	315,989
Equities | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	95,814	110,055
Fair value of plan assets	95,814	110,055
Real estate | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	161,449	150,359
Fair value of plan assets	161,449	150,359
Real estate | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	14,509	13,512
Fair value of plan assets	14,509	13,512
Partnerships | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	208,915	169,937
Fair value of plan assets	208,915	169,937
Partnerships | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	3,060
Fair value of plan assets	3,060
Short-term investments and other | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	112,337	44,066
Fair value of plan assets	112,337	44,066
Short-term investments and other | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	9,851	11,492
Fair value of plan assets	$ 9,851	11,492
Mutual funds - International equities | Pension Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets		116,307
Mutual funds - International equities | Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		116,307
Mutual funds - International equities | Other Benefits | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets		52,568
Mutual funds - International equities | Other Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pinnacle West
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		$ 52,568

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Retirement Plans and Other Benefits - Estimated Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Pension Benefits
Estimated Future Benefit Payments
2017	$ 172,859
2018	173,232
2019	182,944
2020	191,037
2021	196,292
Years 2022-2026	1,049,149
Other Benefits
Estimated Future Benefit Payments
2017	31,126
2018	33,795
2019	36,195
2020	37,998
2021	39,368
Years 2022-2026	$ 201,944

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Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Trust	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 1986 Trust
Estimated future minimum lease payments for operating leases, excluding purchased power agreements
Lease expense	$ 16,000	$ 17,000	$ 18,000
Pinnacle West
Estimated future minimum lease payments for operating leases, excluding purchased power agreements
2017	12,330
2018	10,987
2019	9,019
2020	7,688
2021	5,266
Thereafter	59,647
Total future lease commitments	104,937
Palo Verde Lessor Trusts
Estimated future minimum lease payments for operating leases, excluding purchased power agreements
Number of VIE lessor trusts | Trust				3
APS
Estimated future minimum lease payments for operating leases, excluding purchased power agreements
2017	11,919
2018	10,690
2019	8,767
2020	7,439
2021	5,020
Thereafter	57,207
Total future lease commitments	101,042
Lease expense	$ 15,000	$ 14,000	$ 15,000
Number of VIE lessor trusts | Trust	3			3

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Jointly-Owned Facilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Jul. 06, 2016
4CA
Interests in jointly-owned facilities
Plant in Service	$ 110,000
Accumulated Depreciation	79,000
Construction work in progress	$ 30,000
Palo Verde Units 1 and 3 | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	29.10%
Plant in Service	$ 1,770,324
Accumulated Depreciation	1,080,072
Construction work in progress	$ 17,615
Palo Verde Unit 2 | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	16.80%
Plant in Service	$ 581,572
Accumulated Depreciation	360,757
Construction work in progress	$ 9,717
Palo Verde Common | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	28.00%
Plant in Service	$ 672,799
Accumulated Depreciation	242,649
Construction work in progress	62,479
Palo Verde Sale Leaseback | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Plant in Service	351,050
Accumulated Depreciation	237,535
Construction work in progress	$ 0
Four Corners Generating Station | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	63.00%
Plant in Service	$ 934,837
Accumulated Depreciation	578,924
Construction work in progress	$ 248,072
Navajo Generating Station Units 1, 2 and 3 | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	14.00%
Plant in Service	$ 279,629
Accumulated Depreciation	176,931
Construction work in progress	$ 5,761
Cholla Common Facilities | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	63.30%
Plant in Service	$ 159,707
Accumulated Depreciation	58,276
Construction work in progress	$ 806
ANPP 500kV System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	33.60%
Plant in Service	$ 127,970
Accumulated Depreciation	38,610
Construction work in progress	$ 2,291
Navajo Southern System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	22.50%
Plant in Service	$ 62,135
Accumulated Depreciation	20,491
Construction work in progress	$ 334
Palo Verde — Yuma 500kV System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	19.00%
Plant in Service	$ 13,699
Accumulated Depreciation	5,368
Construction work in progress	$ 408
Four Corners Switchyards | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	51.30%
Plant in Service	$ 39,850
Accumulated Depreciation	10,474
Construction work in progress	$ 1,044
Phoenix — Mead System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	17.10%
Plant in Service	$ 39,330
Accumulated Depreciation	13,725
Construction work in progress	$ 85
Palo Verde — Rudd 500kV System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 91,904
Accumulated Depreciation	19,818
Construction work in progress	$ 227
Morgan — Pinnacle Peak System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	65.20%
Plant in Service	$ 140,374
Accumulated Depreciation	13,557
Construction work in progress	$ 0
Round Valley System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 515
Accumulated Depreciation	127
Construction work in progress	$ 0
Palo Verde — Morgan System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	85.80%
Plant in Service	$ 125,908
Accumulated Depreciation	1,326
Construction work in progress	$ 28,949
Hassayampa — North Gila System | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	80.00%
Plant in Service	$ 142,541
Accumulated Depreciation	3,231
Construction work in progress	$ 0
Cholla 500kV Switchyard | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	85.70%
Plant in Service	$ 5,078
Accumulated Depreciation	1,201
Construction work in progress	$ 0
Saguaro 500kV Switchyard | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	75.00%
Plant in Service	$ 20,456
Accumulated Depreciation	12,426
Construction work in progress	$ 2
Cholla common construction facilities | ARIZONA PUBLIC SERVICE COMPANY
Interests in jointly-owned facilities
Percent Owned	50.50%
El Paso's Interest in Four Corners | 4CA
Interests in jointly-owned facilities
Ownership interest acquired	7.00%	7.00%

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Commitments and Contingencies - Palo Verde Nuclear Generating Station and Contractual Obligations (Details)				9 Months Ended	12 Months Ended
	Feb. 01, 2017 USD ($)	Jan. 01, 2017 USD ($)	Aug. 18, 2014 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) Trust time_period claim	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 1986 Trust
ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
Maximum insurance against public liability per occurrence for a nuclear incident					$ 13,400,000,000.0
Maximum available nuclear liability insurance				$ 375,000,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program					13,100,000,000
Maximum assessment per reactor for each nuclear incident					127,300,000
Annual limit per incident with respect to maximum assessment					$ 18,900,000.0
Number of VIE lessor trusts | Trust					3			3
Maximum potential retrospective assessment per incident of APS					$ 111,100,000
Annual payment limitation with respect to maximum potential retrospective assessment					16,600,000
Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde					2,800,000,000
Maximum amount that APS could incur under the current NEIL policies for each retrospective assessment					23,800,000
Collateral assurance provided based on rating triggers					$ 64,000,000
Period to provide collateral assurance based on rating triggers					20 days
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2017					$ 977,000,000
2018					737,000,000
2019					598,000,000
2020					525,000,000
2021					524,000,000
Thereafter					7,300,000,000
ARIZONA PUBLIC SERVICE COMPANY | Coal take-or-pay commitments
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2017					195,428,000
2018					189,588,000
2019					193,818,000
2020					198,160,000
2021					202,619,000
Thereafter					2,068,355,000
Total obligation					3,047,968,000
Present value of commitments					2,100,000,000
Total purchases					160,066,000	$ 211,327,000	$ 236,773,000
ARIZONA PUBLIC SERVICE COMPANY | Renewable energy credits
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2017					40,000,000
2018					40,000,000
2019					40,000,000
2020					40,000,000
2021					40,000,000
Thereafter					420,000,000
ARIZONA PUBLIC SERVICE COMPANY | Coal Mine Reclamation Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2017					17,000,000
2018					18,000,000
2019					19,000,000
2020					21,000,000
2021					22,000,000
Thereafter					241,000,000
ARIZONA PUBLIC SERVICE COMPANY | Coal Mine Reclamation Balance Sheet Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
Total obligation					207,000,000	$ 202,000,000
4CA | Coal Mine Reclamation Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2017					1,000,000
2018					1,000,000
2019					1,000,000
2020					1,000,000
2021					2,000,000
Thereafter					17,000,000
4CA | Coal Mine Reclamation Balance Sheet Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
Total obligation					15,000,000
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste
Palo Verde Nuclear Generating Station [Abstract]
Litigation settlement, amount			$ 57,400,000
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste | ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
Litigation settlement, amount			$ 16,700,000
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal
Palo Verde Nuclear Generating Station [Abstract]
Proceeds from legal settlements					$ 53,900,000
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal | ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
New claims filed | claim					2
Number of settlement agreement time periods | time_period					2
Proceeds from legal settlements					$ 15,700,000
Subsequent Event | ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
Maximum available nuclear liability insurance		$ 450,000,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program		$ 13,000,000,000
Subsequent Event | Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal
Palo Verde Nuclear Generating Station [Abstract]
Litigation settlement, amount	$ 11,300,000
Subsequent Event | Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal | ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
Litigation settlement, amount	$ 3,300,000

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Commitments and Contingencies - Superfund-Related Matters and Southwest Power Outage (Details) - ARIZONA PUBLIC SERVICE COMPANY $ in Millions			12 Months Ended
	Aug. 06, 2013 Defendant	Sep. 08, 2011 kV Customer	Dec. 31, 2016 USD ($)
Superfund
Costs related to investigation and study under Superfund site | $			$ 2
Southwest Power Outage
Power outage capacity of transmission line that tripped out of service | kV		500
Period, after the transmission line went off-line, over which generation and transmission resources for the Yuma area were lost		10 minutes
Number of customers losing service in Yuma area | Customer		69,700
Contaminated groundwater wells
Superfund
Number of defendants against whom Roosevelt Irrigation District ("RID") filed lawsuit | Defendant	24

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Commitments and Contingencies Commitments and Contingencies - Environmental Matters and Financial Assurances (Details)					9 Months Ended	12 Months Ended
	Jul. 06, 2016 guarantee	Jun. 24, 2016	Mar. 16, 2016 USD ($)	May 23, 2013 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2016 USD ($)
Environmental Matters [Abstract]
Clean power plan, optional extension period						2 years
Payment Guarantee
Financial Assurances
Number of parental guarantees | guarantee	2
Four Corners | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Additional expected environment cost						$ 15,000,000
Cholla Units 1-3 | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Expected environmental cost						8,000,000
New Mexico Tax Matter | Four Corners
Environmental Matters [Abstract]
Coal severance surtax, penalty, and interest				$ 30,000,000
Litigation settlement, amount			$ 1,000,000
New Mexico Tax Matter | Four Corners | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Share of the assessment				12,000,000
Partial payment assessment				$ 800,000
Litigation settlement, amount			$ 800,000
Letter of credit | ARIZONA PUBLIC SERVICE COMPANY
Financial Assurances
Outstanding letters of credit						35,000,000
Equity Lessors Sale Leaseback Letter of Credit | ARIZONA PUBLIC SERVICE COMPANY
Financial Assurances
Outstanding letters of credit						53,000,000
Four Corners Units 4 and 5 | Four Corners | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Additional expected environment cost						45,000,000
Four Corners Units 4 and 5 | Navajo Plant | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Expected environmental cost						$ 200,000,000
Four Corners Units 4 and 5 | Natural Gas Tolling Letter of Credit | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Percentage share cost of control						63.00%
Additional percentage share of cost of control						7.00%
Minimum | Four Corners Units 4 and 5 | Four Corners | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Expected environmental cost						$ 400,000,000
Regional Haze Rules | Cholla | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Expected environmental cost					$ 100,000,000
Mercury and Air Toxic Standards | Navajo Generating Station | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Expected environmental cost						1,000,000
Coal Combustion Waste | Navajo Generating Station | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Additional expected environment cost						1,000,000
Coal Combustion Waste | Boron Inclusion on List of Groundwater Constituents | Navajo Generating Station | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Period to complete rulemaking proceeding		3 years
Coal Combustion Waste | Minimum | Cholla | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Additional expected environment cost						5,000,000
Coal Combustion Waste | Maximum | Cholla | ARIZONA PUBLIC SERVICE COMPANY
Environmental Matters [Abstract]
Additional expected environment cost						$ 40,000,000
El Paso's Interest in Four Corners | 4CA
Financial Assurances
Ownership interest acquired	7.00%					7.00%

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Asset Retirement Obligations (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) turbine_unit	Dec. 31, 2015 USD ($)
Changes attributable to:
Asset retirement obligations, current	$ 9,135	$ 28,573
ARIZONA PUBLIC SERVICE COMPANY
Change in asset retirement obligations
Asset retirement obligations at the beginning of year	443,576	390,750
Changes attributable to:
Accretion expense	26,656	25,163
Settlements	(15,732)	(32,048)
Estimated cash flow revisions	151,046	17,556
Newly incurred or acquired obligations	18,929	42,155
Asset retirement obligations at the end of year	624,475	443,576
Asset retirement obligations, current	$ 8,703	28,573
Ocotillo Steam Units | ARIZONA PUBLIC SERVICE COMPANY
Asset Retirement Obligations
Number of constructed turbine units | turbine_unit	5
Changes attributable to:
Newly incurred or acquired obligations	$ 10,000
El Paso's Share of Four Corners Units 4 & 5 [Member] | 4CA
Changes attributable to:
Newly incurred or acquired obligations	9,000
Four Corners | ARIZONA PUBLIC SERVICE COMPANY
Changes attributable to:
Settlements	(16,000)	(32,000)
Estimated cash flow revisions		24,000
Palo Verde Nuclear Generating Station | ARIZONA PUBLIC SERVICE COMPANY
Asset Retirement Obligations
Increase in plant services	131,000
Decrease in regulatory liability	20,000
Changes attributable to:
Estimated cash flow revisions	$ 151,000
Cholla | ARIZONA PUBLIC SERVICE COMPANY
Asset Retirement Obligations
Increase in plant services		23,000
Decrease in regulatory liability		16,000
Changes attributable to:
Estimated cash flow revisions		(3,000)
Newly incurred or acquired obligations		$ 39,000

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Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Line Items]
OPERATING REVENUES	$ 739,199	$ 1,166,922	$ 915,394	$ 677,167	$ 734,430	$ 1,199,146	$ 890,648	$ 671,219	$ 3,498,682	$ 3,495,443	$ 3,491,632
Operations and maintenance	208,277	217,568	242,279	243,195	222,019	220,449	210,965	214,944	911,319	868,377	908,025
Operating income	122,816	451,258	231,748	50,162	109,834	445,111	231,973	67,684	855,984	854,602	811,242
INCOME TAXES (Note 4)	27,309	141,446	65,742	1,914	22,847	139,555	67,371	7,947	236,411	237,720	220,705
Net income	58,119	267,900	126,182	9,326	45,978	261,978	127,507	20,727	461,527	456,190	423,696
Net income attributable to common shareholders	$ 53,246	$ 263,027	$ 121,308	$ 4,453	$ 41,117	$ 257,116	$ 122,902	$ 16,122	$ 442,034	$ 437,257	$ 397,595
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 0.48	$ 2.36	$ 1.09	$ 0.04	$ 0.37	$ 2.32	$ 1.11	$ 0.15	$ 3.97	$ 3.94	$ 3.59
Net income attributable to common shareholders — diluted (in dollars per share)	$ 0.47	$ 2.35	$ 1.08	$ 0.04	$ 0.37	$ 2.30	$ 1.10	$ 0.14	$ 3.95	$ 3.92	$ 3.58
ARIZONA PUBLIC SERVICE COMPANY
Selected Quarterly Financial Information [Line Items]
Operating revenues	$ 737,006	$ 1,166,359	$ 909,757	$ 676,632	$ 733,586	$ 1,198,380	$ 889,723	$ 670,668	$ 3,489,754	$ 3,492,357	$ 3,488,946
Operations and maintenance	197,319	209,366	233,712	238,711	219,146	216,011	208,031	209,947	879,108	853,135	882,442
Operating income	95,765	307,601	165,684	48,930	86,709	301,238	162,704	61,333	617,980	611,984	592,792
INCOME TAXES (Note 4)									245,842	245,841	237,360
Net income									481,634	469,207	447,320
Net income attributable to common shareholders	$ 58,480	$ 269,220	$ 127,188	$ 7,253	$ 43,857	$ 261,187	$ 125,362	$ 19,868	$ 462,141	$ 450,274	$ 421,219

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Fair Value Measurements - Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets
Nuclear decommissioning trust	$ 779,586	$ 735,196
Total assets	11,076	30,364
Fair value measurement on a recurring basis
Assets
Coal reclamation trust - Cash equivalents	14,521
Other	(35,103)	(25,345)
Derivative assets	19,695	28,011
Other	354,056	314,622
Nuclear decommissioning trust	779,586	735,196
Other	318,953	289,277
Total assets	813,802	763,207
Liabilities
Other	31,049	39,698
Derivative Liability	(73,074)	(167,689)
Fair value measurement on a recurring basis | US commingled equity funds
Assets
Other	353,261	314,957
Nuclear decommissioning trust	353,261	314,957
Fair value measurement on a recurring basis | Cash and cash equivalents
Assets
Other	795	(335)
Nuclear decommissioning trust	795	11,925
Fair value measurement on a recurring basis | U.S. Treasury
Assets
Nuclear decommissioning trust	95,441	117,245
Fair value measurement on a recurring basis | Corporate
Assets
Nuclear decommissioning trust	111,623	96,243
Fair value measurement on a recurring basis | Mortgage-backed securities
Assets
Nuclear decommissioning trust	115,337	99,065
Fair value measurement on a recurring basis | Municipality bonds
Assets
Nuclear decommissioning trust	80,997	72,206
Fair value measurement on a recurring basis | Other
Assets
Nuclear decommissioning trust	22,132	23,555
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Coal reclamation trust - Cash equivalents	14,521
Decommissioning fund investments, gross fair value	95,441	129,505
Gross assets, fair value disclosure	109,962	129,505
Liabilities
Gross derivative liability	0	0
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Assets
Decommissioning fund investments, gross fair value		12,260
Fair value measurement on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury
Assets
Decommissioning fund investments, gross fair value	95,441	117,245
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Gross derivative assets	43,722	22,992
Decommissioning fund investments, gross fair value	330,089	291,069
Gross assets, fair value disclosure	373,811	314,061
Liabilities
Gross derivative liability	(45,641)	(144,044)
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate
Assets
Decommissioning fund investments, gross fair value	111,623	96,243
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities
Assets
Decommissioning fund investments, gross fair value	115,337	99,065
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2) | Municipality bonds
Assets
Decommissioning fund investments, gross fair value	80,997	72,206
Fair value measurement on a recurring basis | Significant Other Observable Inputs (Level 2) | Other
Assets
Decommissioning fund investments, gross fair value	22,132	23,555
Fair value measurement on a recurring basis | Significant Unobservable Inputs (Level 3)
Assets
Gross derivative assets	11,076	30,364
Gross assets, fair value disclosure	11,076	30,364
Liabilities
Gross derivative liability	$ (58,482)	$ (63,343)

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Fair Value Measurements - Level 3 Quantitative Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / MMBTU $ / MWh	Dec. 31, 2015 USD ($) $ / MMBTU $ / MWh
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets | $	$ 11,076	$ 30,364
Liabilities | $	58,482	63,343
Electricity forward contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets | $	10,648	24,543
Liabilities | $	$ 32,042	$ 54,679
Electricity forward contracts | Minimum | Discounted cash flows
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh	16.43	15.92
Electricity forward contracts | Maximum | Discounted cash flows
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh	41.07	40.73
Electricity forward contracts | Weighted Average | Discounted cash flows
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh	29.86	26.86
Option Contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Liabilities | $		$ 5,628
Option Contracts | Minimum | Option model
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh		23.87
Implied electricity price volatilities (as a percent)		40.00%
Implied natural gas price volatilities (as a percent)		32.00%
Natural gas forward price (per MMbtu) | $ / MMBTU
Option Contracts | Maximum | Option model
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh		44.13
Implied electricity price volatilities (as a percent)		59.00%
Implied natural gas price volatilities (as a percent)		40.00%
Natural gas forward price (per MMbtu) | $ / MMBTU
Option Contracts | Weighted Average | Option model
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh		33.91
Implied electricity price volatilities (as a percent)		52.00%
Implied natural gas price volatilities (as a percent)		35.00%
Natural gas forward contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets | $	$ 428	$ 5,821
Liabilities | $	$ 26,440	$ 3,036
Natural gas forward contracts | Minimum | Discounted cash flows
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Natural gas forward price (per MMbtu) | $ / MMBTU	2.32	2.18
Natural gas forward contracts | Maximum | Discounted cash flows
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Natural gas forward price (per MMbtu) | $ / MMBTU	3.60	3.14
Natural gas forward contracts | Weighted Average | Discounted cash flows
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Natural gas forward price (per MMbtu) | $ / MMBTU		2.61
Natural gas forward contracts | Weighted Average | Option model
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (per MWh) | $ / MWh	2.81

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Fair Value Measurements Fair Value Measurements - Changes in Fair Value of Risk Management Assets and Liabilities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Total net gains (losses) realized/unrealized:
Net derivative beginning balance	$ (32,979,000)	$ (41,386,000)
Included in earnings	0	0
Included in OCI	88,000	(452,000)
Deferred as a regulatory asset or liability	(37,543,000)	(4,009,000)
Settlements	15,146,000	14,809,000
Transfers into Level 3 from Level 2	1,900,000	(6,256,000)
Transfers from Level 3 into Level 2	5,982,000	4,315,000
Net derivative ending balance	(47,406,000)	(32,979,000)
Net unrealized gains included in earnings related to instruments still held at end of period	0	$ 0
Significant level 1 transfers	$ 0

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Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 53,246	$ 263,027	$ 121,308	$ 4,453	$ 41,117	$ 257,116	$ 122,902	$ 16,122	$ 442,034	$ 437,257	$ 397,595
Weighted Average common shares outstanding — basic (in shares)									111,409	111,026	110,626
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units									637	526	552
Weighted average common shares outstanding — diluted (in shares)									112,046	111,552	111,178
Earnings per average common share attributable to common shareholders — basic (in dollars per share)	$ 0.48	$ 2.36	$ 1.09	$ 0.04	$ 0.37	$ 2.32	$ 1.11	$ 0.15	$ 3.97	$ 3.94	$ 3.59
Earnings per average common share attributable to common shareholders — diluted (in dollars per share)	$ 0.47	$ 2.35	$ 1.08	$ 0.04	$ 0.37	$ 2.30	$ 1.10	$ 0.14	$ 3.95	$ 3.92	$ 3.58

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Stock-Based Compensation (Details) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2012 shares	Dec. 31, 2016 USD ($) shares	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) performance_criteria non_financial_seperate_performance_metric shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Stock-Based Compensation
Common shares available for issuance (in shares) | shares		2,500,000								2,500,000
Stock compensation cumulative effect adjustments						$ 45,855					$ 45,855
Operations and maintenance		$ (208,277)	$ (217,568)	$ (242,279)	$ (243,195)	(222,019)	$ (220,449)	$ (210,965)	$ (214,944)	$ (911,319)	(868,377)	$ (908,025)
Compensation cost that has been charged against income										19,000	19,000	33,000
Total income tax benefit recognized										10,000	7,000	13,000
Total unrecognized compensation cost related to nonvested share-based compensation arrangements granted		$ 13,000								$ 13,000
Expected weighted-average period of recognition of unrecognized compensation cost										2 years
Total fair value of shares vested										$ 22,000	21,000	22,000
Performance Shares
Number of performance element criteria | performance_criteria										2
Performance period										3 years
Number of non-financial separate performance metrics based on which awards vest | non_financial_seperate_performance_metric										6
Restricted stock unit awards
Stock-Based Compensation
Share-based liabilities paid										$ 3,000	10,000	9,000
Cash flow effect, cash used to settle awards										$ 3,000	3,000	3,000
Restricted Stock Units, Stock Grants and Stock Units
Vesting period										4 years
Percentage of cash that the participant may elect as a dividend for the first option available under the plan										50.00%
Percentage of Fully Transferable Shares of Stock in which Election to Receive Payment May be Made by Participants for Deferrals Option Two										50.00%
Restricted Stock Units, Stock Grants, and Stock Units
Restricted Stock Units, Stock Grants and Stock Units
Granted (in shares) | shares										141,811
Performance Shares
Stock-Based Compensation
Share-based liabilities paid											16,000	$ 12,000
Restricted Stock Units, Stock Grants and Stock Units
Granted (in shares) | shares										166,666
Performance Shares | Maximum
Performance Shares
Exact number of shares issued as a percentage of the target award										200.00%
Performance Shares | Minimum
Performance Shares
Exact number of shares issued as a percentage of the target award										0.00%
Officers and Key Employees | Restricted stock unit awards
Restricted Stock Units, Stock Grants and Stock Units
Percentage of fully transferable shares of stock that the participant may elect as a deferral for the first option available under the plan										100.00%
Chief Executive Officer | Retention units
Restricted Stock Units, Stock Grants and Stock Units
Granted (in shares) | shares	50,617
Additional shares to be granted as retention award if performance requirements are met | shares	33,745
Non-Officer Board of Director Member | Restricted stock unit awards
Restricted Stock Units, Stock Grants and Stock Units
Percentage of cash that the participant may elect as a dividend for the first option available under the plan										50.00%
Percentage of Fully Transferable Shares of Stock in which Election to Receive Payment May be Made by Participants for Deferrals Option Two										50.00%
Percentage of fully transferable shares of stock that the participant may elect as a deferral for the first option available under the plan										100.00%
Percentage of cash that the participant may elect as a dividend equivalent deferral for the first option available under the plan										50.00%
Percentage of fully transferable shares of stock that the participant may elect as a dividend equivalent deferral for the first option available under the plan										50.00%
2012 Plan
Stock-Based Compensation
Common shares available for grant (in shares) | shares		4,600,000								4,600,000
Accountings Standards Update 2016-09 | New Accounting Pronouncement, Early Adoption, Effect
Stock-Based Compensation
Operations and maintenance		$ 12,000
Retained Earnings
Stock-Based Compensation
Stock compensation cumulative effect adjustments						5,475					5,475
Retained Earnings | Accountings Standards Update 2016-09 | New Accounting Pronouncement, Early Adoption, Effect
Stock-Based Compensation
Stock compensation cumulative effect adjustments						6,000					6,000
Retained Earnings | Accountings Standards Update 2016-09, Income Tax Expense Component | New Accounting Pronouncement, Early Adoption, Effect
Stock-Based Compensation
Stock compensation cumulative effect adjustments						$ 3,000					$ 3,000

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Stock-Based Compensation - Summary of Restricted Stock, Stock Grants, Stock Units and Performance Shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock Units, Stock Grants, and Stock Units
Stocks granted and the weighted average fair value
Units granted (in shares)	141,811	152,651	179,291
Grant date fair value (in dollars per share)	$ 67.34	$ 64.12	$ 54.89
Number of granted awards to be settled in cash (in shares)	43,952	45,104	49,018
Performance Shares
Stocks granted and the weighted average fair value
Units granted (in shares)	166,666	151,430	166,244
Grant date fair value (in dollars per share)	$ 66.60	$ 64.97	$ 54.86

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Stock-Based Compensation - Status of Nonvested Restricted Stock, Stock Grants, Stock Units and Performance Shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock Units, Stock Grants, and Stock Units
Nonvested shares
Balance at the beginning of the period (in shares)	428,287
Granted (in shares)	141,811
Change in performance factor (in shares)	0
Vested (in shares)	(230,881)
Forfeited (in shares)	(3,958)
Balance at the end of the period (in shares)	335,259	428,287
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 56.69
Granted (in dollars per share)	67.34	$ 64.12	$ 54.89
Change in performance factor (in dollars per share)	0.00
Vested (in dollars per share)	55.07
Forfeited (in dollars per share)	62.86
Balance at the end of the period (in dollars per share)	$ 62.04	$ 56.69
Vested Awards Outstanding at December 31, 2016	174,201
Vested Awards Outstanding at December 31, 2015 (in shares)
Number of nonvested awards to be settled in cash (in shares)	112,554
Performance Shares
Nonvested shares
Balance at the beginning of the period (in shares)	305,832
Granted (in shares)	166,666
Change in performance factor (in shares)	15,573
Vested (in shares)	(171,303)
Forfeited (in shares)	(4,044)
Balance at the end of the period (in shares)	312,724	305,832
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 58.86
Granted (in dollars per share)	66.60	$ 64.97	$ 54.86
Change in performance factor (in dollars per share)	54.09
Vested (in dollars per share)	54.09
Forfeited (in dollars per share)	62.34
Balance at the end of the period (in dollars per share)	$ 65.32	$ 58.86
Vested Awards Outstanding at December 31, 2016	171,303
Vested Awards Outstanding at December 31, 2015 (in shares)

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Derivative Accounting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Designated as Hedging Instruments
Derivative [Line Items]
Derivative liability	$ 2,000	$ 3,000
ARIZONA PUBLIC SERVICE COMPANY
Derivative [Line Items]
Percentage of unrealized gains and losses on certain derivatives deferred for future rate treatment before accounting treatment change	100.00%
Commodity Contracts
Derivative [Line Items]
Derivative liability	$ 73,074	$ 167,689
Additional collateral to counterparties for energy related non-derivative instrument contracts	144,000
Commodity Contracts | Designated as Hedging Instruments
Derivative [Line Items]
Estimated net gain (loss) before income taxes to be reclassified from accumulated other comprehensive income	$ (3,000)

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Derivative Accounting - Outstanding Gross Notional Amounts Outstanding (Details) - Commodity Contracts MMcf in Thousands	12 Months Ended
	Dec. 31, 2016 GWh MMcf
Outstanding gross notional amount of derivatives
Power | GWh	1,314
Gas | MMcf	194

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Derivative Accounting - Gains and Losses from Derivative Instruments (Details) - Commodity Contracts - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Designated as Hedging Instruments
Derivative Instruments in Designated Cash Flows Hedges
Gain (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	$ 47,000	$ (615,000)	$ (372,000)
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion Realized)	(3,926,000)	(5,988,000)	(21,415,000)
Amount reclassified from accumulated other comprehensive income to earnings related to discontinued cash flow hedges	0	0	0
Not Designated as Hedging Instruments
Derivative Instruments Not Designated as Cash Flows Hedges
Net Gain (Loss) Recognized in Income	26,482,000	(108,399,000)	(66,043,000)
Revenue | Not Designated as Hedging Instruments
Derivative Instruments Not Designated as Cash Flows Hedges
Net Gain (Loss) Recognized in Income	771,000	574,000	324,000
Fuel and purchased power | Not Designated as Hedging Instruments
Derivative Instruments Not Designated as Cash Flows Hedges
Net Gain (Loss) Recognized in Income	$ 25,711,000	$ (108,973,000)	$ (66,367,000)

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Derivative Accounting - Derivative Instruments in the Balance Sheet (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Commodity Contracts
Assets
Gross Recognized Derivatives	$ 54,798,000	$ 53,356,000
Amounts Offset	(35,103,000)	(26,017,000)
Net Recognized Derivatives	19,695,000	27,339,000
Other	0	672,000
Amount Reported on Balance Sheet	19,695,000	28,011,000
Liabilities
Gross Recognized Derivatives	(104,123,000)	(207,387,000)
Amounts Offset	35,103,000	44,077,000
Net Recognized Derivatives	(69,020,000)	(163,310,000)
Other	(4,054,000)	(4,379,000)
Amount Reported on Balance Sheet	(73,074,000)	(167,689,000)
Assets and Liabilities
Gross Recognized Derivatives	(49,325,000)	(154,031,000)
Amounts Offset	0	18,060,000
Net Recognized Derivatives	(49,325,000)	(135,971,000)
Other	(4,054,000)	(3,707,000)
Amount Reported on Balance Sheet	(53,379,000)	(139,678,000)
Commodity Contracts | Current Assets
Assets
Gross Recognized Derivatives	48,094,000	37,396,000
Amounts Offset	(28,400,000)	(22,163,000)
Net Recognized Derivatives	19,694,000	15,233,000
Other	0	672,000
Amount Reported on Balance Sheet	19,694,000	15,905,000
Commodity Contracts | Investments and Other Assets
Assets
Gross Recognized Derivatives	6,704,000	15,960,000
Amounts Offset	(6,703,000)	(3,854,000)
Net Recognized Derivatives	1,000	12,106,000
Other	0	0
Amount Reported on Balance Sheet	1,000	12,106,000
Commodity Contracts | Current Liabilities
Liabilities
Gross Recognized Derivatives	(50,182,000)	(113,560,000)
Amounts Offset	28,400,000	40,223,000
Net Recognized Derivatives	(21,782,000)	(73,337,000)
Other	(4,054,000)	(4,379,000)
Amount Reported on Balance Sheet	(25,836,000)	(77,716,000)
Commodity Contracts | Deferred Credits and Other
Liabilities
Gross Recognized Derivatives	(53,941,000)	(93,827,000)
Amounts Offset	6,703,000	3,854,000
Net Recognized Derivatives	(47,238,000)	(89,973,000)
Other	0	0
Amount Reported on Balance Sheet	(47,238,000)	(89,973,000)
Designated as Hedging Instruments
Liabilities
Amount Reported on Balance Sheet	$ (2,000,000)	$ (3,000,000)

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Derivative Accounting - Credit Risk and Related Contingent Features (Details) - Commodity Contracts $ in Thousands	Dec. 31, 2016 USD ($)
Credit Risk and Credit-Related Contingent Features
Aggregate Fair Value of Derivative Instruments in a Net Liability Position	$ 104,123
Cash Collateral Posted	0
Additional Cash Collateral in the Event Credit-Risk Related Contingent Features were Fully Triggered	$ 23,914

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Other Income and Other Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other income:
Interest income	$ 884	$ 493	$ 1,010
Debt return on the purchase of Four Corners units 4 & 5			8,386
Miscellaneous	17	128	212
Total other income	901	621	9,608
Other expense:
Non-operating costs	(9,235)	(11,292)	(9,657)
Investment losses — net	(1,747)	(2,080)	(9,426)
Miscellaneous	(4,355)	(4,451)	(2,663)
Total other expense	(15,337)	(17,823)	(21,746)
ARIZONA PUBLIC SERVICE COMPANY
Other income:
Interest income	261	163	689
Debt return on the purchase of Four Corners units 4 & 5	0	0	8,386
Gain on disposition of property	5,745	716	1,197
Miscellaneous	2,601	1,955	1,023
Total other income	8,607	2,834	11,295
Other expense:
Non-operating costs	(11,034)	(11,648)	(10,397)
Loss on disposition of property	(1,246)	(2,219)	(615)
Miscellaneous	(5,234)	(5,152)	(2,391)
Total other expense	$ (17,514)	$ (19,019)	$ (13,403)

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Palo Verde Sale Leaseback Variable Interest Entities (Details) $ in Thousands		12 Months Ended
	Jan. 01, 2017 USD ($)	Dec. 31, 2016 USD ($) Trust Lease	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 1986 Trust
Palo Verde Sale Leaseback Variable Interest Entities
Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts		$ 19,493	$ 18,933	$ 26,101
ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Sale Leaseback Variable Interest Entities
Number of VIE lessor trusts | Trust		3			3
Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts		$ 19,493	18,933	26,101
ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts		$ 19,000	$ 19,000	$ 26,000
Period Through 2023 | ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Number of leases under which assets are retained | Lease		1
Period Through 2033 | ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Number of leases under which assets are retained | Lease		2
Period 2017 through 2023 | ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Annual lease payments		$ 23,000
Period 2024 through 2033 | ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Annual lease payments		$ 16,000
Maximum | Period 2024 through 2033 | ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Lease period		2 years
Scenario, Forecast | ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
VIE entity initial loss exposure to noncontrolling interests during lease extension period, amount	$ 291,000
VIE entity maximum loss exposure to noncontrolling interests during lease extension period, amount	$ 456,000

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Palo Verde Sale Leaseback Variable Interest Entities Palo Verde Leaseback Variable Interest Entities - Schedule of VIEs (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback, net of accumulated depreciation	$ 113,515	$ 117,385
Equity - noncontrolling interests	132,290	135,540
ARIZONA PUBLIC SERVICE COMPANY
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback, net of accumulated depreciation	113,515	117,385
Equity - noncontrolling interests	132,290	135,540
ARIZONA PUBLIC SERVICE COMPANY | Consolidation of VIEs
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback, net of accumulated depreciation	113,515	117,385
Equity - noncontrolling interests	$ 132,290	$ 135,540

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Nuclear Decommissioning Trusts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Nuclear decommissioning trust fund assets
Fair Value	$ 779,586	$ 735,196
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities	633,410	478,813	$ 356,195
Fair value of fixed income securities, summarized by contractual maturities
Total	779,586	735,196
ARIZONA PUBLIC SERVICE COMPANY
Nuclear decommissioning trust fund assets
Fair Value	779,586	735,196
Unrealized Gains	197,911	169,053
Unrealized Losses	(4,962)	(2,760)
Net receivables for securities purchases	795
Net payables for securities purchases		(335)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	11,213	5,189	4,725
Realized losses	(10,106)	(6,225)	(4,525)
Proceeds from the sale of securities	633,410	478,813	$ 356,195
Fair value of fixed income securities, summarized by contractual maturities
Total	779,586	735,196
ARIZONA PUBLIC SERVICE COMPANY | Equity Securities
Nuclear decommissioning trust fund assets
Fair Value	353,261	314,957
Unrealized Gains	188,091	157,098
Unrealized Losses	0	(115)
Fair value of fixed income securities, summarized by contractual maturities
Total	353,261	314,957
ARIZONA PUBLIC SERVICE COMPANY | Fixed income securities
Nuclear decommissioning trust fund assets
Fair Value	425,530	420,574
Unrealized Gains	9,820	11,955
Unrealized Losses	(4,962)	(2,645)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	13,063
1 year - 5 years	119,292
5 years - 10 years	105,612
Greater than 10 years	187,563
Total	$ 425,530	$ 420,574

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Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	$ 4,719,457	$ 4,519,102	$ 4,340,460
Total other comprehensive income	926	23,393	9,912
Ending balance	4,935,912	4,719,457	4,519,102
Derivative Instruments
Changes in accumulated other comprehensive income (loss) by component
OCI (loss) before reclassifications	(538)	(957)
Amounts reclassified from accumulated other comprehensive loss	2,941	4,187
Total other comprehensive income	2,403	3,230
Pension and Other Postretirement Benefits
Changes in accumulated other comprehensive income (loss) by component
OCI (loss) before reclassifications	(4,509)	16,980
Amounts reclassified from accumulated other comprehensive loss	3,032	3,183
Total other comprehensive income	(1,477)	20,163
AOCI Including Portion Attributable to Noncontrolling Interest
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(44,748)	(68,141)
Ending balance	(43,822)	(44,748)	(68,141)
ARIZONA PUBLIC SERVICE COMPANY
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	4,814,794	4,629,852	4,454,874
Total other comprehensive income	1,674	21,236	5,039
Ending balance	5,037,970	4,814,794	4,629,852
ARIZONA PUBLIC SERVICE COMPANY | Derivative Instruments
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(27,097)	(48,333)
Ending balance	(25,423)	(27,097)	$ (48,333)
ARIZONA PUBLIC SERVICE COMPANY | Pension and Other Postretirement Benefits
Changes in accumulated other comprehensive income (loss) by component
OCI (loss) before reclassifications	(538)	(957)
Amounts reclassified from accumulated other comprehensive loss	2,941	4,187
Total other comprehensive income	2,403	3,230
ARIZONA PUBLIC SERVICE COMPANY | AOCI Including Portion Attributable to Noncontrolling Interest
Changes in accumulated other comprehensive income (loss) by component
OCI (loss) before reclassifications	(3,821)	14,726
Amounts reclassified from accumulated other comprehensive loss	3,092	3,280
Total other comprehensive income	$ (729)	$ 18,006

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SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CONDENSED FINANCIAL STATEMENTS
Operating revenues	$ 739,199	$ 1,166,922	$ 915,394	$ 677,167	$ 734,430	$ 1,199,146	$ 890,648	$ 671,219	$ 3,498,682	$ 3,495,443	$ 3,491,632
Operating expenses									2,642,698	2,640,841	2,680,390
OPERATING INCOME	122,816	451,258	231,748	50,162	109,834	445,111	231,973	67,684	855,984	854,602	811,242
Other
Total									27,704	18,013	18,652
Interest expense									205,720	194,964	200,950
Income tax benefit	27,309	141,446	65,742	1,914	22,847	139,555	67,371	7,947	236,411	237,720	220,705
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 53,246	$ 263,027	$ 121,308	$ 4,453	$ 41,117	$ 257,116	$ 122,902	$ 16,122	442,034	437,257	397,595
Other comprehensive income									926	23,393	9,912
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									442,960	460,650	407,507
Pinnacle West
CONDENSED FINANCIAL STATEMENTS
Operating revenues									370	550	642
Operating expenses									26,424	12,733	23,507
OPERATING INCOME									(26,054)	(12,183)	(22,865)
Other
Equity in earnings of subsidiaries									462,027	446,508	411,528
Other expense									(1,771)	(3,302)	(3,276)
Total									460,256	443,206	408,252
Interest expense									3,151	2,672	3,663
INCOME BEFORE INCOME TAXES									431,051	428,351	381,724
Income tax benefit									(10,983)	(8,906)	(15,871)
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									442,034	437,257	397,595
Other comprehensive income									926	23,393	9,912
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									$ 442,960	$ 460,650	$ 407,507

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SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 8,881	$ 39,488	$ 7,604	$ 9,526
Accounts receivable	250,491	274,691
Income tax receivable	3,751	589
Other current assets	45,028	37,242
Total current assets	822,219	890,516
Investments and other assets
Other assets	69,063	52,518
Total investments and other assets	848,650	799,820
Total Assets	16,004,253	15,028,258
Current liabilities
Accounts payable	264,631	297,480
Accrued taxes	138,964	138,600
Common dividends payable	72,926	69,363
Short-term borrowings	177,200	0
Current maturities of long-term debt	125,000	357,580
Other current liabilities	244,000	197,861
Total current liabilities	1,292,946	1,442,317
Deferred credits and other
Long-term debt less current maturities	4,021,785	3,462,391
Other	156,784	186,345
Total deferred credits and other	5,753,610	5,404,093
Common stock equity
Common stock	2,596,030	2,541,668
Accumulated other comprehensive loss	(43,822)	(44,748)
Retained earnings	2,255,547	2,092,803
Total shareholders’ equity	4,803,622	4,583,917
Noncontrolling interests	132,290	135,540
Total equity	4,935,912	4,719,457	4,519,102	4,340,460
Total Liabilities and Equity	16,004,253	15,028,258
Pinnacle West
Current assets
Cash and cash equivalents	41	17,432	$ 3,088	$ 5,798
Accounts receivable	81,751	93,093
Income tax receivable	0	14,895
Other current assets	340	197
Total current assets	82,132	125,617
Investments and other assets
Investments in subsidiaries	5,084,035	4,815,236
Deferred income taxes	53,805	41,065
Other assets	38,500	43,422
Total investments and other assets	5,176,340	4,899,723
Total Assets	5,258,472	5,025,340
Current liabilities
Accounts payable	5,421	5,901
Accrued taxes	12,050	6,904
Common dividends payable	72,926	69,363
Short-term borrowings	41,700	0
Current maturities of long-term debt	125,000	0
Other current liabilities	31,182	33,120
Total current liabilities	288,279	115,288
Deferred credits and other
Long-term debt less current maturities	0	125,000
Pension liabilities	21,057	21,933
Other	13,224	43,662
Total deferred credits and other	34,281	65,595
Common stock equity
Common stock	2,591,897	2,535,862
Accumulated other comprehensive loss	(43,822)	(44,748)
Retained earnings	2,255,547	2,092,803
Total shareholders’ equity	4,803,622	4,583,917
Noncontrolling interests	132,290	135,540
Total equity	4,935,912	4,719,457
Total Liabilities and Equity	$ 5,258,472	$ 5,025,340

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SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows from Operating Activities
Net income	$ 58,119	$ 267,900	$ 126,182	$ 9,326	$ 45,978	$ 261,978	$ 127,507	$ 20,727	$ 461,527	$ 456,190	$ 423,696
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									565,011	571,664	496,487
Deferred income taxes									206,870	236,819	159,023
Accounts receivable									(2,489)	(22,219)	(52,672)
Accounts payable									(66,917)	(34,266)	(353)
Net cash flow provided by operating activities									1,023,390	1,094,327	1,099,627
Cash flows from investing activities
Net cash flow used for investing activities									(1,252,078)	(1,066,233)	(922,668)
Cash flows from financing activities
Issuance of long-term debt									693,151	842,415	731,126
Short-term debt borrowings under revolving credit facility									40,000	0	0
Dividends paid on common stock									(274,229)	(260,027)	(246,671)
Repayment of long-term debt									(370,430)	(415,570)	(652,578)
Common stock equity issuance and purchases - net									(4,867)	19,373	15,288
Other									0	1	161
Net cash flow provided by (used for) financing activities									198,081	3,790	(178,881)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(30,607)	31,884	(1,922)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR				39,488				7,604	39,488	7,604	9,526
CASH AND CASH EQUIVALENTS AT END OF YEAR	8,881				39,488				8,881	39,488	7,604
Pinnacle West
Cash Flows from Operating Activities
Net income									442,034	437,257	397,595
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in earnings of subsidiaries - net									(462,027)	(446,508)	(411,528)
Depreciation and amortization									85	92	94
Deferred income taxes									(12,402)	12,967	4,406
Accounts receivable									15,823	11,336	(22,945)
Accounts payable									10,402	637	2,017
Accrued taxes and income tax receivable - net									20,041	(12,882)	(1,795)
Dividends received from subsidiaries									239,300	266,900	253,600
Other									5,514	(6,995)	18,432
Net cash flow provided by operating activities									258,770	262,804	239,876
Cash flows from investing activities
Construction work in progress									(18,457)	(3,462)	0
Investments in subsidiaries									(19,242)	(3,491)	(10,236)
Repayments of loans from subsidiaries									1,026	157	322
Advances of loans to subsidiaries									(2,092)	(1,010)	(1,450)
Net cash flow used for investing activities									(38,765)	(7,806)	(11,364)
Cash flows from financing activities
Issuance of long-term debt									0	0	125,000
Short-term debt borrowings under revolving credit facility									40,000	0	0
Commercial Paper - net									1,700	0	0
Dividends paid on common stock									(274,229)	(260,027)	(246,671)
Repayment of long-term debt									0	0	(125,000)
Common stock equity issuance and purchases - net									(4,867)	19,373	15,288
Other									0	0	161
Net cash flow provided by (used for) financing activities									(237,396)	(240,654)	(231,222)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(17,391)	14,344	(2,710)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR				$ 17,432				$ 3,088	17,432	3,088	5,798
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 41				$ 17,432				$ 41	$ 17,432	$ 3,088

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SCHEDULE II - RESERVE FOR UNCOLLECTIBLES (Details) - Reserve for uncollectibles. - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
ARIZONA PUBLIC SERVICE COMPANY
Changes in reserve for uncollectibles
Balance at beginning of period	$ 3,125	$ 3,094	$ 3,203
Additions, Charged to cost and expenses	4,025	4,073	3,942
Additions, Charged to other accounts	0	0	0
Deductions	4,113	4,042	4,051
Balance at end of period	3,037	3,125	3,094
Pinnacle West
Changes in reserve for uncollectibles
Balance at beginning of period	3,125	3,094	3,203
Additions, Charged to cost and expenses	4,025	4,073	3,942
Additions, Charged to other accounts	0	0	0
Deductions	4,113	4,042	4,051
Balance at end of period	$ 3,037	$ 3,125	$ 3,094

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