10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-Q

(Mark One)

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

For the quarterly period ended September 30, 2019

OR

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

For the transition period from              to          

Commission File Number	Exact Name of Each Registrant as specified in its charter; State of Incorporation; Address; and Telephone Number			IRS Employer Identification No.
1-8962	PINNACLE WEST CAPITAL CORPORATION			86-0512431
	(an Arizona corporation)
	400 North Fifth Street, P.O. Box 53999
	Phoenix	Arizona	85072-3999
	(602)	250-1000
1-4473	ARIZONA PUBLIC SERVICE COMPANY			86-0011170
	(an Arizona corporation)
	400 North Fifth Street, P.O. Box 53999
	Phoenix	Arizona	85072-3999
	(602)	250-1000

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

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock	PNW	The New York Stock Exchange

Indicate by check mark whether each 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	☒	No	☐
ARIZONA PUBLIC SERVICE COMPANY	Yes	☒	No	☐

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	☒	No	☐
ARIZONA PUBLIC SERVICE COMPANY	Yes	☒	No	☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company or an emerging growth company.  See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

 PINNACLE WEST CAPITAL CORPORATION

Large accelerated filer	☒	Accelerated filer	☐	Non-accelerated filer	☐	Smaller reporting company	☐
Emerging growth company	☐

ARIZONA PUBLIC SERVICE COMPANY

Large accelerated filer	☐	Accelerated filer	☐	Non-accelerated filer	☒	Smaller reporting company	☐
Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether each registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

PINNACLE WEST CAPITAL CORPORATION	Yes	☐	No	☒
ARIZONA PUBLIC SERVICE COMPANY	Yes	☐	No	☒

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

PINNACLE WEST CAPITAL CORPORATION	Number of shares of common stock, no par value, outstanding as of October 31, 2019:	112,410,824
ARIZONA PUBLIC SERVICE COMPANY	Number of shares of common stock, $2.50 par value, outstanding as of October 31, 2019:	71,264,947

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

TABLE OF CONTENTS

		Page
Forward-Looking Statements		2
Part I		3
Item 1.	Financial Statements	3
	Pinnacle West Capital Corporation	4
	Arizona Public Service Company	11
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	72
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	98
Item 4.	Controls and Procedures	98
Part II		100
Item 1.	Legal Proceedings	100
Item 1A.	Risk Factors	100
Item 5.	Other Information	100
Item 6.	Exhibits	102
Signatures		104

This combined Form 10-Q is separately provided by Pinnacle West Capital Corporation ("Pinnacle West") and Arizona Public Service Company ("APS").  Any use of the words "Company," "we," and "our" refer to Pinnacle West.  Each registrant is providing on its own behalf all of the information contained in this Form 10-Q that relates to such registrant and, where required, its subsidiaries.  Except as stated in the preceding sentence, neither registrant is providing 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 1 of this report includes Condensed Consolidated Financial Statements of Pinnacle West and Condensed Consolidated Financial Statements of APS.  Item 1 also includes Combined Notes to Condensed Consolidated Financial Statements.

1

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 Part I, Item 1A of the Pinnacle West/APS Annual Report on Form 10-K for the fiscal year ended December 31, 2018 ("2018 Form 10-K"), Part II, Item 1A of this report and in Part I, Item 2 — "Management’s Discussion and Analysis of Financial Condition and Results of Operations" of this report, 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), the effects of energy conservation measures and distributed generation, and technological advancements;

• 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 direct or indirect effect on our facilities or business from cybersecurity threats or intrusions, data security breaches, terrorist attack, physical attack, severe storms, droughts, or other catastrophic events, such as fires, explosions, pandemic health events or similar occurrences;

• 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 Arizona Corporation Commission ("ACC") orders. 

These and other factors are discussed in the Risk Factors described in Part I, Item 1A of our 2018 Form 10-K, in Part II, Item 1A of this report, and in Part I, Item 2 — "Management’s Discussion and Analysis of Financial Condition and Results of Operations" 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.

2

PART I — FINANCIAL INFORMATION

ITEM 1.  FINANCIAL STATEMENTS

 INDEX TO FINANCIAL STATEMENTS AND FINANCIAL STATEMENT SCHEDULES

	Page
Pinnacle West Condensed Consolidated Statements of Income for Three and Nine Months Ended September 30, 2019 and 2018	4
Pinnacle West Condensed Consolidated Statements of Comprehensive Income for Three and Nine Months Ended September 30, 2019 and 2018	5
Pinnacle West Condensed Consolidated Balance Sheets as of September 30, 2019 and December 31, 2018	6
Pinnacle West Condensed Consolidated Statements of Cash Flows for Nine Months Ended September 30, 2019 and 2018	8
Pinnacle West Condensed Consolidated Statements of Changes in Equity for Three and Nine Months Ended September 30, 2019 and 2018	9
APS Condensed Consolidated Statements of Income for Three and Nine Months Ended September 30, 2019 and 2018	11
APS Condensed Consolidated Statements of Comprehensive Income for Three and Nine Months Ended September 30, 2019 and 2018	12
APS Condensed Consolidated Balance Sheets as of September 30, 2019 and December 31, 2018	13
APS Condensed Consolidated Statements of Cash Flows for Nine Months Ended September 30, 2019 and 2018	15
APS Condensed Consolidated Statements of Changes in Equity for Three and Nine Months Ended September 30, 2019 and 2018	16
Combined Notes to Condensed Consolidated Financial Statements	18
Note 1. Consolidation and Nature of Operations	18
Note 2. Revenue	19
Note 3. Long-Term Debt and Liquidity Matters	20
Note 4. Regulatory Matters	22
Note 5. Retirement Plans and Other Postretirement Benefits	38
Note 6. Palo Verde Sale Leaseback Variable Interest Entities	39
Note 7. Derivative Accounting	40
Note 8. Commitments and Contingencies	45
Note 9. Other Income and Other Expense	53
Note 10. Earnings Per Share	54
Note 11. Fair Value Measurements	54
Note 12. Investment in Nuclear Decommissioning Trust and Other Special Use Funds	60
Note 13. New Accounting Standards	64
Note 14. Changes in Accumulated Other Comprehensive Loss	65
Note 15. Income Taxes	67
Note 16. Leases	68

3

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(unaudited)

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
OPERATING REVENUES (NOTE 2)	$	1,190,787		$	1,268,034		$	2,800,818		$	2,934,871
OPERATING EXPENSES
Fuel and purchased power	344,862			389,936			817,672			844,133
Operations and maintenance	238,582			246,545			711,759			780,624
Depreciation and amortization	149,450			145,971			445,531			436,232
Taxes other than income taxes	53,809			51,375			163,989			158,582
Other expenses	794			900			1,904			8,497
Total	787,497			834,727			2,140,855			2,228,068
OPERATING INCOME	403,290			433,307			659,963			706,803
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	5,917			12,259			24,677			39,411
Pension and other postretirement non-service credits - net	5,752			12,449			17,240			37,314
Other income (Note 9)	15,191			6,958			35,245			17,541
Other expense (Note 9)	(5,740		)	(5,063		)	(14,448		)	(12,063		)
Total	21,120			26,603			62,714			82,203
INTEREST EXPENSE
Interest charges	57,481			61,605			175,599			181,267
Allowance for borrowed funds used during construction	(3,486		)	(5,913		)	(14,645		)	(18,959		)
Total	53,995			55,692			160,954			162,308
INCOME BEFORE INCOME TAXES	370,415			404,218			561,723			626,698
INCOME TAXES	53,266			84,333			72,764			127,107
NET INCOME	317,149			319,885			488,959			499,591
Less: Net income attributable to noncontrolling interests (Note 6)	4,873			4,873			14,620			14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$	312,276		$	315,012		$	474,339		$	484,971
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — BASIC	112,463			112,148			112,408			112,094
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — DILUTED	112,746			112,533			112,739			112,499
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders — basic	$	2.78		$	2.81		$	4.22		$	4.33
Net income attributable to common shareholders — diluted	$	2.77		$	2.80		$	4.21		$	4.31

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

4

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(unaudited)

(dollars in thousands)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
NET INCOME	$	317,149	$	319,885	$	488,959	$	499,591
OTHER COMPREHENSIVE INCOME, NET OF TAX
Derivative instruments:
Net unrealized loss, net of tax expense of $0, $0, $0 and $96 for the respective periods	—		—		—		(96		)
Reclassification of net realized loss, net of tax benefit of $71, $149, $313 and $381 for the respective periods	218		451		950		1,316
Pension and other postretirement benefits activity, net of tax expense (benefit) of $290, $361, $72 and ($754) for the respective periods	880		1,099		220		(2,740		)
Total other comprehensive income (loss)	1,098		1,550		1,170		(1,520		)
COMPREHENSIVE INCOME	318,247		321,435		490,129		498,071
Less: Comprehensive income attributable to noncontrolling interests	4,873		4,873		14,620		14,620
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$	313,374	$	316,562	$	475,509	$	483,451

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

5

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(dollars in thousands)

	September 30, 2019			December 31, 2018
ASSETS
CURRENT ASSETS
Cash and cash equivalents	$	29,852		$	5,766
Customer and other receivables	361,951			267,887
Accrued unbilled revenues	155,836			137,170
Allowance for doubtful accounts	(7,282		)	(4,069		)
Materials and supplies (at average cost)	293,899			269,065
Fossil fuel (at average cost)	18,527			25,029
Income tax receivable	14,063			—
Assets from risk management activities (Note 7)	817			1,113
Deferred fuel and purchased power regulatory asset (Note 4)	59,474			37,164
Other regulatory assets (Note 4)	138,033			129,738
Other current assets	67,985			56,128
Total current assets	1,133,155			924,991
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Notes 11 and 12)	967,673			851,134
Other special use funds (Notes 11 and 12)	243,982			236,101
Other assets	102,116			103,247
Total investments and other assets	1,313,771			1,190,482
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	19,677,773			18,736,628
Accumulated depreciation and amortization	(6,552,177		)	(6,366,014		)
Net	13,125,596			12,370,614
Construction work in progress	738,492			1,170,062
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	102,873			105,775
Intangible assets, net of accumulated amortization	266,587			262,902
Nuclear fuel, net of accumulated amortization	141,903			120,217
Total property, plant and equipment	14,375,451			14,029,570
DEFERRED DEBITS
Regulatory assets (Note 4)	1,329,446			1,342,941
Operating lease right-of-use assets (Note 16)	156,050			—
Assets for other postretirement benefits (Note 5)	31,717			46,906
Other	37,976			129,312
Total deferred debits	1,555,189			1,519,159
TOTAL ASSETS	$	18,377,566		$	17,664,202

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

6

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(dollars in thousands)

	September 30, 2019			December 31, 2018
LIABILITIES AND EQUITY
CURRENT LIABILITIES
Accounts payable	$	276,117		$	277,336
Accrued taxes	220,930			154,819
Accrued interest	50,993			61,107
Common dividends payable	—			82,675
Short-term borrowings (Note 3)	57,375			76,400
Current maturities of long-term debt (Note 3)	450,000			500,000
Customer deposits	78,173			91,174
Liabilities from risk management activities (Note 7)	44,349			35,506
Liabilities for asset retirements	12,850			19,842
Operating lease liabilities (Note 16)	26,221			—
Regulatory liabilities (Note 4)	208,022			165,876
Other current liabilities	161,716			184,229
Total current liabilities	1,586,746			1,648,964
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 3)	4,984,996			4,638,232
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,975,989			1,807,421
Regulatory liabilities (Note 4)	2,310,131			2,325,976
Liabilities for asset retirements	736,079			706,703
Liabilities for pension benefits (Note 5)	297,843			443,170
Liabilities from risk management activities (Note 7)	27,305			24,531
Customer advances	192,374			137,153
Coal mine reclamation	165,695			212,785
Deferred investment tax credit	193,118			200,405
Unrecognized tax benefits	6,341			22,517
Operating lease liabilities (Note 16)	52,472			—
Other	166,772			147,640
Total deferred credits and other	6,124,119			6,028,301
COMMITMENTS AND CONTINGENCIES (SEE NOTE 8)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 112,403,751 and 112,159,896 issued at respective dates	2,654,430			2,634,265
Treasury stock at cost; 57,947 and 58,135 shares at respective dates	(5,117		)	(4,825		)
Total common stock	2,649,313			2,629,440
Retained earnings	2,949,891			2,641,183
Accumulated other comprehensive loss	(46,538		)	(47,708		)
Total shareholders’ equity	5,552,666			5,222,915
Noncontrolling interests (Note 6)	129,039			125,790
Total equity	5,681,705			5,348,705
TOTAL LIABILITIES AND EQUITY	$	18,377,566		$	17,664,202

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

7

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited)

(dollars in thousands)

	Nine Months Ended September 30,
	2019			2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$	488,959		$	499,591
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	500,801			489,861
Deferred fuel and purchased power	(60,911		)	(82,486		)
Deferred fuel and purchased power amortization	38,601			92,397
Allowance for equity funds used during construction	(24,677		)	(39,411		)
Deferred income taxes	83,703			117,571
Deferred investment tax credit	(7,288		)	(7,397		)
Stock compensation	16,486			16,140
Changes in current assets and liabilities:
Customer and other receivables	(91,506		)	(65,203		)
Accrued unbilled revenues	(18,666		)	(83,939		)
Materials, supplies and fossil fuel	(18,332		)	(20,591		)
Income tax receivable	(14,063		)	—
Other current assets	(10,104		)	23,661
Accounts payable	33,899			(11,399		)
Accrued taxes	66,111			78,624
Other current liabilities	(68,927		)	12,852
Change in other long-term assets	(52,276		)	14,120
Change in other long-term liabilities	(27,049		)	(74,628		)
Net cash flow provided by operating activities	834,761			959,763
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(857,883		)	(898,455		)
Contributions in aid of construction	34,121			22,611
Allowance for borrowed funds used during construction	(14,645		)	(18,959		)
Proceeds from nuclear decommissioning trust sales and other special use funds	520,996			443,215
Investment in nuclear decommissioning trust and other special use funds	(523,573		)	(461,777		)
Other	8,971			49
Net cash flow used for investing activities	(832,013		)	(913,316		)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	794,981			295,245
Short-term borrowing and payments — net	(6,025		)	19,800
Short-term debt borrowings	49,000			45,000
Short-term debt repayments	(62,000		)	(32,000		)
Dividends paid on common stock	(243,116		)	(228,037		)
Repayment of long-term debt	(500,000		)	(82,000		)
Common stock equity issuance - net of purchases	(130		)	(1,984		)
Distributions to noncontrolling interests	(11,372		)	(11,372		)
Net cash flow provided by financing activities	21,338			4,652
NET INCREASE IN CASH AND CASH EQUIVALENTS	24,086			51,099
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	5,766			13,892
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$	29,852		$	64,991

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

8

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(unaudited)

(dollars in thousands)

	Three Months Ended September 30, 2019
	Common Stock			Treasury Stock					Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests		Total
	Shares	Amount		Shares		Amount
Balance, July 1, 2019	112,361,595	$	2,648,234	(58,219	)	$	(5,140	)	$	2,637,620		$	(47,636	)	$	124,165	$	5,357,243
Net income		—				—			312,276			—			4,873		317,149
Other comprehensive income		—				—			—			1,098			—		1,098
Dividends on common stock		—				—			(5		)	—			—		(5		)
Issuance of common stock	42,156	6,196				—			—			—			—		6,196
Purchase of treasury stock (a)		—		(103	)	(10		)	—			—			—		(10		)
Reissuance of treasury stock for stock-based compensation and other		—		375		33			—			—			—		33
Other		—				—			—			—			1		1
Balance, September 30, 2019	112,403,751	$	2,654,430	(57,947	)	$	(5,117	)	$	2,949,891		$	(46,538	)	$	129,039	$	5,681,705

	Three Months Ended September 30, 2018
	Common Stock			Treasury Stock					Retained Earnings		Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests		Total
	Shares	Amount		Shares		Amount
Balance, July 1, 2018	111,990,222	$	2,624,672	(17,633	)	$	(1,431	)	$	2,465,402	$	(56,624	)	$	127,415	$	5,159,434
Net income		—				—			315,012		—			4,873		319,885
Other comprehensive income		—				—			—		1,550			—		1,550
Dividends on common stock		—				—			14		—			—		14
Issuance of common stock	25,727	4,955				—			—		—			—		4,955
Purchase of treasury stock (a)		—		(101	)	(8		)	—		—			—		(8		)
Reissuance of treasury stock for stock-based compensation and other		—		366		30			—		—			—		30
Other		—				—			—		—			1		1
Balance, September 30, 2018	112,015,949	$	2,629,627	(17,368	)	$	(1,409	)	$	2,780,428	$	(55,074	)	$	132,289	$	5,485,861

(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.

9

PINNACLE WEST CAPITAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(unaudited)

(dollars in thousands)

	Nine Months Ended September 30, 2019
	Common Stock			Treasury Stock					Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests			Total
	Shares	Amount		Shares		Amount
Balance, January 1, 2019	112,159,896	$	2,634,265	(58,135	)	$	(4,825	)	$	2,641,183		$	(47,708	)	$	125,790		$	5,348,705
Net income		—				—			474,339			—			14,620			488,959
Other comprehensive income		—				—			—			1,170			—			1,170
Dividends on common stock ($1.48 per share)		—				—			(165,631		)	—			—			(165,631		)
Issuance of common stock	243,855	20,165				—			—			—			—			20,165
Purchase of treasury stock (a)		—		(75,894	)	(6,892		)	—			—			—			(6,892		)
Reissuance of treasury stock for stock-based compensation and other		—		76,082		6,600			—			—			—			6,600
Capital activities by noncontrolling interests		—				—			—			—			(11,372		)	(11,372		)
Other		—				—			—			—			1			1
Balance, September 30, 2019	112,403,751	$	2,654,430	(57,947	)	$	(5,117	)	$	2,949,891		$	(46,538	)	$	129,039		$	5,681,705

	Nine Months Ended September 30, 2018
	Common Stock			Treasury Stock					Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests			Total
	Shares	Amount		Shares		Amount
Balance, January 1, 2018	111,816,170	$	2,614,805	(64,463	)	$	(5,624	)	$	2,442,511		$	(45,002	)	$	129,040		$	5,135,730
Net income		—				—			484,971			—			14,620			499,591
Other comprehensive loss		—				—			—			(1,520		)	—			(1,520		)
Dividends on common stock ($1.39 per share)		—				—			(155,607		)	—			—			(155,607		)
Issuance of common stock	199,779	14,822				—			—			—			—			14,822
Purchase of treasury stock (a)		—		(81,278	)	(6,285		)	—			—			—			(6,285		)
Reissuance of treasury stock for stock-based compensation and other		—		128,373		10,500			1			—			—			10,501
Capital activities by noncontrolling interests		—				—			—			—			(11,372		)	(11,372		)
Reclassification of income tax effects related to new tax reform (b)		—				—			8,552			(8,552		)	—			—
Other		—				—			—			—			1			1
Balance, September 30, 2018	112,015,949	$	2,629,627	(17,368	)	$	(1,409	)	$	2,780,428		$	(55,074	)	$	132,289		$	5,485,861

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

(b) In 2018, the Company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) on items within accumulated other comprehensive income to retained earnings.

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

10

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(unaudited)

(dollars in thousands)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
OPERATING REVENUES	$	1,190,787		$	1,267,997		$	2,800,818		$	2,931,966
OPERATING EXPENSES
Fuel and purchased power	344,862			389,889			817,672			862,037
Operations and maintenance	235,440			226,346			699,958			732,946
Depreciation and amortization	149,428			145,949			445,467			434,594
Taxes other than income taxes	53,798			51,366			163,957			157,877
Other expenses	794			900			1,904			1,497
Total	784,322			814,450			2,128,958			2,188,951
OPERATING INCOME	406,465			453,547			671,860			743,015
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	5,917			12,259			24,677			39,411
Pension and other postretirement non-service credits - net	6,133			12,812			18,389			38,398
Other income (Note 9)	14,534			6,153			32,641			16,160
Other expense (Note 9)	(2,826		)	(3,361		)	(10,132		)	(9,679		)
Total	23,758			27,863			65,575			84,290
INTEREST EXPENSE
Interest charges	53,812			58,551			164,068			172,440
Allowance for borrowed funds used during construction	(3,486		)	(5,913		)	(14,645		)	(18,959		)
Total	50,326			52,638			149,423			153,481
INCOME BEFORE INCOME TAXES	379,897			428,772			588,012			673,824
INCOME TAXES	56,154			85,533			76,070			133,415
NET INCOME	323,743			343,239			511,942			540,409
Less: Net income attributable to noncontrolling interests (Note 6)	4,873			4,873			14,620			14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER	$	318,870		$	338,366		$	497,322		$	525,789

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

11

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(unaudited)

(dollars in thousands)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019			2018
NET INCOME	$	323,743	$	343,239	$	511,942		$	540,409
OTHER COMPREHENSIVE INCOME, NET OF TAX
Derivative instruments:
Net unrealized loss, net of tax expense of $0, $0, $0 and $96 for the respective periods	—		—		—			(96		)
Reclassification of net realized loss, net of tax benefit of $71, $149, $313 and $381 for the respective periods	218		451		950			1,316
Pension and other postretirement benefits activity, net of tax expense (benefit) of $249, $313, ($48) and ($947) for the respective periods	755		952		(146		)	(2,955		)
Total other comprehensive income (loss)	973		1,403		804			(1,735		)
COMPREHENSIVE INCOME	324,716		344,642		512,746			538,674
Less: Comprehensive income attributable to noncontrolling interests	4,873		4,873		14,620			14,620
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDER	$	319,843	$	339,769	$	498,126		$	524,054

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

12

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(dollars in thousands)

	September 30, 2019			December 31, 2018
ASSETS
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	$	19,674,286		$	18,733,142
Accumulated depreciation and amortization	(6,548,921		)	(6,362,771		)
Net	13,125,365			12,370,371
Construction work in progress	738,493			1,170,062
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	102,873			105,775
Intangible assets, net of accumulated amortization	266,432			262,746
Nuclear fuel, net of accumulated amortization	141,903			120,217
Total property, plant and equipment	14,375,066			14,029,171
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Notes 11 and 12)	967,673			851,134
Other special use funds (Notes 11 and 12)	243,982			236,101
Other assets	55,846			40,817
Total investments and other assets	1,267,501			1,128,052
CURRENT ASSETS
Cash and cash equivalents	29,542			5,707
Customer and other receivables	351,029			257,654
Accrued unbilled revenues	155,836			137,170
Allowance for doubtful accounts	(7,282		)	(4,069		)
Materials and supplies (at average cost)	293,899			269,065
Fossil fuel (at average cost)	18,527			25,029
Income tax receivable	15,982			—
Assets from risk management activities (Note 7)	817			1,113
Deferred fuel and purchased power regulatory asset (Note 4)	59,474			37,164
Other regulatory assets (Note 4)	138,033			129,738
Other current assets	45,506			35,111
Total current assets	1,101,363			893,682
DEFERRED DEBITS
Regulatory assets (Note 4)	1,329,446			1,342,941
Operating lease right-of-use assets (Note 16)	154,205			—
Assets for other postretirement benefits (Note 5)	28,071			43,212
Other	37,080			128,265
Total deferred debits	1,548,802			1,514,418
TOTAL ASSETS	$	18,292,732		$	17,565,323

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

13

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(dollars in thousands) 

	September 30, 2019			December 31, 2018
LIABILITIES AND EQUITY
CAPITALIZATION
Common stock	$	178,162		$	178,162
Additional paid-in capital	2,721,696			2,721,696
Retained earnings	3,119,977			2,788,256
Accumulated other comprehensive loss	(26,303		)	(27,107		)
Total shareholder equity	5,993,532			5,661,007
Noncontrolling interests (Note 6)	129,039			125,790
Total equity	6,122,571			5,786,797
Long-term debt less current maturities (Note 3)	4,535,728			4,189,436
Total capitalization	10,658,299			9,976,233
CURRENT LIABILITIES
Short-term borrowings (Note 3)	2,900			—
Current maturities of long-term debt (Note 3)	450,000			500,000
Accounts payable	268,163			266,277
Accrued taxes	215,320			176,357
Accrued interest	48,374			60,228
Common dividends payable	—			82,700
Customer deposits	78,173			91,174
Liabilities from risk management activities (Note 7)	44,349			35,506
Liabilities for asset retirements	12,850			19,842
Operating lease liabilities (Note 16)	26,028			—
Regulatory liabilities (Note 4)	208,022			165,876
Other current liabilities	159,992			178,137
Total current liabilities	1,514,171			1,576,097
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,976,662			1,812,664
Regulatory liabilities (Note 4)	2,310,131			2,325,976
Liabilities for asset retirements	736,079			706,703
Liabilities for pension benefits (Note 5)	281,605			425,404
Liabilities from risk management activities (Note 7)	27,305			24,531
Customer advances	192,374			137,153
Coal mine reclamation	165,695			212,785
Deferred investment tax credit	193,118			200,405
Unrecognized tax benefits	43,434			41,861
Operating lease liabilities (Note 16)	50,669			—
Other	143,190			125,511
Total deferred credits and other	6,120,262			6,012,993
COMMITMENTS AND CONTINGENCIES (SEE NOTE 8)
TOTAL LIABILITIES AND EQUITY	$	18,292,732		$	17,565,323

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

14

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited)

(dollars in thousands)

	Nine Months Ended September 30,
	2019			2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$	511,942		$	540,409
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	500,737			488,223
Deferred fuel and purchased power	(60,911		)	(82,486		)
Deferred fuel and purchased power amortization	38,601			92,397
Allowance for equity funds used during construction	(24,677		)	(39,411		)
Deferred income taxes	97,002			86,319
Deferred investment tax credit	(7,288		)	(7,397		)
Changes in current assets and liabilities:
Customer and other receivables	(90,817		)	(56,874		)
Accrued unbilled revenues	(18,666		)	(83,939		)
Materials, supplies and fossil fuel	(18,332		)	(20,694		)
Income tax receivable	(15,982		)	—
Other current assets	(8,642		)	20,258
Accounts payable	37,004			(8,857		)
Accrued taxes	38,963			106,172
Other current liabilities	(66,368		)	9,289
Change in other long-term assets	(54,872		)	25,405
Change in other long-term liabilities	(27,521		)	(80,895		)
Net cash flow provided by operating activities	830,173			987,919
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(857,883		)	(889,347		)
Contributions in aid of construction	34,121			22,611
Allowance for borrowed funds used during construction	(14,645		)	(18,959		)
Proceeds from nuclear decommissioning trust sales and other special use funds	520,996			443,040
Investment in nuclear decommissioning trust and other special use funds	(523,573		)	(461,602		)
Other	(3,563		)	(1,261		)
Net cash flow used for investing activities	(844,547		)	(905,518		)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	794,981			295,245
Short-term borrowings and payments — net	2,900			—
Short-term debt borrowings under revolving credit facility	—			25,000
Short-term debt repayments under revolving credit facility	—			(25,000		)
Repayment of long-term debt	(500,000		)	(82,000		)
Dividends paid on common stock	(248,300		)	(233,300		)
Distributions to noncontrolling interests	(11,372		)	(11,372		)
Net cash flow provided by (used for) financing activities	38,209			(31,427		)
NET INCREASE IN CASH AND CASH EQUIVALENTS	23,835			50,974
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	5,707			13,851
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$	29,542		$	64,825

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

15

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(unaudited)

(dollars in thousands)

	Three Months Ended September 30, 2019
	Common Stock			Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests		Total
	Shares	Amount
Balance, July 1, 2019	71,264,947	$	178,162	$	2,721,696	$	2,801,110		$	(27,276	)	$	124,165	$	5,797,857
Net Income		—		—		318,870			—			4,873		323,743
Other comprehensive income		—		—		—			973			—		973
Other		—		—		(3		)	—			1		(2		)
Balance, September 30, 2019	71,264,947	$	178,162	$	2,721,696	$	3,119,977		$	(26,303	)	$	129,039	$	6,122,571

	Three Months Ended September 30, 2018
	Common Stock			Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests		Total
	Shares	Amount
Balance, July 1, 2018	71,264,947	$	178,162	$	2,571,696	$	2,570,816		$	(35,159	)	$	127,415	$	5,412,930
Net Income		—		—		338,366			—			4,873		343,239
Other comprehensive income		—		—		—			1,403			—		1,403
Other		—		—		(2		)	—			1		(1		)
Balance, September 30, 2018	71,264,947	$	178,162	$	2,571,696	$	2,909,180		$	(33,756	)	$	132,289	$	5,757,571

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

16

ARIZONA PUBLIC SERVICE COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(unaudited)

(dollars in thousands)

	Nine Months Ended September 30, 2019
	Common Stock			Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests			Total
	Shares	Amount
Balance, January 1, 2019	71,264,947	$	178,162	$	2,721,696	$	2,788,256		$	(27,107	)	$	125,790		$	5,786,797
Net income		—		—		497,322			—			14,620			511,942
Other comprehensive income		—		—		—			804			—			804
Dividends on common stock		—		—		(165,600		)	—			—			(165,600		)
Net capital activities by noncontrolling interests		—		—		—			—			(11,372		)	(11,372		)
Other		—		—		(1		)	—			1			—
Balance, September 30, 2019	71,264,947	$	178,162	$	2,721,696	$	3,119,977		$	(26,303	)	$	129,039		$	6,122,571

	Nine Months Ended September 30, 2018
	Common Stock			Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Income (Loss)			Noncontrolling Interests			Total
	Shares	Amount
Balance, January 1, 2018	71,264,947	$	178,162	$	2,571,696	$	2,533,954		$	(26,983	)	$	129,040		$	5,385,869
Net Income		—		—		525,789			—			14,620			540,409
Other comprehensive loss		—		—		—			(1,735		)	—			(1,735		)
Dividends on common stock		—		—		(155,601		)	—			—			(155,601		)
Reclassification of income tax effects related to new tax reform (a)		—		—		5,038			(5,038		)	—			—
Net capital activities by noncontrolling interests		—		—		—			—			(11,372		)	(11,372		)
Other		—		—		—			—			1			1
Balance, September 30, 2018	71,264,947	$	178,162	$	2,571,696	$	2,909,180		$	(33,756	)	$	132,289		$	5,757,571

(a) In 2018, the Company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

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

17

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

1.  Consolidation and Nature of Operations

The unaudited condensed consolidated financial statements include the accounts of Pinnacle West and our subsidiaries:  APS, 4C Acquisition, LLC ("4CA"), Bright Canyon Energy Corporation ("BCE") and El Dorado Investment Company ("El Dorado").  See Note 8 for more information on 4CA matters. Intercompany accounts and transactions between the consolidated companies have been eliminated.  The unaudited condensed consolidated financial statements for APS include the accounts of APS and the Palo Verde Generating Station ("Palo Verde") sale leaseback variable interest entities ("VIEs") (see Note 6 for further discussion).  Our accounting records are maintained in accordance with accounting principles generally accepted in the United States of America ("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.

Amounts reported in our interim Condensed Consolidated Statements of Income are not necessarily indicative of amounts expected for the respective annual periods, due to the effects of seasonal temperature variations on energy consumption, timing of maintenance on electric generating units, and other factors.

Our condensed 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 information and footnote disclosures normally included in financial statements prepared in conformity with GAAP have been condensed or omitted pursuant to such regulations, although we believe that the disclosures provided are adequate to make the interim information presented not misleading. The accompanying condensed consolidated financial statements and these notes should be read in conjunction with the audited consolidated financial statements and notes included in our 2018 Form 10-K.

18

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Supplemental Cash Flow Information

The following table summarizes supplemental Pinnacle West cash flow information (dollars in thousands):

	Nine Months Ended September 30,
	2019		2018
Cash paid during the period for:
Income taxes, net of refunds	$	12,488	$	10,091
Interest, net of amounts capitalized	166,907		161,875
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	85,099	$	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759		—
Sale of 4CA's 7% interest in Four Corners	—		68,907

The following table summarizes supplemental APS cash flow information (dollars in thousands):

	Nine Months Ended September 30,
	2019		2018
Cash paid during the period for:
Income taxes, net of refunds	$	35,573	$	24,746
Interest, net of amounts capitalized	157,593		154,788
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	85,099	$	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759		—

2.    Revenue

Sources of Revenue

The following table provides detail of Pinnacle West's consolidated revenue disaggregated by revenue sources (dollars in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Retail Electric Revenue
Residential	$	668,467	$	695,480	$	1,452,601	$	1,512,402
Non-Residential	465,602		496,809		1,194,199		1,275,498
Wholesale energy sales	36,775		53,501		95,218		80,982
Transmission services for others	15,841		15,902		46,247		46,235
Other sources	4,102		6,342		12,553		19,754
Total operating revenues	$	1,190,787	$	1,268,034	$	2,800,818	$	2,934,871

19

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Retail Electric Revenue. Pinnacle West's retail electric revenue is generated by wholly owned regulated subsidiary APS's sale of electricity to our regulated customers within the authorized service territory at tariff rates approved by the ACC and based on customer kilowatt-hour ("KWh") usage. Revenues related to the sale of electricity are generally recognized when service is rendered or electricity is delivered to customers. The billing of electricity sales to individual customers is based on the reading of their meters. We obtain customers' meter data on a systematic basis throughout the month, and generally bill customers within a month from when service was provided. Customers are generally required to pay for services within 15 days of when the services are billed.

Wholesale Energy Sales and Transmission Services for Others. Revenues from wholesale energy sales and transmission services for others represent energy and transmission sales to wholesale customers. These activities primarily consist of managing fuel and purchased power risks in connection with the cost of serving our retail customers' energy requirements. We may also sell into the wholesale markets generation that is not needed for APS’s retail load. Our wholesale activities and tariff rates are regulated by the United States Federal Energy Regulatory Commission ("FERC").

In the electricity business, some contracts to purchase energy are settled by netting against other contracts to sell electricity. This is referred to as a book-out, and usually occurs in contracts that have the same terms (product type, quantities, and delivery points) and for which power does not flow. We net these book-outs, which reduces both wholesale revenues and fuel and purchased power costs.

Revenue Activities

Our revenues primarily consist of activities that are classified as revenues from contracts with customers. We derive our revenues from contracts with customers primarily from sales of electricity to our regulated retail customers. Revenues from contracts with customers also include wholesale and transmission activities. Our revenues from contracts with customers for the three and nine months ended September 30, 2019 were $1,178 million and $2,756 million, respectively, and for the three and nine months ended September 30, 2018 were $1,257 million and $2,897 million, respectively.

We have certain revenues that do not meet the specific accounting criteria to be classified as revenues from contracts with customers. For the three and nine months ended September 30, 2019, our revenues that do not qualify as revenue from contracts with customers were $13 million and $45 million, respectively, and for the three and nine months ended September 30, 2018 were $11 million and $38 million, respectively. This relates primarily to certain regulatory cost recovery mechanisms that are considered alternative revenue programs. We recognize revenue associated with alternative revenue programs when specific events permitting recognition are completed. Certain amounts associated with alternative revenue programs will subsequently be billed to customers; however, we do not reclassify billed amounts into revenue from contracts with customers. See Note 4 for a discussion of our regulatory cost recovery mechanisms.

Contract Assets and Liabilities from Contracts with Customers

There were no material contract assets, contract liabilities, or deferred contract costs recorded on the Condensed Consolidated Balance Sheets as of September 30, 2019 or December 31, 2018.

3. Long-Term Debt and Liquidity Matters

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.

20

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Pinnacle West

On May 9, 2019, Pinnacle West entered into a $50 million term loan agreement that matures May 7, 2020. Pinnacle West used the proceeds to refinance indebtedness under and terminate a prior $150 million revolving credit facility. Borrowings under the agreement bear interest at London Inter-bank Offered Rate ("LIBOR") plus 0.55% per annum. At September 30, 2019, Pinnacle West had $41 million in outstanding borrowings under the agreement.

At September 30, 2019, Pinnacle West had a $200 million revolving credit facility that matures in July 2023. 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. Interest rates are based on Pinnacle West's senior unsecured debt credit ratings. The facility is available to support Pinnacle West's $200 million commercial paper program, for bank borrowings or for issuances of letters of credits. At September 30, 2019, Pinnacle West had no outstanding borrowings under its credit facility, no letters of credit outstanding and $13 million of commercial paper borrowings.

APS

On February 26, 2019, APS entered into a $200 million term loan agreement that matures August 26, 2020. APS used the proceeds to repay existing indebtedness. Borrowings under the agreement bear interest at LIBOR plus 0.50% per annum.

On February 28, 2019, APS issued $300 million of 4.25% unsecured senior notes that mature on March 1, 2049. The net proceeds from the sale, together with funds made available from the term loan described above, were used to repay existing indebtedness.

On March 1, 2019, APS repaid at maturity $500 million aggregate principal amount of its 8.75% senior notes.

On August 19, 2019, APS issued $300 million of 2.6% unsecured senior notes that mature on August 15, 2029. The net proceeds from the sale were used to repay short-term indebtedness, consisting of commercial paper borrowings, and to replenish cash used to fund capital expenditures.

At September 30, 2019, APS had two revolving credit facilities totaling $1 billion, including a $500 million credit facility that matures in June 2022 and a $500 million facility that matures in July 2023.  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 September 30, 2019, APS had $3 million of commercial paper outstanding and no outstanding borrowings or letters of credit under its revolving credit facilities.

See "Financial Assurances" in Note 8 for a discussion of other outstanding letters of credit.

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Debt Fair Value

Our long-term debt fair value estimates are classified within Level 2 of the fair value hierarchy. The following table presents the estimated fair value of our long-term debt, including current maturities (dollars in thousands):

	As of September 30, 2019				As of December 31, 2018
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Pinnacle West	$	449,268	$	449,670	$	448,796	$	443,955
APS	4,985,728		5,617,727		4,689,436		4,789,608
Total	$	5,434,996	$	6,067,397	$	5,138,232	$	5,233,563

4. Regulatory Matters

2019 Retail Rate Case Filing with the Arizona Corporation Commission

On October 31, 2019, APS filed an application with the ACC for an annual increase in retail base rates of $69 million. This amount includes recovery of the deferral and rate base effects of the Four Corners selective catalytic reduction ("SCR") project that is currently the subject of a separate proceeding (see “SCR Cost Recovery” below). It also reflects a net credit to base rates of approximately $115 million primarily due to the prospective inclusion of rate refunds currently provided through the Tax Expense Adjustment Mechanism ("TEAM"). The proposed total revenue increase in APS's application is $184 million. The average annual customer bill impact of APS’s request is an increase of 5.6% (the average annual bill impact for a typical APS residential customer is 5.4%).

The principal provisions of APS's application are:

• a test year comprised of twelve months ended June 30, 2019, adjusted as described below;

• an original cost rate base of $8.87 billion, which approximates the ACC-jurisdictional portion of the book value of utility assets, net of accumulated depreciation and other credits;

• the following proposed capital structure and costs of capital:

	Capital Structure		Cost of Capital
Long-term debt	45.3	%	4.10	%
Common stock equity	54.7	%	10.15	%
Weighted-average cost of capital			7.41	%

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

• authorization to defer until APS'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;

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

▪ a super off-peak period during the winter months for APS’s time-of-use with demand rates;

▪ additional $1.25 million in funding for limited-income crisis bill program; and

▪ a flat bill/subscription rate pilot program;

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• proposed rate design changes for commercial customers, including an experimental program designed to provide access to market pricing for up to 200 MW of medium and large commercial customers;

• recovery of the deferral and rate base effects of the construction and operating costs of the Ocotillo modernization project (see below discussion of the 2017 Settlement Agreement); and

• continued recovery of the remaining investment and other costs related to the retirement and closure of the Navajo Generating Station (the "Navajo Plant") (see "Navajo Plant" below).

APS requested that the increase become effective December 1, 2020.  APS cannot predict the outcome of its request.

2016 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. On March 27, 2017, a majority of the stakeholders in the general retail rate case, including the ACC Staff, the Residential Utility Consumer Office, limited income advocates and private rooftop solar organizations signed a settlement agreement (the "2017 Settlement Agreement") and filed it with the ACC. The 2017 Settlement Agreement provides for a net retail base rate increase of $94.6 million, excluding the transfer of adjustor balances, consisting of: (1) a non-fuel, non-depreciation, base rate increase of $87.2 million per year; (2) a base rate decrease of $53.6 million attributable to reduced fuel and purchased power costs; and (3) a base rate increase of $61.0 million due to changes in depreciation schedules. The average annual customer bill impact under the 2017 Settlement Agreement was calculated as an increase of 3.28% (the average annual bill impact for a typical APS residential customer was calculated as an increase of 4.54%).

Other key provisions of the agreement include the following:

• an agreement by APS not to file another general retail rate case application before June 1, 2019;

• an authorized return on common equity of 10.0%;

• a capital structure comprised of 44.2% debt and 55.8% common equity;

• a cost deferral order for potential future recovery in APS’s next general retail rate case for the construction and operating costs APS incurs for its Ocotillo modernization project;

• a cost deferral and procedure to allow APS to request rate adjustments prior to its next general retail rate case related to its share of the construction costs associated with installing SCR equipment at the Four Corners Power Plant ("Four Corners");

• a deferral for future recovery (or credit to customers) of the Arizona property tax expense above or below a specified test year level caused by changes to the applicable Arizona property tax rate;

• an expansion of the Power Supply Adjustor (“PSA”) to include certain environmental chemical costs and third-party energy storage costs;

• a new AZ Sun II program (now known as "APS Solar Communities") for utility-owned solar distributed generation with the purpose of expanding access to rooftop solar for low and moderate income Arizonans, recoverable through the Arizona Renewable Energy Standard and Tariff ("RES"), to be no less than $10 million per year, and not more than $15 million per year;

• an increase to the per kWh cap for the environmental improvement surcharge from $0.00016 to $0.00050 and the addition of a balancing account;

• rate design changes, including:

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

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▪ non-grandfathered distributed generation ("DG") customers would be required to select a rate option that has time of use rates and either a new grid access charge or demand component;

▪ a Resource Comparison Proxy (“RCP”) for exported energy of 12.9 cents per kWh in year one; and

• an agreement by APS not to pursue any new self-build generation (with certain exceptions) having an in-service date prior to January 1, 2022 (extended to December 31, 2027 for combined-cycle generating units), unless expressly authorized by the ACC.

Through a separate agreement, APS, industry representatives, and solar advocates committed to stand by the 2017 Settlement Agreement and refrain from seeking to undermine it through ballot initiatives, legislation or advocacy at the ACC.

On August 15, 2017, the ACC approved (by a vote of 4-1), the 2017 Settlement Agreement without material modifications.  On August 18, 2017, the ACC issued a final written Opinion and Order reflecting its decision in APS’s general retail rate case (the "2017 Rate Case Decision"), which is subject to requests for rehearing and potential appeal. The new rates went into effect on August 19, 2017.

On October 17, 2017, Warren Woodward (an intervener in APS's general retail rate case) filed a Notice of Appeal in the Arizona Court of Appeals, Division One. The notice raises a single issue related to the application of certain rate schedules to new APS residential customers after May 1, 2018. Mr. Woodward filed a second notice of appeal on November 13, 2017 challenging APS’s $5 per month automated metering infrastructure opt-out program. Mr. Woodward’s two appeals were consolidated, and APS requested and was granted intervention. The Arizona Court of Appeals issued a Memorandum Decision on December 11, 2018 affirming the ACC decisions challenged by Mr. Woodward. Mr. Woodward filed a petition for review with the Arizona Supreme Court on January 9, 2019. The Arizona Supreme Court denied review.

On January 3, 2018, an APS customer filed a petition with the ACC that was determined by the ACC Staff to be a complaint filed pursuant to Arizona Revised Statute §40-246 (the “Complaint”) and not a request for rehearing. Arizona Revised Statute §40-246 requires the ACC to hold a hearing regarding any complaint alleging that a public service corporation is in violation of any commission order or that the rates being charged are not just and reasonable if the complaint is signed by at least twenty-five customers of the public service corporation. The Complaint alleged that APS is “in violation of commission order” [sic]. On February 13, 2018, the complainant filed an amended Complaint alleging that the rates and charges in the 2017 Rate Case Decision are not just and reasonable.  The complainant requested that the ACC hold a hearing on the amended Complaint to determine if the average bill impact on residential customers of the rates and charges approved in the 2017 Rate Case Decision is greater than 4.54% (the average annual bill impact for a typical APS residential customer estimated by APS) and, if so, what effect the alleged greater bill impact has on APS's revenues and the overall reasonableness and justness of APS's rates and charges, in order to determine if there is sufficient evidence to warrant a full-scale rate hearing.  The ACC held a hearing on this matter beginning in September 2018 and the hearing was concluded on October 1, 2018. On April 9, 2019, the Administrative Law Judge issued a Recommended Opinion and Order recommending that the Complaint be dismissed. The ACC considered the matter at its April and May 2019 open meetings, but no decision was issued. On July 3, 2019, the Administrative Law Judge issued an amendment to the Recommended Opinion and Order that incorporated the requirements of the rate review of the 2017 Rate Case Decision (see below discussion regarding the rate review). On July 10, 2019, the ACC reconsidered the matter and adopted the Administrative Law Judge's amended Recommended Opinion and Order along with several ACC Commissioner amendments and an amendment incorporating the results of the rate review and resolved the Complaint.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

On December 24, 2018, certain ACC Commissioners filed a letter stating that because the ACC had received a substantial number of complaints that the rate increase authorized by the 2017 Rate Case Decision was much more than anticipated, they believe there is a possibility that APS is earning more than was authorized by the 2017 Rate Case Decision.  Accordingly, the ACC Commissioners requested the ACC Staff to perform a rate review of APS using calendar year 2018 as a test year and file a report by May 3, 2019. The ACC Commissioners also asked the ACC Staff to evaluate APS’s efforts to educate its customers regarding the new rates approved in the 2017 Rate Case Decision. On April 23, 2019, the ACC Staff indicated that they would need additional time beyond May 3, 2019 to file the requested report.

On June 4, 2019, the ACC Staff filed a proposed order regarding the rate review of the 2017 Rate Case Decision. On June 11, 2019, the ACC Commissioners approved the proposed ACC Staff order with amendments. The key provisions of the amended order include the following:

• APS must file a rate case no later than October 31, 2019, using a June 30, 2019 test-year;

• until the conclusion of the rate case being filed no later than October 31, 2019, APS must provide information on customer bills that shows how much a customer would pay on their most economical rate given their actual usage during each month;

• APS customers can switch rate plans during an open enrollment period of six months;

• APS must identify customers whose bills have increased by more than 9% and that are not on the most economical rate and provide such customers with targeted education materials and an opportunity to switch rate plans;

• APS must provide grandfathered net metering customers on legacy demand rates an opportunity to switch to another legacy rate to enable such customers to fully benefit from legacy net metering rates;

• APS must fund and implement a supplemental customer education and outreach program to be developed with and administered by ACC Staff and a third-party consultant; and

• APS must fund and organize, along with the third-party consultant, a stakeholder group to suggest better ways to communicate the impact of changes to adjustor cost recovery mechanisms (see below for discussion on cost recovery mechanisms), including more effective ways to educate customers on rate plans and to reduce energy usage.

APS cannot predict the outcome or impact of the rate case filed on October 31, 2019. APS is assessing the impact to its financial statements of the implementation of the other key provisions of the amended order regarding the rate review and cannot predict at this time whether they will have a material impact on its financial position, results of operations or cash flows. 

Cost Recovery Mechanisms

APS has received regulatory decisions that allow for more timely recovery of certain costs outside of a general retail rate case 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 2015, the ACC revised the RES rules to allow the ACC to consider all available information, including the number of rooftop solar arrays in a utility’s service territory, to determine compliance with the RES.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

On June 30, 2017, APS filed its 2018 RES Implementation Plan and proposed a budget of approximately $90 million.  APS’s budget request supports existing approved projects and commitments and includes the anticipated transfer of specific revenue requirements into base rates in accordance with the 2017 Settlement Agreement and also requests a permanent waiver of the residential distributed energy requirement for 2018 contained in the RES rules. APS's 2018 RES budget request is lower than the 2017 RES budget due in part to a certain portion of the RES being collected by APS in base rates rather than through the RES adjustor.

On November 20, 2017, APS filed an updated 2018 RES budget to include budget adjustments for APS Solar Communities (formerly known as AZ Sun II), which was approved as part of the 2017 Rate Case Decision. APS Solar Communities is a 3-year program authorizing APS to spend $10 million to $15 million in capital costs each year to install utility-owned DG systems for low to moderate income residential homes, buildings of non-profit entities, Title I schools and rural government facilities. The 2017 Rate Case Decision provided that all operations and maintenance expenses, property taxes, marketing and advertising expenses, and the capital carrying costs for this program will be recovered through the RES. On June 12, 2018, the ACC approved the 2018 RES Implementation Plan including a waiver of the distributed energy requirements for the 2018 implementation year.

On June 29, 2018, APS filed its 2019 RES Implementation Plan and proposed a budget of approximately $89.9 million.  APS’s budget request supports existing approved projects and commitments and requests a permanent waiver of the residential distributed energy requirement for 2019 contained in the RES rules. On October 29, 2019, the ACC approved the 2019 RES Implementation Plan.

On July 1, 2019, APS filed its 2020 RES Implementation Plan and proposed a budget of approximately $86.3 million. APS’s budget request supports existing approved projects and commitments and requests a permanent waiver of the residential distributed energy requirement for 2020 contained in the RES rules. The ACC has not yet ruled on the 2020 RES Implementation Plan.

On July 2, 2019, ACC Staff issued draft rules, which propose a RES goal of 45% of retail energy served be renewable by 2035 and a goal of 20% of retail sales during peak demand to be from clean energy resources by 2035.  The draft rules would also require a certain amount of the RES goal to be derived from distributed renewable storage, for which utilities would be required to offer performance-based incentives. Nuclear energy would be considered a clean resource under the draft rules. See "Energy Modernization Plan" below for more information.

Demand Side Management Adjustor Charge.  The ACC Electric Energy Efficiency Standards require APS to submit a Demand Side Management Implementation Plan ("DSM Plan") annually for review by and approval of the ACC. Verified energy savings from APS's resource savings projects can be counted toward compliance with the Electric Energy Efficiency Standards; however, APS is not allowed to count savings from systems savings projects toward determination of the achievement of performance incentives, nor may APS include savings from these system savings projects in the calculation of its Lost Fixed Cost Recovery (“LFCR”) mechanism (see below for discussion of the LFCR).

On September 1, 2017, APS filed its 2018 DSM Plan, which proposes modifications to the demand side management portfolio to better meet system and customer needs by focusing on peak demand reductions, storage, load shifting and demand response programs in addition to traditional energy savings measures. The 2018 DSM Plan seeks a requested budget of $52.6 million and requests a waiver of the Electric Energy Efficiency Standard for 2018.   On November 14, 2017, APS filed an amended 2018 DSM Plan, which revised

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

the allocations between budget items to address customer participation levels, but kept the overall budget at $52.6 million. The ACC has not yet ruled on the APS 2018 amended DSM Plan.

On December 31, 2018, APS filed its 2019 DSM Plan, which requests a budget of $34.1 million and continues APS's focus on DSM strategies such as peak demand reduction, load shifting, storage and electrification strategies. The ACC has not yet ruled on the APS 2019 DSM Plan.

On May 7, 2019, APS filed a request for an extension to file its 2020 DSM Plan no later than December 31, 2019. On July 10, 2019, the ACC approved this request.

 Power Supply Adjustor Mechanism and Balance.  The PSA provides for the adjustment of retail rates to reflect variations primarily in retail fuel and purchased power costs.  The following table shows the changes in the deferred fuel and purchased power regulatory asset for 2019 and 2018 (dollars in thousands):

	Nine Months Ended September 30,
	2019			2018
Beginning balance	$	37,164		$	75,637
Deferred fuel and purchased power costs — current period	60,911			82,486
Amounts charged to customers	(38,601		)	(92,397		)
Ending balance	$	59,474		$	65,726

The PSA rate for the PSA year beginning February 1, 2017 was $(0.001348) per kWh, as compared to $0.001678 per kWh for the prior year.  This rate was comprised of a forward component of $(0.001027) per kWh and a historical component of $(0.000321) per kWh. On August 19, 2017 the PSA rate was revised to $0.000555 per kWh as part of the 2017 Rate Case Decision. This new rate was comprised of a forward component of $0.000876 per kWh and a historical component of $(0.000321) per kWh.

The PSA rate for the PSA year beginning February 1, 2018 is $0.004555 per kWh, consisting of a forward component of $0.002009 per kWh and a historical component of $0.002546 per kWh. This represented a $0.004 per kWh increase over the August 19, 2017 PSA, the maximum permitted under the Plan of Administration for the PSA. This left $16.4 million of 2017 fuel and purchased power costs above this annual cap. These costs rolled over into the following year and were reflected in the 2019 reset of the PSA.

On November 30, 2018, APS filed its PSA rate for the PSA year beginning February 1, 2019. That rate was $0.001658 per kWh and consisted of a forward component of $0.000536 per kWh and a historical component of $0.001122 per kWh. The 2019 PSA rate is a $0.002897 per kWh decrease compared to 2018. These rates went into effect as filed on February 1, 2019.

Transmission Rates, Transmission Cost Adjustor ("TCA") 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 settlement agreement entered into in 2012 regarding APS's rate case (the "2012 Settlement Agreement"), however, an adjustment to rates to recover

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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, 2017, APS's annual wholesale transmission rates for all users of its transmission system increased by approximately $35.1 million for the twelve-month period beginning June 1, 2017 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, 2017.

On March 7, 2018, APS made a filing to make modifications to its annual transmission formula to provide transmission customers the benefit of the reduced federal corporate income tax rate resulting from the Tax Act beginning in its 2018 annual transmission formula rate update filing. These modifications were approved by FERC on May 22, 2018 and reduced APS’s transmission rates compared to the rate that would have gone into effect absent these changes.

Effective June 1, 2018, APS's annual wholesale transmission rates for all users of its transmission system decreased by approximately $22.7 million for the twelve-month period beginning June 1, 2018 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, 2018.

Effective June 1, 2019, APS's annual wholesale transmission rates for all users of its transmission system increased by approximately $4.9 million for the twelve-month period beginning June 1, 2019 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, 2019.

 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 DG such as rooftop solar arrays.  The fixed costs recoverable by the LFCR mechanism were first 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. These amounts were revised in the 2017 Settlement Agreement to 2.5 cents for both lost residential and non-residential kWh.  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 kWhs lost from energy efficiency are based on a third-party evaluation of APS’s energy efficiency programs.  DG sales losses are determined from the metered output from the DG units.

APS filed its 2017 LFCR adjustment on January 13, 2017 requesting an LFCR adjustment of $63.7 million. On April 5, 2017, the ACC approved the 2017 annual LFCR adjustment as filed, effective with the first billing cycle of April 2017. On February 15, 2018, APS filed its 2018 annual LFCR Adjustment, requesting that effective May 1, 2018, the LFCR be adjusted to $60.7 million (a $3 million per year decrease

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

from 2017 levels). On February 6, 2019, the ACC approved the 2018 annual LFCR adjustment to become effective March 1, 2019. On February 15, 2019, APS filed its 2019 annual LFCR adjustment, requesting that effective May 1, 2019, the annual LFCR recovery amount be reduced to $36.2 million (a $24.5 million decrease from previous levels). On July 10, 2019, the ACC approved APS’s 2019 LFCR adjustment as filed, effective with the next billing cycle of July 2019. Because the LFCR mechanism has a balancing account that trues up any under or over recoveries, the delay in implementation does not have an adverse effect on APS.

Tax Expense Adjustor Mechanism.  As part of the 2017 Settlement Agreement, the parties agreed to a rate adjustment mechanism to address potential federal income tax reform and enable the pass-through of certain income tax effects to customers. The TEAM expressly applies to APS's retail rates with the exception of a small subset of customers taking service under specially-approved tariffs. On December 22, 2017, the Tax Act was enacted.  This legislation made significant changes to the federal income tax laws including a reduction in the corporate tax rate from 35% to 21% effective January 1, 2018.

On January 8, 2018, APS filed an application with the ACC that addressed the change in the marginal federal tax rate from 35% to 21% resulting from the Tax Act and reduced rates by $119.1 million annually through an equal cents per kWh credit ("TEAM Phase I").  On February 22, 2018, the ACC approved the reduction of rates through an equal cents per kWh credit. The rate reduction was effective for the first billing cycle in March 2018.

The impact of the TEAM Phase I, over time, is expected to be earnings neutral. However, on a quarterly basis, there is a difference between the timing and amount of the income tax benefit and the reduction in revenues refunded through the TEAM Phase I related to the lower federal income tax rate. The amount of the benefit of the lower federal income tax rate is based on quarterly pre-tax results, while the reduction in revenues refunded through the TEAM Phase I is based on a per kWh sales credit which follows our seasonal kWh sales pattern and is not impacted by earnings of the Company.

On August 13, 2018, APS filed a second request with the ACC that addressed the return of an additional $86.5 million in tax savings to customers related to the amortization of non-depreciation related excess deferred taxes previously collected from customers ("TEAM Phase II"). The ACC approved this request on March 13, 2019, effective the first billing cycle in April 2019. Both the timing of the reduction in revenues refunded through TEAM Phase II and the offsetting income tax benefit are recognized based upon our seasonal kWh sales pattern.

On April 10, 2019, APS filed a third request with the ACC that addressed the amortization of depreciation related excess deferred taxes over a 28.5 year period (“TEAM Phase III”).  On October 29, 2019, the ACC approved TEAM Phase III providing both (i) a one-time bill credit of $64 million to be credited to customers on their December 2019 bills, and (ii) a monthly bill credit effective the first billing cycle in December 2019 which will provide an additional benefit of $39.5 million to customers through December 31, 2020. It is currently anticipated that benefits related to the amortization of depreciation related excess deferred taxes for periods beginning after December 31, 2020 will be fully incorporated into the 2019 rate case filing.

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Net Metering

In 2015, the ACC voted to conduct a generic evidentiary hearing on the value and cost of DG 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 Administrative Law Judge 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 opinion and order by the Administrative Law Judge. After making several amendments, the ACC approved the recommended decision by a 4-1 vote. As a result of the ACC’s action, effective with APS’s 2017 Rate Case Decision, the net metering tariff that governs payments for energy exported to the grid from residential rooftop solar systems was replaced by a more formula-driven approach that utilizes inputs from historical wholesale solar power until an avoided cost methodology is developed by the ACC.

As amended, the decision provides that payments by utilities for energy exported to the grid from DG solar facilities will be determined using a RCP methodology, a method that is based on the most recent five-year rolling average price that APS pays for utility-scale solar projects, while a forecasted avoided cost methodology is being developed.  The price established by this RCP method will be updated annually (between general retail 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 APS 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 September 1, 2017, based on APS's 2017 Rate Case Decision, will be grandfathered for a period of 20 years from the date the customer’s interconnection application was accepted by the utility;

• 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 general retail rate cases, and the policy determinations themselves may be subject to future change, as are all ACC policies. A first-year export energy price of 12.9 cents per kWh was included in the 2017 Settlement Agreement and became effective on September 1, 2017.

In accordance with the 2017 Rate Case Decision, APS filed its request for a second-year export energy price of 11.6 cents per kWh on May 1, 2018.  This price reflected the 10% annual reduction discussed above. The new rate rider became effective on October 1, 2018. APS filed its request for a third-year export energy price of 10.45 cents per kWh on May 1, 2019.  This price also reflects the 10% annual reduction discussed above. The new rate rider became effective on October 1, 2019. The ACC has not yet ruled on this request.

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 asserted 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 filed a Notice of Appeal in the Arizona

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Court of Appeals and filed a Complaint and Statutory Appeal in the Maricopa County Superior Court on March 10, 2017. As part of the 2017 Settlement Agreement described above, TASC agreed to withdraw these appeals when the ACC decision implementing the 2017 Settlement Agreement is no longer subject to appellate review.

See "2016 Retail Rate Case Filing with the Arizona Corporation Commission" above for information regarding an ACC order in connection with the rate review of the 2017 Rate Case Decision requiring APS to provide grandfathered net metering customers on legacy demand rates with an opportunity to switch to another legacy rate to enable such customers to benefit from legacy net metering rates.

Subpoena from Arizona Corporation Commissioner Robert Burns

On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, served subpoenas in APS’s then current retail rate proceeding on 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 the production of all information previously requested through the subpoenas. Neither APS nor Pinnacle West produced the information requested and instead objected to the subpoena. On March 10, 2017, Commissioner Burns filed suit against APS and Pinnacle West in the Superior Court of Arizona for Maricopa County in an effort to enforce his subpoenas. On March 30, 2017, APS filed a motion to dismiss Commissioner Burns' suit against APS and Pinnacle West. In response to the motion to dismiss, the court stayed the suit and ordered Commissioner Burns to file a motion to compel the production of the information sought by the subpoenas with the ACC. On June 20, 2017, the ACC denied the motion to compel.

On August 4, 2017, Commissioner Burns amended his complaint to add all of the ACC Commissioners and the ACC itself as defendants. All defendants moved to dismiss the amended complaint. On February 15, 2018, the Superior Court dismissed Commissioner Burns’ amended complaint. On March 6, 2018, Commissioner Burns filed an objection to the proposed final order from the Superior Court and a motion to further amend his complaint. The Superior Court permitted Commissioner Burns to amend his complaint to add a claim regarding his attempted investigation into whether his fellow commissioners should have been disqualified from voting on APS’s 2017 rate case. Commissioner Burns filed his second amended complaint, and all defendants filed responses opposing the second amended complaint and requested that it be dismissed.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Oral argument occurred in November 2018 regarding the motion to dismiss. On December 18, 2018, the trial court granted the defendants’ motions to dismiss and entered final judgment on January 18, 2019. On February 13, 2019, Commissioner Burns filed a notice of appeal. On July 12, 2019, Commissioner Burns filed his opening brief in the Arizona Court of Appeals. APS filed its answering brief on October 21, 2019. APS and Pinnacle West cannot predict the outcome of this matter.

Information Requests from Arizona Corporation Commissioners

On January 14, 2019, ACC Commissioner Kennedy opened a docket to investigate campaign expenditures and political participation of APS and Pinnacle West. In addition, on February 27, 2019, ACC Commissioners Burns and Dunn opened a new docket and requested documents from APS and Pinnacle West related to ACC elections and charitable contributions related to the ACC. On March 1, 2019, ACC Commissioner Kennedy issued a subpoena to APS seeking several categories of information for both Pinnacle West and APS including political contributions, lobbying expenditures, marketing and advertising expenditures, and contributions made to 501(c)(3) and 501(c)(4) entities, for the years 2013-2018. Pinnacle West and APS voluntarily responded to both sets of requests on March 29, 2019. APS also received and responded to various follow-on requests from ACC Commissioners on these matters. Pinnacle West and APS cannot predict the outcome of these matters.

Renewable Energy Ballot Initiative

On February 20, 2018, a renewable energy advocacy organization filed with the Arizona Secretary of State a ballot initiative for an Arizona constitutional amendment requiring Arizona public service corporations to provide at least 50% of their annual retail sales of electricity from renewable sources by 2030. For purposes of the proposed amendment, eligible renewable sources would not include nuclear generating facilities. The initiative was placed on the November 2018 Arizona elections ballot. On November 6, 2018, the initiative failed to receive adequate voter support and was defeated.

Energy Modernization Plan

On January 30, 2018, former ACC Commissioner Tobin proposed the Energy Modernization Plan, which consisted of a series of energy policies tied to clean energy sources such as energy storage, biomass, energy efficiency, electric vehicles, and expanded energy planning through the integrated resource plans ("IRP") process. In August 2018, the ACC directed ACC Staff to open a new rulemaking docket which will address a wide range of energy issues, including the Energy Modernization Plan proposals. The rulemaking will consider possible modifications to existing ACC rules, such as the RES, Electric and Gas Energy Efficiency Standards, Net Metering, Resource Planning, and the Biennial Transmission Assessment, as well as the development of new rules regarding forest bioenergy, electric vehicles, interconnection of distributed generation, baseload security, blockchain technology and other technological developments, retail competition, and other energy-related topics. On April 25, 2019, the ACC Staff issued a set of draft rules in regards to the Energy Modernization Plan and workshops were held on April 29, 2019 regarding these draft rules. On July 2, 2019, the ACC Staff issued a revised set of draft rules, which propose a RES goal of 45% of retail energy served be renewable by 2035 and a goal of 20% of retail sales during peak demand to be from clean energy resources by 2035.  The draft rules also require a certain amount of the RES goal to be derived from distributed renewable storage, for which utilities would be required to offer performance-based incentives.  Nuclear energy would be considered a clean resource under the draft rules. The ACC held various stakeholder meetings and workshops on ACC Staff’s draft energy rules in July through September 2019. APS cannot predict the outcome of this matter.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Integrated Resource Planning

ACC rules require utilities to develop fifteen-year IRPs which describe how the utility plans to serve customer load in the plan timeframe.  The ACC reviews each utility’s IRP to determine if it meets the necessary requirements and whether it should be acknowledged.  In March of 2018, the ACC reviewed the 2017 IRPs of its jurisdictional utilities and voted to not acknowledge any of the plans.  APS does not believe that this lack of acknowledgment will have a material impact on our financial position, results of operations or cash flows.  Based on an ACC decision, APS is required to file a Preliminary Resource Plan by April 1, 2019 and its final IRP by April 1, 2020. APS filed a request to extend the deadline to file its Preliminary IRP, which was granted. On August 1, 2019, APS filed its Preliminary IRP.

Public Utility Regulatory Policies Act

In August 2016, APS filed an application requesting that all of its contracts with qualifying facilities over 100 kW be set at a presumptive maximum 2 year term. A qualifying facility is an eligible energy-producing facility as defined by FERC regulations within a host electric utility’s service territory that has a right to sell to the host utility. Host utilities are required to purchase power from qualifying facilities at an avoided cost as determined by the utility subject to state commission oversight. A hearing was held in August 2019 and briefing on this matter was completed in October 2019 regarding APS’s application. APS cannot predict the outcome of this matter.

Residential Electric Utility Customer Service Disconnections

On June 13, 2019, APS voluntarily suspended electric disconnections for residential customers who had not paid their bills.  On June 20, 2019, the ACC voted to enact emergency rule amendments to prevent residential electric utility customer service disconnections during the period from June 1 through October 15. During the moratorium on disconnections, APS could not charge late fees and interest on amounts that were past due from customers.  Customer deposits must also be used to pay delinquent amounts before disconnection can occur and customers will have four months to pay back their deposit and any remaining delinquent amounts.  In accordance with the emergency rules, APS began putting delinquent customers on a mandatory four-month payment plan beginning on October 16, 2019. The emergency rule changes will be effective for 180 days and may be renewed for one additional 180 day period. During that time, the ACC began a formal regular rulemaking process to allow stakeholder input and time for consideration of permanent rule changes.  The ACC further ordered that each regulated electric utility serving retail customers in Arizona update its service conditions by incorporating the emergency rule amendments, restore power to any customers who were disconnected during the month of June 2019 and credit any fees that were charged for a reconnection. The ACC Staff issued draft amendments to the customer service disconnections rules. Stakeholders submitted initial comments to the draft amendments on September 23, 2019. ACC stakeholder meetings were held in September 2019 and October 2019 regarding the customer service disconnections rules. APS currently estimates that the disconnection moratorium will result in a negative impact to its 2019 operating results of approximately $10 million pre-tax depending on certain assumptions, including customer behaviors. APS is further assessing the impact to its financial statements beyond 2019, which will be affected by the results of final rulemaking related to disconnections.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Retail Electric Competition Rules

On November 17, 2018, the ACC voted to re-examine the facilitation of a deregulated retail electric market in Arizona. An ACC special open meeting workshop was held on December 3, 2018. No substantive action was taken, but interested parties were asked to submit written comments and respond to a list of questions from ACC Staff. On July 1 and July 2, 2019, ACC Staff issued a report and initial proposed draft rules regarding possible modifications to the ACC’s retail electric competition rules. Interested parties filed comments to the ACC Staff report and a stakeholder meeting and workshop to discuss the retail electric competition rules was held on July 30, 2019. ACC Commissioners submitted additional questions regarding this matter. APS cannot predict whether these efforts will result in any changes and, if changes to the rules results, what impact these rules would have on APS.

Four Corners 

SCE-Related Matters. On December 30, 2013, APS purchased Southern California Edison Company's ("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 retail 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 included 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 provided 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 $42 million as of September 30, 2019 and is being amortized in rates over a total of 10 years.

 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. On October 5, 2017, FERC issued an order denying APS's request for rehearing. FERC also upheld its prior determination that the agreement relating to the settlement was a jurisdictional contract and should have been filed with FERC. APS cannot predict whether or if the enforcement division will take any action. APS filed an appeal of FERC's July 1, 2016 and October 5, 2017 orders with the United States Court of Appeals for the Ninth Circuit on December 4, 2017. On June 14, 2019, the United States Court of Appeals for the Ninth

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Circuit issued an unpublished memorandum order denying APS’s petition for review of FERC’s orders that denied APS’s request to recover the regulatory asset through its FERC-jurisdictional rates and granting APS’s petition for review of FERC’s orders finding the agreement to be a jurisdictional contract. The United States Court of Appeals for the Ninth Circuit vacated FERC’s determination that the agreement was required to be filed with FERC and remanded the issue to FERC for additional proceedings. APS cannot predict the outcome of the remand proceeding.

SCR Cost Recovery. On December 29, 2017, in accordance with the 2017 Rate Case Decision, APS filed a Notice of Intent to file its SCR Adjustment to permit recovery of costs associated with the installation of SCR equipment at Four Corners Units 4 and 5.  APS filed the SCR Adjustment request in April 2018.  Consistent with the 2017 Rate Case Decision, the request was narrow in scope and addressed only costs associated with this specific environmental compliance equipment.  The SCR Adjustment request provided that there would be a $67.5 million annual revenue impact that would be applied as a percentage of base rates for all applicable customers.  Also, as provided for in the 2017 Rate Case Decision, APS requested that the adjustment become effective no later than January 1, 2019.  The hearing for this matter occurred in September 2018.  At the hearing, APS accepted ACC Staff's recommendation of a lower annual revenue impact of approximately $58.5 million. The Administrative Law Judge issued a Recommended Opinion and Order finding that the costs for the SCR project were prudently incurred and recommending authorization of the $58.5 million annual revenue requirement related to the installation and operation of the SCRs. Exceptions to the Recommended Opinion and Order were filed by the parties and intervenors on December 7, 2018.  The ACC has not issued a decision on this matter. APS included the costs for the SCR project in the retail rate base in its 2019 retail rate case filing with the ACC. APS cannot predict the outcome or timing of the decision on this matter. APS may be required to record a charge to its results of operations if the ACC issues an unfavorable decision (see SCR deferral in the Regulatory Assets and Liabilities table below).

Cholla

On September 11, 2014, APS announced that it would close Unit 2 of the Cholla Power Plant ("Cholla") and cease burning coal at the other APS-owned units (Units 1 and 3) at the plant by the mid-2020s, if the United States Environmental Protection Agency ("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. In early 2017, EPA approved a final rule incorporating APS's compromise proposal, which took effect on April 26, 2017.

Previously, APS estimated Cholla Unit 2’s end of life to be 2033. APS has been recovering a return on and of the net book value of the unit in base rates. Pursuant to the 2017 Settlement Agreement described above, APS will be allowed continued recovery of the net book value of the unit and the unit’s decommissioning and other retirement-related costs ($77 million as of September 30, 2019), 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. The 2017 Settlement Agreement also shortened the depreciation lives of Cholla Units 1 and 3 to 2025.

On March 20, 2019, APS announced that it began evaluating the feasibility and cost of converting a unit at Cholla to burn biomass. Biomass is a fuel comprised of forest trimmings, and a converted unit at Cholla could assist in forest thinning, responsible forest management, an improved watershed, and a reduced wildfire risk. APS’s ability to operate a biomass power plant would depend on third-parties procuring forest biomass for fuel. APS reported the results of its evaluation on May 9, 2019 to the ACC. On July 10, 2019, the ACC voted to not require APS to file a request for proposal to convert the unit at Cholla to burn biomass.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Navajo Plant

The co-owners of the Navajo Plant and the Navajo Nation agreed that the Navajo Plant will remain in operation until December 2019 under the existing plant lease. The co-owners and the Navajo Nation executed a lease extension on November 29, 2017 that will allow for decommissioning activities to begin after the plant ceases operations by December 2019.

APS is currently recovering depreciation and a return on the net book value of its interest in the Navajo Plant over its previously estimated life through 2026. APS will seek continued recovery in rates for the book value of its remaining investment in the plant ($80 million as of September 30, 2019) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and may be material. APS believes it will be allowed recovery of the net book value, in addition to a return on its investment. In accordance with GAAP, in the second quarter of 2017, APS's remaining net book value of its interest in the Navajo Plant 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 this interest, 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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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Regulatory Assets and Liabilities 

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

	Amortization Through	September 30, 2019				December 31, 2018
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	703,460	$	—	$	733,351
Retired power plant costs	2033	28,182		146,076		28,182		167,164
Income taxes — allowance for funds used during construction ("AFUDC") equity	2049	6,457		154,269		6,457		151,467
Deferred fuel and purchased power — mark-to-market (Note 7)	2023	41,643		27,305		31,728		23,768
Deferred property taxes	2027	8,569		60,338		8,569		66,356
Deferred fuel and purchased power (b) (c)	2020	59,474		—		37,164		—
SCR deferral	N/A	—		45,296		—		23,276
Four Corners cost deferral	2024	8,077		34,171		8,077		40,228
Deferred compensation	2036	—		37,589		—		36,523
Lost fixed cost recovery (b)	2020	25,775		—		32,435		—
Income taxes — investment tax credit basis adjustment	2047	1,079		24,555		1,079		25,522
Ocotillo deferral	N/A	—		23,643		—		—
Palo Verde VIEs (Note 6)	2046	—		20,480		—		20,015
Coal reclamation	2026	1,546		18,821		1,546		15,607
Loss on reacquired debt	2038	1,637		12,441		1,637		13,668
Mead-Phoenix transmission line CIAC	2050	332		9,795		332		10,044
TCA balancing account (b)	2021	5,016		2,721		3,860		772
Tax expense of Medicare subsidy	2024	1,235		5,073		1,235		6,176
AG-1 deferral	2022	2,787		3,413		2,654		5,819
Tax expense adjuster mechanism (b)	2019	2,916		—		—		—
Other	Various	2,782		—		1,947		3,185
Total regulatory assets (d)		$	197,507	$	1,329,446	$	166,902	$	1,342,941

(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 other comprehensive income ("OCI") and result in lower future revenues.

(b) See "Cost Recovery Mechanisms" discussion above.

(c) Subject to a carrying charge.

(d) 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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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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

	Amortization Through	September 30, 2019				December 31, 2018
		Current		Non-Current		Current		Non-Current
Excess deferred income taxes - ACC - Tax Cuts and Jobs Act (a)	(b)	$	38,529	$	1,178,216	$	—	$	1,272,709
Excess deferred income taxes - FERC - Tax Cuts and Jobs Act (a)	2058	6,302		238,064		6,302		243,691
Asset retirement obligations	2057	—		367,930		—		278,585
Removal costs	(c)	47,459		151,535		39,866		177,533
Other postretirement benefits	(d)	37,821		95,789		37,864		125,903
Income taxes — change in rates	2048	2,764		67,605		2,769		70,069
Spent nuclear fuel	2027	5,746		53,229		6,503		57,002
Income taxes — deferred investment tax credit	2047	2,164		49,182		2,164		51,120
Four Corners coal reclamation	2038	1,858		49,194		1,858		17,871
Renewable energy standard (b)	2021	42,146		5,675		44,966		20
Demand side management (b)	2021	14,300		24,146		14,604		4,123
Sundance maintenance	2031	4,640		13,393		1,278		17,228
Deferred gains on utility property	2022	2,923		4,766		4,423		6,581
Property tax deferral	N/A	—		6,288		—		2,611
FERC transmission true up	2021	—		2,586		—		—
Other	Various	1,370		2,533		3,279		930
Total regulatory liabilities		$	208,022	$	2,310,131	$	165,876	$	2,325,976

(a) For purposes of presentation on the Statement of Cash Flows, amortization of the regulatory liabilities for excess deferred income taxes are reflected as "Deferred income taxes" under Cash Flows From Operating Activities.

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

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

(d) See Note 5.

5. Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan, a non-qualified supplemental excess benefit retirement plan, and an other postretirement benefit plan for the employees of Pinnacle West and our subsidiaries.  Pinnacle West uses a December 31 measurement date for its pension and other postretirement benefit plans.  The market-related value of our plan assets is their fair value at the measurement dates.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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 or billed to electric plant participants) (dollars in thousands):

	Pension Benefits												Other Benefits
	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018			2019			2018			2019			2018
Service cost — benefits earned during the period	$	12,476		$	14,167		$	37,427		$	42,501		$	4,593		$	5,275		$	13,777		$	15,825
Non-service costs (credits):
Interest cost on benefit obligation	34,211			31,172			102,632			93,517			7,473			7,037			22,420			21,111
Expected return on plan assets	(42,971		)	(45,713		)	(128,913		)	(137,140		)	(9,603		)	(10,520		)	(28,809		)	(31,561		)
Amortization of:
Prior service credit	—			—			—			—			(9,456		)	(9,461		)	(28,366		)	(28,382		)
Net actuarial loss	10,646			8,021			31,938			24,062			—			—			—			—
Net periodic benefit cost (credit)	$	14,362		$	7,647		$	43,084		$	22,940		$	(6,993	)	$	(7,669	)	$	(20,978	)	$	(23,007	)
Portion of cost (credit) charged to expense	$	7,593		$	2,524		$	22,837		$	7,535		$	(4,966	)	$	(5,359	)	$	(14,846	)	$	(16,083	)

Contributions

We have made voluntary contributions of $150 million to our pension plan year-to-date in 2019. 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 $350 million during the 2019-2021 period. We do not expect to make any contributions over the next three years to our other postretirement benefit plans. In 2019, the Company was reimbursed $30 million for prior year retiree medical claims from the other postretirement benefit plan trust assets.

6. 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 through 2023, and $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 the three and nine months ended September 30, 2019 of $5 million and $15 million, respectively, and for the three and nine months ended September 30, 2018 of $5 million and

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

$15 million, respectively, entirely attributable to the noncontrolling interests. Income attributable to Pinnacle West shareholders is not impacted by the consolidation.

Our Condensed Consolidated Balance Sheets at September 30, 2019 and December 31, 2018 include the following amounts relating to the VIEs (dollars in thousands):

	September 30, 2019		December 31, 2018
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	$	102,873	$	105,775
Equity — Noncontrolling interests	129,039		125,790

Assets of the VIEs are restricted and may only be used for payment to the noncontrolling interest holders. These assets are reported on our condensed consolidated financial statements.

APS is exposed to losses relating to these VIEs upon the occurrence of certain events that APS does not consider to be reasonably likely to occur.  Under certain circumstances (for example, the Nuclear Regulatory Commission ("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 $299 million beginning in 2019, and up to $456 million over the lease extension terms.

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.

7.    Derivative Accounting

Derivative financial instruments are used to manage exposure to commodity price and transportation costs of electricity, natural gas, emissions allowances, and in interest rates.  Risks associated with market volatility are managed 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.  Derivative instruments are also entered into for economic hedging purposes.  While economic hedges may 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 Condensed 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 sheets as an asset or liability and are measured at fair value.  See Note 11 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

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

the accrual method of accounting and excluded from our derivative instrument discussion and disclosures below.

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 4).  Gains and losses from derivatives in the following tables represent the amounts reflected in income before the effect of PSA deferrals.

As of September 30, 2019 and December 31, 2018, we had the following outstanding gross notional volume of derivatives, which represent both purchases and sales (does not reflect net position): 

		Quantity
Commodity	Unit of Measure	September 30, 2019	December 31, 2018
Power	GWh	232	250
Gas	Billion cubic feet	187	218

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

 

	Financial Statement Location	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts		2019			2018			2019			2018
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized) (a)	Fuel and purchased power (b)	$	(289	)	$	(600	)	$	(1,263	)	$	(1,697	)

(a) During the three and nine months ended September 30, 2019 and 2018, we had no gains or 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 approximately $1 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.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The following table provides information about gains and losses from derivative instruments not designated as accounting hedging instruments during the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

 

	Financial Statement Location	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts		2019			2018			2019			2018
Net Loss Recognized in Income	Operating revenues	$	—		$	(1,029	)	$	—		$	(2,590	)
Net Gain (Loss) Recognized in Income	Fuel and purchased power (a)	(28,249		)	4,263			(69,765		)	(26,442		)
Total		$	(28,249	)	$	3,234		$	(69,765	)	$	(29,032	)

(a) Amounts are before the effect of PSA deferrals.

Derivative Instruments in the Condensed 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 Condensed Consolidated Balance Sheets.  Transactions that do not allow for offsetting of positive and negative positions are reported gross on the Condensed 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.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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 September 30, 2019 and December 31, 2018.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Condensed Consolidated Balance Sheets.

As of September 30, 2019: (dollars in thousands)	Gross  Recognized  Derivatives  (a)			Amounts Offset  (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	1,776		$	(1,266	)	$	510		$	307		$	817
Total assets	1,776			(1,266		)	510			307			817
Current liabilities	(44,429		)	1,266			(43,163		)	(1,186		)	(44,349		)
Deferred credits and other	(27,305		)	—			(27,305		)	—			(27,305		)
Total liabilities	(71,734		)	1,266			(70,468		)	(1,186		)	(71,654		)
Total	$	(69,958	)	$	—		$	(69,958	)	$	(879	)	$	(70,837	)

(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 $1,186 and cash margin provided to counterparties of $307.

As of December 31, 2018: (dollars in thousands)	Gross Recognized Derivatives  (a)			Amounts Offset (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	3,106		$	(2,149	)	$	957		$	156		$	1,113
Investments and other assets	36			(36		)	—			—			—
Total assets	3,142			(2,185		)	957			156			1,113
Current liabilities	(36,345		)	2,149			(34,196		)	(1,310		)	(35,506		)
Deferred credits and other	(24,567		)	36			(24,531		)	—			(24,531		)
Total liabilities	(60,912		)	2,185			(58,727		)	(1,310		)	(60,037		)
Total	$	(57,770	)	$	—		$	(57,770	)	$	(1,154	)	$	(58,924	)

(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 $1,310 and cash margin provided to counterparties of $156.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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 September 30, 2019, we have one counterparty for which our exposure represents approximately 62% of Pinnacle West’s $0.8 million of risk management assets. This exposure relates to a master agreement with a counterparty that has a very high credit rating. Our risk management process assesses and monitors the financial exposure of all counterparties.  Despite the fact that the great majority of our trading counterparties' debt is rated as investment grade by the credit rating agencies, there is still a possibility that one or more of these counterparties 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 September 30, 2019 (dollars in thousands):

	September 30, 2019
Aggregate fair value of derivative instruments in a net liability position	$	71,503
Cash collateral posted	—
Additional cash collateral in the event credit-risk-related contingent features were fully triggered (a)	70,230

(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 $95 million if our debt credit ratings were to fall below investment grade.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

8. Commitments and Contingencies

Palo Verde 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 United States Department of Energy ("DOE") in the United States Court of Federal Claims ("Court of Federal Claims").  The lawsuit sought to recover damages incurred due to DOE’s breach of the Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste ("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, as amended, provides APS with a method for submitting claims and getting recovery for costs incurred through December 31, 2019.

APS has submitted five claims pursuant to the terms of the August 18, 2014 settlement agreement, for five separate time periods during July 1, 2011 through June 30, 2018. The DOE has approved and paid $84.3 million for these claims (APS’s share is $24.5 million). The amounts recovered were primarily recorded as adjustments to a regulatory liability and had no impact on reported net income. In accordance with the 2017 Rate Case Decision, this regulatory liability is being refunded to customers (see Note 4). On October 31, 2019, APS filed its next claim pursuant to the terms of the August 18, 2014 settlement agreement in the amount of $16 million (APS’s share is $4.7 million).

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 of up to approximately $13.9 billion per occurrence. Palo Verde maintains the maximum available nuclear liability insurance in the amount of $450 million, which is provided by American Nuclear Insurers ("ANI").  The remaining balance of approximately $13.5 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 $137.6 million, subject to a maximum annual premium of approximately $20.5 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 $120.1 million, with a maximum annual retrospective premium of approximately $17.9 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 CONDENSED 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 $25.5 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 $73.4 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.

Contractual Obligations

During 2019 our fuel and purchased power commitments have increased from the information provided in our 2018 10-K. The increase is primarily due to new purchased power commitments of approximately $260 million. The majority of the changes relate to 2024 and thereafter.

During 2019 our coal reclamation commitments have decreased from the information provided in our 2018 10-K by approximately $100 million. The decrease is primarily due to a new coal reclamation cost study for Four Corners. The majority of the changes relate to 2024 and thereafter.

Other than the items described above, there have been no material changes, as of September 30, 2019, outside the normal course of business in contractual obligations from the information provided in our 2018 Form 10-K. See Note 3 for discussion regarding changes in our long-term debt obligations.

Superfund-Related Matters

The Comprehensive Environmental Response Compensation and Liability Act ("Superfund" or "CERCLA") establishes liability for the cleanup of hazardous substances found contaminating the soil, water or air.  Those who released, generated, transported to or disposed of hazardous substances at a contaminated site are among the parties who are potentially responsible ("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 ("RI/FS").  Based upon discussions between the OU3 working group parties and EPA, along with the results of recent technical analyses prepared by the OU3 working group to supplement the RI/FS for OU3, APS anticipates finalizing the RI/FS in the fall or winter of 2019. 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, 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, the Arizona Department of Environmental Quality ("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

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

contamination in this area.  APS responded to ADEQ on May 4, 2015. On December 16, 2016, two RID environmental and engineering contractors filed an ancillary lawsuit for recovery of costs against APS and the other defendants in the RID litigation. That same day, another RID service provider filed an additional ancillary CERCLA lawsuit against certain of the defendants in the main RID litigation, but excluded APS and certain other parties as named defendants. Because the ancillary lawsuits concern past costs allegedly incurred by these RID vendors, which were ruled unrecoverable directly by RID in November of 2016, the additional lawsuits do not increase APS's exposure or risk related to these matters.

On April 5, 2018, RID and the defendants in that particular litigation executed a settlement agreement, fully resolving RID's CERCLA claims concerning both past and future cost recovery. APS's share of this settlement was immaterial. In addition, the two environmental and engineering vendors voluntarily dismissed their lawsuit against APS and the other named defendants without prejudice. An order to this effect was entered on April 17, 2018. With this disposition of the case, the vendors may file their lawsuit again in the future. On August 16, 2019, Maricopa County, one of the three direct defendants in the service provider lawsuit, filed a third-party complaint seeking contribution for its liability, if any, from APS and 28 other third-party 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.

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 coal combustion residuals ("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 pollution control requirements on Four Corners and the Navajo Plant. EPA will require these plants to install pollution control equipment that constitutes best available retrofit technology ("BART") to lessen the impacts of emissions on visibility surrounding the plants. In addition, EPA issued a final 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 Cholla BART approval.

Four Corners. Based on EPA’s final standards, APS's 63% share of the cost of required controls for Four Corners Units 4 and 5 is approximately $400 million, which has been incurred.  In addition, APS and El Paso Electric Company ("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. Navajo Transitional Energy Company, LLC ("NTEC") purchased the interest from 4CA on July 3, 2018. See "Four Corners - 4CA Matter" below for a discussion of the NTEC purchase. The cost of the pollution controls related to the 7% interest is approximately $45 million, which was assumed by NTEC through its purchase of the 7% interest.

Navajo Plant. APS estimates that its share of costs for upgrades at the Navajo Plant, based on EPA’s Federal Implementation Plan ("FIP"), could be up to approximately $200 million; however, given the future plans for the Navajo Plant, we do not expect to incur these costs.  See "Navajo Plant" in Note 4 for information regarding future plans for the Navajo Plant and details related to the resulting regulatory asset.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Cholla. APS believed that EPA’s original 2012 final rule establishing controls constituting BART for Cholla, which would require installation of SCR controls, was unsupported and that EPA had no basis for disapproving Arizona’s State Implementation Plan ("SIP") and promulgating a FIP that was inconsistent with the state’s considered BART determinations under the regional haze program.  In September 2014, APS met with EPA to propose a compromise BART strategy, whereby APS would permanently close Cholla Unit 2 and cease burning coal at Units 1 and 3 by the mid-2020s. (See "Cholla" in Note 4 for information regarding future plans for the Cholla plant and 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 BART requirements for oxides of nitrogen ("NOx") imposed through EPA's BART FIP. In early 2017, EPA approved a final rule incorporating APS's compromise proposal, which took effect for Cholla on April 26, 2017.

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. Such closure requirements are deemed "forced closure" or "closure for cause" of unlined surface impoundments, and are the subject of recent regulatory and judicial activities described below.

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.

ADEQ has initiated a process to evaluate how to develop a state CCR permitting program that would cover electric generating units ("EGUs"), including Cholla. While APS has been working with ADEQ on the development of this program, we are unable to predict when Arizona will be able to finalize and secure EPA approval for a state-specific CCR permitting program. With respect to the Navajo Nation, APS has sought clarification as to when and how EPA would be initiating permit proceedings for facilities on the reservation, including Four Corners. We are unable to predict at this time when EPA will be issuing CCR management permits for the facilities on the Navajo Nation. At this time, it remains unclear how the CCR provisions of the WIIN Act will affect APS and its management of CCR.

Based upon utility industry petitions for EPA to reconsider the RCRA Subtitle D regulations for CCR, which were premised in part on the CCR provisions of the 2016 WIIN Act, on September 13, 2017 EPA agreed

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

to evaluate whether to revise these federal CCR regulations. On July 17, 2018, EPA finalized a revision to its RCRA Subtitle D regulations for CCR, the "Phase I, Part I" revision to its CCR regulations, deferring for future action a number of other proposed changes contemplated in a March 1, 2018 proposal. For the final rule issued on July 17, 2018, EPA established nationwide health-based standards for certain constituents of CCR subject to groundwater corrective action and delayed the closure deadlines for certain unlined CCR surface impoundments by 18 months (for example, those disposal units required to undergo forced closure). These changes to the federal regulations governing CCR disposal are unlikely to have a material impact on APS. As for those aspects of the March 2018 rulemaking proposal for which EPA has yet to take final action, it remains unclear which specific provisions of the federal CCR rules will ultimately be modified, how they will be modified, or when such modification will occur.

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, EPA is required to complete a rulemaking proceeding in the near future concerning whether or not boron must be included on the list of groundwater constituents that might trigger corrective action under EPA’s CCR rules.  Simultaneously with the issuance of EPA's proposed modifications to the federal CCR rules in response to industry petitions, on March 1, 2018, EPA issued a proposed rule seeking comment as to whether or not boron should be included on this list. On August 14, 2019, EPA modified its boron proposal to include a specific, health-based groundwater protection standard for boron. These proposals remain pending, and EPA is not required to take final action including boron among the list of constituents that will determine CCR corrective actions.  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 APS cannot predict the eventual results of this rulemaking proceeding concerning boron.

On August 21, 2018, the D.C. Circuit Court issued its decision on the merits of the industry- and environmental-group litigation challenging the federal CCR regulations. The Court upheld the legality of EPA’s CCR regulations, though it vacated and remanded back to EPA a number of specific provisions, which are to be corrected in accordance with the Court’s order. Among the issues affecting APS’s management of CCR, the D.C. Circuit’s decision vacated and remanded those provisions of the EPA CCR regulations that allow for the operation of unlined CCR surface impoundments, even where those unlined impoundments have not otherwise violated a regulatory location restriction or groundwater protection standard (i.e., otherwise triggering forced closure).

Based on this decision, on December 17, 2018, certain environmental groups filed an emergency motion with the D.C. Circuit to either stay or summarily vacate EPA's July 17, 2018 final rule extending the closure-initiation deadline for certain unlined CCR surface impoundments until October 2020. In response, EPA filed a motion to remand but not vacate that deadline extension regulation. On March 13, 2019, the Court issued its ruling on the pending motions concerning the October 2020 deadline for closure initiation and granted remand without vacatur. This ruling allows the current October 2020 deadline to remain in effect while EPA completes a rulemaking to revise or reaffirm this deadline in accordance with the August 2018 D.C. Circuit decision concerning the closure of unlined CCR surface impoundments. On November 4, 2019, EPA issued a proposed rule responding to this litigation that contemplates an August 2020 closure initiation deadline with an optional three-month extension as needed for the completion of alternative disposal capacity.

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 $22 million and its share of incremental costs to comply with the CCR rule for Cholla is approximately $15 million. The Navajo Plant currently disposes of CCR in a dry landfill storage area. To comply with the CCR

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

rule for the Navajo Plant, APS's share of incremental costs is approximately $1 million, which has been incurred. Additionally, the CCR rule requires ongoing, phased groundwater monitoring. By October 17, 2017, electric utility companies that own or operate CCR disposal units, such as APS, must have collected sufficient groundwater sampling data to initiate a detection monitoring program.  To the extent that certain threshold constituents are identified through this initial detection monitoring at levels above the CCR rule’s standards, the rule required the initiation of an assessment monitoring program by April 15, 2018. 

APS has completed the statistical analyses for its CCR disposal units that triggered assessment monitoring. APS determined that several of its CCR disposal units at Cholla and Four Corners will need to undergo corrective action. In addition, all such disposal units must cease operating and initiate closure by October of 2020. APS currently estimates that the additional incremental costs to complete this corrective action and closure work, along with the costs to develop replacement CCR disposal capacity, could be approximately $5 million for both Cholla and Four Corners. APS initiated an assessment of corrective measures on January 14, 2019 and APS predicts such assessment will continue through early 2020. During this assessment, APS will gather additional groundwater data, solicit input from the public, host public hearings, and select remedies. As such, this $5 million cost estimate may change based upon APS’s performance of the CCR rule’s corrective action assessment process. Given uncertainties that may exist until we have fully completed the corrective action assessment process, we cannot predict any ultimate impacts to the Company; however, at this time we do not believe any potential change to the cost estimate would have a material impact on our financial position, results of operations or cash flows.

Clean Power Plan/Affordable Clean Energy Regulations. On June 19, 2019, EPA took final action on its proposals to repeal EPA's 2015 Clean Power Plan (“CPP”) and replace those regulations with a new rule, the Affordable Clean Energy (“ACE”) regulations. EPA originally finalized the CPP on August 3, 2015, and those regulations had been stayed pending judicial review.

The ACE regulations are based upon measures that can be implemented to improve the heat rate of steam-electric power plants, specifically coal-fired EGUs. In contrast with the CPP, EPA's ACE regulations would not involve utility-level generation dispatch shifting away from coal-fired generation and toward renewable energy resources and natural gas-fired combined cycle power plants. EPA’s ACE regulations provide states and EPA regions such as the Navajo Nation with three years to develop plans establishing source-specific standards of performance based upon application of the ACE rule’s heat-rate improvement emission guidelines. While corresponding New Source Review (“NSR”) reform regulations were proposed as part of EPA’s initial ACE proposal, the finalized ACE regulations did not include such reform measures. EPA announced that it will be taking final action on EPA's NSR reform proposal for EGUs in the near future.

We cannot at this time predict the outcome of EPA's regulatory actions repealing and replacing the CPP. Various state governments, industry organizations, and environmental and public-health public interest groups have filed lawsuits in the D.C. Circuit challenging the legality of EPA’s action, both in repealing the CPP and issuing the ACE regulations. In addition, to the extent that the ACE regulations go into effect as finalized, it is not yet clear how the state of Arizona or EPA will implement these regulations as applied to APS’s coal-fired EGUs. In light of these uncertainties, APS is still evaluating the impact of the ACE regulations on its coal-fired generation fleet.

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

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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 the Office of Surface Mining Reclamation and Enforcement ("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 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.

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. On September 11, 2017, the Arizona District Court issued an order granting NTEC's motion, dismissing the litigation with prejudice, and terminating the proceedings. On November 9, 2017, the environmental group plaintiffs appealed the district court order dismissing their lawsuit. On July 29, 2019, the Ninth Circuit Court of Appeals affirmed the September 2017 dismissal of the lawsuit, after which the environmental group plaintiffs petitioned the Ninth Circuit for rehearing on September 12, 2019. We cannot predict the outcome of any further proceedings.

Four Corners National Pollutant Discharge Elimination System ("NPDES") Permit

On July 16, 2018, several environmental groups filed a petition for review before the EPA Environmental Appeals Board ("EAB") concerning the NPDES wastewater discharge permit for Four Corners, which was reissued on June 12, 2018.  The environmental groups allege that the permit was reissued in contravention of several requirements under the Clean Water Act and did not contain required provisions concerning EPA’s 2015 revised effluent limitation guidelines for steam-electric EGUs, 2014 existing-source regulations governing cooling-water intake structures, and effluent limits for surface seepage and subsurface discharges from coal-ash disposal facilities.  To address certain of these issues through a reconsidered permit, EPA took action on December 19, 2018 to withdraw the NPDES permit reissued in June 2018. Withdrawal of the permit moots the EAB appeal, and EPA filed a motion to dismiss on that basis. The EAB thereafter dismissed the environmental group appeal on February 12, 2019. EPA issued the final NPDES permit for Four Corners on September 30, 2019. This permit is now subject to a petition for review before the EPA Environmental Appeals Board, based upon a November 1, 2019 filing by several environmental groups. We cannot predict the outcome of this review and whether the review will have a material impact on our financial position, results of operations or cash flows.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Four Corners - 4CA Matter

On July 6, 2016, 4CA purchased El Paso’s 7% interest in Four Corners. NTEC had the option to purchase the 7% interest and ultimately purchased the interest on July 3, 2018. NTEC purchased the 7% interest at 4CA’s book value, approximately $70 million, and is paying 4CA the purchase price over a period of four years pursuant to a secured interest-bearing promissory note. In connection with the sale, Pinnacle West guaranteed certain obligations that NTEC will have to the other owners of Four Corners, such as NTEC's 7% share of capital expenditures and operating and maintenance expenses. Pinnacle West's guarantee is secured by a portion of APS's payments to be owed to NTEC under the 2016 Coal Supply Agreement.

The 2016 Coal Supply Agreement contained alternate pricing terms for the 7% interest in the event NTEC did not purchase the interest. Until the time that NTEC purchased the 7% interest, the alternate pricing provisions were applicable to 4CA as the holder of the 7% interest. These terms included a formula under which NTEC must make certain payments to 4CA for reimbursement of operations and maintenance costs and a specified rate of return, offset by revenue generated by 4CA’s power sales. Such payments are due to 4CA at the end of each calendar year. A $10 million payment was due to 4CA at December 31, 2017, which NTEC satisfied by directing to 4CA a prepayment from APS of a portion of a future mine reclamation obligation. The balance of the amount under this formula due December 31, 2018 for calendar year 2017 was approximately $20 million, which was paid to 4CA on December 14, 2018. The balance of the amount under this formula for calendar year 2018 (up to the date that NTEC purchased the 7% interest) is approximately $10 million, which is due to 4CA at December 31, 2019.

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 commodity contract collateral obligations and other transactions. As of September 30, 2019, standby letters of credit totaled $1.7 million and will expire in 2020. As of September 30, 2019, surety bonds expiring through 2020 totaled $14 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 September 30, 2019. In connection with the sale of 4CA's 7% interest to NTEC, Pinnacle West is guaranteeing certain obligations that NTEC will have to the other owners of Four Corners. (See "Four Corners - 4CA Matter" above for information related to this guarantee.) A maximum obligation is not explicitly stated in the guarantee and, therefore, the overall maximum amount of the obligation under such guarantee cannot be reasonably estimated; however, we consider the fair value of this guarantee to be immaterial.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

9. Other Income and Other Expense

The following table provides detail of Pinnacle West's Consolidated other income and other expense for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Other income:
Interest income	$	2,694		$	1,957		$	7,695		$	6,256
Debt return on Four Corners SCR (Note 4)	4,920			4,910			14,651			11,190
Debt return on Ocotillo modernization project (Note 4)	7,555			—			12,849			—
Miscellaneous	22			91			50			95
Total other income	$	15,191		$	6,958		$	35,245		$	17,541
Other expense:
Non-operating costs	$	(2,647	)	$	(2,480	)	$	(8,832	)	$	(7,404	)
Investment losses — net	(716		)	—			(1,445		)	(268		)
Miscellaneous	(2,377		)	(2,583		)	(4,171		)	(4,391		)
Total other expense	$	(5,740	)	$	(5,063	)	$	(14,448	)	$	(12,063	)

The following table provides detail of APS’s other income and other expense for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Other income:
Interest income	$	2,037		$	1,151		$	5,091		$	4,874
Debt return on Four Corners SCR (Note 4)	4,920			4,910			14,651			11,190
Debt return on Ocotillo modernization project (Note 4)	7,555			—			12,849			—
Miscellaneous	22			92			50			96
Total other income	$	14,534		$	6,153		$	32,641		$	16,160
Other expense:
Non-operating costs	$	(2,448	)	$	(2,334	)	$	(7,965	)	$	(6,931	)
Miscellaneous	(378		)	(1,027		)	(2,167		)	(2,748		)
Total other expense	$	(2,826	)	$	(3,361	)	$	(10,132	)	$	(9,679	)

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

10. Earnings Per Share

The following table presents the calculation of Pinnacle West’s basic and diluted earnings per share for the three and nine months ended September 30, 2019 and 2018 (in thousands, except per share amounts):

	Three Months Ended  September 30,				Nine Months Ended   September 30,
	2019		2018		2019		2018
Net income attributable to common shareholders	$	312,276	$	315,012	$	474,339	$	484,971
Weighted average common shares outstanding — basic	112,463		112,148		112,408		112,094
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units	283		385		331		405
Weighted average common shares outstanding — diluted	112,746		112,533		112,739		112,499
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders — basic	$	2.78	$	2.81	$	4.22	$	4.33
Net income attributable to common shareholders — diluted	$	2.77	$	2.80	$	4.21	$	4.31

11. 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 at the measurement date.

Level 2 — Other significant observable inputs, including 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).

 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

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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, their NAV is generally not published and publicly available, nor are these instruments traded on an exchange. Instruments valued using NAV, as a practical expedient are included in our fair value disclosures; however, in accordance with GAAP are not classified within the fair value hierarchy levels.

Recurring Fair Value Measurements

We apply recurring fair value measurements to cash equivalents, derivative instruments, and investments held in the nuclear decommissioning trust and other special use funds. On an annual basis we apply fair value measurements to plan assets held in our retirement and other benefit plans.  See Note 7 in the 2018 Form 10-K for fair value discussion of plan assets held in our retirement and other benefit plans.

Cash Equivalents

Cash equivalents represent certain investments in money market funds that are valued using quoted prices in active markets.

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.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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.

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.

Investments Held in Nuclear Decommissioning Trust and Other Special Use Funds

The nuclear decommissioning trust and other special use funds invest in fixed income and equity securities. Other special use funds include the coal reclamation escrow account and the active union medical account. See Note 12 for additional discussion about our investment accounts.

We value investments in fixed income and equity securities using information provided by our trustees and escrow agent. Our trustees and escrow agent use pricing services that utilize the valuation methodologies described below 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 trustees’ and escrow agent's internal operating controls and valuation processes.

Fixed Income Securities

Fixed income securities issued by the U.S. Treasury 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 fixed income 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.

Fixed income securities may also include short-term investments in certificates of deposit, variable rate notes, time deposit accounts, U.S. Treasury and Agency obligations, U.S. Treasury repurchase agreements, commercial paper, and other short-term instruments. These instruments are valued using active market prices or utilizing observable inputs described above.

Equity Securities

The nuclear decommissioning trust's equity security investments 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

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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.

The nuclear decommissioning trust and other special use funds may also hold equity securities that include exchange traded mutual funds and money market accounts for short-term liquidity purposes. These short-term, highly-liquid, investments are valued using active market prices.

Fair Value Tables

The following table presents the fair value at September 30, 2019 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2			Level 3			Other				Total
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	1,388		$	388		$	(959	)	(a)	$	817
Nuclear decommissioning trust:
Equity securities	8,774		—			—			(1,322		)	(b)	7,452
U.S. commingled equity funds	—		—			—			476,693			(c)	476,693
U.S. Treasury debt	162,092		—			—			—				162,092
Corporate debt	—		124,026			—			—				124,026
Mortgage-backed securities	—		112,704			—			—				112,704
Municipal bonds	—		74,202			—			—				74,202
Other fixed income	—		10,504			—			—				10,504
Subtotal nuclear decommissioning trust	170,866		321,436			—			475,371				967,673
Other special use funds:
Equity securities	1,982		—			—			1,418			(b)	3,400
U.S. Treasury debt	232,165		—			—			—				232,165
Municipal bonds	—		8,417			—			—				8,417
Subtotal other special use funds	234,147		8,417			—			1,418				243,982
Total assets	$	405,013	$	331,241		$	388		$	475,830			$	1,212,472
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(69,752	)	$	(1,982	)	$	80		(a)	$	(71,654	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(b) Represents net pending securities sales and purchases.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The following table presents the fair value at December 31, 2018 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2			Level 3			Other				Total
Assets
Cash equivalents	$	1,200	$	—		$	—		$	—			$	1,200
Risk management activities — derivative instruments:
Commodity contracts	—		3,140			2			(2,029		)	(a)	1,113
Nuclear decommissioning trust:
Equity securities	5,203		—			—			2,148			(b)	7,351
U.S. commingled equity funds	—		—			—			396,805			(c)	396,805
U.S. Treasury debt	148,173		—			—			—				148,173
Corporate debt	—		96,656			—			—				96,656
Mortgage-backed securities	—		113,115			—			—				113,115
Municipal bonds	—		79,073			—			—				79,073
Other fixed income	—		9,961			—			—				9,961
Subtotal nuclear decommissioning trust	153,376		298,805			—			398,953				851,134
Other special use funds:
Equity securities	45,130		—			—			593			(b)	45,723
U.S. Treasury debt	173,310		—			—			—				173,310
Municipal bonds	—		17,068			—			—				17,068
Subtotal other special use funds	218,440		17,068			—			593				236,101
Total assets	$	373,016	$	319,013		$	2		$	397,517			$	1,089,548
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(52,696	)	$	(8,216	)	$	875		(a)	$	(60,037	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(b) Represents net pending securities sales and purchases.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

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.  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 4).

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

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

related contracts.  Conversely, if the price of the underlying commodity decreases, the net fair value of the related contracts would likely decrease.

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 September 30, 2019 and December 31, 2018:

	September 30, 2019 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	388	$	489	Discounted cash flows	Electricity forward price (per MWh)	$17.79 - $17.79	$	17.79
Natural Gas:
Forward Contracts (a)	—		1,493		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.53 - $2.79	$	2.64
Total	$	388	$	1,982

(a) Includes swaps and physical and financial contracts.

	December 31, 2018 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	—	$	2,456	Discounted cash flows	Electricity forward price (per MWh)	$17.88 - $37.03	$	26.10
Natural Gas:
Forward Contracts (a)	2		5,760		Discounted cash flows	Natural gas forward price (per MMBtu)	$1.79 - $2.92	$	2.48
Total	$	2	$	8,216

(a) Includes swaps and physical and financial contracts.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts	2019			2018			2019			2018
Net derivative balance at beginning of period	$	(12,753	)	$	(9,358	)	$	(8,214	)	$	(18,256	)
Total net gains (losses) realized/unrealized:
Deferred as a regulatory asset or liability	(2,324		)	1,244			(12,634		)	(2,067		)
Settlements	8,980			(2,332		)	11,929			(1,056		)
Transfers into Level 3 from Level 2	(613		)	(2,246		)	(3,711		)	(7,225		)
Transfers from Level 3 into Level 2	5,116			2,829			11,036			18,741
Net derivative balance at end of period	$	(1,594	)	$	(9,863	)	$	(1,594	)	$	(9,863	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—		$	—		$	—

Transfers between levels in the fair value hierarchy shown in the table above 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 short-term borrowings approximate fair value and are classified within Level 2 of the fair value hierarchy. See Note 3 for our long-term debt fair values. The NTEC note receivable related to the sale of 4CA’s interest in Four Corners bears interest at 3.9% per annum and has a book value of $49 million as of September 30, 2019 and $61 million as of December 31, 2018 as presented on the Condensed Consolidated Balance Sheets.  The carrying amount is not materially different from the fair value of the note receivable and is classified within Level 3 of the fair value hierarchy.  See Note 8 for more information on 4CA matters.

12. Investments in Nuclear Decommissioning Trust and Other Special Use Funds

We have investments in debt and equity securities held in nuclear decommissioning trust, coal reclamation escrow account, and an active union employee medical account. Investments in debt securities are classified as available-for-sale securities. We record both debt and equity security investments at their fair value on our Condensed Consolidated Balance Sheets. See Note 11 for a discussion of how fair value is determined and the classification of the investments within the fair value hierarchy. The investments in each trust or account are restricted for use and are intended to fund specified costs and activities as further described for each fund below.

Nuclear Decommissioning Trust - To fund the future costs APS expects to incur to decommission Palo Verde, APS established an external decommissioning trust 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. Earnings and proceeds from sales and maturities of securities are reinvested in the trust. Because of the ability of APS to recover decommissioning

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including other-than-temporary impairments) in other regulatory liabilities.

Coal Reclamation Escrow Account - APS has investments restricted for the future coal mine reclamation funding related to Four Corners. This escrow account is primarily invested in fixed income securities. Earnings and proceeds from sales of securities are reinvested in the escrow account. Because of the ability of APS to recover coal reclamation costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including other-than-temporary impairments) in other regulatory liabilities. Activities relating to APS coal reclamation escrow account investments are included within the other special use funds in the table below.

Active Union Employee Medical Account - APS has investments restricted for paying active union employee medical costs. These investments were transferred from APS other postretirement benefit trust assets into the active union employee medical trust in January 2018 (see Note 7 in the 2018 Form 10-K). These investments may be used to pay active union employee medical costs incurred in the current and future periods. In August 2019, the Company was reimbursed $15 million for prior year active union employee medical claims from the active union employee medical account. The account is invested primarily in fixed income securities. In accordance with the ratemaking treatment, APS has deferred the unrealized gains and losses (including other-than-temporary impairments) in other regulatory assets. Activities relating to active union employee medical account investments are included within the other special use funds in the table below.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

APS

The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS's nuclear decommissioning trust and other special use fund assets at September 30, 2019 and December 31, 2018 (dollars in thousands):  

	September 30, 2019
	Fair Value								Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trust			Other Special Use Funds		Total
Equity securities	$	485,467		$	1,982	$	487,449		$	297,032	$	—
Available for sale-fixed income securities	483,528			240,582		724,110		(a)	28,750		(476		)
Other	(1,322		)	1,418		96		(b)	—		—
Total	$	967,673		$	243,982	$	1,211,655		$	325,782	$	(476	)

(a) As of September 30, 2019, the amortized cost basis of these available-for-sale investments is $696 million.

(b) Represents net pending securities sales and purchases.

	December 31, 2018
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trust		Other Special Use Funds		Total
Equity securities	$	402,008	$	45,130	$	447,138		$	222,147	$	(459	)
Available for sale-fixed income securities	446,978		190,378		637,356		(a)	8,634		(6,778		)
Other	2,148		593		2,741		(b)	—		—
Total	$	851,134	$	236,101	$	1,087,235		$	230,781	$	(7,237	)

(a) As of December 31, 2018, the amortized cost basis of these available-for-sale investments is $635 million.

(b) Represents net pending securities sales and purchases.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The following table sets forth APS's realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,
	Nuclear Decommissioning Trust			Other Special Use Funds		Total
2019
Realized gains	$	4,732		$	4	$	4,736
Realized losses	(2,360		)	—		(2,360		)
Proceeds from the sale of securities (a)	155,386			56,255		211,641
2018
Realized gains	$	653		$	—	$	653
Realized losses	(1,965		)	—		(1,965		)
Proceeds from the sale of securities (a)	148,150			25,127		173,277

(a) Proceeds are reinvested in the nuclear decommissioning trust and coal reclamation escrow account.

	Nine Months Ended September 30,
	Nuclear Decommissioning Trust			Other Special Use Funds		Total
2019
Realized gains	$	8,478		$	4	$	8,482
Realized losses	(5,465		)	—		(5,465		)
Proceeds from the sale of securities (a)	371,538			149,458		520,996
2018
Realized gains	$	2,951		$	1	$	2,952
Realized losses	(6,990		)	—		(6,990		)
Proceeds from the sale of securities (a)	401,396			41,644		443,040

(a) Proceeds are reinvested in the nuclear decommissioning trust and coal reclamation escrow account.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The fair value of APS's fixed income securities, summarized by contractual maturities, at September 30, 2019, is as follows (dollars in thousands):

	Nuclear Decommissioning Trust (a)		Coal Reclamation Escrow Account		Active Union Medical Trust		Total
Less than one year	$	40,309	$	32,628	$	37,013	$	109,950
1 year – 5 years	133,488		25,928		140,895		300,311
5 years – 10 years	103,973		720		—		104,693
Greater than 10 years	205,758		3,398		—		209,156
Total	$	483,528	$	62,674	$	177,908	$	724,110

(a) Includes certain fixed income investments that are not due at a single maturity date. These investments have been allocated within the table based on the final payment date of the instrument.

13.    New Accounting Standards

Standards Adopted in 2019

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 requires a lessee to reflect most operating lease arrangements on the balance sheet by recording a right-of-use asset and a lease liability that is initially 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. Since the issuance of the new lease standard, additional lease related guidance has been issued relating to land easements and how entities may elect to account for these arrangements at transition, among other items. The new lease standard and related amendments were effective for us on January 1, 2019, with early application permitted. The standard must be adopted using a modified retrospective approach with a cumulative-effect adjustment to the opening balance of retained earnings determined at either the date of adoption, or the earliest period presented in the financial statements. The standard includes various optional practical expedients provided to facilitate transition. We adopted this standard, and related amendments, on January 1, 2019. See Note 16.

ASU 2018-15, Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract

In August 2018, a new accounting standard was issued that clarifies how customers in a cloud computing service arrangement should account for implementation costs associated with the arrangement. To determine which implementation costs should be capitalized, the new guidance aligns the accounting with existing guidance pertaining to internal-use software. As a result of this new standard, certain cloud computing service arrangement implementation costs will now be subject to capitalization and amortized on a straight-line basis over the cloud computing service arrangement term. The new standard is effective for us on January 1, 2020, with early application permitted, and may be applied using either a retrospective or prospective transition approach. On July 1, 2019, we early adopted this new accounting standard using the prospective approach. The adoption did not have a material impact on our financial statements.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

Standard Pending Adoption

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. Since the issuance of the new standard, various guidance has been issued that amends the new standard, including clarifications of certain aspects of the standard and targeted transition relief, among other changes. The new standard and related amendments are 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.

14.     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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Three Months Ended September 30
Balance June 30, 2019	$	(46,657	)		$	(979	)		$	(47,636	)
Amounts reclassified from accumulated other comprehensive loss	880			(a)	218			(b)	1,098
Balance September 30, 2019	$	(45,777	)		$	(761	)		$	(46,538	)
Balance June 30, 2018	$	(54,233	)		$	(2,391	)		$	(56,624	)
Amounts reclassified from accumulated other comprehensive loss	1,099			(a)	451			(b)	1,550
Balance September 30, 2018	$	(53,134	)		$	(1,940	)		$	(55,074	)

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Nine Months Ended September 30
Balance December 31, 2018	$	(45,997	)		$	(1,711	)		$	(47,708	)
OCI (loss) before reclassifications	(2,422		)		—				(2,422		)
Amounts reclassified from accumulated other comprehensive loss	2,642			(a)	950			(b)	3,592
Balance September 30, 2019	$	(45,777	)		$	(761	)		$	(46,538	)
Balance December 31, 2017	$	(42,440	)		$	(2,562	)		$	(45,002	)
OCI (loss) before reclassifications	(5,928		)		(96		)		(6,024		)
Amounts reclassified from accumulated other comprehensive loss	3,188			(a)	1,316			(b)	4,504
Reclassification of income tax effect related to tax reform	(7,954		)	(c)	(598		)	(c)	(8,552		)
Balance September 30, 2018	$	(53,134	)		$	(1,940	)		$	(55,074	)

(a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost.  See Note 5.

(b) 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 7.

(c) In 2018, the company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

The following table shows the changes in APS's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands): 

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Three Months Ended September 30
Balance June 30, 2019	$	(26,297	)		$	(979	)		$	(27,276	)
Amounts reclassified from accumulated other comprehensive loss	755			(a)	218			(b)	973
Balance September 30, 2019	$	(25,542	)		$	(761	)		$	(26,303	)
Balance June 30, 2018	$	(32,768	)		$	(2,391	)		$	(35,159	)
Amounts reclassified from accumulated other comprehensive loss	952			(a)	451			(b)	1,403
Balance September 30, 2018	$	(31,816	)		$	(1,940	)		$	(33,756	)

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Nine Months Ended September 30
Balance December 31, 2018	$	(25,396	)		$	(1,711	)		$	(27,107	)
OCI (loss) before reclassifications	(2,414		)		—				(2,414		)
Amounts reclassified from accumulated other comprehensive loss	2,268			(a)	950			(b)	3,218
Balance September 30, 2019	$	(25,542	)		$	(761	)		$	(26,303	)
Balance December 31, 2017	$	(24,421	)		$	(2,562	)		$	(26,983	)
OCI (loss) before reclassifications	(5,791		)		(96		)		(5,887		)
Amounts reclassified from accumulated other comprehensive loss	2,836			(a)	1,316			(b)	4,152
Reclassification of income tax effect related to tax reform	(4,440		)	(c)	(598		)	(c)	(5,038		)
Balance September 30, 2018	$	(31,816	)		$	(1,940	)		$	(33,756	)

(a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost.  See Note 5.

(b) 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 7.

(c) In 2018, the company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

15.  Income Taxes

The Tax Cuts and Jobs Act reduced the corporate tax rate to 21% effective January 1, 2018. As a result of this rate reduction, the Company recognized a $1.14 billion reduction in its net deferred income tax liabilities as of December 31, 2017. In accordance with accounting for regulated companies, the effect of this rate reduction was substantially offset by a net regulatory liability.

Federal income tax laws require the amortization of a majority of the balance over the remaining regulatory life of the related property. As a result of the modifications made to the annual transmission formula rate during the second quarter of 2018, the Company began amortization of FERC jurisdictional net excess deferred tax liabilities in 2018. On March 13, 2019, the ACC approved the Company's proposal to amortize non-depreciation related net excess deferred tax liabilities subject to its jurisdiction over a twelve-month period. As a result, the Company began amortization in March 2019. As of September 30, 2019, the Company has recorded $42 million of income tax benefit related to the amortization of these non-depreciation related net excess deferred tax liabilities. On April 10, 2019, the Company filed a request with the ACC which addresses the amortization of depreciation related excess deferred taxes. See Note 4 for more details.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

In August 2018, U.S. Treasury proposed regulations that clarified bonus depreciation transition rules under the Tax Act for regulated public utility property placed in service after September 27, 2017 and before January 1, 2018.  However, these proposed regulations were ambiguous with respect to regulated public utility property placed in service on or after January 1, 2018. In September 2019, U.S. Treasury issued final regulations, which replaced the August 2018 proposed regulations. These final regulations did not materially impact any tax position taken by the Company for property placed in service after September 27, 2017 and before January 1, 2018.

Along with the September 2019 final regulations, U.S. Treasury also issued new proposed regulations which clarify bonus depreciation transition rules under the Tax Act for property placed in service by regulated public utilities after December 31, 2017. The proposed regulations provide that certain regulated public utility property which was under construction prior to September 28, 2017 and placed in service between January 1, 2018 and December 31, 2020 would continue to be eligible for bonus depreciation under the rules and bonus depreciation phase-downs in effect prior to enactment of the Tax Act.  During the third quarter, as a result of the clarification provided by these proposed regulations, the Company recorded deferred tax liabilities of approximately $56 million related to bonus depreciation benefits claimed on the Company’s 2018 tax return.

Net income associated with the Palo Verde sale leaseback VIEs is not subject to tax.  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. See Note 6 for additional details related to the Palo Verde sale leaseback VIEs.

As of the balance sheet date, the tax year ended December 31, 2016 and all subsequent tax years remain subject to examination by the IRS.  With a few exceptions, the Company is no longer subject to state income tax examinations by tax authorities for years before 2014.

16.  Leases

We lease certain land, buildings, vehicles, equipment and other property through operating rental agreements with varying terms, provisions, and expiration dates. APS also has certain purchased power agreements that qualify as lease arrangements. Our leases have remaining terms that expire in 2019 through 2050. Substantially all of our leasing activities relate to APS.

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 6 for a discussion of VIEs.

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

On January 1, 2019 we adopted new lease accounting guidance (see Note 13). We elected the transition method that allows us to apply the new lease guidance on the date of adoption, January 1, 2019, and will not retrospectively adjust prior periods. We also elected certain transition practical expedients that allow us to not reassess (a) whether any expired or existing contracts are or contain leases, (b) the lease classification for any expired or existing leases and (c) initial direct costs for any existing leases. These practical expedients apply to leases that commenced prior to January 1, 2019. Furthermore, we elected the practical expedient transition provisions relating to the treatment of existing land easements.

On January 1, 2019 the adoption of this new accounting standard resulted in the recognition on our Condensed Consolidated Balance Sheets of approximately $194 million of right-of-use lease assets and $119 million of lease liabilities relating to our operating lease arrangements. The right-of-use lease assets include $85 million of prepaid lease costs that have been reclassified from other deferred debits, and $10 million of deferred lease costs that have been reclassified from other current liabilities. In addition to these balance sheet impacts, the adoption of the guidance resulted in expanded lease disclosures, which are included below.

The following tables provide information related to our lease costs for the three and nine months ended September 30, 2019 (dollars in thousands):

	Three Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	21,095	$	4,581	$	25,676
Variable lease cost	36,917		183		37,100
Short-term lease cost	—		812		812
Total lease cost	$	58,012	$	5,576	$	63,588

	Nine Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	35,159	$	13,343	$	48,502
Variable lease cost	95,736		543		96,279
Short-term lease cost	—		3,477		3,477
Total lease cost	$	130,895	$	17,363	$	148,258

Lease costs are primarily included as a component of operating expenses on our Condensed Consolidated Statements of Income. Lease costs relating to purchased power lease contracts are recorded in fuel and purchased power on the Condensed Consolidated Statements of Income, and are subject to recovery under the PSA or RES (see Note 4). The tables above reflect the lease cost amounts before the effect of regulatory deferral under the PSA and RES. Variable lease costs are recognized in the period the costs are incurred, and primarily relate to renewable purchased power lease contracts. Payments under most renewable purchased power lease contracts are dependent upon environmental factors, and due to the inherent uncertainty associated with the reliability of the fuel source, the payments are considered variable and are excluded from the measurement of lease liabilities and right-of-use lease assets. Certain of our lease agreements have lease

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

terms with non-consecutive periods of use. For these agreements we recognize lease costs during the periods of use. Leases with initial terms of 12 months or less are considered short-term leases and are not recorded on the balance sheet.

The following table provides information related to the maturity of our operating lease liabilities at September 30, 2019 (dollars in thousands):

	September 30, 2019
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019 (remaining three months of 2019)	$	13,625	$	3,352	$	16,977
2020	—		14,083		14,083
2021	—		11,244		11,244
2022	—		7,727		7,727
2023	—		6,101		6,101
2024	—		3,915		3,915
Thereafter	—		38,697		38,697
Total lease commitments	13,625		85,119		98,744
Less imputed interest	19		20,032		20,051
Total lease liabilities	$	13,606	$	65,087	$	78,693

We recognize lease assets and liabilities upon lease commencement. At September 30, 2019, we have additional lease arrangements that have been executed, but have not yet commenced. These arrangements primarily relate to purchased power lease contracts. These leases have commencement dates beginning in June 2020 with terms ending through October 2027. We expect the total fixed consideration paid for these arrangements, which includes both lease and nonlease payments, will approximate $705 million over the term of the arrangements.

The following table provides information related to estimated future minimum operating lease payments at December 31, 2018 (dollars in thousands):

	December 31, 2018
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019	$	54,499	$	13,747	$	68,246
2020	—		12,428		12,428
2021	—		9,478		9,478
2022	—		6,513		6,513
2023	—		5,359		5,359
Thereafter	—		42,236		42,236
Total future lease commitments	$	54,499	$	89,761	$	144,260

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COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The following tables provide other additional information related to operating lease liabilities:

	September 30, 2019
Weighted average remaining lease term	12 years
Weighted average discount rate (a)	3.73	%

(a) Most of our lease agreements do not contain an implicit rate that is readily determinable. For these agreements we use our incremental borrowing rate to measure the present value of lease liabilities.  We determine our incremental borrowing rate at lease commencement based on the rate of interest that we would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. We use the implicit rate when it is readily determinable.

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows (dollars in thousands):	$	51,980

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ITEM 2.          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 Condensed Consolidated Financial Statements and APS’s Condensed Consolidated Financial Statements and the related Combined Notes that appear in Item 1 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 Part 1, Item 1A of the 2018 Form 10-K.

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 2018, with its three units achieving a combined year-end capacity factor of 90.2% and an all-time best collective radiation exposure dose performance in the history of Palo Verde’s operation.

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 19, 2019, EPA took final action on its proposals to repeal EPA's 2015 Clean Power Plan (“CPP”) and replace those regulations with a new rule, the Affordable Clean Energy (“ACE”) regulations. EPA originally finalized the CPP on August 3, 2015, and those regulations had been stayed pending judicial review. The ACE regulations are more narrow than the CPP, and are based upon heat-rate improvements at steam-electric power plants. These new regulations are now subject to litigation challenging their legality in the D.C. Circuit, along with the development of jurisdiction specific implementing regulations (e.g., as to states and EPA regional divisions). APS continually analyzes its long-range capital management plans to assess the potential effects of such proposals, 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.

Cholla

On September 11, 2014, APS announced that it would close its 260 megawatts ("MW") Unit 2 at Cholla and cease burning coal at the other APS-owned units (Units 1 and 3) at the plant by the mid-2020s, if EPA approved 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, which was later addressed in the 2017 Settlement Agreement. (See Note 4 for details related to the resulting cost recovery.) 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. In early 2017, EPA

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approved a final rule incorporating APS's compromise proposal, which took effect for Cholla on April 26, 2017.

On March 20, 2019, APS announced that it began evaluating the feasibility and cost of converting a unit at Cholla to burn biomass. Biomass is a fuel comprised of forest trimmings, and a converted unit at Cholla could assist in forest thinning, responsible forest management, an improved watershed, and a reduced wildfire risk. APS’s ability to operate a biomass power plant would depend on third-parties procuring forest biomass for fuel. APS reported the results of its evaluation on May 9, 2019 to the ACC. On July 10, 2019, the ACC voted to not require APS to file a request for proposal to convert the unit at Cholla to burn biomass.

Four Corners

Ownership and Coal Supply Matters.  In 2013, BHP Billiton New Mexico Coal, Inc. ("BHP Billiton"), the parent company of BHP Navajo Coal Company ("BNCC"), the coal supplier and operator of the mine that served 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. At that same time, 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 had an option to purchase the 4CA 7% interest and ultimately purchased the interest on July 3, 2018. NTEC purchased the 7% interest at 4CA’s book value, approximately $70 million, and is paying 4CA the purchase price over a period of four years pursuant to a secured interest-bearing promissory note. In connection with the sale, Pinnacle West guaranteed certain obligations that NTEC will have to the other owners of Four Corners, such as NTEC's 7% share of capital expenditures and operating and maintenance expenses. Pinnacle West's guarantee is secured by a portion of APS's payments to be owed to NTEC under the 2016 Coal Supply Agreement.

The 2016 Coal Supply Agreement contained alternate pricing terms for the 7% interest in the event NTEC did not purchase the interest. Until the time that NTEC purchased the 7% interest, the alternate pricing provisions were applicable to 4CA, as the holder of the 7% interest. These terms included a formula under which NTEC must make certain payments to 4CA for reimbursement of operations and maintenance costs and a specified rate of return, offset by revenue generated by 4CA’s power sales. Such payments are due to 4CA at the end of each calendar year. A $10 million payment was due to 4CA at December 31, 2017, which NTEC satisfied by directing to 4CA a prepayment from APS of a portion of a future mine reclamation obligation. The balance of the amount due under this formula at December 31, 2018 for calendar year 2017 was approximately $20 million, which was paid to 4CA on December 14, 2018. The balance of the amount under this formula for calendar year 2018 (up to the date that NTEC purchased the 7% interest) is approximately $10 million, which is due to 4CA at December 31, 2019.

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 2041.  The Navajo Nation approved these amendments in March 2011.  The effectiveness of the amendments also required the approval of the United States Department of the Interior ("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.  

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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.

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. On September 11, 2017, the Arizona District Court issued an order granting NTEC's motion, dismissing the litigation with prejudice, and terminating the proceedings. On November 9, 2017, the environmental group plaintiffs appealed the district court order dismissing their lawsuit. On July 29, 2019, the Ninth Circuit Court of Appeals affirmed the September 2017 dismissal of the lawsuit, after which the environmental group plaintiffs petitioned the Ninth Circuit for rehearing on September 12, 2019. We cannot predict the outcome of any further proceedings.

Wastewater Permit. On July 16, 2018, several environmental groups filed a petition for review before the EPA EAB concerning the NPDES wastewater discharge permit for Four Corners, which was reissued on June 12, 2018.  The environmental groups allege that the permit was reissued in contravention of several requirements under the Clean Water Act and did not contain required provisions concerning EPA’s 2015 revised effluent limitation guidelines for steam-electric EGUs, 2014 existing-source regulations governing cooling-water intake structures, and effluent limits for surface seepage and subsurface discharges from coal-ash disposal facilities.  To address certain of these issues through a reconsidered permit, EPA took action on December 19, 2018 to withdraw the NPDES permit reissued in June 2018. Withdrawal of the permit moots the EAB appeal, and EPA filed a motion to dismiss on that basis. The EAB thereafter dismissed the environmental group appeal on February 12, 2019. EPA issued the final NPDES permit for Four Corners on September 30, 2019. This permit is now subject to a petition for review before the EPA Environmental Appeals Board, based upon a November 1, 2019 filing by several environmental groups. We cannot predict the outcome of this review and whether the review will have a material impact on our financial position, results of operations or cash flows.

Navajo Plant

The co-owners of the Navajo Plant and the Navajo Nation agreed that the Navajo Plant will remain in operation until December 2019 under the existing plant lease. The co-owners and the Navajo Nation executed a lease extension on November 29, 2017 that will allow for decommissioning activities to begin after the plant ceases operations by December 2019.

APS is currently recovering depreciation and a return on the net book value of its interest in the Navajo Plant over its previously estimated life through 2026. APS will seek continued recovery in rates for the book value of its remaining investment in the plant (see Note 4 for details related to the resulting regulatory asset) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and may be material.

Natural Gas.  APS has six natural gas power plants located throughout Arizona, including Ocotillo. Ocotillo was originally 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.  The modernization of the plant was completed on May 30, 2019 and it increased the capacity of the site by 290 MW to a total of 620 MW. (See Note 4 for details of the rate recovery in our 2017 Rate Case Decision.)

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Transmission and Delivery.  APS continues to work closely with customers, stakeholders, and regulators to identify and plan for transmission needs that support new customers, system reliability, access to markets and clean energy development.  The capital expenditures table presented in the "Liquidity and Capital Resources" section below includes new APS transmission projects, along with other transmission costs for upgrades and replacements, including those for data center development.  APS is also working to establish and expand advanced grid technologies throughout its service 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 new customer sited 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 California Independent System Operator, 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 continues to expect 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. APS has a diverse portfolio of existing and planned renewable resources, including solar, wind, geothermal, biomass and biogas. APS's clean energy strategy includes executing purchased power contracts for new facilities, ongoing development of distributed energy resources and procurement of new facilities to be owned by APS. The following table summarizes the resources in APS's renewable energy portfolio that are in operation and under development as of September 30, 2019. 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.

	Net Capacity in Operation (MW)	Net Capacity Planned / Under Development (MW)
Total APS Owned: Solar	239	—
Purchased Power Agreements:
Solar	310	—
Solar + Energy Storage	—	50
Wind	289	—
Geothermal	10	—
Biomass	14	—
Biogas	3	—
Total Purchased Power Agreements	626	50
Total Distributed Energy: Solar (a)	930	54	(b)
Total Renewable Portfolio	1,795	104

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

(b) Applications received by APS that are not yet installed and online.

APS has developed and owns solar resources through the ACC-approved AZ Sun Program.  APS invested approximately $675 million in the AZ Sun Program.  APS issued two Requests for Proposal ("RFP") in September 2019. The first RFP seeks competitive proposals for up to 150 MW of APS-owned solar resources to be in service by 2021. This solar generation will be designed with the flexibility to add energy

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storage as a future option. A second RFP requests up to 250 MW of wind resources to be in service as soon as possible, but no later than 2022.

Energy Storage. APS deploys a number of advanced technologies on its system, including energy storage. Storage can provide capacity, improve power quality, be utilized for system regulation, integrate renewable generation, and can be used to defer certain traditional infrastructure investments. Energy storage can also aid in integrating higher levels of renewables by storing excess energy when system demand is low and renewable production is high and then releasing the stored energy during peak demand hours later in the day and after sunset. APS is utilizing grid-scale energy storage projects to benefit customers, to increase renewable utilization, and to further our understanding of how storage works with other advanced technologies and the grid. We are preparing for additional energy storage in the future.

In early 2018, APS entered into a 15-year power purchase agreement for a 65 MW solar facility that charges a 50 MW solar-fueled battery. Service under this agreement is scheduled to begin in 2021. In 2018, APS issued a request for proposal for approximately 106 MW of energy storage to be located at up to five of its AZ Sun sites. Based upon our evaluation of the RFP responses, APS decided to expand the initial phase of battery deployment to 141 MW by adding a sixth AZ Sun site. In February 2019, we contracted for the 141 MW and originally anticipated such facilities could be in service by mid-2020. In April 2019, a battery module in APS’s McMicken battery energy storage facility experienced an equipment failure, which prompted an investigation to determine the cause. The results of the investigation will inform the timing of our utilization and implementation of batteries on our system. Due to the April 2019 event, APS is working with the counterparty for the AZ Sun sites to determine appropriate timing and path forward for such facilities. Additionally, in February 2019, APS signed two 20-year power purchase agreements for energy storage totaling 150 MW. Service under these power purchase agreements is expected to begin in mid-2021, pending approval from the ACC to allow for recovery of these agreements through the PSA and the results of the McMicken investigation.  Including the 150 MW of power purchase agreement energy storage projects described above, we currently plan to install at least 850 MW of energy storage by 2025.  The additional 700 MW of APS-owned energy storage will include at least 100 MW of solar with current RFPs evaluating battery-ready solar projects as well. We originally intended to procure the first 260 MW in 2019 (60 MW on additional AZ Sun sites and 100 MW of solar plus 100 MW of energy storage), however given the April 2019 event we are currently evaluating appropriate timing and path forward to support the overall capacity goals for our system.

Regulatory Matters

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 4 for information on APS’s FERC rates.

2019 Retail Rate Case Filing with the Arizona Corporation Commission. On October 31, 2019, APS filed an application with the ACC for an annual increase in retail base rates of $69 million. This amount includes recovery of the deferral and rate base effects of the Four Corners SCR project that is currently the subject of a separate proceeding (see “SCR Cost Recovery” below). It also reflects a net credit to base rates of approximately $115 million primarily due to the prospective inclusion of rate refunds currently provided through the TEAM. The proposed total revenue increase in APS's application is $184 million. The average annual customer bill impact of APS’s request is an increase of 5.6% (the average annual bill impact for a typical APS residential customer is 5.4%).

The principal provisions of APS's application are:

• a test year comprised of twelve months ended June 30, 2019, adjusted as described below;

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• an original cost rate base of $8.87 billion, which approximates the ACC-jurisdictional portion of the book value of utility assets, net of accumulated depreciation and other credits;

• the following proposed capital structure and costs of capital:

	Capital Structure		Cost of Capital
Long-term debt	45.3	%	4.10	%
Common stock equity	54.7	%	10.15	%
Weighted-average cost of capital			7.41	%

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

• authorization to defer until APS'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;

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

▪ a super off-peak period during the winter months for APS’s time-of-use with demand rates;

▪ additional $1.25 million in funding for limited-income crisis bill program; and

▪ a flat bill/subscription rate pilot program;

• proposed rate design changes for commercial customers, including an experimental program designed to provide access to market pricing for up to 200 MW of medium and large commercial customers;

• recovery of the deferral and rate base effects of the construction and operating costs of the Ocotillo modernization project (see Note 4 discussion of the 2017 Settlement Agreement); and

• continued recovery of the remaining investment and other costs related to the retirement and closure of the Navajo Plant (see Note 4 for details related to the resulting regulatory asset).

APS requested that the increase become effective December 1, 2020.  APS cannot predict the outcome of its request.

2016 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. On March 27, 2017, a majority of the stakeholders in the general retail rate case, including the ACC Staff, the Residential Utility Consumer Office, limited income advocates and private rooftop solar organizations signed the 2017 Settlement Agreement and filed it with the ACC. The average annual customer bill impact under the 2017 Settlement Agreement was calculated as an increase of 3.28% (the average annual bill impact for a typical APS residential customer was calculated as 4.54%). (See Note 4 for details of the 2017 Settlement Agreement.)

On August 15, 2017, the ACC approved (by a vote of 4-1), the 2017 Settlement Agreement without material modifications.  On August 18, 2017, the ACC issued a final written Opinion and Order reflecting its decision in APS’s general retail rate case (the "2017 Rate Case Decision"), which is subject to requests for rehearing and potential appeal. The new rates went into effect on August 19, 2017.

On January 3, 2018, an APS customer filed a petition with the ACC that was determined by the Administrative Law Judge to be a complaint filed pursuant to Arizona Revised Statute §40-246 and not a request for rehearing. Arizona Revised Statute §40-246 requires the ACC to hold a hearing regarding any complaint alleging that a public service corporation is in violation of any commission order or that the rates being charged are not just and reasonable if the complaint is signed by at least twenty-five customers of the public service corporation. The Complaint alleged that APS is “in violation of commission order” [sic]. On February 13, 2018, the complainant filed an amended Complaint alleging that the rates and charges in the 2017 Rate Case Decision are not just and reasonable.  The complainant requested that the ACC hold a hearing on the amended Complaint to determine if the average bill impact on residential customers of the rates and charges approved in the 2017 Rate Case Decision is greater than 4.54% (the average annual bill impact for a typical

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APS residential customer estimated by APS) and, if so, what effect the alleged greater bill impact has on APS's revenues and the overall reasonableness and justness of APS's rates and charges, in order to determine if there is sufficient evidence to warrant a full-scale rate hearing.  The ACC held a hearing on this matter beginning in September 2018 and the hearing was concluded on October 1, 2018. On April 9, 2019, the Administrative Law Judge issued a Recommended Opinion and Order recommending that the Complaint be dismissed. The ACC considered the matter at its April and May 2019 open meetings, but no decision was issued. On July 3, 2019, the Administrative Law Judge issued an amendment to the Recommended Opinion and Order that incorporated the requirements of the rate review of the 2017 Rate Case Decision (see below discussion regarding the rate review). On July 10, 2019, the ACC reconsidered the matter and adopted the Administrative Law Judge's amended Recommended Opinion and Order along with several ACC Commissioner amendments and an amendment incorporating the results of the rate review and resolved the Complaint.

On December 24, 2018, certain ACC Commissioners filed a letter stating that because the ACC had received a substantial number of complaints that the rate increase authorized by the 2017 Rate Case Decision was much more than anticipated, they believe there is a possibility that APS is earning more than was authorized by the 2017 Rate Case Decision.  Accordingly, the ACC Commissioners requested the ACC Staff to perform a rate review of APS using calendar year 2018 as a test year and file a report by May 3, 2019.  The ACC Commissioners also asked the ACC Staff to evaluate APS’s efforts to educate its customers regarding the new rates approved in the 2017 Rate Case Decision. On April 23, 2019, the ACC Staff indicated that they would need additional time beyond May 3, 2019 to file the requested report.

On June 5, 2019, the ACC Staff filed a proposed order regarding the rate review of the 2017 Rate Case Decision. On June 11, 2019, the ACC Commissioners approved the proposed ACC Staff order with amendments. The key provisions of the amended order include the following:

• APS must file a rate case no later than October 31, 2019, using a June 30, 2019 test-year;

• until the conclusion of the rate case being filed no later than October 31, 2019, APS must provide information on customer bills that shows how much a customer would pay on their most economical rate given their actual usage during each month;

• APS customers can switch rate plans during an open enrollment period of six months;

• APS must identify customers whose bills have increased by more than 9% and that are not on the most economical rate and provide such customers with targeted education materials and an opportunity to switch rate plans;

• APS must provide grandfathered net metering customers on legacy demand rates an opportunity to switch to another legacy rate to enable such customers to fully benefit from legacy net metering rates;

• APS must fund and implement a supplemental customer education and outreach program to be developed with and administered by ACC Staff and a third-party consultant; and

• APS must fund and organize, along with the third-party consultant, a stakeholder group to suggest better ways to communicate the impact of changes to adjustor cost recovery mechanisms (see Note 4 on cost recovery mechanisms), including more effective ways to educate customers on rate plans and to reduce energy usage.

APS cannot predict the outcome or impact of the rate case filed on October 31, 2019. APS is assessing the impact to its financial statements of the implementation of the other key provisions of the amended order regarding the rate review and cannot predict at this time whether they will have a material impact on its financial position, results of operations or cash flows. 

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, such as the RES and Demand Side Management Adjustor Charge, are described more fully in Note 4.

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SCR Cost Recovery. On December 29, 2017, in accordance with the 2017 Rate Case Decision, APS filed a Notice of Intent to file its SCR Adjustment to permit recovery of costs associated with the installation of SCR equipment at Four Corners Units 4 and 5.  APS filed the SCR Adjustment request in April 2018. Consistent with the 2017 Rate Case Decision, the request was narrow in scope and addressed only costs associated with this specific environmental compliance equipment. The SCR Adjustment request provided that there would be a $67.5 million annual revenue impact that would be applied as a percentage of base rates for all applicable customers. Also, as provided for in the 2017 Rate Case Decision, APS requested that the rate adjustment become effective no later than January 1, 2019. The hearing for this matter occurred in September 2018. At the hearing, APS accepted ACC Staff's recommendation of a lower annual revenue impact of approximately $58.5 million. The Administrative Law Judge issued a Recommended Opinion and Order finding that the costs for the SCR project were prudently incurred and recommending authorization of the $58.5 million annual revenue requirement related to the installation and operation of the SCRs. Exceptions to the Recommended Opinion and Order were filed by the parties and intervenors on December 7, 2018.  The ACC has not issued a decision on this matter.  APS included the costs for the SCR project in the retail rate base in its 2019 retail rate case filing with the ACC. APS cannot predict the outcome or timing of the decision on this matter. APS may be required to record a charge to its results of operations if the ACC issues an unfavorable decision (see SCR deferral in the Regulatory Assets and Liabilities table in Note 4).

Tax Expense Adjustor Mechanism. As part of the 2017 Settlement Agreement, the parties agreed to a rate adjustment mechanism to address potential federal income tax reform and enable the pass-through of certain income tax effects to customers. The TEAM expressly applies to APS's retail rates with the exception of a small subset of customers taking service under specially-approved tariffs. On December 22, 2017, the Tax Act was enacted.  This legislation made significant changes to the federal income tax laws including a reduction in the corporate tax rate from 35% to 21% effective January 1, 2018.

On January 8, 2018, APS filed TEAM Phase I with the ACC that addressed the change in the marginal federal tax rate from 35% to 21% resulting from the Tax Act and reduces rates by $119.1 million annually through an equal cents per kWh credit.  On February 22, 2018, the ACC approved the reduction of rates through an equal cents per kWh credit. The rate reduction was effective for the first billing cycle in March 2018.

The impact of the TEAM Phase I, over time, is expected to be earnings neutral. However, on a quarterly basis, there is a difference between the timing and amount of the income tax benefit and the reduction in revenues refunded through the TEAM Phase I related to the lower federal income tax rate. The amount of the benefit of the lower federal income tax rate is based on quarterly pre-tax results, while the reduction in revenues refunded through the TEAM Phase I is based on a per kWh sales credit which follows our seasonal kWh sales pattern and is not impacted by earnings of the Company.

On August 13, 2018, APS filed TEAM Phase II, a second request with the ACC that addressed the return of an additional $86.5 million in tax savings to customers related to the amortization of non-depreciation related excess deferred taxes previously collected from customers. The ACC approved this request on March 13, 2019, effective the first billing cycle in April 2019. Both the timing of the reduction in revenues refunded through TEAM Phase II and the offsetting income tax benefit are recognized based upon our seasonal kWh sales pattern.

On April 10, 2019, APS filed a third request with the ACC that addresses the amortization of depreciation related excess deferred taxes over a 28.5 year period (“TEAM Phase III”).  On October 29, 2019, the ACC approved TEAM Phase III providing both (i) a one-time bill credit of $64 million to be credited to customers on their December 2019 bills, and (ii) a monthly bill credit effective the first billing cycle in December 2019 which will provide an additional benefit of $39.5 million to customers through

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December 31, 2020. It is currently anticipated that benefits related to the amortization of depreciation related excess deferred taxes for periods beginning after December 31, 2020 will be fully incorporated into the 2019 rate case filing.

Subpoena from Arizona Corporation Commissioner Robert Burns. On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, served subpoenas in APS’s then current retail rate proceeding on 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 the production of all information previously requested through the subpoenas. Neither APS nor Pinnacle West produced the information requested and instead objected to the subpoena. On March 10, 2017, Commissioner Burns filed suit against APS and Pinnacle West in the Superior Court of Arizona for Maricopa County in an effort to enforce his subpoenas. On March 30, 2017, APS filed a motion to dismiss Commissioner Burns' suit against APS and Pinnacle West. In response to the motion to dismiss, the court stayed the suit and ordered Commissioner Burns to file a motion to compel the production of the information sought by the subpoenas with the ACC. On June 20, 2017, the ACC denied the motion to compel.

On August 4, 2017, Commissioner Burns amended his complaint to add all of the ACC Commissioners and the ACC itself as defendants. All defendants moved to dismiss the amended complaint. On February 15, 2018, the Superior Court dismissed Commissioner Burns’ amended complaint. On March 6, 2018, Commissioner Burns filed an objection to the proposed final order from the Superior Court and a motion to further amend his complaint. The Superior Court permitted Commissioner Burns to amend his complaint to add a claim regarding his attempted investigation into whether his fellow commissioners should have been disqualified from voting on APS’s 2017 rate case. Commissioner Burns filed his second amended complaint, and all defendants filed responses opposing the second amended complaint and requested that it be dismissed. Oral argument occurred in November 2018 regarding the motion to dismiss. On December 18, 2018, the trial court granted the defendants’ motions to dismiss and entered final judgment on January 18, 2019. On February 13, 2019, Commissioner Burns filed a notice of appeal. On July 12, 2019, Commissioner Burns filed his opening brief in the Arizona Court of Appeals. APS filed its answering brief on October 21, 2019. APS and Pinnacle West cannot predict the outcome of this matter.

Information Requests from Arizona Corporation Commissioners. On January 14, 2019, ACC Commissioner Kennedy opened a docket to investigate campaign expenditures and political participation of APS and Pinnacle West. In addition, on February 27, 2019, ACC Commissioners Burns and Dunn opened a

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new docket and requested documents from APS and Pinnacle West related to ACC elections and charitable contributions related to the ACC. On March 1, 2019, ACC Commissioner Kennedy issued a subpoena to APS seeking several categories of information for both Pinnacle West and APS including political contributions, lobbying expenditures, marketing and advertising expenditures, and contributions made to 501(c)(3) and 501(c)(4) entities, for the years 2013-2018. Pinnacle West and APS voluntarily responded to both sets of requests on March 29, 2019. APS also received and responded to various follow-on requests from ACC Commissioners on these matters. Pinnacle West and APS cannot predict the outcome of these matters.

Energy Modernization Plan. On January 30, 2018, former ACC Commissioner Tobin proposed the Energy Modernization Plan, which consisted of a series of energy policies tied to clean energy sources such as energy storage, biomass, energy efficiency, electric vehicles, and expanded energy planning through the integrated resource plans ("IRP") process. In August 2018, the ACC directed ACC Staff to open a new rulemaking docket which will address a wide range of energy issues, including the Energy Modernization Plan proposals. The rulemaking will consider possible modifications to existing ACC rules, such as the RES, Electric and Gas Energy Efficiency Standards, Net Metering, Resource Planning, and the Biennial Transmission Assessment, as well as the development of new rules regarding forest bioenergy, electric vehicles, interconnection of distributed generation, baseload security, blockchain technology and other technological developments, retail competition, and other energy-related topics. On April 25, 2019, the ACC Staff issued a set of draft rules in regards to the Energy Modernization Plan and workshops were held on April 29, 2019 regarding these draft rules. On July 2, 2019, the ACC Staff issued a revised set of draft rules, which propose a RES goal of 45% of retail energy served be renewable by 2035 and a goal of 20% of retail sales during peak demand to be from clean energy resources by 2035.  The draft rules also require a certain amount of the RES goal to be derived from distributed renewable storage, for which utilities would be required to offer performance-based incentives.  Nuclear energy would be considered a clean resource under the draft rules. The ACC held various stakeholder meetings and workshops on ACC Staff’s draft energy rules in July through September 2019. APS cannot predict the outcome of this matter.

Integrated Resource Planning. ACC rules require utilities to develop fifteen-year IRPs which describe how the utility plans to serve customer load in the plan timeframe.  The ACC reviews each utility’s IRP to determine if it meets the necessary requirements and whether it should be acknowledged.  In March of 2018, the ACC reviewed the 2017 IRPs of its jurisdictional utilities and voted to not acknowledge any of the plans.  APS does not believe that this lack of acknowledgment will have a material impact on our financial position, results of operations or cash flows.  Based on an ACC decision, APS is required to file a Preliminary Resource Plan by April 1, 2019 and its final IRP by April 1, 2020. APS filed a request to extend the deadline to file its Preliminary IRP, which was granted. On August 1, 2019, APS filed its Preliminary IRP.

Public Utility Regulatory Policies Act. In August 2016, APS filed an application requesting that all of its contracts with qualifying facilities over 100 kW be set at a presumptive maximum 2 year term. A qualifying facility is an eligible energy-producing facility as defined by FERC regulations within a host electric utility’s service territory that has a right to sell to the host utility. Host utilities are required to purchase power from qualifying facilities at an avoided cost as determined by the utility subject to state commission oversight. A hearing was held in August 2019 and briefing on this matter was completed in October 2019 regarding APS’s application. APS cannot predict the outcome of this matter.

Residential Electric Utility Customer Service Disconnections. On June 13, 2019, APS voluntarily suspended electric disconnections for residential customers who had not paid their bills.  On June 20, 2019, the ACC voted to enact emergency rule amendments to prevent residential electric utility customer service disconnections during the period from June 1 through October 15. During the moratorium on disconnections, APS could not charge late fees and interest on amounts that were past due from customers.  Customer deposits must also be used to pay delinquent amounts before disconnection can occur and customers will have four months to pay back their deposit and any remaining delinquent amounts.  In accordance with the emergency

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rules, APS began putting delinquent customers on a mandatory four-month payment plan beginning on October 16, 2019. The emergency rule changes will be effective for 180 days and may be renewed for one additional 180 day period. During that time, the ACC began a formal regular rulemaking process to allow stakeholder input and time for consideration of permanent rule changes.  The ACC further ordered that each regulated electric utility serving retail customers in Arizona update its service conditions by incorporating the emergency rule amendments, restore power to any customers who were disconnected during the month of June 2019 and credit any fees that were charged for a reconnection. The ACC Staff issued draft amendments to the customer service disconnections rules. Stakeholders submitted initial comments to the draft amendments on September 23, 2019. ACC stakeholder meetings were held in September 2019 and October 2019 regarding the customer service disconnections rules. APS currently estimates that the disconnection moratorium will result in a negative impact to its 2019 financial statements of approximately $10 million depending on certain assumptions, including customer behaviors. APS is further assessing the impact to its financial statements beyond 2019, which will be affected by the results of final rulemaking related to disconnections.

Retail Electric Competition Rules. On November 17, 2018, the ACC voted to re-examine the facilitation of a deregulated retail electric market in Arizona. An ACC special open meeting workshop was held on December 3, 2018. No substantive action was taken, but interested parties were asked to submit written comments and respond to a list of questions from ACC Staff. On July 1 and July 2, 2019, ACC Staff issued a report and initial proposed draft rules regarding possible modifications to the ACC’s retail electric competition rules. Interested parties filed comments to the ACC Staff report and a stakeholder meeting and workshop to discuss the retail electric competition rules and energy modernization plan proposals was held on July 30, 2019. ACC Commissioners submitted additional questions regarding this matter. APS cannot predict whether these efforts will result in any changes and, if changes to the rules results, what impact these rules would have on APS.

FERC Matter. 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 Transmission Agreement was a jurisdictional contract that should have been filed with FERC. On October 5, 2017, FERC issued an order denying APS's request for rehearing. FERC also upheld its prior determination that the agreement relating to the settlement was a jurisdictional contract and should have been filed with FERC. APS cannot predict whether or if the enforcement division will take any action. APS filed an appeal of FERC's July 1, 2016 and October 5, 2017 orders with the United States Court of Appeals for the Ninth Circuit on December 4, 2017. On June 14, 2019, the United States Court of Appeals for the Ninth Circuit issued an unpublished memorandum order denying APS’s petition for review of FERC’s orders that denied APS’s request to recover the regulatory asset through its FERC-jurisdictional rates and granting APS’s petition for review of FERC’s orders finding the agreement to be a jurisdictional contract. The United States Court of Appeals for the Ninth Circuit vacated FERC’s determination that the agreement was

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required to be filed with FERC and remanded the issue to FERC for additional proceedings. APS cannot predict the outcome of the remand proceeding.

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 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's focus is 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.

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 - Ownership 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 2016 through 2018, retail electric revenues comprised approximately 95% of our total 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 1.9% for the nine-month period ended September 30, 2019 compared with the prior-year period.  For the three years 2016 through 2018, APS’s customer growth averaged 1.6% per year. We currently project annual customer growth to be 1.5 - 2.5% for 2019 and to average in the range of 1.5 - 2.5% for 2019 through 2021 based on our assessment of improving economic conditions in Arizona.

Retail electricity sales in kWh, adjusted to exclude the effects of weather variations, increased 0.5% for the nine-month period ended September 30, 2019 compared with the prior-year period. Improving economic

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conditions and customer growth were offset by energy savings driven by customer conservation, energy efficiency, and distributed renewable generation initiatives.  For the three years 2016 through 2018, annual retail electricity sales were about flat, adjusted to exclude the effects of weather variations.  We currently project that annual retail electricity sales in kWh will increase in the range of 0.0 - 1.0% for 2019 and increase on average in the range of 1.0 - 2.0% during 2019 through 2021, including the effects of customer conservation and energy efficiency and distributed renewable generation initiatives, but excluding the effects of weather variations and excluding the impacts of several new large data centers opening operations in Metro Phoenix.  The impact of new large data centers could raise the range of expected sales annual growth rate over the 2019 to 2021 period but demand from these customers remains uncertain at this point. Slower than expected growth 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 DG, 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 approximately $15 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 $25 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 $15 million.

Fuel and Purchased Power Costs. Fuel and purchased power costs included on our Condensed 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, unplanned outages, planned outages (typically scheduled in the spring and fall), 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 "Liquidity and Capital Resources" below for information regarding the planned additions to our facilities and income tax impacts related to bonus depreciation. 

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 10.9% of the assessed value for 2019, 11.0% for 2018 and 11.2% for 2017. We expect property taxes to increase as we add new generating units and continue with improvements and expansions to our existing generating units and transmission and distribution facilities. 

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Pension and other postretirement non-service credits - net.  Pension and other postretirement non-service credits can be impacted by changes in our actuarial assumptions. The most relevant actuarial assumptions are the discount rate used to measure our net periodic costs/credit, 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.

Interest Expense.  Interest expense is affected by the amount of debt outstanding and the interest rates on that debt (see Note 3).  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.

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. On December 22, 2017, the Tax Act was enacted and was generally effective on January 1, 2018. Changes impacting the Company include a reduction in the corporate tax rate to 21%, revisions to the rules related to tax bonus depreciation, limitations on interest deductibility and an associated exception for certain public utilities, and requirements that certain excess deferred tax amounts of regulated utilities be normalized. (See Note 15 for details of the impacts on the Company as of September 30, 2019.) In APS's 2017 rate case decision, the ACC approved a Tax Expense Adjustor Mechanism which will be used to pass through the income tax effects to retail customers of the Tax Act. (See Note 4 for details of the TEAM.)

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 sales supplied under traditional cost based rate regulation) and related activities and includes electricity generation, transmission and distribution.

Operating Results — Three-month period ended September 30, 2019 compared with three-month period ended September 30, 2018.

Our consolidated net income attributable to common shareholders for the three months ended September 30, 2019 was $312 million, compared with consolidated net income attributable to common shareholders of $315 million for the prior-year period.  The results reflect a decrease of approximately $1 million for the regulated electricity segment primarily due to the effects of weather, lower transmission revenues and lower pension and other postretirement non-service credits, partially offset by lower operations and maintenance expense.

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

	Three Months Ended September 30,
	2019			2018			Net Change
	(dollars in millions)
Regulated Electricity Segment:
Operating revenues less fuel and purchased power expenses	$	845		$	877		$	(32	)
Operations and maintenance	(238		)	(246		)	8
Depreciation and amortization	(149		)	(146		)	(3		)
Taxes other than income taxes	(53		)	(51		)	(2		)
Pension and other postretirement non-service credits - net	6			12			(6		)
All other income and expenses, net	14			14			—
Interest charges, net of allowance for borrowed funds used during construction	(54		)	(56		)	2
Income taxes	(53		)	(85		)	32
Less income related to noncontrolling interests (Note 6)	(5		)	(5		)	—
Regulated electricity segment income	313			314			(1		)
All other	(1		)	1			(2		)
Net Income Attributable to Common Shareholders	$	312		$	315		$	(3	)

Operating revenues less fuel and purchased power expenses.  Regulated electricity segment operating revenues less fuel and purchased power expenses were $32 million lower for the three months ended September 30, 2019 compared with the prior-year period.  The following table summarizes the major components of this change:

	Increase (Decrease)
	Operating revenues			Fuel and purchased power expenses			Net change
	(dollars in millions)
Refunds due to lower Federal corporate income tax rate (Note 4)	$	(27	)	$	—		$	(27	)
Effects of weather	(9		)	(2		)	(7		)
Lower transmission revenues (Note 4)	(5		)	—			(5		)
Changes in net fuel and purchased power costs, including off-system sales margins and related deferrals	(48		)	(51		)	3
Higher retail revenue due to higher customer growth, partially offset by the impacts of energy efficiency, distributed generation and changes in customer usage patterns	4			2			2
Miscellaneous items, net	8			6			2
Total	$	(77	)	$	(45	)	$	(32	)

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Operations and maintenance.  Operations and maintenance expenses decreased $8 million for the three months ended September 30, 2019 compared with the prior-year period primarily because of:

• A decrease of $16 million related to public outreach costs at the parent company primarily associated with the ballot initiative in 2018;

• An increase of $5 million related to consulting costs; and

• An increase of $3 million for other miscellaneous factors.

Pension and other postretirement non-service credits, net. Pension and other postretirement non-service credits, net were $6 million lower for the three months ended September 30, 2019 compared to the prior-year period primarily due to lower market returns.

Income taxes.  Income taxes were $32 million lower for the three months ended September 30, 2019 compared with the prior-year period primarily due to amortization of excess deferred taxes (Note 4) and lower pretax income.

Operating Results — Nine-month period ended September 30, 2019 compared with nine-month period ended September 30, 2018.

Our consolidated net income attributable to common shareholders for the nine months ended September 30, 2019 was $474 million, compared with consolidated net income attributable to common shareholders of $485 million for the prior-year period.  The results reflect a decrease of approximately $9 million for the regulated electricity segment primarily due to the effects of weather and lower pension and other postretirement non-service credits, partially offset by lower operations and maintenance expense.

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

	Nine Months Ended September 30,
	2019			2018			Net Change
	(dollars in millions)
Regulated Electricity Segment:
Operating revenues less fuel and purchased power expenses	$	1,980		$	2,067		$	(87	)
Operations and maintenance	(710		)	(769		)	59
Depreciation and amortization	(446		)	(435		)	(11		)
Taxes other than income taxes	(164		)	(158		)	(6		)
Pension and other postretirement non-service credits - net	17			37			(20		)
All other income and expenses, net	46			46			—
Interest charges, net of allowance for borrowed funds used during construction	(161		)	(162		)	1
Income taxes	(72		)	(127		)	55
Less income related to noncontrolling interests (Note 6)	(15		)	(15		)	—
Regulated electricity segment income	475			484			(9		)
All other	(1		)	1			(2		)
Net Income Attributable to Common Shareholders	$	474		$	485		$	(11	)

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Operating revenues less fuel and purchased power expenses.  Regulated electricity segment operating revenues less fuel and purchased power expenses were $87 million lower for the nine months ended September 30, 2019 compared with the prior-year period.  The following table summarizes the major components of this change:

	Increase (Decrease)
	Operating revenues			Fuel and purchased power expenses			Net change
	(dollars in millions)
Refunds due to lower Federal corporate income tax rate (Note 4)	$	(59	)	$	—		$	(59	)
Effects of weather	(42		)	(10		)	(32		)
Lower renewable energy regulatory surcharges and higher purchased power, partially offset by operations and maintenance costs	(15		)	1			(16		)
Lower transmission revenues (Note 4)	(8		)	—			(8		)
Change in residential rate design and seasonal rates (a)	13			—			13
Lost fixed cost recovery	8			—			8
Higher retail revenue due to higher customer growth, partially offset by the impacts of energy efficiency, distributed generation and changes in customer usage patterns	11			4			7
Changes in net fuel and purchased power costs, including off-system sales margins and related deferrals	(43		)	(46		)	3
Miscellaneous items, net	4			7			(3		)
Total	$	(131	)	$	(44	)	$	(87	)

(a) As part of the 2017 Settlement Agreement, rate design changes were implemented in the spring of 2018 that moved some revenue responsibility from summer to non-summer months. The change was made to better align revenue collections with costs of service.

Operations and maintenance.  Operations and maintenance expenses decreased $59 million for the nine months ended September 30, 2019 compared with the prior-year period primarily because of:

• A decrease of $26 million related to public outreach costs at the parent company primarily associated with the ballot initiative in 2018;

• A decrease of $19 million related to costs for renewable energy and similar regulatory programs, which is partially offset by operating revenues and purchased power;

• A decrease of $16 million in fossil generation primarily due to lower planned outages and other operating costs;

• A decrease of $7 million related to transmission, distribution and customer service costs;

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• A decrease of $6 million related to employee benefit costs;

• An increase of $9 million for costs related to information technology;

• An increase of $7 million related to consulting costs; and

• A decrease of $1 million for other miscellaneous factors.

Depreciation and amortization.  Depreciation and amortization expenses were $11 million higher for the nine months ended September 30, 2019 compared with the prior-year period primarily related to increased plant in service.

Taxes other than income taxes. Taxes other than income taxes were $6 million higher for the nine months ended September 30, 2019 compared to the prior-year period primarily due to higher property values.

Pension and other postretirement non-service credits, net. Pension and other postretirement non-service credits, net were $20 million lower for the nine months ended September 30, 2019 compared to the prior-year period primarily due to lower market returns.

Income taxes.  Income taxes were $55 million lower for the nine months ended September 30, 2019 compared with the prior-year period primarily due to amortization of excess deferred taxes (Note 4) and lower pretax income.

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 September 30, 2019, APS’s common equity ratio, as defined, was 54%.  Its total shareholder equity was approximately $6.0 billion, and total capitalization was approximately $11.1 billion.  Under this order, APS would be prohibited from paying dividends if such payment would reduce its total shareholder equity below approximately $4.5 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.

In September 2019, U.S. Treasury issued new proposed regulations which clarify bonus depreciation transition rules under the Tax Act for property placed in service by regulated public utilities after December 31, 2017. The proposed regulations provide that certain regulated public utility property which was under

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construction prior to September 28, 2017 and placed in service between January 1, 2018 and December 31, 2020 would continue to be eligible for bonus depreciation under the rules and bonus depreciation phase-downs in effect prior to enactment of the Tax Act. Taxpayers are able to rely on these proposed regulations for taxable years ending on or after September 28, 2017 and until final regulations are eventually issued.

Based on the September 2019 proposed regulations, the Company believes the continued availability of bonus depreciation for certain property under construction prior to September 28, 2017 and placed in service during 2019 or 2020 may generate $35-$50 million of bonus depreciation cash tax benefits. The cash generated by 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 continued availability of bonus depreciation is expected to delay until 2020 full cash realization of approximately $31 million of currently unrealized Investment Tax Credits and other tax credits, which are recorded as a deferred tax asset on the Condensed Consolidated Balance Sheets as of September 30, 2019.

Summary of Cash Flows

The following tables present net cash provided by (used for) operating, investing and financing activities for the nine months ended September 30, 2019 and 2018 (dollars in millions):

Pinnacle West Consolidated

	Nine Months Ended September 30,						Net
	2019			2018			Change
Net cash flow provided by operating activities	$	835		$	960		$	(125	)
Net cash flow used for investing activities	(832		)	(913		)	81
Net cash flow provided by financing activities	21			4			17
Net change in cash and cash equivalents	$	24		$	51		$	(27	)

Arizona Public Service Company

	Nine Months Ended September 30,						Net
	2019			2018			Change
Net cash flow provided by operating activities	$	830		$	988		$	(158	)
Net cash flow used for investing activities	(844		)	(906		)	62
Net cash flow provided by (used for) financing activities	38			(31		)	69
Net change in cash and cash equivalents	$	24		$	51		$	(27	)

Operating Cash Flows

Nine-month period ended September 30, 2019 compared with nine-month period ended September 30, 2018.  Pinnacle West’s consolidated net cash provided by operating activities was $835 million in 2019, compared to $960 million in 2018, a decrease of $125 million in net cash provided by operating activities primarily due to lower cash receipts from electric revenues and higher pension contributions, partially offset by lower fuel and purchased power costs and operations and maintenance cost.

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

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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 112% funded as of January 1, 2019 and 117% as of January 1, 2018.  Under GAAP, the qualified pension plan was 90% funded as of January 1, 2019 and 95% funded as of January 1, 2018. See Note 5 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 of $150 million to our pension plan year-to-date in 2019. 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 $350 million during the 2019-2021 period. We do not expect to make any contributions over the next three years to our other postretirement benefit plans. In 2019, the Company was reimbursed $30 million for prior year retiree medical claims from the other postretirement benefit plan trust assets.

Investing Cash Flows

Nine-month period ended September 30, 2019 compared with nine-month period ended September 30, 2018.  Pinnacle West’s consolidated net cash used for investing activities was $832 million in 2019, compared to $913 million in 2018, a decrease of $81 million primarily related to decreased capital expenditures and active union employee medical claim reimbursements (See Note 12). The difference between APS and Pinnacle West's net cash used for investing activities primarily relates to Pinnacle West's investing cash activity related to 4CA.

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,
	2019		2020		2021
APS
Generation:
Clean:
Nuclear Fuel	$	71	$	63	$	64
Nuclear Generation	70		68		67
Renewables (a)	23		18		3
New Resources (b)	3		118		387
Environmental	29		47		53
New Gas Generation	16		—		—
Other Generation	156		137		118
Distribution	515		530		402
Transmission	205		190		236
Other (c)	149		160		142
Total APS	$	1,237	$	1,331	$	1,472

(a) Primarily APS Solar Communities program

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(b) Projected future generation resources, which may include energy storage, renewable projects, and other clean energy projects

(c) Primarily information systems and facilities projects

 Generation capital expenditures are comprised of various additions and improvements to APS’s clean resources, including nuclear plants, renewables and projected future new resources. Generation capital expenditures also include improvements to existing fossil plants. Examples of the types of projects included in the forecast of generation capital expenditures are additions of roof top solar systems, new clean resources, and upgrades and capital replacements of various nuclear and fossil power plant equipment, such as turbines, boilers and environmental equipment.  We are monitoring the status of environmental matters, which, depending on their final outcome, could require modification to our planned environmental expenditures.

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.

Financing Cash Flows and Liquidity

Nine-month period ended September 30, 2019 compared with nine-month period ended September 30, 2018.  Pinnacle West’s consolidated net cash provided by financing activities was $21 million in 2019, compared to $4 million in 2018, an increase of $17 million in net cash provided.  The increase in net cash provided by financing activities includes $500 million in higher issuances of long-term debt, partially offset by higher long-term debt repayments of $418 million and a net decrease in short term borrowings of $52 million. The difference between APS and Pinnacle West's net cash provided by financing activities primarily relates to short-term borrowings and repayments at Pinnacle West on behalf of 4CA.

Significant Financing Activities.  On October 23, 2019, the Pinnacle West Board of Directors declared a dividend of $0.7825 per share of common stock, payable on December 2, 2019 to shareholders of record on November 4, 2019. This represents an increase in the indicated annual dividend from $2.95 per share to $3.13 per share.

On February 26, 2019, APS entered into a $200 million term loan agreement that matures August 26, 2020. APS used the proceeds to repay existing indebtedness. Borrowings under the agreement bear interest at LIBOR plus 0.50% per annum.

On February 28, 2019, APS issued $300 million of 4.25% unsecured senior notes that mature on March 1, 2049. The net proceeds from the sale, together with funds made available from the term loan described above, were used to repay existing indebtedness.

On March 1, 2019, APS repaid at maturity $500 million aggregate principal amount of its 8.75% senior notes.

On August 19, 2019, APS issued $300 million of 2.6% unsecured senior notes that mature on August 15, 2029. The net proceeds from the sale were used to repay short-term indebtedness, consisting of commercial paper borrowings, and to replenish cash used to fund capital expenditures.

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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, to finance indebtedness, and other general corporate purposes.

On May 9, 2019, Pinnacle West entered into a $50 million term loan agreement that matures May 7, 2020. Pinnacle West used the proceeds to refinance indebtedness under and terminate a prior $150 million revolving credit facility. Borrowings under the agreement bear interest at LIBOR plus 0.55% per annum. At September 30, 2019, Pinnacle West had $41 million in outstanding borrowings under the agreement.

At September 30, 2019, Pinnacle West had a $200 million revolving credit facility that matures in July 2023. 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. Interest rates are based on Pinnacle West's senior unsecured debt credit ratings. The facility is available to support Pinnacle West's $200 million commercial paper program, for bank borrowings or for issuances of letters of credits. At September 30, 2019, Pinnacle West had no outstanding borrowings under its credit facility, no letters of credit outstanding and $13 million of commercial paper borrowings.

At September 30, 2019, APS had two revolving credit facilities totaling $1 billion, including a $500 million credit facility that matures in June 2022 and a $500 million facility that matures in July 2023.  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 September 30, 2019, APS had $3 million of commercial paper outstanding and no outstanding borrowings or letters of credit under its revolving credit facilities.

 See "Financial Assurances" in Note 8 for a discussion of separate outstanding letters of credit and surety bonds.

Other Financing Matters. See Note 7 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 September 30, 2019, the ratio was approximately 50% for Pinnacle West and 46% 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

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default under certain other material agreements.  Pinnacle West and APS do not have a material adverse change restriction for credit facility borrowings.

On November 27, 2018, the ACC issued a financing order that, subject to specified parameters and procedures, increased APS’s long-term debt limit from $5.1 billion to $5.9 billion, and authorized APS’s short-term debt limit equal to a sum of (i) 7% of APS’s capitalization, and (ii) $500 million (which is required to be used for costs relating to purchases of natural gas and power).

Credit Ratings

The ratings of securities of Pinnacle West and APS as of October 31, 2019 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-
Senior unsecured	A3	BBB+	A-
Commercial paper	P-2	A-2	F2
Outlook	Stable	Stable	Negative
APS
Corporate credit rating	A2	A-	A-
Senior unsecured	A2	A-	A
Commercial paper	P-1	A-2	F2
Outlook	Stable	Stable	Negative

Off-Balance Sheets Arrangements

See Note 6 for a discussion of the impacts on our financial statements of consolidating certain VIEs.

Contractual Obligations

During 2019 our fuel and purchased power commitments have increased from the information provided in our 2018 10-K. The increase is primarily due to new purchased power commitments of approximately $260 million. The majority of the changes relate to 2024 and thereafter.

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During 2019 our coal reclamation commitments have decreased from the information provided in our 2018 10-K by approximately $100 million. The decrease is primarily due to a new coal reclamation cost study for Four Corners. The majority of the changes relate to 2024 and thereafter.

Other than the items described above, there have been no material changes, as of September 30, 2019, outside the normal course of business in contractual obligations from the information provided in our 2018 Form 10-K. See Note 3 for discussion regarding changes in our long-term debt obligations.

CRITICAL ACCOUNTING POLICIES

In preparing the financial statements in accordance with 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.  There have been no changes to our critical accounting policies since our 2018 Form 10-K.  See "Critical Accounting Policies" in Item 7 of the 2018 Form 10-K for further details about our critical accounting policies.

OTHER ACCOUNTING MATTERS

On January 1, 2019 we adopted new lease accounting guidance, ASU 2016-02, and related amendments. See Note 16. On July 1, 2019 we early adopted, ASU 2018-15, relating to accounting for cloud computing implementation costs. We are currently evaluating the impacts of the pending adoption of ASU 2016-13, and related amendments, pertaining to the measurement of credit losses on financial instruments. This new credit loss standard is effective for us on January 1, 2020. See Note 13 for additional information related to new accounting standards.

MARKET AND CREDIT RISKS

Market Risks

Our operations include managing market risks related to changes in interest rates, commodity prices, investments held by our nuclear decommissioning trust, other special use funds 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, other special use funds (see Note 11 and Note 12), and benefit plan assets.  The nuclear decommissioning trust, other special use funds 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.

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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 for the nine months ended September 30, 2019 and 2018 (dollars in millions):

	Nine Months Ended September 30,
	2019			2018
Mark-to-market of net positions at beginning of period	$	(59	)	$	(91	)
Decrease (Increase) in regulatory asset	(13		)	12
Recognized in OCI:
Mark-to-market losses realized during the period	1			2
Change in valuation techniques	—			—
Mark-to-market of net positions at end of period	$	(71	)	$	(77	)

The table below shows the fair value of maturities of our derivative contracts (dollars in millions) at September 30, 2019 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," in Item 8 of our 2018 Form 10-K and Note 11 for more discussion of our valuation methods.

Source of Fair Value	2019			2020			2021			2022			2023			Total  Fair  Value
Observable prices provided by other external sources	$	(15	)	$	(30	)	$	(16	)	$	(7	)	$	—		$	(68	)
Prices based on unobservable inputs	—			—			—			—			(2		)	(2		)
Total by maturity	$	(15	)	$	(30	)	$	(16	)	$	(7	)	$	(2	)	$	(70	)

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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 Condensed Consolidated Balance Sheets at September 30, 2019 and December 31, 2018 (dollars in millions):

	September 30, 2019					December 31, 2018
	Gain (Loss)					Gain (Loss)
	Price Up 10%		Price Down 10%			Price Up 10%		Price Down 10%
Mark-to-market changes reported in:
Regulatory asset (a)
Electricity	$	—	$	—		$	1	$	(1	)
Natural gas	39		(39		)	44		(44		)
Total	$	39	$	(39	)	$	45	$	(45	)

(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 7 for a discussion of our credit valuation adjustment policy.

Item 3.        QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

See "Key Financial Drivers" and "Market and Credit Risks" in Item 2 above for a discussion of quantitative and qualitative disclosures about market risks.

Item 4.         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, as amended (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 September 30, 2019.  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.

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APS’s management, with the participation of APS’s Chief Executive Officer and Chief Financial Officer, has evaluated the effectiveness of APS’s disclosure controls and procedures as of September 30, 2019.  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)                                 Changes in Internal Control Over Financial Reporting

The term "internal control over financial reporting" (defined in SEC Rule 13a-15(f)) refers to the process of a company that is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with GAAP.

No change in Pinnacle West’s or APS’s internal control over financial reporting occurred during the fiscal quarter ended September 30, 2019 that materially affected, or is reasonably likely to materially affect, Pinnacle West’s or APS’s internal control over financial reporting.

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PART II — OTHER INFORMATION

Item 1.                   LEGAL PROCEEDINGS

See "Business of Arizona Public Service Company — Environmental Matters" in Item 1 of the 2018 Form 10-K with regard to pending or threatened litigation and other disputes.

See Note 4 for ACC and FERC-related matters.

See Note 8 for information regarding environmental matters and Superfund-related matters.

Item 1A.                RISK FACTORS

In addition to the other information set forth in this report, you should carefully consider the factors discussed in Part I, Item 1A — Risk Factors in the 2018 Form 10-K, which could materially affect the business, financial condition, cash flows or future results of Pinnacle West and APS.  The risks described in the 2018 Form 10-K are not the only risks facing Pinnacle West and APS.  Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect the business, financial condition, cash flows and/or operating results of Pinnacle West and APS. 

Item 5.                OTHER INFORMATION

Modification to Compensation

On November 4, 2019, the Human Resources Committee (“HRC”) of the Pinnacle West Board of Directors approved the following compensation arrangement for Jeffrey B. Guldner, the President of APS and Executive Vice President Public Policy of Pinnacle West that is effective on November 15, 2019 when Mr. Guldner becomes Chairman of the Board of Directors, President, and Chief Executive Officer of Pinnacle West and APS:

• Mr. Guldner’s base salary increases to $1,100,000 (“CEO Base Salary”);

• Equity awards are expected to be granted in February 2020 with a grant date fair value of $3,250,000, under the regular long-term incentive program applicable to the Chief Executive Officer and Executive Vice Presidents, and, subject to the normal approval process by the HRC;

• The award opportunities for Mr. Guldner under the APS 2019 Annual Incentive Award Plan (the “APS Plan”) will continue to be tied to his services as President of APS and Executive Vice President Public Policy of Pinnacle West from January 1, 2019 until November 15, 2019. From November 15, 2019 until December 31, 2019, Mr. Guldner will continue to participate in the APS Plan but the award opportunities will be based 50% on the achievement of specified 2019 Pinnacle West earnings levels and 50% on the achievement of performance goals established for business units of APS in the functional areas of customer service, transmission and distribution, fossil generation, corporate resources and the Palo Verde Generating Station and Mr. Guldner’s target award opportunity under the APS Plan will be 110% of his CEO Base Salary.  Mr. Guldner may earn less or more than the target amount, up to a maximum award opportunity of 200% of target, depending on the achievement of the earnings and business unit performance goals separately or in combination.

Consulting Services Agreement

On November 4, 2019, the HRC of the Pinnacle West Board of Directors approved a Consulting Services Agreement with Donald E. Brandt, the Chairman of the Board, President, and Chief Executive Officer of Pinnacle West and the Chairman of the Board and Chief Executive Officer of APS that is effective

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November 15, 2019 (the “Agreement”). For a period of 12 months, Mr. Brandt will consult and advise on matters as requested by the Board of Directors, including without limitation, assisting Pinnacle West and its Board of Directors in the transition of the responsibilities of the Chief Executive Officer to Mr. Guldner. In particular, Mr. Brandt will provide advice and support regarding the transition of oversight of the Palo Verde Generating Station.

Mr. Brandt may receive a total consulting fee of up to $1.75 million that will be payable as $25,000 per month for the first 11 months and the balance of the consulting fee will be paid at the end of the term of the Agreement, subject to an evaluation by the HRC and the Corporate Governance Committee of the Pinnacle West Board of Directors that Mr. Brandt has performed the duties in the Agreement. Mr. Brandt is subject to certain restrictions and covenants in the Agreement, including confidentiality, non-compete and non-solicitation provisions.

The foregoing description of the terms of the Agreement does not purport to be complete, and is qualified in its entirety by reference to the full text thereof, a copy of which is filed as Exhibit 10.1 to this Form 10-Q, and incorporated herein by reference.

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Item 6.                 EXHIBITS

(a) Exhibits

Exhibit No.	Registrant(s)	Description
10.1	Pinnacle West	Consulting Services Agreement between Pinnacle West and Donald E. Brandt
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, Executive Vice President and 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, Executive Vice President and Chief Financial Officer, pursuant to Rule 13a-14(a) and Rule 15d-14(a) of the Securities Exchange Act, as amended
32.1*	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
32.2*	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
101.INS	Pinnacle West APS	XBRL Instance Document - the instance document does not appear in the interactive data file because its XBRL tags are embedded within the inline XBRL document.
101.SCH	Pinnacle West APS	XBRL Taxonomy Extension Schema Document
101.CAL	Pinnacle West APS	XBRL Taxonomy Extension Calculation Linkbase Document

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
104	Pinnacle West APS	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

________________________________

*Furnished herewith as an Exhibit.

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In addition, Pinnacle West and APS hereby incorporate the following Exhibits pursuant to Exchange Act Rule 12b-32 and Regulation §229.10(d) by reference to the filings set forth below:

Exhibit No.	Registrant(s)	Description	Previously Filed as Exhibit(1)	Date Filed
3.1	Pinnacle West	Pinnacle West Capital Corporation Bylaws, amended as of February 22, 2017	3.1 to Pinnacle West/APS February 28, 2017 Form 8-K Report, File Nos. 1-8962 and 1-4473	2/28/2017
3.2	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 Nos. 1-8962 and 1-4473	8/7/2008
3.3	APS	Articles of Incorporation, restated as of May 25, 1988	4.2 to APS’s Form S-3 Registration Nos. 33-33910 and 33-55248 by means of September 24, 1993 Form  8-K Report, File No. 1-4473	9/29/1993
3.4	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
3.5	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 Nos. 1-8962 and 1-4473	2/20/2009

_______________________________

(1)  Reports filed under File Nos. 1-4473 and 1-8962 were filed in the office of the Securities and Exchange Commission located in Washington, D.C.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		PINNACLE WEST CAPITAL CORPORATION
		(Registrant)
Dated:	November 7, 2019	By:	/s/ James R. Hatfield
			James R. Hatfield
			Executive Vice President and
			Chief Financial Officer
			(Principal Financial Officer and
			Officer Duly Authorized to sign this Report)
		ARIZONA PUBLIC SERVICE COMPANY
		(Registrant)
Dated:	November 7, 2019	By:	/s/ James R. Hatfield
			James R. Hatfield
			Executive Vice President and
			Chief Financial Officer
			(Principal Financial Officer and
			Officer Duly Authorized to sign this Report)

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EX-10.1

CONSULTING SERVICES AGREEMENT

This Consulting Services Agreement (“Agreement”) is entered into as of the 4th day of November, 2019 and is between Pinnacle West Capital Corporation (“Company”), and Donald E. Brandt (“Consultant”).

WHEREAS, Consultant currently serves as the Chairman, President and Chief Executive Officer of the Company;

WHEREAS, Consultant has announced plans to retire from the Company effective as of the 15^th day of November, 2019 (“Retirement Date”);

WHEREAS, the Company desires to retain Consultant to provide certain services, for the period beginning on the Retirement Date and continuing for a period of 12 months (“Retention Period”); and

WHEREAS, Consultant desires to accept such retention, subject to the terms and conditions set forth below.

NOW THEREFORE, the Company and Consultant agree as follows:

1. Consultant Responsibilities. Consultant agrees, at the specific request of the Company made from time to time during the Retention Period, to consult and advise with respect to such matters as may be specifically requested from time to time by the Company through the Lead Director of its Board of Directors (“Lead Director”), including without limitation assisting the Company and its Board of Directors in the transition of the responsibilities of the Chief Executive Officer of the Company to Consultant’s successor (“Services”).

2. Consultant Status as Independent Contractor. The parties acknowledge that Consultant will perform the Services hereunder as an independent contractor and not as the agent, employee, joint venturer, partner or servant of the Company for any purpose whatsoever. Consistent with the foregoing, Consultant acknowledges that the Company shall not deduct withholding taxes, social security taxes or any other taxes required to be deducted by an employer from amounts paid to Consultant, and neither the Company nor its officers, directors or employees shall have any obligation or liability to Consultant for any such taxes, unemployment compensation, minimum wages, or similar charges, taxes or assessments applicable to an employment relationship. Consultant shall be responsible for maintaining his own books and records and shall make all withholdings and contributions for taxes, and shall pay all taxes, assessments, penalties, and fines related to Consultant’s activities. Consultant shall not be entitled by virtue of this Agreement to any fringe benefits, workers’ compensation, medical coverage, disability, pensions, holiday or vacation pay or any other benefits provided to the Company’s employees. The parties further acknowledge that:

• the Company shall not control the manner or means by which the Consultant performs the Services, including but not limited to the time and place the Consultant performs the Services.

• the Company shall not provide Consultant with any registrations or licenses required to perform the Services, all of which it shall be the responsibility of Consultant to obtain and maintain.

• the Company shall not provide any accommodations or equipment to Consultant other than temporary office space when Consultant is performing Services on-site.

• the Company shall pay Consultant in the name that appears on this Agreement.

• the parties shall not combine business operations and shall instead maintain separate business operations.

3. Term and Termination. The term of this Agreement shall be for the Retention Period unless sooner terminated as hereinafter provided. This Agreement may be terminated with or without Cause by either the Company or Consultant upon 30 days’ written notice to the other party. If the Agreement is terminated prior to the end of the Retention Period, the Consultant shall be entitled to the payments set forth in Section 6.

4. Compensation and Expenses. If Consultant satisfies the terms and conditions of this Agreement during the Retention Period, the Consultant will receive payments totaling $1,750,000, which shall be paid as follows: (1) $25,000 per month for the first 11 months in the Retention Period (the “Monthly Fee”) and (2) a final payment of $1,475,000 (the “Final Fee”), subject to the terms of Section 5. The parties reasonably anticipate that the level of bona fide consulting services will be required for less than eight hours per week, which is less than 20% of the average level of services the Consultant provided to the Company and its affiliates as an employee during the immediately preceding 36-month period prior to the Retirement Date. Consultant shall be responsible for all expenses incurred by Consultant in the performance of his duties, except for travel expenses incurred for out-of-town travel undertaken by Consultant at the request of the Company, for which Consultant shall be promptly reimbursed upon submission of receipts.

5. Payment of Monthly Fee and Final Fee. The Company shall remit the Monthly Fee to Consultant no later than the last day of each month during the Retention Period, commencing with November, 2019. Within 60 days following the end of the Retention Period, the Company’s Human Resources Committee and Corporate Governance Committee (the “Committees”) shall determine if the Consultant performed the Services required by the Agreement. If the Committees determine that the Consultant performed the Services required by the Agreement, the Consultant shall receive the Final Fee, paid in a single lump sum no later than 60 days following the end of the Retention Period.

6. Termination Prior to End of Retention Period. If the Company or Consultant terminates this Agreement on or prior to the last day of the Retention Period for any reason set forth in this Section 6 other than death or Disability, the parties shall provide prior notice as required in Section 3 of this Agreement.

6.1 Termination by Consultant. If this Agreement is terminated by the Consultant for any reason other than due to death or Disability prior to the end of the Retention Period, the Consultant will receive the Monthly Fee for the month in which the

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Agreement is terminated. The Consultant will not receive the Monthly Fee for any month following the month in which the Agreement is terminated, nor will the Consultant be entitled to receive the Final Fee. For purposes of this Agreement, “Disability” means that Consultant is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or can be expected to last for a continuous period of not less than 12 months.

6.2 Termination by Company for Cause or Violation of Section 7. If this Agreement is terminated by the Board of Directors for Cause or for a violation of Section 7 prior to the end of the Retention Period, the Consultant will receive the Monthly Fee for the month in which the Agreement is terminated. The Consultant will not receive the Monthly Fee for any month following the month in which the Agreement is terminated, nor will the Consultant be entitled to receive the Final Fee. For purposes of this Agreement, “Cause” means (A) embezzlement, theft, fraud, deceit and/or dishonesty by the Consultant 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 Board of Directors 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.

6.3 Termination due to Death or Disability. If this Agreement is terminated prior to the end of the Retention Period due to the Consultant’s death or Disability, the Consultant or his estate, as appropriate, will receive all of the unpaid Monthly Fees for the remainder of the Retention Period and the Final Fee in a single lump sum within 30 days following the date on which the Agreement is terminated.

6.4 Other Company Terminations. If the Board of Directors terminates this Agreement on or prior to the last day of the Retention Period for any reason other than those set forth in Section 6.2, including without limitation as a result of a Change of Control (as defined in the Company’s 2012 Long-Term Incentive Plan), the Consultant will receive all of the unpaid Monthly Fees for the remainder of the Retention Period and the Final Fee in a single lump sum within 30 days following the date on which the Agreement is terminated.

7. Non-Disclosure and Other Restrictions.

7.1 Confidentiality. While serving as a Consultant to the Company, Consultant agrees that Consultant will not, directly or indirectly, in one or a series of transactions, disclose to any person, or use or otherwise exploit for Consultant’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 Consultant or not; provided, however, that during the term of this Agreement, 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 Consultant in connection with the performance of Consultant’s job duties to persons who are authorized to receive such

3

information by the Company or its affiliates. Consultant 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 or to enforce the terms of this Agreement; provided, however, that in the event disclosure is required by applicable law or to enforce the terms of this Agreement, Consultant shall provide the Company with prompt notice of such requirement, prior to making any disclosure, so that it may seek an appropriate protective order. This Agreement also does not limit Consultant’s ability to communicate with any government agency regarding matters within the agency’s jurisdiction or otherwise participate in any investigation or proceedings that may be conducted by such agency, including providing documents or other information without notice to the Company. Nothing in this Agreement shall prevent Consultant from the disclosure of Confidential Information or trade secrets that: (i) is made: (a) in confidence to a federal, state or local government official, either directly or indirectly, or to an attorney; and (b) solely for the purpose of reporting or investigating a suspected violation of law; or (ii) is made in a complaint or other document filed in a lawsuit or other proceeding, if such filing is permitted to be made, and is made, under seal. In the event that Consultant files a lawsuit alleging retaliation by Company for reporting a suspected violation of law, Consultant may disclose Confidential Information or trade secrets related to the suspected violation of law or alleged retaliation to Consultant’s attorney and use the Confidential Information or trade secrets in the court proceeding if Consultant or Consultant’s attorney: (i) files any document containing Confidential Information or trade secrets, under seal if permitted; and (ii) does not disclose the Confidential Information or trade secrets, except pursuant to or in accordance with a court order. The Company provides this notice in compliance with federal law, including the Defend Trade Secrets Act of 2016.

Consultant 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 Consultant).    

During the term of this Agreement, the Company agrees that it will not, directly or indirectly, disclose any information regarding the Consultant which is not generally known to the public, without the prior written consent of the Consultant; provided, however, that the Company is not prohibited from such disclosure if the information is required to be disclosed in compliance with applicable laws, rules, regulations, or by order of a court or other regulatory, administrative, or similar body. The Company will give reasonable prior notice to the Consultant of its intent to make any such disclosure to the extent not restricted by law.

For purposes of this Section 7.1, the term “Confidential Information” shall mean and include any information disclosed to Consultant any time during Consultant’s service with the Company or its affiliates or thereafter which relates to the business of the Company and 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,

4

procedures, processes, practices, policies, plans, programs, personnel and/or reports or other information prepared by appraisers, consultants, advisors, bankers or attorneys.

7.2 Non-Competition. Consultant agrees during the term of this Agreement and for a period of 12 months following the termination or expiration of this Agreement, Consultant 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 for which the Company or its affiliates is authorized to do business as of the date of this Agreement. Upon the approval, which will not be unreasonably withheld, of the Company’s Lead Director, the Consultant may serve on the board of directors of another company.

7.3 Non-Solicitation. Consultant agrees during the term of this Agreement and for a period of 12 months following the termination or expiration of this Agreement, Consultant shall not, without the prior written consent of the Company’s General Counsel, 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.

7.4 Remedies. If either party to this agreement fails to comply with Section 7 of this Agreement in a material respect, the other party may pursue any rights and remedies it or he may have pursuant to this Agreement at law or in equity including, specifically, injunctive relief.

8. Intellectual Property. Consultant agrees that all inventions, data, works, discoveries, designs, technology and improvements, (whether or not protectable by a patent or a copyright) (“Work Product”) related to the business of the Company, which are conceived of, made, reduced to practice, created, written, designed or developed, authored or made by principals or employees of Consultant, alone or in combination with others, in the course of the performance of services under this Agreement, shall be the sole and exclusive property of the Company. The Work Product are to be promptly reported to the Company but otherwise maintained in confidence by Consultant. All works authored by principals or employees of Consultant under this Agreement shall be deemed “works made for hire” to the extent permitted by the copyright law.

Consultant hereby assigns to the Company all Work Product and any and all related patents, copyrights, trademarks, trade names, and other industrial and intellectual property rights and applications therefore, in the United States and elsewhere, and appoints any officer of the Company as its duly authorized agent to execute, file, prosecute and protect the same before any government agency, court or authority.

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9. Notices. All notices, demands and communications required by this Agreement shall be in writing and shall be deemed to have been given for all purposes when sent to the respective addresses set forth below: (a) upon personal delivery; (b) one (1) day after being sent, when sent by overnight courier service; (c) five (5) days after posting when sent by registered, certified or regular mail, or (d) on the day of transmission when sent by electronic mail or facsimile.

To Company:    Pinnacle West Capital Corporation

400 N. Fifth Street

Phoenix, AZ 85004

Attention: General Counsel

To Consultant:    Donald E. Brandt

Each party may change its address by giving written notice of such change in the manner provided in this Section 10.

10. Interpretation.

10.1 Construction. Titles, captions or headings to this Agreement are for convenience and reference only and shall not be deemed part of this Agreement.

10.2 No Waiver. No requirement hereof nor default hereunder shall be deemed waived by either party except by a writing to that effect signed by the waiving party and then only to the extent specifically set forth in the writing. A waiver with reference to one event shall not be construed as continuing or as a bar to or waiver of any right or remedy as to a subsequent event.

10.3 Modification. This Agreement may be amended, modified, superseded or canceled only by a written instrument executed by the Company and Consultant.

10.4 Integration. This Agreement constitutes the complete and final agreement of the parties and supersedes any and all prior negotiations and agreements, written or oral, of the parties with respect to its subject matter.

10.5 Governing Law. This Agreement shall be interpreted, construed, governed by and enforced in accordance with the internal laws of the State of Arizona without regard to its conflict of law rules.

10.6 Severability. If any provision of this Agreement is held to be invalid or unenforceable, then the court making such determination shall modify the provision deemed invalid or unenforceable to the least possible extent needed so as to make it valid and enforceable, but if that cannot be done, the provision shall be severed and the remaining provisions shall then be interpreted in a manner allowing maximum enforcement of the Agreement.

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10.7 Assignment. Consultant shall not assign this Agreement or any rights or obligations hereunder without the Company's express written consent.

10.8 Section 409A. This Agreement shall be administered in compliance with Section 409A of the Internal Revenue Code and each provision of this Agreement shall be interpreted to comply with Section 409A of the Internal Revenue Code or an exception thereto. For purposes of Section 409A, the right to a series of installment payments under this Agreement shall be treated as a right to a series of separate payments under Treasury Regulation Section 1.409A-2(b)(2)(iii).

IN WITNESS WHEREOF, we have set our hands as of the date first above written.

PINNACLE WEST CAPITAL CORPORATION

By:/s/ Robert E. Smith            

Robert E. Smith, Senior Vice President and General Counsel

/s/ Donald E. Brandt

Donald E. Brandt, Consultant

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EX-31.1

Exhibit 31.1

CERTIFICATION

I, Donald E. Brandt, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q 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 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:    November 7, 2019

/s/ Donald E. Brandt

Donald E. Brandt

Chairman, President and Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION

I, James R. Hatfield, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q 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 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:    November 7, 2019

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and Chief Financial Officer

EX-31.3

Exhibit 31.3

CERTIFICATION

I, Donald E. Brandt, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q 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 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:    November 7, 2019

/s/ Donald E. Brandt

Donald E. Brandt

Chairman and Chief Executive Officer

1

EX-31.4

Exhibit 31.4

CERTIFICATION

I, James R. Hatfield, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q 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 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:    November 7, 2019

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and Chief Financial Officer

1

EX-32.1

Exhibit 32.1

CERTIFICATION

OF

CHIEF EXECUTIVE OFFICER

AND

CHIEF FINANCIAL OFFICER

PURSUANT TO 18 U.S.C. 1350,

AS ADOPTED PURSUANT TO

SECTION 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 Quarterly Report on Form 10-Q of Pinnacle West Capital Corporation for the quarter ended September 30, 2019 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 Quarterly Report on Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of Pinnacle West Capital Corporation.

Date:      November 7, 2019

/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 Quarterly Report on Form 10-Q of Pinnacle West Capital Corporation for the quarter ended September 30, 2019 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 Quarterly Report on Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of Pinnacle West Capital Corporation.

Date:     November 7, 2019

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and

Chief Financial Officer

EX-32.2

Exhibit 32.2

CERTIFICATION

OF

CHIEF EXECUTIVE OFFICER

AND

CHIEF FINANCIAL OFFICER

PURSUANT TO 18 U.S.C. 1350,

AS ADOPTED PURSUANT TO

SECTION 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 Quarterly Report on Form 10-Q of Arizona Public Service Company for the quarter ended September 30, 2019 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 Quarterly Report on Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of Arizona Public Service Company.

Date:      November 7, 2019

/s/ Donald E. Brandt

Donald E. Brandt

Chairman 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 Quarterly Report on Form 10-Q of Arizona Public Service Company for the quarter ended September 30, 2019 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 Quarterly Report on Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of Arizona Public Service Company.

Date:     November 7, 2019

/s/ James R. Hatfield

James R. Hatfield

Executive Vice President and

Chief Financial Officer

XML

Other Income and Other Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other income:
Interest income	$ 2,694	$ 1,957	$ 7,695	$ 6,256
Miscellaneous	22	91	50	95
Total other income	15,191	6,958	35,245	17,541
Other expense:
Non-operating costs	(2,647)	(2,480)	(8,832)	(7,404)
Investment losses — net	(716)	0	(1,445)	(268)
Miscellaneous	(2,377)	(2,583)	(4,171)	(4,391)
Total other expense	(5,740)	(5,063)	(14,448)	(12,063)
APS
Other income:
Interest income	2,037	1,151	5,091	4,874
Miscellaneous	22	92	50	96
Total other income	14,534	6,153	32,641	16,160
Other expense:
Non-operating costs	(2,448)	(2,334)	(7,965)	(6,931)
Miscellaneous	(378)	(1,027)	(2,167)	(2,748)
Total other expense	(2,826)	(3,361)	(10,132)	(9,679)
SCR deferral
Other income:
Debt return on Four Corners SCR (Note 4)	4,920	4,910	14,651	11,190
SCR deferral | APS
Other income:
Debt return on Four Corners SCR (Note 4)	4,920	4,910	14,651	11,190
Ocotillo deferral
Other income:
Debt return on Four Corners SCR (Note 4)	7,555	0	12,849	0
Ocotillo deferral | APS
Other income:
Debt return on Four Corners SCR (Note 4)	$ 7,555	$ 0	$ 12,849	$ 0

XML

Fair Value Measurements - Level 3 Rollforward Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net derivative balance at beginning of period	$ (12,753)	$ (9,358)	$ (8,214)	$ (18,256)
Deferred as a regulatory asset or liability	(2,324)	1,244	(12,634)	(2,067)
Settlements	8,980	(2,332)	11,929	(1,056)
Transfers into Level 3 from Level 2	(613)	(2,246)	(3,711)	(7,225)
Transfers from Level 3 into Level 2	5,116	2,829	11,036	18,741
Net derivative balance at end of period	(1,594)	(9,863)	(1,594)	(9,863)
Net unrealized gains included in earnings related to instruments still held at end of period	$ 0	$ 0	$ 0	$ 0

XML

Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Detail of regulatory liabilities
Current	$ 208,022	$ 165,876
Non-Current	2,310,131	2,325,976
Asset retirement obligations
Detail of regulatory liabilities
Current	0	0
Non-Current	367,930	278,585
Removal costs
Detail of regulatory liabilities
Current	47,459	39,866
Non-Current	151,535	177,533
Other postretirement benefits
Detail of regulatory liabilities
Current	37,821	37,864
Non-Current	95,789	125,903
Income taxes — change in rates
Detail of regulatory liabilities
Current	2,764	2,769
Non-Current	67,605	70,069
Spent nuclear fuel
Detail of regulatory liabilities
Current	5,746	6,503
Non-Current	53,229	57,002
Income taxes — deferred investment tax credit
Detail of regulatory liabilities
Current	2,164	2,164
Non-Current	49,182	51,120
Four Corners coal reclamation
Detail of regulatory liabilities
Current	1,858	1,858
Non-Current	49,194	17,871
Renewable energy standard
Detail of regulatory liabilities
Current	42,146	44,966
Non-Current	5,675	20
Demand side management
Detail of regulatory liabilities
Current	14,300	14,604
Non-Current	24,146	4,123
Sundance maintenance
Detail of regulatory liabilities
Current	4,640	1,278
Non-Current	13,393	17,228
Deferred gains on utility property
Detail of regulatory liabilities
Current	2,923	4,423
Non-Current	4,766	6,581
Deferred property taxes
Detail of regulatory liabilities
Current	0	0
Non-Current	6,288	2,611
FERC transmission true up
Detail of regulatory liabilities
Current	0	0
Non-Current	2,586	0
Other
Detail of regulatory liabilities
Current	1,370	3,279
Non-Current	2,533	930
ACC | Excess deferred income taxes - ACC - Tax Cuts and Jobs Act
Detail of regulatory liabilities
Current	38,529	0
Non-Current	1,178,216	1,272,709
United States Federal Energy Regulatory Commission | Excess deferred income taxes - ACC - Tax Cuts and Jobs Act
Detail of regulatory liabilities
Current	6,302	6,302
Non-Current	$ 238,064	$ 243,691

XML

Regulatory Matters Regulatory Matters - Capital Structure and Costs of Capital (Details) - Subsequent Event	Oct. 31, 2019
Cost of Capital
Long-term debt	4.10%
Common stock equity	10.15%
Weighted-average cost of capital	7.41%
Retail Rate Case Filing with Arizona Corporation Commission | APS
Capital Structure
Common stock equity	54.70%
Retail Rate Case Filing with Arizona Corporation Commission | ACC | APS
Capital Structure
Long-term debt	45.30%

XML

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Operating revenues	$ 1,190,787	$ 1,268,034	$ 2,800,818	$ 2,934,871
Regulatory cost recovery revenue	13,000	11,000	45,000	38,000
Electric Service | Residential
Disaggregation of Revenue [Line Items]
Operating revenues	668,467	695,480	1,452,601	1,512,402
Electric Service | Non-Residential
Disaggregation of Revenue [Line Items]
Operating revenues	465,602	496,809	1,194,199	1,275,498
Electric Service | Wholesale energy sales
Disaggregation of Revenue [Line Items]
Operating revenues	36,775	53,501	95,218	80,982
Transmission services for others
Disaggregation of Revenue [Line Items]
Operating revenues	15,841	15,902	46,247	46,235
Other sources
Disaggregation of Revenue [Line Items]
Operating revenues	4,102	6,342	12,553	19,754
Electric and Transmission Service
Disaggregation of Revenue [Line Items]
Operating revenues	$ 1,178,000	$ 1,257,000	$ 2,756,000	$ 2,897,000

XML

Fair Value Measurements

9 Months Ended

Sep. 30, 2019

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 at the measurement date.

Level 2 — Other significant observable inputs, including 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).

 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, their NAV is generally not published and publicly available, nor are these instruments traded on an exchange. Instruments valued using NAV, as a practical expedient are included in our fair value disclosures; however, in accordance with GAAP are not classified within the fair value hierarchy levels.

Recurring Fair Value Measurements

We apply recurring fair value measurements to cash equivalents, derivative instruments, and investments held in the nuclear decommissioning trust and other special use funds. On an annual basis we apply fair value measurements to plan assets held in our retirement and other benefit plans.  See Note 7 in the 2018 Form 10-K for fair value discussion of plan assets held in our retirement and other benefit plans.

Cash Equivalents

Cash equivalents represent certain investments in money market funds that are valued using quoted prices in active markets.

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.

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.

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.

Investments Held in Nuclear Decommissioning Trust and Other Special Use Funds

The nuclear decommissioning trust and other special use funds invest in fixed income and equity securities. Other special use funds include the coal reclamation escrow account and the active union medical account. See Note 12 for additional discussion about our investment accounts.

We value investments in fixed income and equity securities using information provided by our trustees and escrow agent. Our trustees and escrow agent use pricing services that utilize the valuation methodologies described below 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 trustees’ and escrow agent's internal operating controls and valuation processes.

Fixed Income Securities

Fixed income securities issued by the U.S. Treasury 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 fixed income 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.

Fixed income securities may also include short-term investments in certificates of deposit, variable rate notes, time deposit accounts, U.S. Treasury and Agency obligations, U.S. Treasury repurchase agreements, commercial paper, and other short-term instruments. These instruments are valued using active market prices or utilizing observable inputs described above.

Equity Securities

The nuclear decommissioning trust's equity security investments 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.

The nuclear decommissioning trust and other special use funds may also hold equity securities that include exchange traded mutual funds and money market accounts for short-term liquidity purposes. These short-term, highly-liquid, investments are valued using active market prices.

Fair Value Tables

The following table presents the fair value at September 30, 2019 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2			Level 3			Other				Total
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	1,388		$	388		$	(959	)	(a)	$	817
Nuclear decommissioning trust:
Equity securities	8,774		—			—			(1,322		)	(b)	7,452
U.S. commingled equity funds	—		—			—			476,693			(c)	476,693
U.S. Treasury debt	162,092		—			—			—				162,092
Corporate debt	—		124,026			—			—				124,026
Mortgage-backed securities	—		112,704			—			—				112,704
Municipal bonds	—		74,202			—			—				74,202
Other fixed income	—		10,504			—			—				10,504
Subtotal nuclear decommissioning trust	170,866		321,436			—			475,371				967,673
Other special use funds:
Equity securities	1,982		—			—			1,418			(b)	3,400
U.S. Treasury debt	232,165		—			—			—				232,165
Municipal bonds	—		8,417			—			—				8,417
Subtotal other special use funds	234,147		8,417			—			1,418				243,982
Total assets	$	405,013	$	331,241		$	388		$	475,830			$	1,212,472
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(69,752	)	$	(1,982	)	$	80		(a)	$	(71,654	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(b) Represents net pending securities sales and purchases.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

The following table presents the fair value at December 31, 2018 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2			Level 3			Other				Total
Assets
Cash equivalents	$	1,200	$	—		$	—		$	—			$	1,200
Risk management activities — derivative instruments:
Commodity contracts	—		3,140			2			(2,029		)	(a)	1,113
Nuclear decommissioning trust:
Equity securities	5,203		—			—			2,148			(b)	7,351
U.S. commingled equity funds	—		—			—			396,805			(c)	396,805
U.S. Treasury debt	148,173		—			—			—				148,173
Corporate debt	—		96,656			—			—				96,656
Mortgage-backed securities	—		113,115			—			—				113,115
Municipal bonds	—		79,073			—			—				79,073
Other fixed income	—		9,961			—			—				9,961
Subtotal nuclear decommissioning trust	153,376		298,805			—			398,953				851,134
Other special use funds:
Equity securities	45,130		—			—			593			(b)	45,723
U.S. Treasury debt	173,310		—			—			—				173,310
Municipal bonds	—		17,068			—			—				17,068
Subtotal other special use funds	218,440		17,068			—			593				236,101
Total assets	$	373,016	$	319,013		$	2		$	397,517			$	1,089,548
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(52,696	)	$	(8,216	)	$	875		(a)	$	(60,037	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(b) Represents net pending securities sales and purchases.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

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.  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 4).

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.

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 September 30, 2019 and December 31, 2018:

	September 30, 2019 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	388	$	489	Discounted cash flows	Electricity forward price (per MWh)	$17.79 - $17.79	$	17.79
Natural Gas:
Forward Contracts (a)	—		1,493		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.53 - $2.79	$	2.64
Total	$	388	$	1,982

(a) Includes swaps and physical and financial contracts.

	December 31, 2018 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	—	$	2,456	Discounted cash flows	Electricity forward price (per MWh)	$17.88 - $37.03	$	26.10
Natural Gas:
Forward Contracts (a)	2		5,760		Discounted cash flows	Natural gas forward price (per MMBtu)	$1.79 - $2.92	$	2.48
Total	$	2	$	8,216

(a) Includes swaps and physical and financial contracts.

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts	2019			2018			2019			2018
Net derivative balance at beginning of period	$	(12,753	)	$	(9,358	)	$	(8,214	)	$	(18,256	)
Total net gains (losses) realized/unrealized:
Deferred as a regulatory asset or liability	(2,324		)	1,244			(12,634		)	(2,067		)
Settlements	8,980			(2,332		)	11,929			(1,056		)
Transfers into Level 3 from Level 2	(613		)	(2,246		)	(3,711		)	(7,225		)
Transfers from Level 3 into Level 2	5,116			2,829			11,036			18,741
Net derivative balance at end of period	$	(1,594	)	$	(9,863	)	$	(1,594	)	$	(9,863	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—		$	—		$	—

Transfers between levels in the fair value hierarchy shown in the table above 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 short-term borrowings approximate fair value and are classified within Level 2 of the fair value hierarchy. See Note 3 for our long-term debt fair values. The NTEC note receivable related to the sale of 4CA’s interest in Four Corners bears interest at 3.9% per annum and has a book value of $49 million as of September 30, 2019 and $61 million as of December 31, 2018 as presented on the Condensed Consolidated Balance Sheets.  The carrying amount is not materially different from the fair value of the note receivable and is classified within Level 3 of the fair value hierarchy.  See Note 8 for more information on 4CA matters.

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Income Taxes

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

The Tax Cuts and Jobs Act reduced the corporate tax rate to 21% effective January 1, 2018. As a result of this rate reduction, the Company recognized a $1.14 billion reduction in its net deferred income tax liabilities as of December 31, 2017. In accordance with accounting for regulated companies, the effect of this rate reduction was substantially offset by a net regulatory liability.

Federal income tax laws require the amortization of a majority of the balance over the remaining regulatory life of the related property. As a result of the modifications made to the annual transmission formula rate during the second quarter of 2018, the Company began amortization of FERC jurisdictional net excess deferred tax liabilities in 2018. On March 13, 2019, the ACC approved the Company's proposal to amortize non-depreciation related net excess deferred tax liabilities subject to its jurisdiction over a twelve-month period. As a result, the Company began amortization in March 2019. As of September 30, 2019, the Company has recorded $42 million of income tax benefit related to the amortization of these non-depreciation related net excess deferred tax liabilities. On April 10, 2019, the Company filed a request with the ACC which addresses the amortization of depreciation related excess deferred taxes. See Note 4 for more details.

In August 2018, U.S. Treasury proposed regulations that clarified bonus depreciation transition rules under the Tax Act for regulated public utility property placed in service after September 27, 2017 and before January 1, 2018.  However, these proposed regulations were ambiguous with respect to regulated public utility property placed in service on or after January 1, 2018. In September 2019, U.S. Treasury issued final regulations, which replaced the August 2018 proposed regulations. These final regulations did not materially impact any tax position taken by the Company for property placed in service after September 27, 2017 and before January 1, 2018.

Along with the September 2019 final regulations, U.S. Treasury also issued new proposed regulations which clarify bonus depreciation transition rules under the Tax Act for property placed in service by regulated public utilities after December 31, 2017. The proposed regulations provide that certain regulated public utility property which was under construction prior to September 28, 2017 and placed in service between January 1, 2018 and December 31, 2020 would continue to be eligible for bonus depreciation under the rules and bonus depreciation phase-downs in effect prior to enactment of the Tax Act.  During the third quarter, as a result of the clarification provided by these proposed regulations, the Company recorded deferred tax liabilities of approximately $56 million related to bonus depreciation benefits claimed on the Company’s 2018 tax return.

Net income associated with the Palo Verde sale leaseback VIEs is not subject to tax.  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. See Note 6 for additional details related to the Palo Verde sale leaseback VIEs.

As of the balance sheet date, the tax year ended December 31, 2016 and all subsequent tax years remain subject to examination by the IRS.  With a few exceptions, the Company is no longer subject to state income tax examinations by tax authorities for years before 2014.

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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
NET INCOME	$ 317,149	$ 319,885	$ 488,959	$ 499,591
Derivative instruments:
Net unrealized loss, net of tax expense	0	0	0	(96)
Reclassification of net realized loss, net of tax benefit	218	451	950	1,316
Pension and other postretirement benefits activity, net of tax expense (benefit)	880	1,099	220	(2,740)
Total other comprehensive income (loss)	1,098	1,550	1,170	(1,520)
COMPREHENSIVE INCOME	318,247	321,435	490,129	498,071
Less: Comprehensive income attributable to noncontrolling interests	4,873	4,873	14,620	14,620
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	313,374	316,562	475,509	483,451
APS
NET INCOME	323,743	343,239	511,942	540,409
Derivative instruments:
Net unrealized loss, net of tax expense	0	0	0	(96)
Reclassification of net realized loss, net of tax benefit	218	451	950	1,316
Pension and other postretirement benefits activity, net of tax expense (benefit)	755	952	(146)	(2,955)
Total other comprehensive income (loss)	973	1,403	804	(1,735)
COMPREHENSIVE INCOME	324,716	344,642	512,746	538,674
Less: Comprehensive income attributable to noncontrolling interests	4,873	4,873	14,620	14,620
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 319,843	$ 339,769	$ 498,126	$ 524,054

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CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
NET INCOME	$ 488,959	$ 499,591
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	500,801	489,861
Deferred fuel and purchased power	(60,911)	(82,486)
Deferred fuel and purchased power amortization	38,601	92,397
Allowance for equity funds used during construction	(24,677)	(39,411)
Deferred income taxes	83,703	117,571
Deferred investment tax credit	(7,288)	(7,397)
Stock compensation	16,486	16,140
Changes in current assets and liabilities:
Customer and other receivables	(91,506)	(65,203)
Accrued unbilled revenues	(18,666)	(83,939)
Materials, supplies and fossil fuel	(18,332)	(20,591)
Income tax receivable	(14,063)	0
Other current assets	(10,104)	23,661
Accounts payable	33,899	(11,399)
Accrued taxes	66,111	78,624
Other current liabilities	(68,927)	12,852
Change in other long-term assets	(52,276)	14,120
Change in other long-term liabilities	(27,049)	(74,628)
Net cash flow provided by operating activities	834,761	959,763
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(857,883)	(898,455)
Contributions in aid of construction	34,121	22,611
Allowance for borrowed funds used during construction	(14,645)	(18,959)
Proceeds from nuclear decommissioning trust sales and other special use funds	520,996	443,215
Investment in nuclear decommissioning trust and other special use funds	(523,573)	(461,777)
Other	8,971	49
Net cash flow used for investing activities	(832,013)	(913,316)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	794,981	295,245
Short-term borrowing and payments — net	(6,025)	19,800
Short-term debt borrowings	49,000	45,000
Short-term debt repayments	(62,000)	(32,000)
Repayment of long-term debt	(500,000)	(82,000)
Dividends paid on common stock	(243,116)	(228,037)
Common stock equity issuance - net of purchases	(130)	(1,984)
Distributions to noncontrolling interests	(11,372)	(11,372)
Net cash flow provided by financing activities	21,338	4,652
NET INCREASE IN CASH AND CASH EQUIVALENTS	24,086	51,099
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	5,766	13,892
CASH AND CASH EQUIVALENTS AT END OF PERIOD	29,852	64,991
APS
CASH FLOWS FROM OPERATING ACTIVITIES
NET INCOME	511,942	540,409
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	500,737	488,223
Deferred fuel and purchased power	(60,911)	(82,486)
Deferred fuel and purchased power amortization	38,601	92,397
Allowance for equity funds used during construction	(24,677)	(39,411)
Deferred income taxes	97,002	86,319
Deferred investment tax credit	(7,288)	(7,397)
Changes in current assets and liabilities:
Customer and other receivables	(90,817)	(56,874)
Accrued unbilled revenues	(18,666)	(83,939)
Materials, supplies and fossil fuel	(18,332)	(20,694)
Income tax receivable	(15,982)	0
Other current assets	(8,642)	20,258
Accounts payable	37,004	(8,857)
Accrued taxes	38,963	106,172
Other current liabilities	(66,368)	9,289
Change in other long-term assets	(54,872)	25,405
Change in other long-term liabilities	(27,521)	(80,895)
Net cash flow provided by operating activities	830,173	987,919
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(857,883)	(889,347)
Contributions in aid of construction	34,121	22,611
Allowance for borrowed funds used during construction	(14,645)	(18,959)
Proceeds from nuclear decommissioning trust sales and other special use funds	520,996	443,040
Investment in nuclear decommissioning trust and other special use funds	(523,573)	(461,602)
Other	(3,563)	(1,261)
Net cash flow used for investing activities	(844,547)	(905,518)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	794,981	295,245
Short-term borrowing and payments — net	2,900	0
Short-term debt borrowings	0	25,000
Short-term debt repayments	0	(25,000)
Repayment of long-term debt	(500,000)	(82,000)
Dividends paid on common stock	(248,300)	(233,300)
Distributions to noncontrolling interests	(11,372)	(11,372)
Net cash flow provided by financing activities	38,209	(31,427)
NET INCREASE IN CASH AND CASH EQUIVALENTS	23,835	50,974
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	5,707	13,851
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 29,542	$ 64,825

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Revenue (Tables)

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table provides detail of Pinnacle West's consolidated revenue disaggregated by revenue sources (dollars in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Retail Electric Revenue
Residential	$	668,467	$	695,480	$	1,452,601	$	1,512,402
Non-Residential	465,602		496,809		1,194,199		1,275,498
Wholesale energy sales	36,775		53,501		95,218		80,982
Transmission services for others	15,841		15,902		46,247		46,235
Other sources	4,102		6,342		12,553		19,754
Total operating revenues	$	1,190,787	$	1,268,034	$	2,800,818	$	2,934,871

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Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Lease cost

The following tables provide information related to our lease costs for the three and nine months ended September 30, 2019 (dollars in thousands):

	Three Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	21,095	$	4,581	$	25,676
Variable lease cost	36,917		183		37,100
Short-term lease cost	—		812		812
Total lease cost	$	58,012	$	5,576	$	63,588

	Nine Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	35,159	$	13,343	$	48,502
Variable lease cost	95,736		543		96,279
Short-term lease cost	—		3,477		3,477
Total lease cost	$	130,895	$	17,363	$	148,258

The following tables provide other additional information related to operating lease liabilities:

	September 30, 2019
Weighted average remaining lease term	12 years
Weighted average discount rate (a)	3.73	%

(a) Most of our lease agreements do not contain an implicit rate that is readily determinable. For these agreements we use our incremental borrowing rate to measure the present value of lease liabilities.  We determine our incremental borrowing rate at lease commencement based on the rate of interest that we would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. We use the implicit rate when it is readily determinable.

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows (dollars in thousands):	$	51,980

Schedule of future minimum payments

The following table provides information related to the maturity of our operating lease liabilities at September 30, 2019 (dollars in thousands):

	September 30, 2019
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019 (remaining three months of 2019)	$	13,625	$	3,352	$	16,977
2020	—		14,083		14,083
2021	—		11,244		11,244
2022	—		7,727		7,727
2023	—		6,101		6,101
2024	—		3,915		3,915
Thereafter	—		38,697		38,697
Total lease commitments	13,625		85,119		98,744
Less imputed interest	19		20,032		20,051
Total lease liabilities	$	13,606	$	65,087	$	78,693

We recognize lease assets and liabilities upon lease commencement. At September 30, 2019, we have additional lease arrangements that have been executed, but have not yet commenced. These arrangements primarily relate to purchased power lease contracts. These leases have commencement dates beginning in June 2020 with terms ending through October 2027. We expect the total fixed consideration paid for these arrangements, which includes both lease and nonlease payments, will approximate $705 million over the term of the arrangements.

The following table provides information related to estimated future minimum operating lease payments at December 31, 2018 (dollars in thousands):

	December 31, 2018
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019	$	54,499	$	13,747	$	68,246
2020	—		12,428		12,428
2021	—		9,478		9,478
2022	—		6,513		6,513
2023	—		5,359		5,359
Thereafter	—		42,236		42,236
Total future lease commitments	$	54,499	$	89,761	$	144,260

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Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2019

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 the three and nine months ended September 30, 2019 and 2018 (in thousands, except per share amounts):

	Three Months Ended  September 30,				Nine Months Ended   September 30,
	2019		2018		2019		2018
Net income attributable to common shareholders	$	312,276	$	315,012	$	474,339	$	484,971
Weighted average common shares outstanding — basic	112,463		112,148		112,408		112,094
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units	283		385		331		405
Weighted average common shares outstanding — diluted	112,746		112,533		112,739		112,499
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders — basic	$	2.78	$	2.81	$	4.22	$	4.33
Net income attributable to common shareholders — diluted	$	2.77	$	2.80	$	4.21	$	4.31

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Retirement Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2019

Retirement Benefits [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 or billed to electric plant participants) (dollars in thousands):

	Pension Benefits												Other Benefits
	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018			2019			2018			2019			2018
Service cost — benefits earned during the period	$	12,476		$	14,167		$	37,427		$	42,501		$	4,593		$	5,275		$	13,777		$	15,825
Non-service costs (credits):
Interest cost on benefit obligation	34,211			31,172			102,632			93,517			7,473			7,037			22,420			21,111
Expected return on plan assets	(42,971		)	(45,713		)	(128,913		)	(137,140		)	(9,603		)	(10,520		)	(28,809		)	(31,561		)
Amortization of:
Prior service credit	—			—			—			—			(9,456		)	(9,461		)	(28,366		)	(28,382		)
Net actuarial loss	10,646			8,021			31,938			24,062			—			—			—			—
Net periodic benefit cost (credit)	$	14,362		$	7,647		$	43,084		$	22,940		$	(6,993	)	$	(7,669	)	$	(20,978	)	$	(23,007	)
Portion of cost (credit) charged to expense	$	7,593		$	2,524		$	22,837		$	7,535		$	(4,966	)	$	(5,359	)	$	(14,846	)	$	(16,083	)

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Long-Term Debt and Liquidity Matters

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Long-Term Debt and Liquidity Matters

Long-Term Debt and Liquidity Matters

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.

Pinnacle West

On May 9, 2019, Pinnacle West entered into a $50 million term loan agreement that matures May 7, 2020. Pinnacle West used the proceeds to refinance indebtedness under and terminate a prior $150 million revolving credit facility. Borrowings under the agreement bear interest at London Inter-bank Offered Rate ("LIBOR") plus 0.55% per annum. At September 30, 2019, Pinnacle West had $41 million in outstanding borrowings under the agreement.

At September 30, 2019, Pinnacle West had a $200 million revolving credit facility that matures in July 2023. 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. Interest rates are based on Pinnacle West's senior unsecured debt credit ratings. The facility is available to support Pinnacle West's $200 million commercial paper program, for bank borrowings or for issuances of letters of credits. At September 30, 2019, Pinnacle West had no outstanding borrowings under its credit facility, no letters of credit outstanding and $13 million of commercial paper borrowings.

APS

On February 26, 2019, APS entered into a $200 million term loan agreement that matures August 26, 2020. APS used the proceeds to repay existing indebtedness. Borrowings under the agreement bear interest at LIBOR plus 0.50% per annum.

On February 28, 2019, APS issued $300 million of 4.25% unsecured senior notes that mature on March 1, 2049. The net proceeds from the sale, together with funds made available from the term loan described above, were used to repay existing indebtedness.

On March 1, 2019, APS repaid at maturity $500 million aggregate principal amount of its 8.75% senior notes.

On August 19, 2019, APS issued $300 million of 2.6% unsecured senior notes that mature on August 15, 2029. The net proceeds from the sale were used to repay short-term indebtedness, consisting of commercial paper borrowings, and to replenish cash used to fund capital expenditures.

At September 30, 2019, APS had two revolving credit facilities totaling $1 billion, including a $500 million credit facility that matures in June 2022 and a $500 million facility that matures in July 2023.  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 September 30, 2019, APS had $3 million of commercial paper outstanding and no outstanding borrowings or letters of credit under its revolving credit facilities.

See "Financial Assurances" in Note 8 for a discussion of other outstanding letters of credit.

Debt Fair Value

Our long-term debt fair value estimates are classified within Level 2 of the fair value hierarchy. The following table presents the estimated fair value of our long-term debt, including current maturities (dollars in thousands):

	As of September 30, 2019				As of December 31, 2018
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Pinnacle West	$	449,268	$	449,670	$	448,796	$	443,955
APS	4,985,728		5,617,727		4,689,436		4,789,608
Total	$	5,434,996	$	6,067,397	$	5,138,232	$	5,233,563

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Derivative Accounting

9 Months Ended

Sep. 30, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Accounting

Derivative Accounting

Derivative financial instruments are used to manage exposure to commodity price and transportation costs of electricity, natural gas, emissions allowances, and in interest rates.  Risks associated with market volatility are managed 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.  Derivative instruments are also entered into for economic hedging purposes.  While economic hedges may 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 Condensed 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 sheets as an asset or liability and are measured at fair value.  See Note 11 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.

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 4).  Gains and losses from derivatives in the following tables represent the amounts reflected in income before the effect of PSA deferrals.

As of September 30, 2019 and December 31, 2018, we had the following outstanding gross notional volume of derivatives, which represent both purchases and sales (does not reflect net position): 

		Quantity
Commodity	Unit of Measure	September 30, 2019	December 31, 2018
Power	GWh	232	250
Gas	Billion cubic feet	187	218

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

 

	Financial Statement Location	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts		2019			2018			2019			2018
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized) (a)	Fuel and purchased power (b)	$	(289	)	$	(600	)	$	(1,263	)	$	(1,697	)

(a) During the three and nine months ended September 30, 2019 and 2018, we had no gains or 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 approximately $1 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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

 

	Financial Statement Location	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts		2019			2018			2019			2018
Net Loss Recognized in Income	Operating revenues	$	—		$	(1,029	)	$	—		$	(2,590	)
Net Gain (Loss) Recognized in Income	Fuel and purchased power (a)	(28,249		)	4,263			(69,765		)	(26,442		)
Total		$	(28,249	)	$	3,234		$	(69,765	)	$	(29,032	)

(a) Amounts are before the effect of PSA deferrals.

Derivative Instruments in the Condensed 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 Condensed Consolidated Balance Sheets.  Transactions that do not allow for offsetting of positive and negative positions are reported gross on the Condensed 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 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 September 30, 2019 and December 31, 2018.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Condensed Consolidated Balance Sheets.

As of September 30, 2019: (dollars in thousands)	Gross  Recognized  Derivatives  (a)			Amounts Offset  (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	1,776		$	(1,266	)	$	510		$	307		$	817
Total assets	1,776			(1,266		)	510			307			817
Current liabilities	(44,429		)	1,266			(43,163		)	(1,186		)	(44,349		)
Deferred credits and other	(27,305		)	—			(27,305		)	—			(27,305		)
Total liabilities	(71,734		)	1,266			(70,468		)	(1,186		)	(71,654		)
Total	$	(69,958	)	$	—		$	(69,958	)	$	(879	)	$	(70,837	)

(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 $1,186 and cash margin provided to counterparties of $307.

As of December 31, 2018: (dollars in thousands)	Gross Recognized Derivatives  (a)			Amounts Offset (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	3,106		$	(2,149	)	$	957		$	156		$	1,113
Investments and other assets	36			(36		)	—			—			—
Total assets	3,142			(2,185		)	957			156			1,113
Current liabilities	(36,345		)	2,149			(34,196		)	(1,310		)	(35,506		)
Deferred credits and other	(24,567		)	36			(24,531		)	—			(24,531		)
Total liabilities	(60,912		)	2,185			(58,727		)	(1,310		)	(60,037		)
Total	$	(57,770	)	$	—		$	(57,770	)	$	(1,154	)	$	(58,924	)

(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 $1,310 and cash margin provided to counterparties of $156.

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 September 30, 2019, we have one counterparty for which our exposure represents approximately 62% of Pinnacle West’s $0.8 million of risk management assets. This exposure relates to a master agreement with a counterparty that has a very high credit rating. Our risk management process assesses and monitors the financial exposure of all counterparties.  Despite the fact that the great majority of our trading counterparties' debt is rated as investment grade by the credit rating agencies, there is still a possibility that one or more of these counterparties 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 September 30, 2019 (dollars in thousands):

	September 30, 2019
Aggregate fair value of derivative instruments in a net liability position	$	71,503
Cash collateral posted	—
Additional cash collateral in the event credit-risk-related contingent features were fully triggered (a)	70,230

(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 $95 million if our debt credit ratings were to fall below investment grade.

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Leases - Maturity of our operating lease liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
2019 (remaining three months of 2019)	$ 16,977
2019			$ 68,246
2020	14,083		12,428
2021	11,244		9,478
2022	7,727		6,513
2023	6,101		5,359
2024	3,915
Thereafter	38,697
Thereafter			42,236
Total lease commitments	98,744		144,260
Less imputed interest	20,051
Total lease liabilities	78,693	$ 119,000
Purchased Power Lease Contracts
Lessee, Lease, Description [Line Items]
2019 (remaining three months of 2019)	13,625
2019			54,499
2020	0		0
2021	0		0
2022	0		0
2023	0		0
2024	0
Thereafter	0
Thereafter			0
Total lease commitments	13,625		54,499
Less imputed interest	19
Total lease liabilities	13,606
Land, Property & Equipment Leases
Lessee, Lease, Description [Line Items]
2019 (remaining three months of 2019)	3,352
2019			13,747
2020	14,083		12,428
2021	11,244		9,478
2022	7,727		6,513
2023	6,101		5,359
2024	3,915
Thereafter	38,697
Thereafter			42,236
Total lease commitments	85,119		$ 89,761
Less imputed interest	20,032
Total lease liabilities	$ 65,087

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Retirement Plans and Other Postretirement Benefits - Schedule of Net Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Amortization of:
Portion of cost (credit) charged to expense	$ (5,752)	$ (12,449)	$ (17,240)	$ (37,314)
Pension Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	12,476	14,167	37,427	42,501
Interest cost on benefit obligation	34,211	31,172	102,632	93,517
Expected return on plan assets	(42,971)	(45,713)	(128,913)	(137,140)
Amortization of:
Prior service credit	0	0	0	0
Net actuarial loss	10,646	8,021	31,938	24,062
Net periodic benefit cost (credit)	14,362	7,647	43,084	22,940
Portion of cost (credit) charged to expense	7,593	2,524	22,837	7,535
Other Benefits
Retirement Plans and Other Benefits
Service cost — benefits earned during the period	4,593	5,275	13,777	15,825
Interest cost on benefit obligation	7,473	7,037	22,420	21,111
Expected return on plan assets	(9,603)	(10,520)	(28,809)	(31,561)
Amortization of:
Prior service credit	(9,456)	(9,461)	(28,366)	(28,382)
Net actuarial loss	0	0	0	0
Net periodic benefit cost (credit)	(6,993)	(7,669)	(20,978)	(23,007)
Portion of cost (credit) charged to expense	$ (4,966)	$ (5,359)	$ (14,846)	$ (16,083)

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Derivative Accounting - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivative Accounting
Derivative liability	$ 71,654,000	$ 71,654,000		$ 71,654,000		$ 60,037,000
Commodity Contracts
Derivative Accounting
Derivative liability	71,654,000	71,654,000		71,654,000		$ 60,037,000
Additional collateral to counterparties for energy related non-derivative instrument contracts	$ 95,000,000	95,000,000		95,000,000
Commodity Contracts | Designated as Hedging Instruments
Derivative Accounting
Amount reclassified from accumulated other comprehensive income to earnings related to discontinued cash flow hedges		$ 0	$ 0	0	$ 0
Estimated loss before income taxes to be reclassified from accumulated other comprehensive income				$ 1,000,000
APS
Derivative Accounting
Percentage of unrealized gains and losses on certain derivatives deferred for future rate treatment	100.00%	100.00%		100.00%
Risk Management Assets | Credit Concentration Risk
Derivative Accounting
Concentration risk	62.00%
Derivative liability	$ 800,000	$ 800,000		$ 800,000

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Derivative Accounting - Credit Risk and Credit Related Contingent Features (Details) - Commodity Contracts $ in Thousands	Sep. 30, 2019 USD ($)
Credit Risk and Credit-Related Contingent Features
Aggregate fair value of derivative instruments in a net liability position	$ 71,503
Cash collateral posted	0
Additional cash collateral in the event credit-risk-related contingent features were fully triggered	$ 70,230

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Other Income and Other Expense (Tables)

9 Months Ended

Sep. 30, 2019

Other Income and Expenses [Abstract]

Detail of other income and other expense

The following table provides detail of Pinnacle West's Consolidated other income and other expense for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Other income:
Interest income	$	2,694		$	1,957		$	7,695		$	6,256
Debt return on Four Corners SCR (Note 4)	4,920			4,910			14,651			11,190
Debt return on Ocotillo modernization project (Note 4)	7,555			—			12,849			—
Miscellaneous	22			91			50			95
Total other income	$	15,191		$	6,958		$	35,245		$	17,541
Other expense:
Non-operating costs	$	(2,647	)	$	(2,480	)	$	(8,832	)	$	(7,404	)
Investment losses — net	(716		)	—			(1,445		)	(268		)
Miscellaneous	(2,377		)	(2,583		)	(4,171		)	(4,391		)
Total other expense	$	(5,740	)	$	(5,063	)	$	(14,448	)	$	(12,063	)

The following table provides detail of APS’s other income and other expense for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Other income:
Interest income	$	2,037		$	1,151		$	5,091		$	4,874
Debt return on Four Corners SCR (Note 4)	4,920			4,910			14,651			11,190
Debt return on Ocotillo modernization project (Note 4)	7,555			—			12,849			—
Miscellaneous	22			92			50			96
Total other income	$	14,534		$	6,153		$	32,641		$	16,160
Other expense:
Non-operating costs	$	(2,448	)	$	(2,334	)	$	(7,965	)	$	(6,931	)
Miscellaneous	(378		)	(1,027		)	(2,167		)	(2,748		)
Total other expense	$	(2,826	)	$	(3,361	)	$	(10,132	)	$	(9,679	)

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Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2019

Regulated Operations [Abstract]

Schedule of capital structure and cost of capital

the following proposed capital structure and costs of capital:

	Capital Structure		Cost of Capital
Long-term debt	45.3	%	4.10	%
Common stock equity	54.7	%	10.15	%
Weighted-average cost of capital			7.41	%

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 for 2019 and 2018 (dollars in thousands):

	Nine Months Ended September 30,
	2019			2018
Beginning balance	$	37,164		$	75,637
Deferred fuel and purchased power costs — current period	60,911			82,486
Amounts charged to customers	(38,601		)	(92,397		)
Ending balance	$	59,474		$	65,726

Schedule of regulatory assets

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

	Amortization Through	September 30, 2019				December 31, 2018
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	703,460	$	—	$	733,351
Retired power plant costs	2033	28,182		146,076		28,182		167,164
Income taxes — allowance for funds used during construction ("AFUDC") equity	2049	6,457		154,269		6,457		151,467
Deferred fuel and purchased power — mark-to-market (Note 7)	2023	41,643		27,305		31,728		23,768
Deferred property taxes	2027	8,569		60,338		8,569		66,356
Deferred fuel and purchased power (b) (c)	2020	59,474		—		37,164		—
SCR deferral	N/A	—		45,296		—		23,276
Four Corners cost deferral	2024	8,077		34,171		8,077		40,228
Deferred compensation	2036	—		37,589		—		36,523
Lost fixed cost recovery (b)	2020	25,775		—		32,435		—
Income taxes — investment tax credit basis adjustment	2047	1,079		24,555		1,079		25,522
Ocotillo deferral	N/A	—		23,643		—		—
Palo Verde VIEs (Note 6)	2046	—		20,480		—		20,015
Coal reclamation	2026	1,546		18,821		1,546		15,607
Loss on reacquired debt	2038	1,637		12,441		1,637		13,668
Mead-Phoenix transmission line CIAC	2050	332		9,795		332		10,044
TCA balancing account (b)	2021	5,016		2,721		3,860		772
Tax expense of Medicare subsidy	2024	1,235		5,073		1,235		6,176
AG-1 deferral	2022	2,787		3,413		2,654		5,819
Tax expense adjuster mechanism (b)	2019	2,916		—		—		—
Other	Various	2,782		—		1,947		3,185
Total regulatory assets (d)		$	197,507	$	1,329,446	$	166,902	$	1,342,941

(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 other comprehensive income ("OCI") and result in lower future revenues.

(b) See "Cost Recovery Mechanisms" discussion above.

(c) Subject to a carrying charge.

(d)

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	September 30, 2019				December 31, 2018
		Current		Non-Current		Current		Non-Current
Excess deferred income taxes - ACC - Tax Cuts and Jobs Act (a)	(b)	$	38,529	$	1,178,216	$	—	$	1,272,709
Excess deferred income taxes - FERC - Tax Cuts and Jobs Act (a)	2058	6,302		238,064		6,302		243,691
Asset retirement obligations	2057	—		367,930		—		278,585
Removal costs	(c)	47,459		151,535		39,866		177,533
Other postretirement benefits	(d)	37,821		95,789		37,864		125,903
Income taxes — change in rates	2048	2,764		67,605		2,769		70,069
Spent nuclear fuel	2027	5,746		53,229		6,503		57,002
Income taxes — deferred investment tax credit	2047	2,164		49,182		2,164		51,120
Four Corners coal reclamation	2038	1,858		49,194		1,858		17,871
Renewable energy standard (b)	2021	42,146		5,675		44,966		20
Demand side management (b)	2021	14,300		24,146		14,604		4,123
Sundance maintenance	2031	4,640		13,393		1,278		17,228
Deferred gains on utility property	2022	2,923		4,766		4,423		6,581
Property tax deferral	N/A	—		6,288		—		2,611
FERC transmission true up	2021	—		2,586		—		—
Other	Various	1,370		2,533		3,279		930
Total regulatory liabilities		$	208,022	$	2,310,131	$	165,876	$	2,325,976

(a) For purposes of presentation on the Statement of Cash Flows, amortization of the regulatory liabilities for excess deferred income taxes are reflected as "Deferred income taxes" under Cash Flows From Operating Activities.

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

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

(d)

See Note 5.

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Changes in Accumulated Other Comprehensive Loss (Tables)

9 Months Ended

Sep. 30, 2019

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Schedule of changes in accumulated other comprehensive loss including reclassification adjustments, net of tax, 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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Three Months Ended September 30
Balance June 30, 2019	$	(46,657	)		$	(979	)		$	(47,636	)
Amounts reclassified from accumulated other comprehensive loss	880			(a)	218			(b)	1,098
Balance September 30, 2019	$	(45,777	)		$	(761	)		$	(46,538	)
Balance June 30, 2018	$	(54,233	)		$	(2,391	)		$	(56,624	)
Amounts reclassified from accumulated other comprehensive loss	1,099			(a)	451			(b)	1,550
Balance September 30, 2018	$	(53,134	)		$	(1,940	)		$	(55,074	)

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Nine Months Ended September 30
Balance December 31, 2018	$	(45,997	)		$	(1,711	)		$	(47,708	)
OCI (loss) before reclassifications	(2,422		)		—				(2,422		)
Amounts reclassified from accumulated other comprehensive loss	2,642			(a)	950			(b)	3,592
Balance September 30, 2019	$	(45,777	)		$	(761	)		$	(46,538	)
Balance December 31, 2017	$	(42,440	)		$	(2,562	)		$	(45,002	)
OCI (loss) before reclassifications	(5,928		)		(96		)		(6,024		)
Amounts reclassified from accumulated other comprehensive loss	3,188			(a)	1,316			(b)	4,504
Reclassification of income tax effect related to tax reform	(7,954		)	(c)	(598		)	(c)	(8,552		)
Balance September 30, 2018	$	(53,134	)		$	(1,940	)		$	(55,074	)

(a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost.  See Note 5.

(b) 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 7.

(c)

In 2018, the company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

The following table shows the changes in APS's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands): 

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Three Months Ended September 30
Balance June 30, 2019	$	(26,297	)		$	(979	)		$	(27,276	)
Amounts reclassified from accumulated other comprehensive loss	755			(a)	218			(b)	973
Balance September 30, 2019	$	(25,542	)		$	(761	)		$	(26,303	)
Balance June 30, 2018	$	(32,768	)		$	(2,391	)		$	(35,159	)
Amounts reclassified from accumulated other comprehensive loss	952			(a)	451			(b)	1,403
Balance September 30, 2018	$	(31,816	)		$	(1,940	)		$	(33,756	)

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Nine Months Ended September 30
Balance December 31, 2018	$	(25,396	)		$	(1,711	)		$	(27,107	)
OCI (loss) before reclassifications	(2,414		)		—				(2,414		)
Amounts reclassified from accumulated other comprehensive loss	2,268			(a)	950			(b)	3,218
Balance September 30, 2019	$	(25,542	)		$	(761	)		$	(26,303	)
Balance December 31, 2017	$	(24,421	)		$	(2,562	)		$	(26,983	)
OCI (loss) before reclassifications	(5,791		)		(96		)		(5,887		)
Amounts reclassified from accumulated other comprehensive loss	2,836			(a)	1,316			(b)	4,152
Reclassification of income tax effect related to tax reform	(4,440		)	(c)	(598		)	(c)	(5,038		)
Balance September 30, 2018	$	(31,816	)		$	(1,940	)		$	(33,756	)

(a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost.  See Note 5.

(b) 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 7.

(c)

In 2018, the company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

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Regulatory Matters

9 Months Ended

Sep. 30, 2019

Regulated Operations [Abstract]

Regulatory Matters

Regulatory Matters

2019 Retail Rate Case Filing with the Arizona Corporation Commission

On October 31, 2019, APS filed an application with the ACC for an annual increase in retail base rates of $69 million. This amount includes recovery of the deferral and rate base effects of the Four Corners selective catalytic reduction ("SCR") project that is currently the subject of a separate proceeding (see “SCR Cost Recovery” below). It also reflects a net credit to base rates of approximately $115 million primarily due to the prospective inclusion of rate refunds currently provided through the Tax Expense Adjustment Mechanism ("TEAM"). The proposed total revenue increase in APS's application is $184 million. The average annual customer bill impact of APS’s request is an increase of 5.6% (the average annual bill impact for a typical APS residential customer is 5.4%).

The principal provisions of APS's application are:

• a test year comprised of twelve months ended June 30, 2019, adjusted as described below;

• an original cost rate base of $8.87 billion, which approximates the ACC-jurisdictional portion of the book value of utility assets, net of accumulated depreciation and other credits;

• the following proposed capital structure and costs of capital:

	Capital Structure		Cost of Capital
Long-term debt	45.3	%	4.10	%
Common stock equity	54.7	%	10.15	%
Weighted-average cost of capital			7.41	%

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

• authorization to defer until APS'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;

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

▪ a super off-peak period during the winter months for APS’s time-of-use with demand rates;

▪ additional $1.25 million in funding for limited-income crisis bill program; and

▪ a flat bill/subscription rate pilot program;

• proposed rate design changes for commercial customers, including an experimental program designed to provide access to market pricing for up to 200 MW of medium and large commercial customers;

• recovery of the deferral and rate base effects of the construction and operating costs of the Ocotillo modernization project (see below discussion of the 2017 Settlement Agreement); and

• continued recovery of the remaining investment and other costs related to the retirement and closure of the Navajo Generating Station (the "Navajo Plant") (see "Navajo Plant" below).

APS requested that the increase become effective December 1, 2020.  APS cannot predict the outcome of its request.

2016 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. On March 27, 2017, a majority of the stakeholders in the general retail rate case, including the ACC Staff, the Residential Utility Consumer Office, limited income advocates and private rooftop solar organizations signed a settlement agreement (the "2017 Settlement Agreement") and filed it with the ACC. The 2017 Settlement Agreement provides for a net retail base rate increase of $94.6 million, excluding the transfer of adjustor balances, consisting of: (1) a non-fuel, non-depreciation, base rate increase of $87.2 million per year; (2) a base rate decrease of $53.6 million attributable to reduced fuel and purchased power costs; and (3) a base rate increase of $61.0 million due to changes in depreciation schedules. The average annual customer bill impact under the 2017 Settlement Agreement was calculated as an increase of 3.28% (the average annual bill impact for a typical APS residential customer was calculated as an increase of 4.54%).

Other key provisions of the agreement include the following:

• an agreement by APS not to file another general retail rate case application before June 1, 2019;

• an authorized return on common equity of 10.0%;

• a capital structure comprised of 44.2% debt and 55.8% common equity;

• a cost deferral order for potential future recovery in APS’s next general retail rate case for the construction and operating costs APS incurs for its Ocotillo modernization project;

• a cost deferral and procedure to allow APS to request rate adjustments prior to its next general retail rate case related to its share of the construction costs associated with installing SCR equipment at the Four Corners Power Plant ("Four Corners");

• a deferral for future recovery (or credit to customers) of the Arizona property tax expense above or below a specified test year level caused by changes to the applicable Arizona property tax rate;

• an expansion of the Power Supply Adjustor (“PSA”) to include certain environmental chemical costs and third-party energy storage costs;

• a new AZ Sun II program (now known as "APS Solar Communities") for utility-owned solar distributed generation with the purpose of expanding access to rooftop solar for low and moderate income Arizonans, recoverable through the Arizona Renewable Energy Standard and Tariff ("RES"), to be no less than $10 million per year, and not more than $15 million per year;

• an increase to the per kWh cap for the environmental improvement surcharge from $0.00016 to $0.00050 and the addition of a balancing account;

• rate design changes, including:

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

▪ non-grandfathered distributed generation ("DG") customers would be required to select a rate option that has time of use rates and either a new grid access charge or demand component;

▪ a Resource Comparison Proxy (“RCP”) for exported energy of 12.9 cents per kWh in year one; and

• an agreement by APS not to pursue any new self-build generation (with certain exceptions) having an in-service date prior to January 1, 2022 (extended to December 31, 2027 for combined-cycle generating units), unless expressly authorized by the ACC.

Through a separate agreement, APS, industry representatives, and solar advocates committed to stand by the 2017 Settlement Agreement and refrain from seeking to undermine it through ballot initiatives, legislation or advocacy at the ACC.

On August 15, 2017, the ACC approved (by a vote of 4-1), the 2017 Settlement Agreement without material modifications.  On August 18, 2017, the ACC issued a final written Opinion and Order reflecting its decision in APS’s general retail rate case (the "2017 Rate Case Decision"), which is subject to requests for rehearing and potential appeal. The new rates went into effect on August 19, 2017.

On October 17, 2017, Warren Woodward (an intervener in APS's general retail rate case) filed a Notice of Appeal in the Arizona Court of Appeals, Division One. The notice raises a single issue related to the application of certain rate schedules to new APS residential customers after May 1, 2018. Mr. Woodward filed a second notice of appeal on November 13, 2017 challenging APS’s $5 per month automated metering infrastructure opt-out program. Mr. Woodward’s two appeals were consolidated, and APS requested and was granted intervention. The Arizona Court of Appeals issued a Memorandum Decision on December 11, 2018 affirming the ACC decisions challenged by Mr. Woodward. Mr. Woodward filed a petition for review with the Arizona Supreme Court on January 9, 2019. The Arizona Supreme Court denied review.

On January 3, 2018, an APS customer filed a petition with the ACC that was determined by the ACC Staff to be a complaint filed pursuant to Arizona Revised Statute §40-246 (the “Complaint”) and not a request for rehearing. Arizona Revised Statute §40-246 requires the ACC to hold a hearing regarding any complaint alleging that a public service corporation is in violation of any commission order or that the rates being charged are not just and reasonable if the complaint is signed by at least twenty-five customers of the public service corporation. The Complaint alleged that APS is “in violation of commission order” [sic]. On February 13, 2018, the complainant filed an amended Complaint alleging that the rates and charges in the 2017 Rate Case Decision are not just and reasonable.  The complainant requested that the ACC hold a hearing on the amended Complaint to determine if the average bill impact on residential customers of the rates and charges approved in the 2017 Rate Case Decision is greater than 4.54% (the average annual bill impact for a typical APS residential customer estimated by APS) and, if so, what effect the alleged greater bill impact has on APS's revenues and the overall reasonableness and justness of APS's rates and charges, in order to determine if there is sufficient evidence to warrant a full-scale rate hearing.  The ACC held a hearing on this matter beginning in September 2018 and the hearing was concluded on October 1, 2018. On April 9, 2019, the Administrative Law Judge issued a Recommended Opinion and Order recommending that the Complaint be dismissed. The ACC considered the matter at its April and May 2019 open meetings, but no decision was issued. On July 3, 2019, the Administrative Law Judge issued an amendment to the Recommended Opinion and Order that incorporated the requirements of the rate review of the 2017 Rate Case Decision (see below discussion regarding the rate review). On July 10, 2019, the ACC reconsidered the matter and adopted the Administrative Law Judge's amended Recommended Opinion and Order along with several ACC Commissioner amendments and an amendment incorporating the results of the rate review and resolved the Complaint.

On December 24, 2018, certain ACC Commissioners filed a letter stating that because the ACC had received a substantial number of complaints that the rate increase authorized by the 2017 Rate Case Decision was much more than anticipated, they believe there is a possibility that APS is earning more than was authorized by the 2017 Rate Case Decision.  Accordingly, the ACC Commissioners requested the ACC Staff to perform a rate review of APS using calendar year 2018 as a test year and file a report by May 3, 2019. The ACC Commissioners also asked the ACC Staff to evaluate APS’s efforts to educate its customers regarding the new rates approved in the 2017 Rate Case Decision. On April 23, 2019, the ACC Staff indicated that they would need additional time beyond May 3, 2019 to file the requested report.

On June 4, 2019, the ACC Staff filed a proposed order regarding the rate review of the 2017 Rate Case Decision. On June 11, 2019, the ACC Commissioners approved the proposed ACC Staff order with amendments. The key provisions of the amended order include the following:

• APS must file a rate case no later than October 31, 2019, using a June 30, 2019 test-year;

• until the conclusion of the rate case being filed no later than October 31, 2019, APS must provide information on customer bills that shows how much a customer would pay on their most economical rate given their actual usage during each month;

• APS customers can switch rate plans during an open enrollment period of six months;

• APS must identify customers whose bills have increased by more than 9% and that are not on the most economical rate and provide such customers with targeted education materials and an opportunity to switch rate plans;

• APS must provide grandfathered net metering customers on legacy demand rates an opportunity to switch to another legacy rate to enable such customers to fully benefit from legacy net metering rates;

• APS must fund and implement a supplemental customer education and outreach program to be developed with and administered by ACC Staff and a third-party consultant; and

• APS must fund and organize, along with the third-party consultant, a stakeholder group to suggest better ways to communicate the impact of changes to adjustor cost recovery mechanisms (see below for discussion on cost recovery mechanisms), including more effective ways to educate customers on rate plans and to reduce energy usage.

APS cannot predict the outcome or impact of the rate case filed on October 31, 2019. APS is assessing the impact to its financial statements of the implementation of the other key provisions of the amended order regarding the rate review and cannot predict at this time whether they will have a material impact on its financial position, results of operations or cash flows. 

Cost Recovery Mechanisms

APS has received regulatory decisions that allow for more timely recovery of certain costs outside of a general retail rate case 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 2015, the ACC revised the RES rules to allow the ACC to consider all available information, including the number of rooftop solar arrays in a utility’s service territory, to determine compliance with the RES.

On June 30, 2017, APS filed its 2018 RES Implementation Plan and proposed a budget of approximately $90 million.  APS’s budget request supports existing approved projects and commitments and includes the anticipated transfer of specific revenue requirements into base rates in accordance with the 2017 Settlement Agreement and also requests a permanent waiver of the residential distributed energy requirement for 2018 contained in the RES rules. APS's 2018 RES budget request is lower than the 2017 RES budget due in part to a certain portion of the RES being collected by APS in base rates rather than through the RES adjustor.

On November 20, 2017, APS filed an updated 2018 RES budget to include budget adjustments for APS Solar Communities (formerly known as AZ Sun II), which was approved as part of the 2017 Rate Case Decision. APS Solar Communities is a 3-year program authorizing APS to spend $10 million to $15 million in capital costs each year to install utility-owned DG systems for low to moderate income residential homes, buildings of non-profit entities, Title I schools and rural government facilities. The 2017 Rate Case Decision provided that all operations and maintenance expenses, property taxes, marketing and advertising expenses, and the capital carrying costs for this program will be recovered through the RES. On June 12, 2018, the ACC approved the 2018 RES Implementation Plan including a waiver of the distributed energy requirements for the 2018 implementation year.

On June 29, 2018, APS filed its 2019 RES Implementation Plan and proposed a budget of approximately $89.9 million.  APS’s budget request supports existing approved projects and commitments and requests a permanent waiver of the residential distributed energy requirement for 2019 contained in the RES rules. On October 29, 2019, the ACC approved the 2019 RES Implementation Plan.

On July 1, 2019, APS filed its 2020 RES Implementation Plan and proposed a budget of approximately $86.3 million. APS’s budget request supports existing approved projects and commitments and requests a permanent waiver of the residential distributed energy requirement for 2020 contained in the RES rules. The ACC has not yet ruled on the 2020 RES Implementation Plan.

On July 2, 2019, ACC Staff issued draft rules, which propose a RES goal of 45% of retail energy served be renewable by 2035 and a goal of 20% of retail sales during peak demand to be from clean energy resources by 2035.  The draft rules would also require a certain amount of the RES goal to be derived from distributed renewable storage, for which utilities would be required to offer performance-based incentives. Nuclear energy would be considered a clean resource under the draft rules. See "Energy Modernization Plan" below for more information.

Demand Side Management Adjustor Charge.  The ACC Electric Energy Efficiency Standards require APS to submit a Demand Side Management Implementation Plan ("DSM Plan") annually for review by and approval of the ACC. Verified energy savings from APS's resource savings projects can be counted toward compliance with the Electric Energy Efficiency Standards; however, APS is not allowed to count savings from systems savings projects toward determination of the achievement of performance incentives, nor may APS include savings from these system savings projects in the calculation of its Lost Fixed Cost Recovery (“LFCR”) mechanism (see below for discussion of the LFCR).

On September 1, 2017, APS filed its 2018 DSM Plan, which proposes modifications to the demand side management portfolio to better meet system and customer needs by focusing on peak demand reductions, storage, load shifting and demand response programs in addition to traditional energy savings measures. The 2018 DSM Plan seeks a requested budget of $52.6 million and requests a waiver of the Electric Energy Efficiency Standard for 2018.   On November 14, 2017, APS filed an amended 2018 DSM Plan, which revised

the allocations between budget items to address customer participation levels, but kept the overall budget at $52.6 million. The ACC has not yet ruled on the APS 2018 amended DSM Plan.

On December 31, 2018, APS filed its 2019 DSM Plan, which requests a budget of $34.1 million and continues APS's focus on DSM strategies such as peak demand reduction, load shifting, storage and electrification strategies. The ACC has not yet ruled on the APS 2019 DSM Plan.

On May 7, 2019, APS filed a request for an extension to file its 2020 DSM Plan no later than December 31, 2019. On July 10, 2019, the ACC approved this request.

 Power Supply Adjustor Mechanism and Balance.  The PSA provides for the adjustment of retail rates to reflect variations primarily in retail fuel and purchased power costs.  The following table shows the changes in the deferred fuel and purchased power regulatory asset for 2019 and 2018 (dollars in thousands):

	Nine Months Ended September 30,
	2019			2018
Beginning balance	$	37,164		$	75,637
Deferred fuel and purchased power costs — current period	60,911			82,486
Amounts charged to customers	(38,601		)	(92,397		)
Ending balance	$	59,474		$	65,726

The PSA rate for the PSA year beginning February 1, 2017 was $(0.001348) per kWh, as compared to $0.001678 per kWh for the prior year.  This rate was comprised of a forward component of $(0.001027) per kWh and a historical component of $(0.000321) per kWh. On August 19, 2017 the PSA rate was revised to $0.000555 per kWh as part of the 2017 Rate Case Decision. This new rate was comprised of a forward component of $0.000876 per kWh and a historical component of $(0.000321) per kWh.

The PSA rate for the PSA year beginning February 1, 2018 is $0.004555 per kWh, consisting of a forward component of $0.002009 per kWh and a historical component of $0.002546 per kWh. This represented a $0.004 per kWh increase over the August 19, 2017 PSA, the maximum permitted under the Plan of Administration for the PSA. This left $16.4 million of 2017 fuel and purchased power costs above this annual cap. These costs rolled over into the following year and were reflected in the 2019 reset of the PSA.

On November 30, 2018, APS filed its PSA rate for the PSA year beginning February 1, 2019. That rate was $0.001658 per kWh and consisted of a forward component of $0.000536 per kWh and a historical component of $0.001122 per kWh. The 2019 PSA rate is a $0.002897 per kWh decrease compared to 2018. These rates went into effect as filed on February 1, 2019.

Transmission Rates, Transmission Cost Adjustor ("TCA") 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 settlement agreement entered into in 2012 regarding APS's rate case (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, 2017, APS's annual wholesale transmission rates for all users of its transmission system increased by approximately $35.1 million for the twelve-month period beginning June 1, 2017 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, 2017.

On March 7, 2018, APS made a filing to make modifications to its annual transmission formula to provide transmission customers the benefit of the reduced federal corporate income tax rate resulting from the Tax Act beginning in its 2018 annual transmission formula rate update filing. These modifications were approved by FERC on May 22, 2018 and reduced APS’s transmission rates compared to the rate that would have gone into effect absent these changes.

Effective June 1, 2018, APS's annual wholesale transmission rates for all users of its transmission system decreased by approximately $22.7 million for the twelve-month period beginning June 1, 2018 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, 2018.

Effective June 1, 2019, APS's annual wholesale transmission rates for all users of its transmission system increased by approximately $4.9 million for the twelve-month period beginning June 1, 2019 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, 2019.

 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 DG such as rooftop solar arrays.  The fixed costs recoverable by the LFCR mechanism were first 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. These amounts were revised in the 2017 Settlement Agreement to 2.5 cents for both lost residential and non-residential kWh.  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 kWhs lost from energy efficiency are based on a third-party evaluation of APS’s energy efficiency programs.  DG sales losses are determined from the metered output from the DG units.

APS filed its 2017 LFCR adjustment on January 13, 2017 requesting an LFCR adjustment of $63.7 million. On April 5, 2017, the ACC approved the 2017 annual LFCR adjustment as filed, effective with the first billing cycle of April 2017. On February 15, 2018, APS filed its 2018 annual LFCR Adjustment, requesting that effective May 1, 2018, the LFCR be adjusted to $60.7 million (a $3 million per year decrease

from 2017 levels). On February 6, 2019, the ACC approved the 2018 annual LFCR adjustment to become effective March 1, 2019. On February 15, 2019, APS filed its 2019 annual LFCR adjustment, requesting that effective May 1, 2019, the annual LFCR recovery amount be reduced to $36.2 million (a $24.5 million decrease from previous levels). On July 10, 2019, the ACC approved APS’s 2019 LFCR adjustment as filed, effective with the next billing cycle of July 2019. Because the LFCR mechanism has a balancing account that trues up any under or over recoveries, the delay in implementation does not have an adverse effect on APS.

Tax Expense Adjustor Mechanism.  As part of the 2017 Settlement Agreement, the parties agreed to a rate adjustment mechanism to address potential federal income tax reform and enable the pass-through of certain income tax effects to customers. The TEAM expressly applies to APS's retail rates with the exception of a small subset of customers taking service under specially-approved tariffs. On December 22, 2017, the Tax Act was enacted.  This legislation made significant changes to the federal income tax laws including a reduction in the corporate tax rate from 35% to 21% effective January 1, 2018.

On January 8, 2018, APS filed an application with the ACC that addressed the change in the marginal federal tax rate from 35% to 21% resulting from the Tax Act and reduced rates by $119.1 million annually through an equal cents per kWh credit ("TEAM Phase I").  On February 22, 2018, the ACC approved the reduction of rates through an equal cents per kWh credit. The rate reduction was effective for the first billing cycle in March 2018.

The impact of the TEAM Phase I, over time, is expected to be earnings neutral. However, on a quarterly basis, there is a difference between the timing and amount of the income tax benefit and the reduction in revenues refunded through the TEAM Phase I related to the lower federal income tax rate. The amount of the benefit of the lower federal income tax rate is based on quarterly pre-tax results, while the reduction in revenues refunded through the TEAM Phase I is based on a per kWh sales credit which follows our seasonal kWh sales pattern and is not impacted by earnings of the Company.

On August 13, 2018, APS filed a second request with the ACC that addressed the return of an additional $86.5 million in tax savings to customers related to the amortization of non-depreciation related excess deferred taxes previously collected from customers ("TEAM Phase II"). The ACC approved this request on March 13, 2019, effective the first billing cycle in April 2019. Both the timing of the reduction in revenues refunded through TEAM Phase II and the offsetting income tax benefit are recognized based upon our seasonal kWh sales pattern.

On April 10, 2019, APS filed a third request with the ACC that addressed the amortization of depreciation related excess deferred taxes over a 28.5 year period (“TEAM Phase III”).  On October 29, 2019, the ACC approved TEAM Phase III providing both (i) a one-time bill credit of $64 million to be credited to customers on their December 2019 bills, and (ii) a monthly bill credit effective the first billing cycle in December 2019 which will provide an additional benefit of $39.5 million to customers through December 31, 2020. It is currently anticipated that benefits related to the amortization of depreciation related excess deferred taxes for periods beginning after December 31, 2020 will be fully incorporated into the 2019 rate case filing.

Net Metering

In 2015, the ACC voted to conduct a generic evidentiary hearing on the value and cost of DG 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 Administrative Law Judge 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 opinion and order by the Administrative Law Judge. After making several amendments, the ACC approved the recommended decision by a 4-1 vote. As a result of the ACC’s action, effective with APS’s 2017 Rate Case Decision, the net metering tariff that governs payments for energy exported to the grid from residential rooftop solar systems was replaced by a more formula-driven approach that utilizes inputs from historical wholesale solar power until an avoided cost methodology is developed by the ACC.

As amended, the decision provides that payments by utilities for energy exported to the grid from DG solar facilities will be determined using a RCP methodology, a method that is based on the most recent five-year rolling average price that APS pays for utility-scale solar projects, while a forecasted avoided cost methodology is being developed.  The price established by this RCP method will be updated annually (between general retail 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 APS 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 September 1, 2017, based on APS's 2017 Rate Case Decision, will be grandfathered for a period of 20 years from the date the customer’s interconnection application was accepted by the utility;

• 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 general retail rate cases, and the policy determinations themselves may be subject to future change, as are all ACC policies. A first-year export energy price of 12.9 cents per kWh was included in the 2017 Settlement Agreement and became effective on September 1, 2017.

In accordance with the 2017 Rate Case Decision, APS filed its request for a second-year export energy price of 11.6 cents per kWh on May 1, 2018.  This price reflected the 10% annual reduction discussed above. The new rate rider became effective on October 1, 2018. APS filed its request for a third-year export energy price of 10.45 cents per kWh on May 1, 2019.  This price also reflects the 10% annual reduction discussed above. The new rate rider became effective on October 1, 2019. The ACC has not yet ruled on this request.

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 asserted 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 filed a Notice of Appeal in the Arizona

Court of Appeals and filed a Complaint and Statutory Appeal in the Maricopa County Superior Court on March 10, 2017. As part of the 2017 Settlement Agreement described above, TASC agreed to withdraw these appeals when the ACC decision implementing the 2017 Settlement Agreement is no longer subject to appellate review.

See "2016 Retail Rate Case Filing with the Arizona Corporation Commission" above for information regarding an ACC order in connection with the rate review of the 2017 Rate Case Decision requiring APS to provide grandfathered net metering customers on legacy demand rates with an opportunity to switch to another legacy rate to enable such customers to benefit from legacy net metering rates.

Subpoena from Arizona Corporation Commissioner Robert Burns

On August 25, 2016, Commissioner Burns, individually and not by action of the ACC as a whole, served subpoenas in APS’s then current retail rate proceeding on 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 the production of all information previously requested through the subpoenas. Neither APS nor Pinnacle West produced the information requested and instead objected to the subpoena. On March 10, 2017, Commissioner Burns filed suit against APS and Pinnacle West in the Superior Court of Arizona for Maricopa County in an effort to enforce his subpoenas. On March 30, 2017, APS filed a motion to dismiss Commissioner Burns' suit against APS and Pinnacle West. In response to the motion to dismiss, the court stayed the suit and ordered Commissioner Burns to file a motion to compel the production of the information sought by the subpoenas with the ACC. On June 20, 2017, the ACC denied the motion to compel.

On August 4, 2017, Commissioner Burns amended his complaint to add all of the ACC Commissioners and the ACC itself as defendants. All defendants moved to dismiss the amended complaint. On February 15, 2018, the Superior Court dismissed Commissioner Burns’ amended complaint. On March 6, 2018, Commissioner Burns filed an objection to the proposed final order from the Superior Court and a motion to further amend his complaint. The Superior Court permitted Commissioner Burns to amend his complaint to add a claim regarding his attempted investigation into whether his fellow commissioners should have been disqualified from voting on APS’s 2017 rate case. Commissioner Burns filed his second amended complaint, and all defendants filed responses opposing the second amended complaint and requested that it be dismissed.

Oral argument occurred in November 2018 regarding the motion to dismiss. On December 18, 2018, the trial court granted the defendants’ motions to dismiss and entered final judgment on January 18, 2019. On February 13, 2019, Commissioner Burns filed a notice of appeal. On July 12, 2019, Commissioner Burns filed his opening brief in the Arizona Court of Appeals. APS filed its answering brief on October 21, 2019. APS and Pinnacle West cannot predict the outcome of this matter.

Information Requests from Arizona Corporation Commissioners

On January 14, 2019, ACC Commissioner Kennedy opened a docket to investigate campaign expenditures and political participation of APS and Pinnacle West. In addition, on February 27, 2019, ACC Commissioners Burns and Dunn opened a new docket and requested documents from APS and Pinnacle West related to ACC elections and charitable contributions related to the ACC. On March 1, 2019, ACC Commissioner Kennedy issued a subpoena to APS seeking several categories of information for both Pinnacle West and APS including political contributions, lobbying expenditures, marketing and advertising expenditures, and contributions made to 501(c)(3) and 501(c)(4) entities, for the years 2013-2018. Pinnacle West and APS voluntarily responded to both sets of requests on March 29, 2019. APS also received and responded to various follow-on requests from ACC Commissioners on these matters. Pinnacle West and APS cannot predict the outcome of these matters.

Renewable Energy Ballot Initiative

On February 20, 2018, a renewable energy advocacy organization filed with the Arizona Secretary of State a ballot initiative for an Arizona constitutional amendment requiring Arizona public service corporations to provide at least 50% of their annual retail sales of electricity from renewable sources by 2030. For purposes of the proposed amendment, eligible renewable sources would not include nuclear generating facilities. The initiative was placed on the November 2018 Arizona elections ballot. On November 6, 2018, the initiative failed to receive adequate voter support and was defeated.

Energy Modernization Plan

On January 30, 2018, former ACC Commissioner Tobin proposed the Energy Modernization Plan, which consisted of a series of energy policies tied to clean energy sources such as energy storage, biomass, energy efficiency, electric vehicles, and expanded energy planning through the integrated resource plans ("IRP") process. In August 2018, the ACC directed ACC Staff to open a new rulemaking docket which will address a wide range of energy issues, including the Energy Modernization Plan proposals. The rulemaking will consider possible modifications to existing ACC rules, such as the RES, Electric and Gas Energy Efficiency Standards, Net Metering, Resource Planning, and the Biennial Transmission Assessment, as well as the development of new rules regarding forest bioenergy, electric vehicles, interconnection of distributed generation, baseload security, blockchain technology and other technological developments, retail competition, and other energy-related topics. On April 25, 2019, the ACC Staff issued a set of draft rules in regards to the Energy Modernization Plan and workshops were held on April 29, 2019 regarding these draft rules. On July 2, 2019, the ACC Staff issued a revised set of draft rules, which propose a RES goal of 45% of retail energy served be renewable by 2035 and a goal of 20% of retail sales during peak demand to be from clean energy resources by 2035.  The draft rules also require a certain amount of the RES goal to be derived from distributed renewable storage, for which utilities would be required to offer performance-based incentives.  Nuclear energy would be considered a clean resource under the draft rules. The ACC held various stakeholder meetings and workshops on ACC Staff’s draft energy rules in July through September 2019. APS cannot predict the outcome of this matter.

Integrated Resource Planning

ACC rules require utilities to develop fifteen-year IRPs which describe how the utility plans to serve customer load in the plan timeframe.  The ACC reviews each utility’s IRP to determine if it meets the necessary requirements and whether it should be acknowledged.  In March of 2018, the ACC reviewed the 2017 IRPs of its jurisdictional utilities and voted to not acknowledge any of the plans.  APS does not believe that this lack of acknowledgment will have a material impact on our financial position, results of operations or cash flows.  Based on an ACC decision, APS is required to file a Preliminary Resource Plan by April 1, 2019 and its final IRP by April 1, 2020. APS filed a request to extend the deadline to file its Preliminary IRP, which was granted. On August 1, 2019, APS filed its Preliminary IRP.

Public Utility Regulatory Policies Act

In August 2016, APS filed an application requesting that all of its contracts with qualifying facilities over 100 kW be set at a presumptive maximum 2 year term. A qualifying facility is an eligible energy-producing facility as defined by FERC regulations within a host electric utility’s service territory that has a right to sell to the host utility. Host utilities are required to purchase power from qualifying facilities at an avoided cost as determined by the utility subject to state commission oversight. A hearing was held in August 2019 and briefing on this matter was completed in October 2019 regarding APS’s application. APS cannot predict the outcome of this matter.

Residential Electric Utility Customer Service Disconnections

On June 13, 2019, APS voluntarily suspended electric disconnections for residential customers who had not paid their bills.  On June 20, 2019, the ACC voted to enact emergency rule amendments to prevent residential electric utility customer service disconnections during the period from June 1 through October 15. During the moratorium on disconnections, APS could not charge late fees and interest on amounts that were past due from customers.  Customer deposits must also be used to pay delinquent amounts before disconnection can occur and customers will have four months to pay back their deposit and any remaining delinquent amounts.  In accordance with the emergency rules, APS began putting delinquent customers on a mandatory four-month payment plan beginning on October 16, 2019. The emergency rule changes will be effective for 180 days and may be renewed for one additional 180 day period. During that time, the ACC began a formal regular rulemaking process to allow stakeholder input and time for consideration of permanent rule changes.  The ACC further ordered that each regulated electric utility serving retail customers in Arizona update its service conditions by incorporating the emergency rule amendments, restore power to any customers who were disconnected during the month of June 2019 and credit any fees that were charged for a reconnection. The ACC Staff issued draft amendments to the customer service disconnections rules. Stakeholders submitted initial comments to the draft amendments on September 23, 2019. ACC stakeholder meetings were held in September 2019 and October 2019 regarding the customer service disconnections rules. APS currently estimates that the disconnection moratorium will result in a negative impact to its 2019 operating results of approximately $10 million pre-tax depending on certain assumptions, including customer behaviors. APS is further assessing the impact to its financial statements beyond 2019, which will be affected by the results of final rulemaking related to disconnections.

Retail Electric Competition Rules

On November 17, 2018, the ACC voted to re-examine the facilitation of a deregulated retail electric market in Arizona. An ACC special open meeting workshop was held on December 3, 2018. No substantive action was taken, but interested parties were asked to submit written comments and respond to a list of questions from ACC Staff. On July 1 and July 2, 2019, ACC Staff issued a report and initial proposed draft rules regarding possible modifications to the ACC’s retail electric competition rules. Interested parties filed comments to the ACC Staff report and a stakeholder meeting and workshop to discuss the retail electric competition rules was held on July 30, 2019. ACC Commissioners submitted additional questions regarding this matter. APS cannot predict whether these efforts will result in any changes and, if changes to the rules results, what impact these rules would have on APS.

Four Corners 

SCE-Related Matters. On December 30, 2013, APS purchased Southern California Edison Company's ("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 retail 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 included 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 provided 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 $42 million as of September 30, 2019 and is being amortized in rates over a total of 10 years.

 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. On October 5, 2017, FERC issued an order denying APS's request for rehearing. FERC also upheld its prior determination that the agreement relating to the settlement was a jurisdictional contract and should have been filed with FERC. APS cannot predict whether or if the enforcement division will take any action. APS filed an appeal of FERC's July 1, 2016 and October 5, 2017 orders with the United States Court of Appeals for the Ninth Circuit on December 4, 2017. On June 14, 2019, the United States Court of Appeals for the Ninth

Circuit issued an unpublished memorandum order denying APS’s petition for review of FERC’s orders that denied APS’s request to recover the regulatory asset through its FERC-jurisdictional rates and granting APS’s petition for review of FERC’s orders finding the agreement to be a jurisdictional contract. The United States Court of Appeals for the Ninth Circuit vacated FERC’s determination that the agreement was required to be filed with FERC and remanded the issue to FERC for additional proceedings. APS cannot predict the outcome of the remand proceeding.

SCR Cost Recovery. On December 29, 2017, in accordance with the 2017 Rate Case Decision, APS filed a Notice of Intent to file its SCR Adjustment to permit recovery of costs associated with the installation of SCR equipment at Four Corners Units 4 and 5.  APS filed the SCR Adjustment request in April 2018.  Consistent with the 2017 Rate Case Decision, the request was narrow in scope and addressed only costs associated with this specific environmental compliance equipment.  The SCR Adjustment request provided that there would be a $67.5 million annual revenue impact that would be applied as a percentage of base rates for all applicable customers.  Also, as provided for in the 2017 Rate Case Decision, APS requested that the adjustment become effective no later than January 1, 2019.  The hearing for this matter occurred in September 2018.  At the hearing, APS accepted ACC Staff's recommendation of a lower annual revenue impact of approximately $58.5 million. The Administrative Law Judge issued a Recommended Opinion and Order finding that the costs for the SCR project were prudently incurred and recommending authorization of the $58.5 million annual revenue requirement related to the installation and operation of the SCRs. Exceptions to the Recommended Opinion and Order were filed by the parties and intervenors on December 7, 2018.  The ACC has not issued a decision on this matter. APS included the costs for the SCR project in the retail rate base in its 2019 retail rate case filing with the ACC. APS cannot predict the outcome or timing of the decision on this matter. APS may be required to record a charge to its results of operations if the ACC issues an unfavorable decision (see SCR deferral in the Regulatory Assets and Liabilities table below).

Cholla

On September 11, 2014, APS announced that it would close Unit 2 of the Cholla Power Plant ("Cholla") and cease burning coal at the other APS-owned units (Units 1 and 3) at the plant by the mid-2020s, if the United States Environmental Protection Agency ("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. In early 2017, EPA approved a final rule incorporating APS's compromise proposal, which took effect on April 26, 2017.

Previously, APS estimated Cholla Unit 2’s end of life to be 2033. APS has been recovering a return on and of the net book value of the unit in base rates. Pursuant to the 2017 Settlement Agreement described above, APS will be allowed continued recovery of the net book value of the unit and the unit’s decommissioning and other retirement-related costs ($77 million as of September 30, 2019), 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. The 2017 Settlement Agreement also shortened the depreciation lives of Cholla Units 1 and 3 to 2025.

On March 20, 2019, APS announced that it began evaluating the feasibility and cost of converting a unit at Cholla to burn biomass. Biomass is a fuel comprised of forest trimmings, and a converted unit at Cholla could assist in forest thinning, responsible forest management, an improved watershed, and a reduced wildfire risk. APS’s ability to operate a biomass power plant would depend on third-parties procuring forest biomass for fuel. APS reported the results of its evaluation on May 9, 2019 to the ACC. On July 10, 2019, the ACC voted to not require APS to file a request for proposal to convert the unit at Cholla to burn biomass.

Navajo Plant

The co-owners of the Navajo Plant and the Navajo Nation agreed that the Navajo Plant will remain in operation until December 2019 under the existing plant lease. The co-owners and the Navajo Nation executed a lease extension on November 29, 2017 that will allow for decommissioning activities to begin after the plant ceases operations by December 2019.

APS is currently recovering depreciation and a return on the net book value of its interest in the Navajo Plant over its previously estimated life through 2026. APS will seek continued recovery in rates for the book value of its remaining investment in the plant ($80 million as of September 30, 2019) plus a return on the net book value as well as other costs related to retirement and closure, which are still being assessed and may be material. APS believes it will be allowed recovery of the net book value, in addition to a return on its investment. In accordance with GAAP, in the second quarter of 2017, APS's remaining net book value of its interest in the Navajo Plant 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 this interest, 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.    

Regulatory Assets and Liabilities 

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

	Amortization Through	September 30, 2019				December 31, 2018
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	703,460	$	—	$	733,351
Retired power plant costs	2033	28,182		146,076		28,182		167,164
Income taxes — allowance for funds used during construction ("AFUDC") equity	2049	6,457		154,269		6,457		151,467
Deferred fuel and purchased power — mark-to-market (Note 7)	2023	41,643		27,305		31,728		23,768
Deferred property taxes	2027	8,569		60,338		8,569		66,356
Deferred fuel and purchased power (b) (c)	2020	59,474		—		37,164		—
SCR deferral	N/A	—		45,296		—		23,276
Four Corners cost deferral	2024	8,077		34,171		8,077		40,228
Deferred compensation	2036	—		37,589		—		36,523
Lost fixed cost recovery (b)	2020	25,775		—		32,435		—
Income taxes — investment tax credit basis adjustment	2047	1,079		24,555		1,079		25,522
Ocotillo deferral	N/A	—		23,643		—		—
Palo Verde VIEs (Note 6)	2046	—		20,480		—		20,015
Coal reclamation	2026	1,546		18,821		1,546		15,607
Loss on reacquired debt	2038	1,637		12,441		1,637		13,668
Mead-Phoenix transmission line CIAC	2050	332		9,795		332		10,044
TCA balancing account (b)	2021	5,016		2,721		3,860		772
Tax expense of Medicare subsidy	2024	1,235		5,073		1,235		6,176
AG-1 deferral	2022	2,787		3,413		2,654		5,819
Tax expense adjuster mechanism (b)	2019	2,916		—		—		—
Other	Various	2,782		—		1,947		3,185
Total regulatory assets (d)		$	197,507	$	1,329,446	$	166,902	$	1,342,941

(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 other comprehensive income ("OCI") and result in lower future revenues.

(b) See "Cost Recovery Mechanisms" discussion above.

(c) Subject to a carrying charge.

(d) 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	September 30, 2019				December 31, 2018
		Current		Non-Current		Current		Non-Current
Excess deferred income taxes - ACC - Tax Cuts and Jobs Act (a)	(b)	$	38,529	$	1,178,216	$	—	$	1,272,709
Excess deferred income taxes - FERC - Tax Cuts and Jobs Act (a)	2058	6,302		238,064		6,302		243,691
Asset retirement obligations	2057	—		367,930		—		278,585
Removal costs	(c)	47,459		151,535		39,866		177,533
Other postretirement benefits	(d)	37,821		95,789		37,864		125,903
Income taxes — change in rates	2048	2,764		67,605		2,769		70,069
Spent nuclear fuel	2027	5,746		53,229		6,503		57,002
Income taxes — deferred investment tax credit	2047	2,164		49,182		2,164		51,120
Four Corners coal reclamation	2038	1,858		49,194		1,858		17,871
Renewable energy standard (b)	2021	42,146		5,675		44,966		20
Demand side management (b)	2021	14,300		24,146		14,604		4,123
Sundance maintenance	2031	4,640		13,393		1,278		17,228
Deferred gains on utility property	2022	2,923		4,766		4,423		6,581
Property tax deferral	N/A	—		6,288		—		2,611
FERC transmission true up	2021	—		2,586		—		—
Other	Various	1,370		2,533		3,279		930
Total regulatory liabilities		$	208,022	$	2,310,131	$	165,876	$	2,325,976

(a) For purposes of presentation on the Statement of Cash Flows, amortization of the regulatory liabilities for excess deferred income taxes are reflected as "Deferred income taxes" under Cash Flows From Operating Activities.

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

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

(d)

See Note 5.

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Commitments and Contingencies

9 Months Ended

Sep. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments and Contingencies

Palo Verde 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 United States Department of Energy ("DOE") in the United States Court of Federal Claims ("Court of Federal Claims").  The lawsuit sought to recover damages incurred due to DOE’s breach of the Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste ("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, as amended, provides APS with a method for submitting claims and getting recovery for costs incurred through December 31, 2019.

APS has submitted five claims pursuant to the terms of the August 18, 2014 settlement agreement, for five separate time periods during July 1, 2011 through June 30, 2018. The DOE has approved and paid $84.3 million for these claims (APS’s share is $24.5 million). The amounts recovered were primarily recorded as adjustments to a regulatory liability and had no impact on reported net income. In accordance with the 2017 Rate Case Decision, this regulatory liability is being refunded to customers (see Note 4). On October 31, 2019, APS filed its next claim pursuant to the terms of the August 18, 2014 settlement agreement in the amount of $16 million (APS’s share is $4.7 million).

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 of up to approximately $13.9 billion per occurrence. Palo Verde maintains the maximum available nuclear liability insurance in the amount of $450 million, which is provided by American Nuclear Insurers ("ANI").  The remaining balance of approximately $13.5 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 $137.6 million, subject to a maximum annual premium of approximately $20.5 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 $120.1 million, with a maximum annual retrospective premium of approximately $17.9 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 $25.5 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 $73.4 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.

Contractual Obligations

During 2019 our fuel and purchased power commitments have increased from the information provided in our 2018 10-K. The increase is primarily due to new purchased power commitments of approximately $260 million. The majority of the changes relate to 2024 and thereafter.

During 2019 our coal reclamation commitments have decreased from the information provided in our 2018 10-K by approximately $100 million. The decrease is primarily due to a new coal reclamation cost study for Four Corners. The majority of the changes relate to 2024 and thereafter.

Other than the items described above, there have been no material changes, as of September 30, 2019, outside the normal course of business in contractual obligations from the information provided in our 2018 Form 10-K. See Note 3 for discussion regarding changes in our long-term debt obligations.

Superfund-Related Matters

The Comprehensive Environmental Response Compensation and Liability Act ("Superfund" or "CERCLA") establishes liability for the cleanup of hazardous substances found contaminating the soil, water or air.  Those who released, generated, transported to or disposed of hazardous substances at a contaminated site are among the parties who are potentially responsible ("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 ("RI/FS").  Based upon discussions between the OU3 working group parties and EPA, along with the results of recent technical analyses prepared by the OU3 working group to supplement the RI/FS for OU3, APS anticipates finalizing the RI/FS in the fall or winter of 2019. 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, 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, the Arizona Department of Environmental Quality ("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 environmental and engineering contractors filed an ancillary lawsuit for recovery of costs against APS and the other defendants in the RID litigation. That same day, another RID service provider filed an additional ancillary CERCLA lawsuit against certain of the defendants in the main RID litigation, but excluded APS and certain other parties as named defendants. Because the ancillary lawsuits concern past costs allegedly incurred by these RID vendors, which were ruled unrecoverable directly by RID in November of 2016, the additional lawsuits do not increase APS's exposure or risk related to these matters.

On April 5, 2018, RID and the defendants in that particular litigation executed a settlement agreement, fully resolving RID's CERCLA claims concerning both past and future cost recovery. APS's share of this settlement was immaterial. In addition, the two environmental and engineering vendors voluntarily dismissed their lawsuit against APS and the other named defendants without prejudice. An order to this effect was entered on April 17, 2018. With this disposition of the case, the vendors may file their lawsuit again in the future. On August 16, 2019, Maricopa County, one of the three direct defendants in the service provider lawsuit, filed a third-party complaint seeking contribution for its liability, if any, from APS and 28 other third-party 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.

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 coal combustion residuals ("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 pollution control requirements on Four Corners and the Navajo Plant. EPA will require these plants to install pollution control equipment that constitutes best available retrofit technology ("BART") to lessen the impacts of emissions on visibility surrounding the plants. In addition, EPA issued a final 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 Cholla BART approval.

Four Corners. Based on EPA’s final standards, APS's 63% share of the cost of required controls for Four Corners Units 4 and 5 is approximately $400 million, which has been incurred.  In addition, APS and El Paso Electric Company ("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. Navajo Transitional Energy Company, LLC ("NTEC") purchased the interest from 4CA on July 3, 2018. See "Four Corners - 4CA Matter" below for a discussion of the NTEC purchase. The cost of the pollution controls related to the 7% interest is approximately $45 million, which was assumed by NTEC through its purchase of the 7% interest.

Navajo Plant. APS estimates that its share of costs for upgrades at the Navajo Plant, based on EPA’s Federal Implementation Plan ("FIP"), could be up to approximately $200 million; however, given the future plans for the Navajo Plant, we do not expect to incur these costs.  See "Navajo Plant" in Note 4 for information regarding future plans for the Navajo Plant and details related to the resulting regulatory asset.

Cholla. APS believed that EPA’s original 2012 final rule establishing controls constituting BART for Cholla, which would require installation of SCR controls, was unsupported and that EPA had no basis for disapproving Arizona’s State Implementation Plan ("SIP") and promulgating a FIP that was inconsistent with the state’s considered BART determinations under the regional haze program.  In September 2014, APS met with EPA to propose a compromise BART strategy, whereby APS would permanently close Cholla Unit 2 and cease burning coal at Units 1 and 3 by the mid-2020s. (See "Cholla" in Note 4 for information regarding future plans for the Cholla plant and 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 BART requirements for oxides of nitrogen ("NOx") imposed through EPA's BART FIP. In early 2017, EPA approved a final rule incorporating APS's compromise proposal, which took effect for Cholla on April 26, 2017.

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. Such closure requirements are deemed "forced closure" or "closure for cause" of unlined surface impoundments, and are the subject of recent regulatory and judicial activities described below.

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.

ADEQ has initiated a process to evaluate how to develop a state CCR permitting program that would cover electric generating units ("EGUs"), including Cholla. While APS has been working with ADEQ on the development of this program, we are unable to predict when Arizona will be able to finalize and secure EPA approval for a state-specific CCR permitting program. With respect to the Navajo Nation, APS has sought clarification as to when and how EPA would be initiating permit proceedings for facilities on the reservation, including Four Corners. We are unable to predict at this time when EPA will be issuing CCR management permits for the facilities on the Navajo Nation. At this time, it remains unclear how the CCR provisions of the WIIN Act will affect APS and its management of CCR.

Based upon utility industry petitions for EPA to reconsider the RCRA Subtitle D regulations for CCR, which were premised in part on the CCR provisions of the 2016 WIIN Act, on September 13, 2017 EPA agreed

to evaluate whether to revise these federal CCR regulations. On July 17, 2018, EPA finalized a revision to its RCRA Subtitle D regulations for CCR, the "Phase I, Part I" revision to its CCR regulations, deferring for future action a number of other proposed changes contemplated in a March 1, 2018 proposal. For the final rule issued on July 17, 2018, EPA established nationwide health-based standards for certain constituents of CCR subject to groundwater corrective action and delayed the closure deadlines for certain unlined CCR surface impoundments by 18 months (for example, those disposal units required to undergo forced closure). These changes to the federal regulations governing CCR disposal are unlikely to have a material impact on APS. As for those aspects of the March 2018 rulemaking proposal for which EPA has yet to take final action, it remains unclear which specific provisions of the federal CCR rules will ultimately be modified, how they will be modified, or when such modification will occur.

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, EPA is required to complete a rulemaking proceeding in the near future concerning whether or not boron must be included on the list of groundwater constituents that might trigger corrective action under EPA’s CCR rules.  Simultaneously with the issuance of EPA's proposed modifications to the federal CCR rules in response to industry petitions, on March 1, 2018, EPA issued a proposed rule seeking comment as to whether or not boron should be included on this list. On August 14, 2019, EPA modified its boron proposal to include a specific, health-based groundwater protection standard for boron. These proposals remain pending, and EPA is not required to take final action including boron among the list of constituents that will determine CCR corrective actions.  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 APS cannot predict the eventual results of this rulemaking proceeding concerning boron.

On August 21, 2018, the D.C. Circuit Court issued its decision on the merits of the industry- and environmental-group litigation challenging the federal CCR regulations. The Court upheld the legality of EPA’s CCR regulations, though it vacated and remanded back to EPA a number of specific provisions, which are to be corrected in accordance with the Court’s order. Among the issues affecting APS’s management of CCR, the D.C. Circuit’s decision vacated and remanded those provisions of the EPA CCR regulations that allow for the operation of unlined CCR surface impoundments, even where those unlined impoundments have not otherwise violated a regulatory location restriction or groundwater protection standard (i.e., otherwise triggering forced closure).

Based on this decision, on December 17, 2018, certain environmental groups filed an emergency motion with the D.C. Circuit to either stay or summarily vacate EPA's July 17, 2018 final rule extending the closure-initiation deadline for certain unlined CCR surface impoundments until October 2020. In response, EPA filed a motion to remand but not vacate that deadline extension regulation. On March 13, 2019, the Court issued its ruling on the pending motions concerning the October 2020 deadline for closure initiation and granted remand without vacatur. This ruling allows the current October 2020 deadline to remain in effect while EPA completes a rulemaking to revise or reaffirm this deadline in accordance with the August 2018 D.C. Circuit decision concerning the closure of unlined CCR surface impoundments. On November 4, 2019, EPA issued a proposed rule responding to this litigation that contemplates an August 2020 closure initiation deadline with an optional three-month extension as needed for the completion of alternative disposal capacity.

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 $22 million and its share of incremental costs to comply with the CCR rule for Cholla is approximately $15 million. The Navajo Plant currently disposes of CCR in a dry landfill storage area. To comply with the CCR

rule for the Navajo Plant, APS's share of incremental costs is approximately $1 million, which has been incurred. Additionally, the CCR rule requires ongoing, phased groundwater monitoring. By October 17, 2017, electric utility companies that own or operate CCR disposal units, such as APS, must have collected sufficient groundwater sampling data to initiate a detection monitoring program.  To the extent that certain threshold constituents are identified through this initial detection monitoring at levels above the CCR rule’s standards, the rule required the initiation of an assessment monitoring program by April 15, 2018. 

APS has completed the statistical analyses for its CCR disposal units that triggered assessment monitoring. APS determined that several of its CCR disposal units at Cholla and Four Corners will need to undergo corrective action. In addition, all such disposal units must cease operating and initiate closure by October of 2020. APS currently estimates that the additional incremental costs to complete this corrective action and closure work, along with the costs to develop replacement CCR disposal capacity, could be approximately $5 million for both Cholla and Four Corners. APS initiated an assessment of corrective measures on January 14, 2019 and APS predicts such assessment will continue through early 2020. During this assessment, APS will gather additional groundwater data, solicit input from the public, host public hearings, and select remedies. As such, this $5 million cost estimate may change based upon APS’s performance of the CCR rule’s corrective action assessment process. Given uncertainties that may exist until we have fully completed the corrective action assessment process, we cannot predict any ultimate impacts to the Company; however, at this time we do not believe any potential change to the cost estimate would have a material impact on our financial position, results of operations or cash flows.

Clean Power Plan/Affordable Clean Energy Regulations. On June 19, 2019, EPA took final action on its proposals to repeal EPA's 2015 Clean Power Plan (“CPP”) and replace those regulations with a new rule, the Affordable Clean Energy (“ACE”) regulations. EPA originally finalized the CPP on August 3, 2015, and those regulations had been stayed pending judicial review.

The ACE regulations are based upon measures that can be implemented to improve the heat rate of steam-electric power plants, specifically coal-fired EGUs. In contrast with the CPP, EPA's ACE regulations would not involve utility-level generation dispatch shifting away from coal-fired generation and toward renewable energy resources and natural gas-fired combined cycle power plants. EPA’s ACE regulations provide states and EPA regions such as the Navajo Nation with three years to develop plans establishing source-specific standards of performance based upon application of the ACE rule’s heat-rate improvement emission guidelines. While corresponding New Source Review (“NSR”) reform regulations were proposed as part of EPA’s initial ACE proposal, the finalized ACE regulations did not include such reform measures. EPA announced that it will be taking final action on EPA's NSR reform proposal for EGUs in the near future.

We cannot at this time predict the outcome of EPA's regulatory actions repealing and replacing the CPP. Various state governments, industry organizations, and environmental and public-health public interest groups have filed lawsuits in the D.C. Circuit challenging the legality of EPA’s action, both in repealing the CPP and issuing the ACE regulations. In addition, to the extent that the ACE regulations go into effect as finalized, it is not yet clear how the state of Arizona or EPA will implement these regulations as applied to APS’s coal-fired EGUs. In light of these uncertainties, APS is still evaluating the impact of the ACE regulations on its coal-fired generation fleet.

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 the Office of Surface Mining Reclamation and Enforcement ("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 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.

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. On September 11, 2017, the Arizona District Court issued an order granting NTEC's motion, dismissing the litigation with prejudice, and terminating the proceedings. On November 9, 2017, the environmental group plaintiffs appealed the district court order dismissing their lawsuit. On July 29, 2019, the Ninth Circuit Court of Appeals affirmed the September 2017 dismissal of the lawsuit, after which the environmental group plaintiffs petitioned the Ninth Circuit for rehearing on September 12, 2019. We cannot predict the outcome of any further proceedings.

Four Corners National Pollutant Discharge Elimination System ("NPDES") Permit

On July 16, 2018, several environmental groups filed a petition for review before the EPA Environmental Appeals Board ("EAB") concerning the NPDES wastewater discharge permit for Four Corners, which was reissued on June 12, 2018.  The environmental groups allege that the permit was reissued in contravention of several requirements under the Clean Water Act and did not contain required provisions concerning EPA’s 2015 revised effluent limitation guidelines for steam-electric EGUs, 2014 existing-source regulations governing cooling-water intake structures, and effluent limits for surface seepage and subsurface discharges from coal-ash disposal facilities.  To address certain of these issues through a reconsidered permit, EPA took action on December 19, 2018 to withdraw the NPDES permit reissued in June 2018. Withdrawal of the permit moots the EAB appeal, and EPA filed a motion to dismiss on that basis. The EAB thereafter dismissed the environmental group appeal on February 12, 2019. EPA issued the final NPDES permit for Four Corners on September 30, 2019. This permit is now subject to a petition for review before the EPA Environmental Appeals Board, based upon a November 1, 2019 filing by several environmental groups. We cannot predict the outcome of this review and whether the review will have a material impact on our financial position, results of operations or cash flows.

Four Corners - 4CA Matter

On July 6, 2016, 4CA purchased El Paso’s 7% interest in Four Corners. NTEC had the option to purchase the 7% interest and ultimately purchased the interest on July 3, 2018. NTEC purchased the 7% interest at 4CA’s book value, approximately $70 million, and is paying 4CA the purchase price over a period of four years pursuant to a secured interest-bearing promissory note. In connection with the sale, Pinnacle West guaranteed certain obligations that NTEC will have to the other owners of Four Corners, such as NTEC's 7% share of capital expenditures and operating and maintenance expenses. Pinnacle West's guarantee is secured by a portion of APS's payments to be owed to NTEC under the 2016 Coal Supply Agreement.

The 2016 Coal Supply Agreement contained alternate pricing terms for the 7% interest in the event NTEC did not purchase the interest. Until the time that NTEC purchased the 7% interest, the alternate pricing provisions were applicable to 4CA as the holder of the 7% interest. These terms included a formula under which NTEC must make certain payments to 4CA for reimbursement of operations and maintenance costs and a specified rate of return, offset by revenue generated by 4CA’s power sales. Such payments are due to 4CA at the end of each calendar year. A $10 million payment was due to 4CA at December 31, 2017, which NTEC satisfied by directing to 4CA a prepayment from APS of a portion of a future mine reclamation obligation. The balance of the amount under this formula due December 31, 2018 for calendar year 2017 was approximately $20 million, which was paid to 4CA on December 14, 2018. The balance of the amount under this formula for calendar year 2018 (up to the date that NTEC purchased the 7% interest) is approximately $10 million, which is due to 4CA at December 31, 2019.

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 commodity contract collateral obligations and other transactions. As of September 30, 2019, standby letters of credit totaled $1.7 million and will expire in 2020. As of September 30, 2019, surety bonds expiring through 2020 totaled $14 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 September 30, 2019. In connection with the sale of 4CA's 7% interest to NTEC, Pinnacle West is guaranteeing certain obligations that NTEC will have to the other owners of Four Corners. (See "Four Corners - 4CA Matter" above for information related to this guarantee.) A maximum obligation is not explicitly stated in the guarantee and, therefore, the overall maximum amount of the obligation under such guarantee cannot be reasonably estimated; however, we consider the fair value of this guarantee to be immaterial.

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Leases - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Operating Leased Assets [Line Items]
Operating lease cost	$ 25,676	$ 48,502
Variable lease cost	37,100	96,279
Short-term lease cost	812	3,477
Total lease cost	63,588	148,258
Purchased Power Lease Contracts
Operating Leased Assets [Line Items]
Operating lease cost	21,095	35,159
Variable lease cost	36,917	95,736
Short-term lease cost	0	0
Total lease cost	58,012	130,895
Land, Property & Equipment Leases
Operating Leased Assets [Line Items]
Operating lease cost	4,581	13,343
Variable lease cost	183	543
Short-term lease cost	812	3,477
Total lease cost	$ 5,576	$ 17,363

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Commitments and Contingencies - Palo Verde Nuclear Generating Station and Contractual Obligations (Details)			9 Months Ended	84 Months Ended
	Oct. 31, 2019 USD ($)	Aug. 18, 2014 USD ($)	Sep. 30, 2019 USD ($) power_plant	Jun. 30, 2018 USD ($) time_period claim	Dec. 31, 1986 Trust
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste
Commitments and Contingencies
Litigation settlement amount		$ 57,400,000		$ 84,300,000
APS
Commitments and Contingencies
Maximum insurance against public liability per occurrence for a nuclear incident (up to)			$ 13,900,000,000
Maximum available nuclear liability insurance (up to)			450,000,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program			13,500,000,000
Maximum retrospective premium assessment per reactor for each nuclear liability incident			137,600,000
Annual limit per incident with respect to maximum retrospective premium assessment			$ 20,500,000
Number of VIE lessor trusts			3		3
Maximum potential retrospective assessment per incident of APS			$ 120,100,000
Annual payment limitation with respect to maximum potential retrospective premium assessment			17,900,000
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			25,500,000
Collateral assurance provided based on rating triggers			$ 73,400,000
Period to provide collateral assurance based on rating triggers			20 days
Purchase obligation, increase			$ (260,000,000)
APS | Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste
Commitments and Contingencies
Litigation settlement amount		$ 16,700,000		$ 24,500,000
Number of claims submitted | claim				5
Number of settlement agreement time periods | time_period				5
Four Corners coal reclamation | APS
Commitments and Contingencies
Purchase obligation, increase			$ 100,000,000
Subsequent Event | Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste
Commitments and Contingencies
Litigation settlement amount	$ 16,000,000
Subsequent Event | APS | Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste
Commitments and Contingencies
Litigation settlement amount	$ 4,700,000

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Retirement Plans and Other Postretirement Benefits - Narrative (Details)	9 Months Ended
	Sep. 30, 2019 USD ($)
Pension Benefits
Contributions
Voluntary employer contributions to pension plan	$ 150,000,000
Minimum employer contributions for the next three years	0
Maximum employer contributions for the next two years (up to)	350,000,000
Other Benefits
Contributions
Estimated future employer contributions in next three years	0
Retiree medical cost reimbursement	$ 30,000,000

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Derivative Accounting - Schedule of Gross Notional Amounts Outstanding (Details) - Commodity Contracts GWh in Thousands, Bcf in Thousands	Sep. 30, 2019 GWh Bcf	Dec. 31, 2018 GWh Bcf
Outstanding gross notional amount of derivatives
Power | GWh	232	250
Gas | Bcf	187	218

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Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 312,276	$ 315,012	$ 474,339	$ 484,971
Weighted average common shares outstanding - basic (in shares)	112,463	112,148	112,408	112,094
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	283	385	331	405
Weighted average common shares outstanding — diluted (in shares)	112,746	112,533	112,739	112,499
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 2.78	$ 2.81	$ 4.22	$ 4.33
Net income attributable to common shareholders - diluted (in dollars per share)	$ 2.77	$ 2.80	$ 4.21	$ 4.31

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Fair Value Measurements - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Stated interest rate for notes receivable	3.90%
Note receivable, net book value	$ 49	$ 61

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Regulatory Matters - Retail Rate Case Filing (Details) - ACC - APS										12 Months Ended
	Oct. 31, 2019 USD ($) GW	Jun. 30, 2019 USD ($)	Apr. 10, 2019 USD ($)	Aug. 13, 2018 USD ($)	Feb. 13, 2018	Jan. 08, 2018 USD ($)	Jan. 03, 2018 Customer	Nov. 13, 2017 USD ($) appeal	Mar. 27, 2017 USD ($) $ / kWh	Dec. 31, 2019 USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount, Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)			$ 184,000,000	$ (86,500,000)		$ (119,100,000)
Retail Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Approximate percentage of increase in average customer bill									3.28%
Rate matter, cost base rate		$ 8,870,000,000
Net retail base rate, increase									$ 94,600,000
Non-fuel and non-depreciation base rate, increase									87,200,000
Fuel-related base rate decrease									53,600,000
Base rate increase, changes in depreciation schedules									$ 61,000,000.0
Approximate percentage of increase in average residential customer bill					4.54%				4.54%
Authorized return on common equity (as a percent)									10.00%
Percentage of debt in capital structure									44.20%
Percentage of common equity in capital structure									55.80%
Rate matter, resource comparison proxy for exported energy (in dollars per kWh) | $ / kWh									0.129
Periodic metering infrastructure opt-out fee								$ 5
Number of appeals | appeal								2
Number of customers named in complaint | Customer							25
AZ Sun Program Phase 2 | Retail Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Public utilities, minimum annual renewable energy standard and tariff									$ 10,000,000
Public utilities, maximum annual renewable energy standard and tariff									$ 15,000,000
Minimum | Retail Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Rate matter, environmental surcharge cap rate (in dollars per kWh) | $ / kWh									0.00016
Maximum | Retail Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Rate matter, environmental surcharge cap rate (in dollars per kWh) | $ / kWh									0.00050
Subsequent Event | Retail Rate Case Filing with Arizona Corporation Commission
Public Utilities, General Disclosures [Line Items]
Retail base rate, increase	$ 0.054
Base rate decrease, elimination of tax expense adjustment mechanism	$ 115,000,000
Approximate percentage of increase in average customer bill	5.60%
Funding limited income crisis bill program	$ 1,250,000
Commercial customers, market pricing, threshold | GW	0.2
Forecast
Public Utilities, General Disclosures [Line Items]
Operating Results										$ (10,000,000)
Forecast | Minimum
Public Utilities, General Disclosures [Line Items]
Operating Results	$ 69,000,000

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Consolidation and Nature of Operations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash paid during the period for:
Income taxes, net of refunds	$ 12,488	$ 10,091
Interest, net of amounts capitalized	166,907	161,875
Significant non-cash investing and financing activities:
Accrued capital expenditures	85,099	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759	0
Sale of 4CA's 7% interest in Four Corners	0	68,907
APS
Cash paid during the period for:
Income taxes, net of refunds	35,573	24,746
Interest, net of amounts capitalized	157,593	154,788
Significant non-cash investing and financing activities:
Accrued capital expenditures	85,099	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	$ 8,759	$ 0
APS | Four Corners
Significant non-cash investing and financing activities:
Ownership percentage	7.00%

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Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Detail of regulatory assets
Current	$ 197,507	$ 166,902
Non-Current	1,329,446	1,342,941
Pension
Detail of regulatory assets
Current	0	0
Non-Current	703,460	733,351
Retired power plant costs
Detail of regulatory assets
Current	28,182	28,182
Non-Current	146,076	167,164
Income taxes — allowance for funds used during construction (AFUDC) equity
Detail of regulatory assets
Current	6,457	6,457
Non-Current	154,269	151,467
Deferred fuel and purchased power — mark-to-market (Note 7)
Detail of regulatory assets
Current	41,643	31,728
Non-Current	27,305	23,768
Deferred property taxes
Detail of regulatory assets
Current	8,569	8,569
Non-Current	60,338	66,356
Deferred fuel and purchased power
Detail of regulatory assets
Current	59,474	37,164
Non-Current	0	0
SCR deferral
Detail of regulatory assets
Current	0	0
Non-Current	45,296	23,276
Four Corners cost deferral
Detail of regulatory assets
Current	8,077	8,077
Non-Current	34,171	40,228
Deferred compensation
Detail of regulatory assets
Current	0	0
Non-Current	37,589	36,523
Lost fixed cost recovery
Detail of regulatory assets
Current	25,775	32,435
Non-Current	0	0
Income taxes — investment tax credit basis adjustment
Detail of regulatory assets
Current	1,079	1,079
Non-Current	24,555	25,522
Ocotillo deferral
Detail of regulatory assets
Current	0	0
Non-Current	23,643	0
Palo Verde VIEs (Note 6)
Detail of regulatory assets
Current	0	0
Non-Current	20,480	20,015
Coal reclamation
Detail of regulatory assets
Current	1,546	1,546
Non-Current	18,821	15,607
Loss on reacquired debt
Detail of regulatory assets
Current	1,637	1,637
Non-Current	12,441	13,668
Mead-Phoenix transmission line CIAC
Detail of regulatory assets
Current	332	332
Non-Current	9,795	10,044
TCA balancing account
Detail of regulatory assets
Current	5,016	3,860
Non-Current	2,721	772
Tax expense of Medicare subsidy
Detail of regulatory assets
Current	1,235	1,235
Non-Current	5,073	6,176
AG-1 deferral
Detail of regulatory assets
Current	2,787	2,654
Non-Current	3,413	5,819
Tax expense adjustor mechanism
Detail of regulatory assets
Current	2,916	0
Non-Current	0	0
Other
Detail of regulatory assets
Current	2,782	1,947
Non-Current	$ 0	$ 3,185

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CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
OPERATING REVENUES	$ 1,190,787	$ 1,268,034	$ 2,800,818	$ 2,934,871
OPERATING EXPENSES
Fuel and purchased power	344,862	389,936	817,672	844,133
Operations and maintenance	238,582	246,545	711,759	780,624
Depreciation and amortization	149,450	145,971	445,531	436,232
Taxes other than income taxes	53,809	51,375	163,989	158,582
Other expenses	794	900	1,904	8,497
Total	787,497	834,727	2,140,855	2,228,068
OPERATING INCOME	403,290	433,307	659,963	706,803
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	5,917	12,259	24,677	39,411
Pension and other postretirement non-service credits - net	5,752	12,449	17,240	37,314
Other income (Note 9)	15,191	6,958	35,245	17,541
Other expense (Note 9)	(5,740)	(5,063)	(14,448)	(12,063)
Total	21,120	26,603	62,714	82,203
INTEREST EXPENSE
Interest charges	57,481	61,605	175,599	181,267
Allowance for borrowed funds used during construction	(3,486)	(5,913)	(14,645)	(18,959)
Total	53,995	55,692	160,954	162,308
INCOME BEFORE INCOME TAXES	370,415	404,218	561,723	626,698
INCOME TAXES	53,266	84,333	72,764	127,107
NET INCOME	317,149	319,885	488,959	499,591
Less: Net income attributable to noncontrolling interests (Note 6)	4,873	4,873	14,620	14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 312,276	$ 315,012	$ 474,339	$ 484,971
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	112,463	112,148	112,408	112,094
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	112,746	112,533	112,739	112,499
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 2.78	$ 2.81	$ 4.22	$ 4.33
Net income attributable to common shareholders - diluted (in dollars per share)	$ 2.77	$ 2.80	$ 4.21	$ 4.31
APS
OPERATING REVENUES	$ 1,190,787	$ 1,267,997	$ 2,800,818	$ 2,931,966
OPERATING EXPENSES
Fuel and purchased power	344,862	389,889	817,672	862,037
Operations and maintenance	235,440	226,346	699,958	732,946
Depreciation and amortization	149,428	145,949	445,467	434,594
Taxes other than income taxes	53,798	51,366	163,957	157,877
Other expenses	794	900	1,904	1,497
Total	784,322	814,450	2,128,958	2,188,951
OPERATING INCOME	406,465	453,547	671,860	743,015
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	5,917	12,259	24,677	39,411
Pension and other postretirement non-service credits - net	6,133	12,812	18,389	38,398
Other income (Note 9)	14,534	6,153	32,641	16,160
Other expense (Note 9)	(2,826)	(3,361)	(10,132)	(9,679)
Total	23,758	27,863	65,575	84,290
INTEREST EXPENSE
Interest charges	53,812	58,551	164,068	172,440
Allowance for borrowed funds used during construction	(3,486)	(5,913)	(14,645)	(18,959)
Total	50,326	52,638	149,423	153,481
INCOME BEFORE INCOME TAXES	379,897	428,772	588,012	673,824
INCOME TAXES	56,154	85,533	76,070	133,415
NET INCOME	323,743	343,239	511,942	540,409
Less: Net income attributable to noncontrolling interests (Note 6)	4,873	4,873	14,620	14,620
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 318,870	$ 338,366	$ 497,322	$ 525,789

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Long-Term Debt and Liquidity Matters (Tables)

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Schedule of estimated fair value of long-term debt, including current maturities

The following table presents the estimated fair value of our long-term debt, including current maturities (dollars in thousands):

	As of September 30, 2019				As of December 31, 2018
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Pinnacle West	$	449,268	$	449,670	$	448,796	$	443,955
APS	4,985,728		5,617,727		4,689,436		4,789,608
Total	$	5,434,996	$	6,067,397	$	5,138,232	$	5,233,563

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CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common stock, par value (in dollars per share)
Common stock, authorized shares (in shares)	150,000,000	150,000,000
Common stock, issued shares (in shares)	112,403,751	112,159,896
Treasury stock at cost, shares (in shares)	57,947	58,135

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Investments in Nuclear Decommissioning Trusts and Other Special Use Funds

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Investments in Nuclear Decommissioning Trusts and Other Special Use Funds

Investments in Nuclear Decommissioning Trust and Other Special Use Funds

We have investments in debt and equity securities held in nuclear decommissioning trust, coal reclamation escrow account, and an active union employee medical account. Investments in debt securities are classified as available-for-sale securities. We record both debt and equity security investments at their fair value on our Condensed Consolidated Balance Sheets. See Note 11 for a discussion of how fair value is determined and the classification of the investments within the fair value hierarchy. The investments in each trust or account are restricted for use and are intended to fund specified costs and activities as further described for each fund below.

Nuclear Decommissioning Trust - To fund the future costs APS expects to incur to decommission Palo Verde, APS established an external decommissioning trust 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. Earnings and proceeds from sales and maturities of securities are reinvested in the trust. Because of the ability of APS to recover decommissioning

costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including other-than-temporary impairments) in other regulatory liabilities.

Coal Reclamation Escrow Account - APS has investments restricted for the future coal mine reclamation funding related to Four Corners. This escrow account is primarily invested in fixed income securities. Earnings and proceeds from sales of securities are reinvested in the escrow account. Because of the ability of APS to recover coal reclamation costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including other-than-temporary impairments) in other regulatory liabilities. Activities relating to APS coal reclamation escrow account investments are included within the other special use funds in the table below.

Active Union Employee Medical Account - APS has investments restricted for paying active union employee medical costs. These investments were transferred from APS other postretirement benefit trust assets into the active union employee medical trust in January 2018 (see Note 7 in the 2018 Form 10-K). These investments may be used to pay active union employee medical costs incurred in the current and future periods. In August 2019, the Company was reimbursed $15 million for prior year active union employee medical claims from the active union employee medical account. The account is invested primarily in fixed income securities. In accordance with the ratemaking treatment, APS has deferred the unrealized gains and losses (including other-than-temporary impairments) in other regulatory assets. Activities relating to active union employee medical account investments are included within the other special use funds in the table below.

APS

The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS's nuclear decommissioning trust and other special use fund assets at September 30, 2019 and December 31, 2018 (dollars in thousands):  

	September 30, 2019
	Fair Value								Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trust			Other Special Use Funds		Total
Equity securities	$	485,467		$	1,982	$	487,449		$	297,032	$	—
Available for sale-fixed income securities	483,528			240,582		724,110		(a)	28,750		(476		)
Other	(1,322		)	1,418		96		(b)	—		—
Total	$	967,673		$	243,982	$	1,211,655		$	325,782	$	(476	)

(a) As of September 30, 2019, the amortized cost basis of these available-for-sale investments is $696 million.

(b) Represents net pending securities sales and purchases.

	December 31, 2018
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trust		Other Special Use Funds		Total
Equity securities	$	402,008	$	45,130	$	447,138		$	222,147	$	(459	)
Available for sale-fixed income securities	446,978		190,378		637,356		(a)	8,634		(6,778		)
Other	2,148		593		2,741		(b)	—		—
Total	$	851,134	$	236,101	$	1,087,235		$	230,781	$	(7,237	)

(a) As of December 31, 2018, the amortized cost basis of these available-for-sale investments is $635 million.

(b) Represents net pending securities sales and purchases.

The following table sets forth APS's realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,
	Nuclear Decommissioning Trust			Other Special Use Funds		Total
2019
Realized gains	$	4,732		$	4	$	4,736
Realized losses	(2,360		)	—		(2,360		)
Proceeds from the sale of securities (a)	155,386			56,255		211,641
2018
Realized gains	$	653		$	—	$	653
Realized losses	(1,965		)	—		(1,965		)
Proceeds from the sale of securities (a)	148,150			25,127		173,277

(a) Proceeds are reinvested in the nuclear decommissioning trust and coal reclamation escrow account.

	Nine Months Ended September 30,
	Nuclear Decommissioning Trust			Other Special Use Funds		Total
2019
Realized gains	$	8,478		$	4	$	8,482
Realized losses	(5,465		)	—		(5,465		)
Proceeds from the sale of securities (a)	371,538			149,458		520,996
2018
Realized gains	$	2,951		$	1	$	2,952
Realized losses	(6,990		)	—		(6,990		)
Proceeds from the sale of securities (a)	401,396			41,644		443,040

(a) Proceeds are reinvested in the nuclear decommissioning trust and coal reclamation escrow account.

The fair value of APS's fixed income securities, summarized by contractual maturities, at September 30, 2019, is as follows (dollars in thousands):

	Nuclear Decommissioning Trust (a)		Coal Reclamation Escrow Account		Active Union Medical Trust		Total
Less than one year	$	40,309	$	32,628	$	37,013	$	109,950
1 year – 5 years	133,488		25,928		140,895		300,311
5 years – 10 years	103,973		720		—		104,693
Greater than 10 years	205,758		3,398		—		209,156
Total	$	483,528	$	62,674	$	177,908	$	724,110

(a)

Includes certain fixed income investments that are not due at a single maturity date. These investments have been allocated within the table based on the final payment date of the instrument.

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Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Leases

Leases

We lease certain land, buildings, vehicles, equipment and other property through operating rental agreements with varying terms, provisions, and expiration dates. APS also has certain purchased power agreements that qualify as lease arrangements. Our leases have remaining terms that expire in 2019 through 2050. Substantially all of our leasing activities relate to APS.

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 6 for a discussion of VIEs.

On January 1, 2019 we adopted new lease accounting guidance (see Note 13). We elected the transition method that allows us to apply the new lease guidance on the date of adoption, January 1, 2019, and will not retrospectively adjust prior periods. We also elected certain transition practical expedients that allow us to not reassess (a) whether any expired or existing contracts are or contain leases, (b) the lease classification for any expired or existing leases and (c) initial direct costs for any existing leases. These practical expedients apply to leases that commenced prior to January 1, 2019. Furthermore, we elected the practical expedient transition provisions relating to the treatment of existing land easements.

On January 1, 2019 the adoption of this new accounting standard resulted in the recognition on our Condensed Consolidated Balance Sheets of approximately $194 million of right-of-use lease assets and $119 million of lease liabilities relating to our operating lease arrangements. The right-of-use lease assets include $85 million of prepaid lease costs that have been reclassified from other deferred debits, and $10 million of deferred lease costs that have been reclassified from other current liabilities. In addition to these balance sheet impacts, the adoption of the guidance resulted in expanded lease disclosures, which are included below.

The following tables provide information related to our lease costs for the three and nine months ended September 30, 2019 (dollars in thousands):

	Three Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	21,095	$	4,581	$	25,676
Variable lease cost	36,917		183		37,100
Short-term lease cost	—		812		812
Total lease cost	$	58,012	$	5,576	$	63,588

	Nine Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	35,159	$	13,343	$	48,502
Variable lease cost	95,736		543		96,279
Short-term lease cost	—		3,477		3,477
Total lease cost	$	130,895	$	17,363	$	148,258

Lease costs are primarily included as a component of operating expenses on our Condensed Consolidated Statements of Income. Lease costs relating to purchased power lease contracts are recorded in fuel and purchased power on the Condensed Consolidated Statements of Income, and are subject to recovery under the PSA or RES (see Note 4). The tables above reflect the lease cost amounts before the effect of regulatory deferral under the PSA and RES. Variable lease costs are recognized in the period the costs are incurred, and primarily relate to renewable purchased power lease contracts. Payments under most renewable purchased power lease contracts are dependent upon environmental factors, and due to the inherent uncertainty associated with the reliability of the fuel source, the payments are considered variable and are excluded from the measurement of lease liabilities and right-of-use lease assets. Certain of our lease agreements have lease

terms with non-consecutive periods of use. For these agreements we recognize lease costs during the periods of use. Leases with initial terms of 12 months or less are considered short-term leases and are not recorded on the balance sheet.

The following table provides information related to the maturity of our operating lease liabilities at September 30, 2019 (dollars in thousands):

	September 30, 2019
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019 (remaining three months of 2019)	$	13,625	$	3,352	$	16,977
2020	—		14,083		14,083
2021	—		11,244		11,244
2022	—		7,727		7,727
2023	—		6,101		6,101
2024	—		3,915		3,915
Thereafter	—		38,697		38,697
Total lease commitments	13,625		85,119		98,744
Less imputed interest	19		20,032		20,051
Total lease liabilities	$	13,606	$	65,087	$	78,693

We recognize lease assets and liabilities upon lease commencement. At September 30, 2019, we have additional lease arrangements that have been executed, but have not yet commenced. These arrangements primarily relate to purchased power lease contracts. These leases have commencement dates beginning in June 2020 with terms ending through October 2027. We expect the total fixed consideration paid for these arrangements, which includes both lease and nonlease payments, will approximate $705 million over the term of the arrangements.

The following table provides information related to estimated future minimum operating lease payments at December 31, 2018 (dollars in thousands):

	December 31, 2018
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019	$	54,499	$	13,747	$	68,246
2020	—		12,428		12,428
2021	—		9,478		9,478
2022	—		6,513		6,513
2023	—		5,359		5,359
Thereafter	—		42,236		42,236
Total future lease commitments	$	54,499	$	89,761	$	144,260

The following tables provide other additional information related to operating lease liabilities:

	September 30, 2019
Weighted average remaining lease term	12 years
Weighted average discount rate (a)	3.73	%

(a) Most of our lease agreements do not contain an implicit rate that is readily determinable. For these agreements we use our incremental borrowing rate to measure the present value of lease liabilities.  We determine our incremental borrowing rate at lease commencement based on the rate of interest that we would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. We use the implicit rate when it is readily determinable.

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows (dollars in thousands):	$	51,980

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Revenue

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Revenue

Revenue

Sources of Revenue

The following table provides detail of Pinnacle West's consolidated revenue disaggregated by revenue sources (dollars in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Retail Electric Revenue
Residential	$	668,467	$	695,480	$	1,452,601	$	1,512,402
Non-Residential	465,602		496,809		1,194,199		1,275,498
Wholesale energy sales	36,775		53,501		95,218		80,982
Transmission services for others	15,841		15,902		46,247		46,235
Other sources	4,102		6,342		12,553		19,754
Total operating revenues	$	1,190,787	$	1,268,034	$	2,800,818	$	2,934,871

Retail Electric Revenue. Pinnacle West's retail electric revenue is generated by wholly owned regulated subsidiary APS's sale of electricity to our regulated customers within the authorized service territory at tariff rates approved by the ACC and based on customer kilowatt-hour ("KWh") usage. Revenues related to the sale of electricity are generally recognized when service is rendered or electricity is delivered to customers. The billing of electricity sales to individual customers is based on the reading of their meters. We obtain customers' meter data on a systematic basis throughout the month, and generally bill customers within a month from when service was provided. Customers are generally required to pay for services within 15 days of when the services are billed.

Wholesale Energy Sales and Transmission Services for Others. Revenues from wholesale energy sales and transmission services for others represent energy and transmission sales to wholesale customers. These activities primarily consist of managing fuel and purchased power risks in connection with the cost of serving our retail customers' energy requirements. We may also sell into the wholesale markets generation that is not needed for APS’s retail load. Our wholesale activities and tariff rates are regulated by the United States Federal Energy Regulatory Commission ("FERC").

In the electricity business, some contracts to purchase energy are settled by netting against other contracts to sell electricity. This is referred to as a book-out, and usually occurs in contracts that have the same terms (product type, quantities, and delivery points) and for which power does not flow. We net these book-outs, which reduces both wholesale revenues and fuel and purchased power costs.

Revenue Activities

Our revenues primarily consist of activities that are classified as revenues from contracts with customers. We derive our revenues from contracts with customers primarily from sales of electricity to our regulated retail customers. Revenues from contracts with customers also include wholesale and transmission activities. Our revenues from contracts with customers for the three and nine months ended September 30, 2019 were $1,178 million and $2,756 million, respectively, and for the three and nine months ended September 30, 2018 were $1,257 million and $2,897 million, respectively.

We have certain revenues that do not meet the specific accounting criteria to be classified as revenues from contracts with customers. For the three and nine months ended September 30, 2019, our revenues that do not qualify as revenue from contracts with customers were $13 million and $45 million, respectively, and for the three and nine months ended September 30, 2018 were $11 million and $38 million, respectively. This relates primarily to certain regulatory cost recovery mechanisms that are considered alternative revenue programs. We recognize revenue associated with alternative revenue programs when specific events permitting recognition are completed. Certain amounts associated with alternative revenue programs will subsequently be billed to customers; however, we do not reclassify billed amounts into revenue from contracts with customers. See Note 4 for a discussion of our regulatory cost recovery mechanisms.

Contract Assets and Liabilities from Contracts with Customers

There were no material contract assets, contract liabilities, or deferred contract costs recorded on the Condensed Consolidated Balance Sheets as of September 30, 2019 or December 31, 2018.

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Palo Verde Sale Leaseback Variable Interest Entities

9 Months Ended

Sep. 30, 2019

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 through 2023, and $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 the three and nine months ended September 30, 2019 of $5 million and $15 million, respectively, and for the three and nine months ended September 30, 2018 of $5 million and

$15 million, respectively, entirely attributable to the noncontrolling interests. Income attributable to Pinnacle West shareholders is not impacted by the consolidation.

Our Condensed Consolidated Balance Sheets at September 30, 2019 and December 31, 2018 include the following amounts relating to the VIEs (dollars in thousands):

	September 30, 2019		December 31, 2018
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	$	102,873	$	105,775
Equity — Noncontrolling interests	129,039		125,790

Assets of the VIEs are restricted and may only be used for payment to the noncontrolling interest holders. These assets are reported on our condensed consolidated financial statements.

APS is exposed to losses relating to these VIEs upon the occurrence of certain events that APS does not consider to be reasonably likely to occur.  Under certain circumstances (for example, the Nuclear Regulatory Commission ("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 $299 million beginning in 2019, and up to $456 million over the lease extension terms.

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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Earnings Per Share

9 Months Ended

Sep. 30, 2019

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 the three and nine months ended September 30, 2019 and 2018 (in thousands, except per share amounts):

	Three Months Ended  September 30,				Nine Months Ended   September 30,
	2019		2018		2019		2018
Net income attributable to common shareholders	$	312,276	$	315,012	$	474,339	$	484,971
Weighted average common shares outstanding — basic	112,463		112,148		112,408		112,094
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units	283		385		331		405
Weighted average common shares outstanding — diluted	112,746		112,533		112,739		112,499
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders — basic	$	2.78	$	2.81	$	4.22	$	4.33
Net income attributable to common shareholders — diluted	$	2.77	$	2.80	$	4.21	$	4.31

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Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

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 September 30, 2019 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2			Level 3			Other				Total
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	1,388		$	388		$	(959	)	(a)	$	817
Nuclear decommissioning trust:
Equity securities	8,774		—			—			(1,322		)	(b)	7,452
U.S. commingled equity funds	—		—			—			476,693			(c)	476,693
U.S. Treasury debt	162,092		—			—			—				162,092
Corporate debt	—		124,026			—			—				124,026
Mortgage-backed securities	—		112,704			—			—				112,704
Municipal bonds	—		74,202			—			—				74,202
Other fixed income	—		10,504			—			—				10,504
Subtotal nuclear decommissioning trust	170,866		321,436			—			475,371				967,673
Other special use funds:
Equity securities	1,982		—			—			1,418			(b)	3,400
U.S. Treasury debt	232,165		—			—			—				232,165
Municipal bonds	—		8,417			—			—				8,417
Subtotal other special use funds	234,147		8,417			—			1,418				243,982
Total assets	$	405,013	$	331,241		$	388		$	475,830			$	1,212,472
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(69,752	)	$	(1,982	)	$	80		(a)	$	(71,654	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(b) Represents net pending securities sales and purchases.

(c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

The following table presents the fair value at December 31, 2018 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2			Level 3			Other				Total
Assets
Cash equivalents	$	1,200	$	—		$	—		$	—			$	1,200
Risk management activities — derivative instruments:
Commodity contracts	—		3,140			2			(2,029		)	(a)	1,113
Nuclear decommissioning trust:
Equity securities	5,203		—			—			2,148			(b)	7,351
U.S. commingled equity funds	—		—			—			396,805			(c)	396,805
U.S. Treasury debt	148,173		—			—			—				148,173
Corporate debt	—		96,656			—			—				96,656
Mortgage-backed securities	—		113,115			—			—				113,115
Municipal bonds	—		79,073			—			—				79,073
Other fixed income	—		9,961			—			—				9,961
Subtotal nuclear decommissioning trust	153,376		298,805			—			398,953				851,134
Other special use funds:
Equity securities	45,130		—			—			593			(b)	45,723
U.S. Treasury debt	173,310		—			—			—				173,310
Municipal bonds	—		17,068			—			—				17,068
Subtotal other special use funds	218,440		17,068			—			593				236,101
Total assets	$	373,016	$	319,013		$	2		$	397,517			$	1,089,548
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(52,696	)	$	(8,216	)	$	875		(a)	$	(60,037	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(b) Represents net pending securities sales and purchases.

(c)

Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments

The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at September 30, 2019 and December 31, 2018:

	September 30, 2019 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	388	$	489	Discounted cash flows	Electricity forward price (per MWh)	$17.79 - $17.79	$	17.79
Natural Gas:
Forward Contracts (a)	—		1,493		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.53 - $2.79	$	2.64
Total	$	388	$	1,982

(a) Includes swaps and physical and financial contracts.

	December 31, 2018 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	—	$	2,456	Discounted cash flows	Electricity forward price (per MWh)	$17.88 - $37.03	$	26.10
Natural Gas:
Forward Contracts (a)	2		5,760		Discounted cash flows	Natural gas forward price (per MMBtu)	$1.79 - $2.92	$	2.48
Total	$	2	$	8,216

(a)

Includes swaps and physical and financial contracts.

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts	2019			2018			2019			2018
Net derivative balance at beginning of period	$	(12,753	)	$	(9,358	)	$	(8,214	)	$	(18,256	)
Total net gains (losses) realized/unrealized:
Deferred as a regulatory asset or liability	(2,324		)	1,244			(12,634		)	(2,067		)
Settlements	8,980			(2,332		)	11,929			(1,056		)
Transfers into Level 3 from Level 2	(613		)	(2,246		)	(3,711		)	(7,225		)
Transfers from Level 3 into Level 2	5,116			2,829			11,036			18,741
Net derivative balance at end of period	$	(1,594	)	$	(9,863	)	$	(1,594	)	$	(9,863	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—		$	—		$	—

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Palo Verde Sale Leaseback Variable Interest Entities (Tables)

9 Months Ended

Sep. 30, 2019

Variable Interest Entities [Abstract]

Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets

Our Condensed Consolidated Balance Sheets at September 30, 2019 and December 31, 2018 include the following amounts relating to the VIEs (dollars in thousands):

	September 30, 2019		December 31, 2018
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	$	102,873	$	105,775
Equity — Noncontrolling interests	129,039		125,790

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Palo Verde Sale Leaseback Variable Interest Entities - Schedule of VIEs (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	$ 102,873	$ 105,775
Equity — Noncontrolling interests	129,039	125,790
APS
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	102,873	105,775
Equity — Noncontrolling interests	129,039	125,790
APS | Consolidation of VIEs
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Palo Verde sale leaseback property plant and equipment, net of accumulated depreciation	102,873	105,775
Equity — Noncontrolling interests	$ 129,039	$ 125,790

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Derivative Accounting - Derivative Instruments in the Balance Sheets (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Assets
Gross Recognized Derivatives	$ 817,000	$ 1,113,000
Liabilities
Amount Reported on Balance Sheets	(71,654,000)	(60,037,000)
Commodity Contracts
Assets
Gross Recognized Derivatives	1,776,000	3,142,000
Amounts Offset	(1,266,000)	(2,185,000)
Net Recognized Derivatives	510,000	957,000
Other	307,000	156,000
Amount Reported on Balance Sheets	817,000	1,113,000
Liabilities
Gross Recognized Derivatives	(71,734,000)	(60,912,000)
Amounts Offset	1,266,000	2,185,000
Net Recognized Derivatives	(70,468,000)	(58,727,000)
Other	(1,186,000)	(1,310,000)
Amount Reported on Balance Sheets	(71,654,000)	(60,037,000)
Assets and Liabilities
Gross Recognized Derivatives	(69,958,000)	(57,770,000)
Amounts Offset	0	0
Net Recognized Derivatives	(69,958,000)	(57,770,000)
Other	(879,000)	(1,154,000)
Amount Reported on Balance Sheets	(70,837,000)	(58,924,000)
Cash collateral received from counterparties	1,186,000	1,310,000
Commodity Contracts | Current assets
Assets
Gross Recognized Derivatives	1,776,000	3,106,000
Amounts Offset	(1,266,000)	(2,149,000)
Net Recognized Derivatives	510,000	957,000
Other	307,000	156,000
Amount Reported on Balance Sheets	817,000	1,113,000
Commodity Contracts | Investments and other assets
Assets
Gross Recognized Derivatives		36,000
Amounts Offset		(36,000)
Net Recognized Derivatives		0
Other		0
Amount Reported on Balance Sheets		0
Commodity Contracts | Current liabilities
Liabilities
Gross Recognized Derivatives	(44,429,000)	(36,345,000)
Amounts Offset	1,266,000	2,149,000
Net Recognized Derivatives	(43,163,000)	(34,196,000)
Other	(1,186,000)	(1,310,000)
Amount Reported on Balance Sheets	(44,349,000)	(35,506,000)
Assets and Liabilities
Cash collateral received from counterparties	1,186,000	1,310,000
Commodity Contracts | Deferred credits and other
Liabilities
Gross Recognized Derivatives	(27,305,000)	(24,567,000)
Amounts Offset	0	36,000
Net Recognized Derivatives	(27,305,000)	(24,531,000)
Other	0	0
Amount Reported on Balance Sheets	(27,305,000)	(24,531,000)
Assets and Liabilities
Cash collateral received from counterparties	$ 0	$ 0

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Leases - Other additional information related to operating lease liabilities (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Leases [Abstract]
Weighted average remaining lease term	12 years
Weighted average discount rate (a)	3.73%
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows	$ 51,980

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Income Taxes (Details) - USD ($) $ in Millions		12 Months Ended
	Sep. 30, 2019	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Reduction in net deferred income tax liabilities		$ 1,140
Amortization of an excess deferred tax liability	$ 42
Deferred tax liability	$ 56

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Regulatory Matters - Cost Recovery Mechanism and Net Metering (Details)																					1 Months Ended	9 Months Ended		12 Months Ended
	Oct. 31, 2019 USD ($)	Oct. 29, 2019 USD ($)	Jun. 01, 2019 USD ($)	Apr. 10, 2019 USD ($)	Feb. 15, 2019 USD ($)	Feb. 01, 2019 $ / kWh	Aug. 13, 2018 USD ($)	Jun. 01, 2018 USD ($)	May 01, 2018 $ / kWh	Feb. 20, 2018	Feb. 15, 2018 USD ($)	Feb. 01, 2018 $ / kWh	Jan. 08, 2018 USD ($)	Nov. 20, 2017 USD ($)	Aug. 19, 2017 $ / kWh	Jun. 01, 2017 USD ($)	Feb. 01, 2017 $ / kWh	Jan. 13, 2017 USD ($)	Dec. 20, 2016 $ / kWh	Feb. 01, 2016 $ / kWh	Aug. 31, 2016	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 USD ($) $ / kWh	Dec. 31, 2012 $ / kWh	Jul. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 29, 2018 USD ($)	Nov. 14, 2017 USD ($)	Sep. 01, 2017 USD ($)	Jun. 30, 2017 USD ($)
Change in regulatory asset
Deferred fuel and purchased power costs — current period																						$ 60,911,000	$ 82,486,000
Amounts charged to customers																						(38,601,000)	(92,397,000)
Ballot Initiative, proposed required energy supply from renewable sources (as a percent)										50.00%
APS
Change in regulatory asset
Deferred fuel and purchased power costs — current period																						60,911,000	82,486,000
Amounts charged to customers																						$ (38,601,000)	(92,397,000)
Lost Fixed Cost Recovery Mechanisms | APS
Change in regulatory asset
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
Fixed cost recoverable per power lost (in dollars per kWh) | $ / kWh																									0.025
Percentage of retail revenues																						1.00%
Amount of adjustment representing prorated sales losses approval																		$ 63,700,000
Amount of adjustment representing prorated sales losses pending approval					$ 36,200,000						$ 60,700,000
Increase (decrease) in amount of adjustment representing prorated sales losses					$ (24,500,000)						$ (3,000,000)
ACC | APS
Settlement Agreement
Program term																					2 years
Change in regulatory asset
Gross-up for revenue requirement of rate regulation				$ (184,000,000)			$ 86,500,000						$ 119,100,000
Deferred taxes amortization, period				28 years 6 months
ACC | RES | APS
Settlement Agreement
Plan term																						5 years
ACC | RES 2018 | APS
Settlement Agreement
Amount of proposed budget																											$ 86,300,000		$ 89,900,000			$ 90,000,000
ACC | RES 2018 | APS | Solar Communities
Settlement Agreement
Program term														3 years
ACC | Demand Side Management Adjustor Charge 2018 | APS
Settlement Agreement
Amount of proposed budget																												$ 34,100,000		$ 52,600,000	$ 52,600,000
ACC | Power Supply Adjustor (PSA) | APS
Change in regulatory asset
Beginning balance																						$ 37,164,000	75,637,000	$ 37,164,000
Deferred fuel and purchased power costs — current period																						60,911,000	82,486,000
Amounts charged to customers																						(38,601,000)	(92,397,000)
Ending balance																						59,474,000	$ 65,726,000		$ 75,637,000
PSA rate (in dollars per kWh) | $ / kWh						0.001658						0.004555			0.000555		(0.001348)
PSA rate for prior year (in dollars per kWh) | $ / kWh						0.000536						0.002009			0.000876		(0.001027)
Forward component of increase in PSA (in dollars per kWh) | $ / kWh						0.001122						0.002546			(0.000321)		(0.000321)
Maximum increase (decrease) in PSA rate | $ / kWh												0.004
Fuel and purchased power costs, excess annual limit																						$ 16,400,000
ACC | Net Metering | APS
Change in regulatory asset
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
Cost of service for new customers, guaranteed export price period																			10 years
First-year export energy price (in dollars per kWh) | $ / kWh																			0.129
Second-year export energy price (in dollars per kWh) | $ / kWh									0.116
United States Federal Energy Regulatory Commission | Open Access Transmission Tariff | APS
Change in regulatory asset
Increase (decrease) in annual wholesale transmission rates			$ (4,900,000)					$ (22,700,000)								$ (35,100,000)
Cost Recovery Mechanisms | ACC | Power Supply Adjustor (PSA) | APS
Change in regulatory asset
Historical component of increase in PSA (in dollars per kWh) | $ / kWh						(0.002897)														0.001678
Forecast | ACC | APS
Change in regulatory asset
Operating Results																								$ 10,000,000
Minimum | ACC | RES 2018 | APS | Solar Communities
Settlement Agreement
Required annual capital investment														$ 10,000,000
Minimum | Forecast | ACC | APS
Change in regulatory asset
Operating Results	$ (69,000,000)
Maximum | ACC | RES 2018 | APS | Solar Communities
Settlement Agreement
Required annual capital investment														$ 15,000,000
Subsequent Event | ACC | APS
Change in regulatory asset
Public Utilities, one-time bill credit		$ 64,000,000
Public Utilities, one-time bill credit, additional benefit		$ 39,500,000

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Long-Term Debt and Liquidity Matters - Narrative (Details)	May 09, 2019 USD ($)	Mar. 01, 2019 USD ($)	Feb. 26, 2019 USD ($)	Sep. 30, 2019 USD ($) Facility	Aug. 19, 2019 USD ($)	Feb. 28, 2019 USD ($)
Pinnacle West | Revolving Credit Facility | Revolving credit facility maturing June 2019
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)	$ 150,000,000
Pinnacle West | Revolving Credit Facility | Revolving credit Facility maturing July 2023
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)				$ 300,000,000
Long-term line of credit				0
Current borrowing capacity on credit facility				200,000,000
Pinnacle West | Term Loan
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)	$ 50,000,000
Long-term line of credit				41,000,000
Pinnacle West | Letter of Credit | Revolving credit Facility maturing July 2023
Long-Term Debt and Liquidity Matters
Outstanding letters of credit				0
Pinnacle West | Commercial paper | Revolving credit Facility maturing July 2023
Long-Term Debt and Liquidity Matters
Commercial paper				13,000,000
APS | Term Loan
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)			$ 200,000,000
APS | Senior notes
Long-Term Debt and Liquidity Matters
Debt instrument, face amount					$ 300,000,000	$ 300,000,000
Debt instrument, interest rate		8.75%			2.60%	4.25%
Extinguishment of debt		$ 500,000,000
APS | Revolving Credit Facility | Revolving credit Facility maturing July 2023
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)				700,000,000
Current borrowing capacity on credit facility				500,000,000
APS | Revolving Credit Facility | Revolving Credit Facility Maturing in 2022 and 2023
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)				1,400,000,000
Long-term line of credit				0
Current borrowing capacity on credit facility				$ 1,000,000,000
Number of line of credit facilities | Facility				2
APS | Revolving Credit Facility | Revolving credit facility maturing June 2022
Long-Term Debt and Liquidity Matters
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders (up to)				$ 700,000,000
Current borrowing capacity on credit facility				500,000,000
APS | Commercial paper
Long-Term Debt and Liquidity Matters
Maximum commercial paper support available under credit facility				500,000,000
APS | Commercial paper | Revolving Credit Facility Maturing in 2022 and 2023
Long-Term Debt and Liquidity Matters
Commercial paper				$ 3,000,000
LIBOR | Pinnacle West | Term Loan
Long-Term Debt and Liquidity Matters
Debt instrument, basis spread on variable rate	0.55%
LIBOR | APS | Term Loan
Long-Term Debt and Liquidity Matters
Debt instrument, basis spread on variable rate			0.50%

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Commitments and Contingencies - Environmental Matters and Financial Assurances (Details) - USD ($) $ in Millions			9 Months Ended	12 Months Ended
	Jul. 03, 2018	Jul. 06, 2016	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2018
APS | Letters of Credit Expiring in 2020
Financial Assurances
Outstanding letters of credit			$ 1.7
APS | Surety Bonds Expiring in 2020
Financial Assurances
Surety bonds expiring, amount			14.0
4C Acquisition, LLC | Four Corners
Environmental Matters
Percentage of share of cost of control		7.00%
4C Acquisition, LLC | Coal Supply Agreement Arbitration | Four Corners
Four Corners Coal Supply Agreement
Proceeds from operating and maintenance cost reimbursement				$ 10.0
Reimbursement payments due to 4CA			$ 10.0		$ 20.0
NTEC | Four Corners
Four Corners Coal Supply Agreement
Option to purchase ownership interest (as a percent)	7.00%	7.00%
Proceeds from operating and maintenance cost reimbursement	$ 70.0
NTEC | Coal Supply Agreement Arbitration | Four Corners
Four Corners Coal Supply Agreement
Option to purchase ownership interest (as a percent)		7.00%
Regional Haze Rules | APS | Four Corners Units 4 and 5
Environmental Matters
Percentage of share of cost of control			63.00%
Expected environmental cost			$ 400.0
Regional Haze Rules | APS | Natural gas tolling contract obligations | Four Corners Units 4 and 5
Environmental Matters
Additional percentage share of cost of control			7.00%
Regional Haze Rules | APS | Four Corners | Four Corners Units 4 and 5
Environmental Matters
Site contingency increase in loss exposure not accrued, best estimate			$ 45.0
Regional Haze Rules | APS | Navajo Plant
Environmental Matters
Expected environmental cost			200.0
Coal combustion waste | APS | Four Corners
Environmental Matters
Site contingency increase in loss exposure not accrued, best estimate			22.0
Coal combustion waste | APS | Navajo Plant
Environmental Matters
Site contingency increase in loss exposure not accrued, best estimate			1.0
Coal combustion waste | APS | Cholla and Four Corners
Environmental Matters
Site contingency increase in loss exposure not accrued, best estimate			5.0
Minimum | Coal combustion waste | APS | Cholla
Environmental Matters
Site contingency increase in loss exposure not accrued, best estimate			$ 15.0

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Fair Value Measurements - Significant Unobservable Inputs Used to Value Level 3 Instruments (Details 2) - Forward Price $ in Thousands	Sep. 30, 2019 USD ($) $ / MWh	Dec. 31, 2018 USD ($) $ / MWh
Level 3
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets | $	$ 388	$ 2
Financial and Nonfinancial Liabilities, Fair Value Disclosure | $	1,982	$ 8,216
Electricity forward contracts | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input		17.88
Electricity forward contracts | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input		37.03
Electricity forward contracts | Level 3
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets | $	388	$ 0
Financial and Nonfinancial Liabilities, Fair Value Disclosure | $	$ 489	$ 2,456
Electricity forward contracts | Level 3 | Weighted-Average
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input	17.79	26.10
Electricity forward contracts | Level 3 | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input	17.79
Electricity forward contracts | Level 3 | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input	17.19
Natural gas contracts | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input		1.79
Natural gas contracts | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input		2.92
Natural gas contracts | Level 3
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets | $	$ 0	$ 2
Financial and Nonfinancial Liabilities, Fair Value Disclosure | $	$ 1,493	$ 5,760
Natural gas contracts | Level 3 | Weighted-Average
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input	2.64	2.48
Natural gas contracts | Level 3 | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input	2.53
Natural gas contracts | Level 3 | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Significant Unobservable Input	2.79

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Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		$ 5,357,243	$ 5,159,434	$ 5,348,705	$ 5,135,730
OCI (loss) before reclassifications				(2,422)	(6,024)
Amounts reclassified from accumulated other comprehensive loss		1,098	1,550	3,592	4,504
Reclassification of income tax effect related to tax reform					(8,552)
Balance at end of period		5,681,705	5,485,861	5,681,705	5,485,861
Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(46,657)	(54,233)	(45,997)	(42,440)
OCI (loss) before reclassifications				(2,422)	(5,928)
Amounts reclassified from accumulated other comprehensive loss		880	1,099	2,642	3,188
Reclassification of income tax effect related to tax reform					(7,954)
Balance at end of period		(45,777)	(53,134)	(45,777)	(53,134)
Derivative Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(979)	(2,391)	(1,711)	(2,562)
OCI (loss) before reclassifications				0	(96)
Amounts reclassified from accumulated other comprehensive loss		218	451	950	1,316
Reclassification of income tax effect related to tax reform					(598)
Balance at end of period		(761)	(1,940)	(761)	(1,940)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(47,636)	(56,624)	(47,708)	(45,002)
Reclassification of income tax effect related to tax reform	[1]				(8,552)
Balance at end of period		(46,538)	(55,074)	(46,538)	(55,074)
APS
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		5,797,857	5,412,930	5,786,797	5,385,869
Amounts reclassified from accumulated other comprehensive loss		973	1,403
Balance at end of period		6,122,571	5,757,571	6,122,571	5,757,571
APS | Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(26,297)	(32,768)	(25,396)	(24,421)
OCI (loss) before reclassifications				(2,414)	(5,791)
Amounts reclassified from accumulated other comprehensive loss		755	952	2,268	2,836
Reclassification of income tax effect related to tax reform					(4,440)
Balance at end of period		(25,542)	(31,816)	(25,542)	(31,816)
APS | Derivative Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(979)	(2,391)	(1,711)	(2,562)
OCI (loss) before reclassifications				0	(96)
Amounts reclassified from accumulated other comprehensive loss		218	451	950	1,316
Reclassification of income tax effect related to tax reform					(598)
Balance at end of period		(761)	(1,940)	(761)	(1,940)
APS | Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(27,276)	(35,159)	(27,107)	(26,983)
OCI (loss) before reclassifications				(2,414)	(5,887)
Amounts reclassified from accumulated other comprehensive loss				3,218	4,152
Reclassification of income tax effect related to tax reform	[2]				(5,038)
Balance at end of period		$ (26,303)	$ (33,756)	$ (26,303)	$ (33,756)

[1] In 2018, the Company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) on items within accumulated other comprehensive income to retained earnings.

[2] In 2018, the Company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net unrealized loss, tax expense	$ 0	$ 0	$ 0	$ 96
Reclassification of net realized loss, net of tax benefit	(71)	(149)	(313)	(381)
Pension and other postretirement benefits activity, net of tax expense (benefit)	290	361	72	(754)
APS
Net unrealized loss, tax expense	0	0	0	96
Reclassification of net realized loss, net of tax benefit	(71)	(149)	(313)	(381)
Pension and other postretirement benefits activity, net of tax expense (benefit)	$ 249	$ 313	$ (48)	$ (947)

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Changes in Accumulated Other Comprehensive Loss

9 Months Ended

Sep. 30, 2019

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Three Months Ended September 30
Balance June 30, 2019	$	(46,657	)		$	(979	)		$	(47,636	)
Amounts reclassified from accumulated other comprehensive loss	880			(a)	218			(b)	1,098
Balance September 30, 2019	$	(45,777	)		$	(761	)		$	(46,538	)
Balance June 30, 2018	$	(54,233	)		$	(2,391	)		$	(56,624	)
Amounts reclassified from accumulated other comprehensive loss	1,099			(a)	451			(b)	1,550
Balance September 30, 2018	$	(53,134	)		$	(1,940	)		$	(55,074	)

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Nine Months Ended September 30
Balance December 31, 2018	$	(45,997	)		$	(1,711	)		$	(47,708	)
OCI (loss) before reclassifications	(2,422		)		—				(2,422		)
Amounts reclassified from accumulated other comprehensive loss	2,642			(a)	950			(b)	3,592
Balance September 30, 2019	$	(45,777	)		$	(761	)		$	(46,538	)
Balance December 31, 2017	$	(42,440	)		$	(2,562	)		$	(45,002	)
OCI (loss) before reclassifications	(5,928		)		(96		)		(6,024		)
Amounts reclassified from accumulated other comprehensive loss	3,188			(a)	1,316			(b)	4,504
Reclassification of income tax effect related to tax reform	(7,954		)	(c)	(598		)	(c)	(8,552		)
Balance September 30, 2018	$	(53,134	)		$	(1,940	)		$	(55,074	)

(a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost.  See Note 5.

(b) 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 7.

(c)

In 2018, the company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

The following table shows the changes in APS's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands): 

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Three Months Ended September 30
Balance June 30, 2019	$	(26,297	)		$	(979	)		$	(27,276	)
Amounts reclassified from accumulated other comprehensive loss	755			(a)	218			(b)	973
Balance September 30, 2019	$	(25,542	)		$	(761	)		$	(26,303	)
Balance June 30, 2018	$	(32,768	)		$	(2,391	)		$	(35,159	)
Amounts reclassified from accumulated other comprehensive loss	952			(a)	451			(b)	1,403
Balance September 30, 2018	$	(31,816	)		$	(1,940	)		$	(33,756	)

	Pension and Other Postretirement Benefits				Derivative Instruments				Total
Nine Months Ended September 30
Balance December 31, 2018	$	(25,396	)		$	(1,711	)		$	(27,107	)
OCI (loss) before reclassifications	(2,414		)		—				(2,414		)
Amounts reclassified from accumulated other comprehensive loss	2,268			(a)	950			(b)	3,218
Balance September 30, 2019	$	(25,542	)		$	(761	)		$	(26,303	)
Balance December 31, 2017	$	(24,421	)		$	(2,562	)		$	(26,983	)
OCI (loss) before reclassifications	(5,791		)		(96		)		(5,887		)
Amounts reclassified from accumulated other comprehensive loss	2,836			(a)	1,316			(b)	4,152
Reclassification of income tax effect related to tax reform	(4,440		)	(c)	(598		)	(c)	(5,038		)
Balance September 30, 2018	$	(31,816	)		$	(1,940	)		$	(33,756	)

(a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost.  See Note 5.

(b) 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 7.

(c)

In 2018, the company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

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CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands		Total	Common Stock	Treasury Stock	Retained Earnings		Accumulated Other Comprehensive Income (Loss)		Noncontrolling Interests	APS	APS Common Stock	APS Additional Paid-In Capital	APS Retained Earnings		APS Accumulated Other Comprehensive Income (Loss)		APS Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2017			111,816,170	64,463							71,264,947
Balance at beginning of period at Dec. 31, 2017		$ 5,135,730	$ 2,614,805	$ (5,624)	$ 2,442,511		$ (45,002)		$ 129,040	$ 5,385,869	$ 178,162	$ 2,571,696	$ 2,533,954		$ (26,983)		$ 129,040
Increase (Decrease) in Shareholders' Equity
Net Income		499,591			484,971				14,620	540,409			525,789				14,620
Other comprehensive income (loss)		(1,520)					(1,520)			(1,735)					(1,735)
Dividends on common stock		(155,607)			(155,607)					(155,601)			(155,601)
Issuance of common stock (in shares)			199,779
Issuance of common stock		14,822	$ 14,822
Purchase of treasury stock (in shares)	[1]			(81,278)
Purchase of treasury stock	[1]	(6,285)		$ (6,285)
Reissuance of treasury stock for stock-based compensation and other (in shares)				128,373
Reissuance of treasury stock for stock-based compensation and other		10,501		$ 10,500	1
Capital activities by noncontrolling interests		11,372							11,372	11,372							11,372
Reclassification of income tax effects related to new tax reform		(8,552)			8,552	[2]	(8,552)	[2]					5,038	[3]	(5,038)	[3]
Other		1							1	1							1
Ending balance (in shares) at Sep. 30, 2018			112,015,949	17,368							71,264,947
Balance at end of period at Sep. 30, 2018		5,485,861	$ 2,629,627	$ (1,409)	2,780,428		(55,074)		132,289	5,757,571	$ 178,162	2,571,696	2,909,180		(33,756)		132,289
Beginning balance (in shares) at Jun. 30, 2018			111,990,222	17,633							71,264,947
Balance at beginning of period at Jun. 30, 2018		5,159,434	$ 2,624,672	$ (1,431)	2,465,402		(56,624)		127,415	5,412,930	$ 178,162	2,571,696	2,570,816		(35,159)		127,415
Increase (Decrease) in Shareholders' Equity
Net Income		319,885			315,012				4,873	343,239			338,366				4,873
Other comprehensive income (loss)		1,550					1,550			1,403					1,403
Dividends on common stock		14			14
Issuance of common stock (in shares)			25,727
Issuance of common stock		4,955	$ 4,955
Purchase of treasury stock (in shares)	[4]			(101)
Purchase of treasury stock	[4]	(8)		$ (8)
Reissuance of treasury stock for stock-based compensation and other (in shares)				366
Reissuance of treasury stock for stock-based compensation and other		30		$ 30	0
Other		1							1	(1)			(2)				1
Ending balance (in shares) at Sep. 30, 2018			112,015,949	17,368							71,264,947
Balance at end of period at Sep. 30, 2018		$ 5,485,861	$ 2,629,627	$ (1,409)	2,780,428		(55,074)		132,289	5,757,571	$ 178,162	2,571,696	2,909,180		(33,756)		132,289
Beginning balance (in shares) at Dec. 31, 2018		112,159,896	112,159,896	58,135							71,264,947
Balance at beginning of period at Dec. 31, 2018		$ 5,348,705	$ 2,634,265	$ (4,825)	2,641,183		(47,708)		125,790	5,786,797	$ 178,162	2,721,696	2,788,256		(27,107)		125,790
Increase (Decrease) in Shareholders' Equity
Net Income		488,959			474,339				14,620	511,942			497,322				14,620
Other comprehensive income (loss)		1,170					1,170			804					804
Dividends on common stock		(165,631)			(165,631)					(165,600)			(165,600)
Issuance of common stock (in shares)			243,855
Issuance of common stock		20,165	$ 20,165
Purchase of treasury stock (in shares)	[1]			(75,894)
Purchase of treasury stock	[1]	(6,892)		$ (6,892)
Reissuance of treasury stock for stock-based compensation and other (in shares)				76,082
Reissuance of treasury stock for stock-based compensation and other		6,600		$ 6,600	0
Capital activities by noncontrolling interests		11,372							11,372	11,372							11,372
Other		$ 1							1	0			(1)				1
Ending balance (in shares) at Sep. 30, 2019		112,403,751	112,403,751	57,947							71,264,947
Balance at end of period at Sep. 30, 2019		$ 5,681,705	$ 2,654,430	$ (5,117)	2,949,891		(46,538)		129,039	6,122,571	$ 178,162	2,721,696	3,119,977		(26,303)		129,039
Beginning balance (in shares) at Jun. 30, 2019			112,361,595	58,219							71,264,947
Balance at beginning of period at Jun. 30, 2019		5,357,243	$ 2,648,234	$ (5,140)	2,637,620		(47,636)		124,165	5,797,857	$ 178,162	2,721,696	2,801,110		(27,276)		124,165
Increase (Decrease) in Shareholders' Equity
Net Income		317,149			312,276				4,873	323,743			318,870				4,873
Other comprehensive income (loss)		1,098					1,098			973					973
Dividends on common stock		(5)			(5)
Issuance of common stock (in shares)			42,156
Issuance of common stock		6,196	$ 6,196
Purchase of treasury stock (in shares)	[4]			(103)
Purchase of treasury stock	[4]	(10)		$ (10)
Reissuance of treasury stock for stock-based compensation and other (in shares)				375
Reissuance of treasury stock for stock-based compensation and other		33		$ 33	0
Other		$ 1							1	(2)			(3)				1
Ending balance (in shares) at Sep. 30, 2019		112,403,751	112,403,751	57,947							71,264,947
Balance at end of period at Sep. 30, 2019		$ 5,681,705	$ 2,654,430	$ (5,117)	$ 2,949,891		$ (46,538)		$ 129,039	$ 6,122,571	$ 178,162	$ 2,721,696	$ 3,119,977		$ (26,303)		$ 129,039

[1] Primarily represents shares of common stock withheld from certain stock awards for tax purposes.

[2] In 2018, the Company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) on items within accumulated other comprehensive income to retained earnings.

[3] In 2018, the Company adopted new accounting guidance and elected to reclassify income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings.

[4] Primarily represents shares of common stock withheld from certain stock awards for tax purposes.

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Consolidation and Nature of Operations (Tables)

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of supplemental cash flow information

The following table summarizes supplemental Pinnacle West cash flow information (dollars in thousands):

	Nine Months Ended September 30,
	2019		2018
Cash paid during the period for:
Income taxes, net of refunds	$	12,488	$	10,091
Interest, net of amounts capitalized	166,907		161,875
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	85,099	$	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759		—
Sale of 4CA's 7% interest in Four Corners	—		68,907

The following table summarizes supplemental APS cash flow information (dollars in thousands):

	Nine Months Ended September 30,
	2019		2018
Cash paid during the period for:
Income taxes, net of refunds	$	35,573	$	24,746
Interest, net of amounts capitalized	157,593		154,788
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	85,099	$	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759		—

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Regulatory Matters - Four Corners and Cholla (Details) - APS - USD ($) $ in Millions			1 Months Ended		3 Months Ended	9 Months Ended
	Dec. 23, 2014	Dec. 30, 2013	Sep. 30, 2018	Apr. 30, 2018	Jun. 30, 2016	Sep. 30, 2019	Dec. 31, 2015
SCE | Four Corners Units 4 and 5
Business Acquisition [Line Items]
Ownership interest acquired		48.00%
Settlement agreement, ACC approved rate adjustment, annualized customer impact	$ 57.1		$ 58.5	$ 67.5
Net receipt due to negotiation of alternate arrangement		$ 40.0
Four Corners cost deferral | SCE | Four Corners Units 4 and 5
Business Acquisition [Line Items]
Regulatory assets, non-current						$ 42.0
Regulatory noncurrent asset amortization period						10 years
Retired power plant costs
Business Acquisition [Line Items]
Net book value						$ 77.0
Navajo Plant
Business Acquisition [Line Items]
Net book value						$ 80.0
Four Corners | SCE
Business Acquisition [Line Items]
Regulatory assets, non-current							$ 12.0
Regulatory asset, write off amount					$ 12.0

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Long-Term Debt and Liquidity Matters - Estimated Fair Value of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Estimated fair value of long-term debt, including current maturities
Carrying Amount	$ 5,434,996	$ 5,138,232
Fair Value	6,067,397	5,233,563
Pinnacle West
Estimated fair value of long-term debt, including current maturities
Carrying Amount	449,268	448,796
Fair Value	449,670	443,955
APS
Estimated fair value of long-term debt, including current maturities
Carrying Amount	4,985,728	4,689,436
Fair Value	$ 5,617,727	$ 4,789,608

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Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - APS - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Aug. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Nuclear decommissioning trust fund assets
Fair Value		$ 1,211,655		$ 1,211,655		$ 1,087,235
Total Unrealized Gains		325,782		325,782		230,781
Total Unrealized Losses		(476)		(476)		(7,237)
Amortized cost		696,000		696,000		635,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains		4,736	$ 653	8,482	$ 2,952
Realized losses		(2,360)	(1,965)	(5,465)	(6,990)
Proceeds from the sale of securities		211,641	173,277	520,996	443,040
Fair value of fixed income securities, summarized by contractual maturities
Employee medical claims amount	$ 15,000
Equity securities
Nuclear decommissioning trust fund assets
Equity securities		487,449		487,449		447,138
Total Unrealized Gains		297,032		297,032		222,147
Total Unrealized Losses		0		0		(459)
Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Fair Value		724,110		724,110		637,356
Total Unrealized Gains		28,750		28,750		8,634
Total Unrealized Losses		(476)		(476)		(6,778)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year		109,950		109,950
1 year – 5 years		300,311		300,311
5 years – 10 years		104,693		104,693
Greater than 10 years		209,156		209,156
Total		724,110		724,110
Other
Nuclear decommissioning trust fund assets
Fair Value		96		96		2,741
Total Unrealized Gains		0		0		0
Total Unrealized Losses		0		0		0
Nuclear Decommissioning Trusts [Member]
Nuclear decommissioning trust fund assets
Fair Value		967,673		967,673		851,134
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains		4,732	653	8,478	2,951
Realized losses		(2,360)	(1,965)	(5,465)	(6,990)
Proceeds from the sale of securities		155,386	148,150	371,538	401,396
Nuclear Decommissioning Trusts [Member] | Equity securities
Nuclear decommissioning trust fund assets
Equity securities		485,467		485,467		402,008
Nuclear Decommissioning Trusts [Member] | Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Fair Value		483,528		483,528		446,978
Fair value of fixed income securities, summarized by contractual maturities
Less than one year		40,309		40,309
1 year – 5 years		133,488		133,488
5 years – 10 years		103,973		103,973
Greater than 10 years		205,758		205,758
Total		483,528		483,528
Nuclear Decommissioning Trusts [Member] | Other
Nuclear decommissioning trust fund assets
Fair Value		(1,322)		(1,322)		2,148
Other Special Use Funds [Member]
Nuclear decommissioning trust fund assets
Fair Value		243,982		243,982		236,101
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains		4	0	4	1
Realized losses		0	0	0	0
Proceeds from the sale of securities		56,255	$ 25,127	149,458	$ 41,644
Other Special Use Funds [Member] | Equity securities
Nuclear decommissioning trust fund assets
Equity securities		1,982		1,982		45,130
Other Special Use Funds [Member] | Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Fair Value		240,582		240,582		190,378
Other Special Use Funds [Member] | Other
Nuclear decommissioning trust fund assets
Fair Value		1,418		1,418		$ 593
Coal Reclamation Escrow Accounts [Member] | Available for sale-fixed income securities
Fair value of fixed income securities, summarized by contractual maturities
Less than one year		32,628		32,628
1 year – 5 years		25,928		25,928
5 years – 10 years		720		720
Greater than 10 years		3,398		3,398
Total		62,674		62,674
Active Union Medical Trust [Member] | Available for sale-fixed income securities
Fair value of fixed income securities, summarized by contractual maturities
Less than one year		37,013		37,013
1 year – 5 years		140,895		140,895
5 years – 10 years		0		0
Greater than 10 years		0		0
Total		$ 177,908		$ 177,908

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Commitments and Contingencies - Superfund-Related Matters, Southwest Power Outage and Clean Air Act (Details) - APS - Contaminated groundwater wells $ in Millions				9 Months Ended
	Apr. 05, 2018 plaintiff Defendant	Dec. 16, 2016 plaintiff	Aug. 06, 2013 Defendant	Sep. 30, 2019 USD ($)
Loss Contingencies [Line Items]
Costs related to investigation and study under Superfund site | $				$ 2
Number of defendants against whom Roosevelt Irrigation District (RID) filed lawsuit | Defendant	28		24
Number of plaintiffs		2
Settled Litigation
Loss Contingencies [Line Items]
Number of plaintiffs	2

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Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Cash equivalents		$ 1,200
Commodity contracts, assets	$ 817	1,113
Commodity contracts, liabilities	(959)	(2,029)
Nuclear decommissioning trust	967,673	851,134
Nuclear decommissioning trust, other	475,371	398,953
Other special use funds	243,982	236,101
Other special use funds, other	1,418	593
Total assets	1,212,472	1,089,548
Total assets, other	475,830	397,517
Liabilities
Total, other	80	875
Amount reported on balance sheet	(71,654)	(60,037)
Equity securities
Assets
Nuclear decommissioning trust	7,452	7,351
Nuclear decommissioning trust, other	(1,322)	2,148
Other special use funds	3,400	45,723
Other special use funds, other	1,418	593
U.S. commingled equity funds
Assets
Nuclear decommissioning trust	476,693	396,805
U.S. Treasury debt
Assets
Nuclear decommissioning trust	162,092	148,173
Other special use funds	232,165	173,310
Corporate debt
Assets
Nuclear decommissioning trust	124,026	96,656
Mortgage-backed securities
Assets
Nuclear decommissioning trust	112,704	113,115
Municipal bonds
Assets
Nuclear decommissioning trust	74,202	79,073
Other special use funds	8,417	17,068
Other fixed income
Assets
Nuclear decommissioning trust	10,504	9,961
Level 1
Assets
Cash equivalents		1,200
Commodity contracts, assets	0	0
Nuclear decommissioning trust	170,866	153,376
Other special use funds	234,147	218,440
Total assets	405,013	373,016
Liabilities
Gross derivative liability	0	0
Level 1 | Equity securities
Assets
Nuclear decommissioning trust	8,774	5,203
Other special use funds	1,982	45,130
Level 1 | U.S. commingled equity funds
Assets
Nuclear decommissioning trust	0	0
Level 1 | U.S. Treasury debt
Assets
Nuclear decommissioning trust	162,092	148,173
Other special use funds	232,165	173,310
Level 1 | Corporate debt
Assets
Nuclear decommissioning trust	0	0
Level 1 | Mortgage-backed securities
Assets
Nuclear decommissioning trust	0	0
Level 1 | Municipal bonds
Assets
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Level 1 | Other fixed income
Assets
Nuclear decommissioning trust	0	0
Level 2
Assets
Cash equivalents		0
Commodity contracts, assets	1,388	3,140
Nuclear decommissioning trust	321,436	298,805
Other special use funds	8,417	17,068
Total assets	331,241	319,013
Liabilities
Gross derivative liability	(69,752)	(52,696)
Level 2 | Equity securities
Assets
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Level 2 | U.S. commingled equity funds
Assets
Nuclear decommissioning trust	0	0
Level 2 | U.S. Treasury debt
Assets
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Level 2 | Corporate debt
Assets
Nuclear decommissioning trust	124,026	96,656
Level 2 | Mortgage-backed securities
Assets
Nuclear decommissioning trust	112,704	113,115
Level 2 | Municipal bonds
Assets
Nuclear decommissioning trust	74,202	79,073
Other special use funds	8,417	17,068
Level 2 | Other fixed income
Assets
Nuclear decommissioning trust	10,504	9,961
Level 3
Assets
Cash equivalents		0
Commodity contracts, assets	388	2
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Total assets	388	2
Liabilities
Gross derivative liability	(1,982)	(8,216)
Level 3 | Equity securities
Assets
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Level 3 | U.S. commingled equity funds
Assets
Nuclear decommissioning trust	0	0
Level 3 | U.S. Treasury debt
Assets
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Level 3 | Corporate debt
Assets
Nuclear decommissioning trust	0	0
Level 3 | Mortgage-backed securities
Assets
Nuclear decommissioning trust	0	0
Level 3 | Municipal bonds
Assets
Nuclear decommissioning trust	0	0
Other special use funds	0	0
Level 3 | Other fixed income
Assets
Nuclear decommissioning trust	0	0
Fair Value Measured at Net Asset Value Per Share | U.S. commingled equity funds
Assets
Nuclear decommissioning trust	$ 476,693	$ 396,805

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New Accounting Standards

9 Months Ended

Sep. 30, 2019

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

New Accounting Standards

New Accounting Standards

Standards Adopted in 2019

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 requires a lessee to reflect most operating lease arrangements on the balance sheet by recording a right-of-use asset and a lease liability that is initially 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. Since the issuance of the new lease standard, additional lease related guidance has been issued relating to land easements and how entities may elect to account for these arrangements at transition, among other items. The new lease standard and related amendments were effective for us on January 1, 2019, with early application permitted. The standard must be adopted using a modified retrospective approach with a cumulative-effect adjustment to the opening balance of retained earnings determined at either the date of adoption, or the earliest period presented in the financial statements. The standard includes various optional practical expedients provided to facilitate transition. We adopted this standard, and related amendments, on January 1, 2019. See Note 16.

ASU 2018-15, Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract

In August 2018, a new accounting standard was issued that clarifies how customers in a cloud computing service arrangement should account for implementation costs associated with the arrangement. To determine which implementation costs should be capitalized, the new guidance aligns the accounting with existing guidance pertaining to internal-use software. As a result of this new standard, certain cloud computing service arrangement implementation costs will now be subject to capitalization and amortized on a straight-line basis over the cloud computing service arrangement term. The new standard is effective for us on January 1, 2020, with early application permitted, and may be applied using either a retrospective or prospective transition approach. On July 1, 2019, we early adopted this new accounting standard using the prospective approach. The adoption did not have a material impact on our financial statements.

Standard Pending Adoption

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. Since the issuance of the new standard, various guidance has been issued that amends the new standard, including clarifications of certain aspects of the standard and targeted transition relief, among other changes. The new standard and related amendments are 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.

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New Accounting Standards (Policies)

9 Months Ended

Sep. 30, 2019

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

New Accounting Standards

Standards Adopted in 2019

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 requires a lessee to reflect most operating lease arrangements on the balance sheet by recording a right-of-use asset and a lease liability that is initially 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. Since the issuance of the new lease standard, additional lease related guidance has been issued relating to land easements and how entities may elect to account for these arrangements at transition, among other items. The new lease standard and related amendments were effective for us on January 1, 2019, with early application permitted. The standard must be adopted using a modified retrospective approach with a cumulative-effect adjustment to the opening balance of retained earnings determined at either the date of adoption, or the earliest period presented in the financial statements. The standard includes various optional practical expedients provided to facilitate transition. We adopted this standard, and related amendments, on January 1, 2019. See Note 16.

ASU 2018-15, Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract

In August 2018, a new accounting standard was issued that clarifies how customers in a cloud computing service arrangement should account for implementation costs associated with the arrangement. To determine which implementation costs should be capitalized, the new guidance aligns the accounting with existing guidance pertaining to internal-use software. As a result of this new standard, certain cloud computing service arrangement implementation costs will now be subject to capitalization and amortized on a straight-line basis over the cloud computing service arrangement term. The new standard is effective for us on January 1, 2020, with early application permitted, and may be applied using either a retrospective or prospective transition approach. On July 1, 2019, we early adopted this new accounting standard using the prospective approach. The adoption did not have a material impact on our financial statements.

Standard Pending Adoption

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. Since the issuance of the new standard, various guidance has been issued that amends the new standard, including clarifications of certain aspects of the standard and targeted transition relief, among other changes. The new standard and related amendments are 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.

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CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) Parenthetical - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Stockholders' Equity [Abstract]
DIVIDENDS DECLARED PER SHARE (in dollars per share)	$ 0	$ 0	$ 1.48	$ 1.39

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Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Entity Information [Line Items]
Entity Shell Company	false
Entity Interactive Data Current	Yes
Security Exchange Name	NYSE
Trading Symbol	PNW
Title of 12(b) Security	Common Stock
Entity Tax Identification Number	86-0512431
Entity Address, Address Line One	400 North Fifth Street, P.O. Box 53999
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85072-3999
City Area Code	(602)
Local Phone Number	250-1000
Entity File Number	1-8962
Document Transition Report	false
Document Quarterly Report	true
Entity Registrant Name	PINNACLE WEST CAPITAL CORPORATION
Entity Central Index Key	0000764622
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		112,410,824
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	AZ
APS
Entity Information [Line Items]
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Tax Identification Number	86-0011170
Entity Address, Address Line One	400 North Fifth Street, P.O. Box 53999
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85072-3999
City Area Code	(602)
Local Phone Number	250-1000
Entity File Number	1-4473
Entity Registrant Name	ARIZONA PUBLIC SERVICE COMPANY
Entity Central Index Key	0000007286
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		71,264,947
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	AZ

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CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 29,852	$ 5,766
Customer and other receivables	361,951	267,887
Accrued unbilled revenues	155,836	137,170
Allowance for doubtful accounts	(7,282)	(4,069)
Materials and supplies (at average cost)	293,899	269,065
Fossil fuel (at average cost)	18,527	25,029
Income tax receivable	14,063		$ 0
Assets from risk management activities (Note 7)	817	1,113
Deferred fuel and purchased power regulatory asset (Note 4)	59,474	37,164
Other regulatory assets (Note 4)	138,033	129,738
Other current assets	67,985	56,128
Total current assets	1,133,155	924,991
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Notes 11 and 12)	967,673	851,134
Other special use funds (Notes 11 and 12)	243,982	236,101
Other assets	102,116	103,247
Total investments and other assets	1,313,771	1,190,482
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	19,677,773	18,736,628
Accumulated depreciation and amortization	(6,552,177)	(6,366,014)
Net	13,125,596	12,370,614
Construction work in progress	738,492	1,170,062
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	102,873	105,775
Intangible assets, net of accumulated amortization	266,587	262,902
Nuclear fuel, net of accumulated amortization	141,903	120,217
Total property, plant and equipment	14,375,451	14,029,570
DEFERRED DEBITS
Regulatory assets (Note 4)	1,329,446	1,342,941
Operating lease right-of-use assets (Note 16)	156,050	0
Assets for other postretirement benefits (Note 5)	31,717	46,906
Other	37,976	129,312
Total deferred debits	1,555,189	1,519,159
TOTAL ASSETS	18,377,566	17,664,202
CURRENT LIABILITIES
Accounts payable	276,117	277,336
Accrued taxes	220,930	154,819
Accrued interest	50,993	61,107
Common dividends payable	0	82,675
Short-term borrowings (Note 3)	57,375	76,400
Current maturities of long-term debt (Note 3)	450,000	500,000
Customer deposits	78,173	91,174
Liabilities from risk management activities (Note 7)	44,349	35,506
Liabilities for asset retirements	12,850	19,842
Operating lease liabilities (Note 16)	26,221	0
Regulatory liabilities (Note 4)	208,022	165,876
Other current liabilities	161,716	184,229
Total current liabilities	1,586,746	1,648,964
Long-term debt less current maturities (Note 3)	4,984,996	4,638,232
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,975,989	1,807,421
Regulatory liabilities (Note 4)	2,310,131	2,325,976
Liabilities for asset retirements	736,079	706,703
Liabilities for pension benefits (Note 5)	297,843	443,170
Liabilities from risk management activities (Note 7)	27,305	24,531
Customer advances	192,374	137,153
Coal mine reclamation	165,695	212,785
Deferred investment tax credit	193,118	200,405
Unrecognized tax benefits	6,341	22,517
Operating lease liabilities (Note 16)	52,472	0
Other	166,772	147,640
Total deferred credits and other	6,124,119	6,028,301
COMMITMENTS AND CONTINGENCIES (SEE NOTE 8)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 112,403,751 and 112,159,896 issued at respective dates	2,654,430	2,634,265
Treasury stock at cost; 57,947 and 58,135 shares at respective dates	(5,117)	(4,825)
Total common stock	2,649,313	2,629,440
Retained earnings	2,949,891	2,641,183
Accumulated other comprehensive loss	(46,538)	(47,708)
Total shareholders’ equity	5,552,666	5,222,915
Noncontrolling interests (Note 6)	129,039	125,790
Total equity	5,681,705	5,348,705	5,135,730
TOTAL LIABILITIES AND EQUITY	18,377,566	17,664,202
APS
CURRENT ASSETS
Cash and cash equivalents	29,542	5,707
Customer and other receivables	351,029	257,654
Accrued unbilled revenues	155,836	137,170
Allowance for doubtful accounts	(7,282)	(4,069)
Materials and supplies (at average cost)	293,899	269,065
Fossil fuel (at average cost)	18,527	25,029
Income tax receivable	15,982	0
Assets from risk management activities (Note 7)	817	1,113
Deferred fuel and purchased power regulatory asset (Note 4)	59,474	37,164
Other regulatory assets (Note 4)	138,033	129,738
Other current assets	45,506	35,111
Total current assets	1,101,363	893,682
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trust (Notes 11 and 12)	967,673	851,134
Other special use funds (Notes 11 and 12)	243,982	236,101
Other assets	55,846	40,817
Total investments and other assets	1,267,501	1,128,052
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	19,674,286	18,733,142
Accumulated depreciation and amortization	(6,548,921)	(6,362,771)
Net	13,125,365	12,370,371
Construction work in progress	738,493	1,170,062
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	102,873	105,775
Intangible assets, net of accumulated amortization	266,432	262,746
Nuclear fuel, net of accumulated amortization	141,903	120,217
Total property, plant and equipment	14,375,066	14,029,171
DEFERRED DEBITS
Regulatory assets (Note 4)	1,329,446	1,342,941
Operating lease right-of-use assets (Note 16)	154,205	0
Assets for other postretirement benefits (Note 5)	28,071	43,212
Other	37,080	128,265
Total deferred debits	1,548,802	1,514,418
TOTAL ASSETS	18,292,732	17,565,323
CURRENT LIABILITIES
Accounts payable	268,163	266,277
Accrued taxes	215,320	176,357
Accrued interest	48,374	60,228
Common dividends payable	0	82,700
Short-term borrowings (Note 3)	2,900	0
Current maturities of long-term debt (Note 3)	450,000	500,000
Customer deposits	78,173	91,174
Liabilities from risk management activities (Note 7)	44,349	35,506
Liabilities for asset retirements	12,850	19,842
Operating lease liabilities (Note 16)	26,028	0
Regulatory liabilities (Note 4)	208,022	165,876
Other current liabilities	159,992	178,137
Total current liabilities	1,514,171	1,576,097
Long-term debt less current maturities (Note 3)	4,535,728	4,189,436
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,976,662	1,812,664
Regulatory liabilities (Note 4)	2,310,131	2,325,976
Liabilities for asset retirements	736,079	706,703
Liabilities for pension benefits (Note 5)	281,605	425,404
Liabilities from risk management activities (Note 7)	27,305	24,531
Customer advances	192,374	137,153
Coal mine reclamation	165,695	212,785
Deferred investment tax credit	193,118	200,405
Unrecognized tax benefits	43,434	41,861
Operating lease liabilities (Note 16)	50,669	0
Other	143,190	125,511
Total deferred credits and other	6,120,262	6,012,993
COMMITMENTS AND CONTINGENCIES (SEE NOTE 8)
EQUITY
Total common stock	178,162	178,162
Additional paid-in capital	2,721,696	2,721,696
Retained earnings	3,119,977	2,788,256
Accumulated other comprehensive loss	(26,303)	(27,107)
Total shareholders’ equity	5,993,532	5,661,007
Noncontrolling interests (Note 6)	129,039	125,790
Total equity	6,122,571	5,786,797	$ 5,385,869
Total capitalization	10,658,299	9,976,233
TOTAL LIABILITIES AND EQUITY	$ 18,292,732	$ 17,565,323

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Other Income and Other Expense

9 Months Ended

Sep. 30, 2019

Other Income and Expenses [Abstract]

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 the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Other income:
Interest income	$	2,694		$	1,957		$	7,695		$	6,256
Debt return on Four Corners SCR (Note 4)	4,920			4,910			14,651			11,190
Debt return on Ocotillo modernization project (Note 4)	7,555			—			12,849			—
Miscellaneous	22			91			50			95
Total other income	$	15,191		$	6,958		$	35,245		$	17,541
Other expense:
Non-operating costs	$	(2,647	)	$	(2,480	)	$	(8,832	)	$	(7,404	)
Investment losses — net	(716		)	—			(1,445		)	(268		)
Miscellaneous	(2,377		)	(2,583		)	(4,171		)	(4,391		)
Total other expense	$	(5,740	)	$	(5,063	)	$	(14,448	)	$	(12,063	)

The following table provides detail of APS’s other income and other expense for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Other income:
Interest income	$	2,037		$	1,151		$	5,091		$	4,874
Debt return on Four Corners SCR (Note 4)	4,920			4,910			14,651			11,190
Debt return on Ocotillo modernization project (Note 4)	7,555			—			12,849			—
Miscellaneous	22			92			50			96
Total other income	$	14,534		$	6,153		$	32,641		$	16,160
Other expense:
Non-operating costs	$	(2,448	)	$	(2,334	)	$	(7,965	)	$	(6,931	)
Miscellaneous	(378		)	(1,027		)	(2,167		)	(2,748		)
Total other expense	$	(2,826	)	$	(3,361	)	$	(10,132	)	$	(9,679	)

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Consolidation and Nature of Operations

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Consolidation and Nature of Operations

Consolidation and Nature of Operations

The unaudited condensed consolidated financial statements include the accounts of Pinnacle West and our subsidiaries:  APS, 4C Acquisition, LLC ("4CA"), Bright Canyon Energy Corporation ("BCE") and El Dorado Investment Company ("El Dorado").  See Note 8 for more information on 4CA matters. Intercompany accounts and transactions between the consolidated companies have been eliminated.  The unaudited condensed consolidated financial statements for APS include the accounts of APS and the Palo Verde Generating Station ("Palo Verde") sale leaseback variable interest entities ("VIEs") (see Note 6 for further discussion).  Our accounting records are maintained in accordance with accounting principles generally accepted in the United States of America ("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.

Amounts reported in our interim Condensed Consolidated Statements of Income are not necessarily indicative of amounts expected for the respective annual periods, due to the effects of seasonal temperature variations on energy consumption, timing of maintenance on electric generating units, and other factors.

Our condensed 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 information and footnote disclosures normally included in financial statements prepared in conformity with GAAP have been condensed or omitted pursuant to such regulations, although we believe that the disclosures provided are adequate to make the interim information presented not misleading. The accompanying condensed consolidated financial statements and these notes should be read in conjunction with the audited consolidated financial statements and notes included in our 2018 Form 10-K.

Supplemental Cash Flow Information

The following table summarizes supplemental Pinnacle West cash flow information (dollars in thousands):

	Nine Months Ended September 30,
	2019		2018
Cash paid during the period for:
Income taxes, net of refunds	$	12,488	$	10,091
Interest, net of amounts capitalized	166,907		161,875
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	85,099	$	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759		—
Sale of 4CA's 7% interest in Four Corners	—		68,907

The following table summarizes supplemental APS cash flow information (dollars in thousands):

	Nine Months Ended September 30,
	2019		2018
Cash paid during the period for:
Income taxes, net of refunds	$	35,573	$	24,746
Interest, net of amounts capitalized	157,593		154,788
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	85,099	$	99,405
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	8,759		—

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Retirement Plans and Other Postretirement Benefits

9 Months Ended

Sep. 30, 2019

Retirement Benefits [Abstract]

Retirement Plans and Other Postretirement Benefits

Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan, a non-qualified supplemental excess benefit retirement plan, and an other postretirement benefit plan for the employees of Pinnacle West and our subsidiaries.  Pinnacle West uses a December 31 measurement date for its pension and other postretirement benefit plans.  The market-related value of our plan assets is their fair value at the measurement dates.

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 or billed to electric plant participants) (dollars in thousands):

	Pension Benefits												Other Benefits
	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018			2019			2018			2019			2018
Service cost — benefits earned during the period	$	12,476		$	14,167		$	37,427		$	42,501		$	4,593		$	5,275		$	13,777		$	15,825
Non-service costs (credits):
Interest cost on benefit obligation	34,211			31,172			102,632			93,517			7,473			7,037			22,420			21,111
Expected return on plan assets	(42,971		)	(45,713		)	(128,913		)	(137,140		)	(9,603		)	(10,520		)	(28,809		)	(31,561		)
Amortization of:
Prior service credit	—			—			—			—			(9,456		)	(9,461		)	(28,366		)	(28,382		)
Net actuarial loss	10,646			8,021			31,938			24,062			—			—			—			—
Net periodic benefit cost (credit)	$	14,362		$	7,647		$	43,084		$	22,940		$	(6,993	)	$	(7,669	)	$	(20,978	)	$	(23,007	)
Portion of cost (credit) charged to expense	$	7,593		$	2,524		$	22,837		$	7,535		$	(4,966	)	$	(5,359	)	$	(14,846	)	$	(16,083	)

Contributions

We have made voluntary contributions of $150 million to our pension plan year-to-date in 2019. 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 $350 million during the 2019-2021 period. We do not expect to make any contributions over the next three years to our other postretirement benefit plans. In 2019, the Company was reimbursed $30 million for prior year retiree medical claims from the other postretirement benefit plan trust assets.

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Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Tables)

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Fair value of APS's nuclear decommissioning trust fund assets

The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS's nuclear decommissioning trust and other special use fund assets at September 30, 2019 and December 31, 2018 (dollars in thousands):  

	September 30, 2019
	Fair Value								Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trust			Other Special Use Funds		Total
Equity securities	$	485,467		$	1,982	$	487,449		$	297,032	$	—
Available for sale-fixed income securities	483,528			240,582		724,110		(a)	28,750		(476		)
Other	(1,322		)	1,418		96		(b)	—		—
Total	$	967,673		$	243,982	$	1,211,655		$	325,782	$	(476	)

(a) As of September 30, 2019, the amortized cost basis of these available-for-sale investments is $696 million.

(b) Represents net pending securities sales and purchases.

	December 31, 2018
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trust		Other Special Use Funds		Total
Equity securities	$	402,008	$	45,130	$	447,138		$	222,147	$	(459	)
Available for sale-fixed income securities	446,978		190,378		637,356		(a)	8,634		(6,778		)
Other	2,148		593		2,741		(b)	—		—
Total	$	851,134	$	236,101	$	1,087,235		$	230,781	$	(7,237	)

(a) As of December 31, 2018, the amortized cost basis of these available-for-sale investments is $635 million.

(b) Represents net pending securities sales and purchases.

Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds

The following table sets forth APS's realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities for the three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,
	Nuclear Decommissioning Trust			Other Special Use Funds		Total
2019
Realized gains	$	4,732		$	4	$	4,736
Realized losses	(2,360		)	—		(2,360		)
Proceeds from the sale of securities (a)	155,386			56,255		211,641
2018
Realized gains	$	653		$	—	$	653
Realized losses	(1,965		)	—		(1,965		)
Proceeds from the sale of securities (a)	148,150			25,127		173,277

(a) Proceeds are reinvested in the nuclear decommissioning trust and coal reclamation escrow account.

	Nine Months Ended September 30,
	Nuclear Decommissioning Trust			Other Special Use Funds		Total
2019
Realized gains	$	8,478		$	4	$	8,482
Realized losses	(5,465		)	—		(5,465		)
Proceeds from the sale of securities (a)	371,538			149,458		520,996
2018
Realized gains	$	2,951		$	1	$	2,952
Realized losses	(6,990		)	—		(6,990		)
Proceeds from the sale of securities (a)	401,396			41,644		443,040

(a)

Proceeds are reinvested in the nuclear decommissioning trust and coal reclamation escrow account.

Fair value of fixed income securities, summarized by contractual maturities

The fair value of APS's fixed income securities, summarized by contractual maturities, at September 30, 2019, is as follows (dollars in thousands):

	Nuclear Decommissioning Trust (a)		Coal Reclamation Escrow Account		Active Union Medical Trust		Total
Less than one year	$	40,309	$	32,628	$	37,013	$	109,950
1 year – 5 years	133,488		25,928		140,895		300,311
5 years – 10 years	103,973		720		—		104,693
Greater than 10 years	205,758		3,398		—		209,156
Total	$	483,528	$	62,674	$	177,908	$	724,110

(a)

Includes certain fixed income investments that are not due at a single maturity date. These investments have been allocated within the table based on the final payment date of the instrument.

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Derivative Accounting (Tables)

9 Months Ended

Sep. 30, 2019

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 September 30, 2019 and December 31, 2018, we had the following outstanding gross notional volume of derivatives, which represent both purchases and sales (does not reflect net position): 

		Quantity
Commodity	Unit of Measure	September 30, 2019	December 31, 2018
Power	GWh	232	250
Gas	Billion cubic feet	187	218

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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

 

	Financial Statement Location	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts		2019			2018			2019			2018
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized) (a)	Fuel and purchased power (b)	$	(289	)	$	(600	)	$	(1,263	)	$	(1,697	)

(a) During the three and nine months ended September 30, 2019 and 2018, we had no gains or 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 three and nine months ended September 30, 2019 and 2018 (dollars in thousands):

 

	Financial Statement Location	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts		2019			2018			2019			2018
Net Loss Recognized in Income	Operating revenues	$	—		$	(1,029	)	$	—		$	(2,590	)
Net Gain (Loss) Recognized in Income	Fuel and purchased power (a)	(28,249		)	4,263			(69,765		)	(26,442		)
Total		$	(28,249	)	$	3,234		$	(69,765	)	$	(29,032	)

(a)

Amounts are before the effect of PSA deferrals.

Schedule of 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 September 30, 2019 and December 31, 2018.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Condensed Consolidated Balance Sheets.

As of September 30, 2019: (dollars in thousands)	Gross  Recognized  Derivatives  (a)			Amounts Offset  (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	1,776		$	(1,266	)	$	510		$	307		$	817
Total assets	1,776			(1,266		)	510			307			817
Current liabilities	(44,429		)	1,266			(43,163		)	(1,186		)	(44,349		)
Deferred credits and other	(27,305		)	—			(27,305		)	—			(27,305		)
Total liabilities	(71,734		)	1,266			(70,468		)	(1,186		)	(71,654		)
Total	$	(69,958	)	$	—		$	(69,958	)	$	(879	)	$	(70,837	)

(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 $1,186 and cash margin provided to counterparties of $307.

As of December 31, 2018: (dollars in thousands)	Gross Recognized Derivatives  (a)			Amounts Offset (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	3,106		$	(2,149	)	$	957		$	156		$	1,113
Investments and other assets	36			(36		)	—			—			—
Total assets	3,142			(2,185		)	957			156			1,113
Current liabilities	(36,345		)	2,149			(34,196		)	(1,310		)	(35,506		)
Deferred credits and other	(24,567		)	36			(24,531		)	—			(24,531		)
Total liabilities	(60,912		)	2,185			(58,727		)	(1,310		)	(60,037		)
Total	$	(57,770	)	$	—		$	(57,770	)	$	(1,154	)	$	(58,924	)

(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 $1,310 and cash margin provided to counterparties of $156.

Schedule of 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 September 30, 2019 and December 31, 2018.  These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of our Condensed Consolidated Balance Sheets.

As of September 30, 2019: (dollars in thousands)	Gross  Recognized  Derivatives  (a)			Amounts Offset  (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	1,776		$	(1,266	)	$	510		$	307		$	817
Total assets	1,776			(1,266		)	510			307			817
Current liabilities	(44,429		)	1,266			(43,163		)	(1,186		)	(44,349		)
Deferred credits and other	(27,305		)	—			(27,305		)	—			(27,305		)
Total liabilities	(71,734		)	1,266			(70,468		)	(1,186		)	(71,654		)
Total	$	(69,958	)	$	—		$	(69,958	)	$	(879	)	$	(70,837	)

(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 $1,186 and cash margin provided to counterparties of $307.

As of December 31, 2018: (dollars in thousands)	Gross Recognized Derivatives  (a)			Amounts Offset (b)			Net  Recognized  Derivatives			Other  (c)			Amount Reported on Balance Sheets
Current assets	$	3,106		$	(2,149	)	$	957		$	156		$	1,113
Investments and other assets	36			(36		)	—			—			—
Total assets	3,142			(2,185		)	957			156			1,113
Current liabilities	(36,345		)	2,149			(34,196		)	(1,310		)	(35,506		)
Deferred credits and other	(24,567		)	36			(24,531		)	—			(24,531		)
Total liabilities	(60,912		)	2,185			(58,727		)	(1,310		)	(60,037		)
Total	$	(57,770	)	$	—		$	(57,770	)	$	(1,154	)	$	(58,924	)

(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 $1,310 and cash margin provided to counterparties of $156.

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 September 30, 2019 (dollars in thousands):

	September 30, 2019
Aggregate fair value of derivative instruments in a net liability position	$	71,503
Cash collateral posted	—
Additional cash collateral in the event credit-risk-related contingent features were fully triggered (a)	70,230

(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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Palo Verde Sale Leaseback Variable Interest Entities - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) power_plant	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Lease power_plant	Sep. 30, 2018 USD ($)	Dec. 31, 1986 Trust
Palo Verde Sale Leaseback Variable Interest Entities
Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts	$ 4,873,000	$ 4,873,000	$ 14,620,000	$ 14,620,000
APS
Palo Verde Sale Leaseback Variable Interest Entities
Number of VIE lessor trusts	3		3		3
Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts	$ 4,873,000	4,873,000	$ 14,620,000	14,620,000
APS | Consolidation of VIEs
Palo Verde Sale Leaseback Variable Interest Entities
Increase in net income due to consolidation of Palo Verde Sale Leaseback Trusts	$ 5,000,000	$ 5,000,000	15,000,000	$ 15,000,000
Initial loss exposure to the VIE's noncontrolling equity participants during lease extension period			299,000,000
Maximum loss exposure to the VIE's noncontrolling equity participants during lease extension period			$ 456,000,000
APS | Consolidation of VIEs | Through 2023
Palo Verde Sale Leaseback Variable Interest Entities
Number of leases under which assets are retained | Lease			1
APS | Consolidation of VIEs | Through 2033
Palo Verde Sale Leaseback Variable Interest Entities
Number of leases under which assets are retained | Lease			2
APS | Consolidation of VIEs | Period 2017 through 2023
Palo Verde Sale Leaseback Variable Interest Entities
Annual lease payments			$ 23,000,000
APS | Consolidation of VIEs | Period 2024 through 2033
Palo Verde Sale Leaseback Variable Interest Entities
Annual lease payments			$ 16,000,000
APS | Consolidation of VIEs | Period 2024 through 2033 | Maximum
Palo Verde Sale Leaseback Variable Interest Entities
Lease period (up to)			2 years

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Derivative Accounting - Gains and Losses from Derivative Instruments (Details) - Commodity Contracts - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Designated as Hedging Instruments
Gains and losses from derivative instruments
Amount reclassified from accumulated other comprehensive income to earnings related to discontinued cash flow hedges	$ 0	$ 0	$ 0	$ 0
Designated as Hedging Instruments | Fuel and purchased power
Gains and losses from derivative instruments
Loss Reclassified from Accumulated OCI into Income (Effective Portion Realized)	(289,000)	(600,000)	(1,263,000)	(1,697,000)
Not Designated as Hedging Instruments
Gains and losses from derivative instruments
Net Gain (Loss) Recognized in Income	(28,249,000)	3,234,000	(69,765,000)	(29,032,000)
Not Designated as Hedging Instruments | Operating revenues
Gains and losses from derivative instruments
Net Gain (Loss) Recognized in Income	0	(1,029,000)	0	(2,590,000)
Not Designated as Hedging Instruments | Fuel and purchased power
Gains and losses from derivative instruments
Net Gain (Loss) Recognized in Income	$ (28,249,000)	$ 4,263,000	$ (69,765,000)	$ (26,442,000)

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Leases - Additional information (Details) $ in Thousands	Sep. 30, 2019 USD ($) Lease	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
Number of lease agreements | Lease	3
Operating lease right-of-use assets (Note 16)	$ 156,050	$ 194,000	$ 0
Operating lease, liability	78,693	119,000
Other	(37,976)		(129,312)
Other current liabilities	(161,716)		$ (184,229)
Lease not yet commenced	$ 705,000
Accounting Standards Update 2016-02
Operating Leased Assets [Line Items]
Other		85,000
Other current liabilities		$ 10,000