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 Sept. 30, 2019 or

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

001-03280	84-0296600
(Commission File Number)	(I.R.S. Employer Identification No.)

(Registrant, State of Incorporation or Organization, Address of Principal Executive Officers and Telephone Number)

Public Service Company of Colorado

Colorado

1800 Larimer, Suite 1100

Denver Colorado 80202

303 571-7511

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

Title of each class	Trading Symbol	Name of each exchange on which registered
N/A	N/A	N/A

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. ☒ Yes ☐ No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). ☒ 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.

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 the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). ☐ Yes ☒ No

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

Class	Oct. 25, 2019
Common Stock, $0.01 par value	100 shares

Public Service Company of Colorado meets the conditions set forth in General Instruction H(1)(a) and (b) of Form 10-Q and is therefore filing this Form 10-Q with the reduced disclosure format specified in General Instruction H(2) to such Form 10-Q.

TABLE OF CONTENTS

PART I — FINANCIAL INFORMATION
Item l —	Financial Statements (Unaudited)	4
Item 2 —	Management’s Discussion and Analysis of Financial Condition and Results of Operations	20
Item 4 —	Controls and Procedures	22
PART II — OTHER INFORMATION
Item 1 —	Legal Proceedings	23
Item 1A —	Risk Factors	23
Item 6 —	Exhibits	23
SIGNATURES		24
Certifications Pursuant to Section 302
Certifications Pursuant to Section 906

This Form 10-Q is filed by Public Service Company of Colorado (PSCo). PSCo is a wholly owned subsidiary of Xcel Energy Inc. Additional information on Xcel Energy is available in various filings with the SEC. This report should be read in its entirety.

ABBREVIATIONS AND INDUSTRY TERMS

Xcel Energy Inc.’s Subsidiaries and Affiliates (current and former)
NSP-Minnesota	Northern States Power Company, a Minnesota corporation
NSP-Wisconsin	Northern States Power Company, a Wisconsin corporation
PSCo	Public Service Company of Colorado
SPS	Southwestern Public Service Company
Utility subsidiaries	NSP-Minnesota, NSP-Wisconsin, PSCo and SPS
WYCO	WYCO Development, LLC
Xcel Energy	Xcel Energy Inc. and subsidiaries

Federal and State Regulatory Agencies
CEC	Colorado Energy Consumers
CPUC	Colorado Public Utilities Commission
EPA	United States Environmental Protection Agency
FEA	Federal Executive Agencies
FERC	Federal Energy Regulatory Commission
IRS	Internal Revenue Service
OCC	Office of Consumer Counsel
SEC	Securities and Exchange Commission

Electric, Purchased Gas and Resource Adjustment Clauses
DSM	Demand side management

Other
ACE	Affordable Clean Energy
AFUDC	Allowance for funds used during construction
ASC	FASB Accounting Standards Codification
ASU	FASB Accounting Standards Update
C&I	Commercial and Industrial
CCR	Coal combustion residual
CCR Rule	Final rule (40 CFR 257.50 - 257.107) published by the EPA regulating the management, storage and disposal of CCRs as a nonhazardous waste
CEO	Chief executive officer
CFO	Chief financial officer
CIG	Colorado Interstate Gas Company, LLC
DRC	Development Recovery Company
ETR	Effective tax rate
FASB	Financial Accounting Standards Board
GAAP	Generally accepted accounting principles
IPP	Independent power producing entity
MDL	Multi district litigation
MGP	Manufactured gas plant
NOL	Net operating loss
O&M	Operating and maintenance
PPA	Power purchase agreement
PTC	Production tax credit
ROE	Return on equity
ROU	Right-of-use

Measurements
MW	Megawatts

Forward-Looking Statements

Except for the historical statements contained in this report, the matters discussed herein are forward-looking statements that are subject to certain risks, uncertainties and assumptions. Such forward-looking statements, assumptions and other statements are intended to be identified in this document by the words “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “objective,” “outlook,” “plan,” “project,” “possible,” “potential,” “should,” “will,” “would” and similar expressions. Actual results may vary materially. Forward-looking statements speak only as of the date they are made, and we expressly disclaim any obligation to update any forward-looking information. The following factors, in addition to those discussed elsewhere in this Quarterly Report on Form 10-Q and in other securities filings (including PSCo’s Annual Report on Form 10-K for the fiscal year ended Dec. 31, 2018 and subsequent securities filings), could cause actual results to differ materially from management expectations as suggested by such forward-looking information: changes in environmental laws and regulations; climate change and other weather natural disaster and resource depletion, including compliance with any accompanying legislative and regulatory changes; ability to recover costs from customers; reductions in our credit ratings and the cost of maintaining certain contractual relationships; general economic conditions, including inflation rates, monetary fluctuations and their impact on capital expenditures and the ability of PSCo and its subsidiaries to obtain financing on favorable terms; availability or cost of capital; our customers’ and counterparties’ ability to pay their debts to us; assumptions and costs relating to funding our employee benefit plans and health care benefits; tax laws; operational safety; successful long-term operational planning; commodity risks associated with energy markets and production; rising energy prices; costs of potential regulatory penalties; effects of geopolitical events, including war and acts of terrorism; cyber security threats and data security breaches; fuel costs; and employee work force and third party contractor factors.

PART I — FINANCIAL INFORMATION

Item 1 — FINANCIAL STATEMENTS

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(amounts in millions)

	Three Months Ended Sept. 30						Nine Months Ended Sept. 30
	2019			2018			2019			2018
Operating revenues
Electric	$	880.7		$	894.8		$	2,314.8		$	2,309.3
Natural gas	153.9			157.2			830.7			707.8
Steam and other	9.7			8.7			31.8			28.7
Total operating revenues	1,044.3			1,060.7			3,177.3			3,045.8
Operating expenses
Electric fuel and purchased power	284.7			288.6			829.5			841.7
Cost of natural gas sold and transported	34.3			32.3			376.7			282.1
Cost of sales — steam and other	3.5			3.3			11.9			10.9
Operating and maintenance expenses	198.4			201.4			597.9			573.5
Demand side management expenses	36.6			39.4			100.9			105.3
Depreciation and amortization	153.5			168.0			448.6			406.1
Taxes (other than income taxes)	49.0			50.8			154.8			153.2
Total operating expenses	760.0			783.8			2,520.3			2,372.8
Operating income	284.3			276.9			657.0			673.0
Other income, net	1.4			1.3			1.9			2.4
Allowance for funds used during construction — equity	3.8			16.4			12.9			40.9
Interest charges and financing costs
Interest charges — includes other financing costs of $1.6, $1.7, $4.9 and $4.9, respectively	59.2			53.2			176.3			154.3
Allowance for funds used during construction — debt	(2.2		)	(6.4		)	(7.0		)	(16.1		)
Total interest charges and financing costs	57.0			46.8			169.3			138.2
Income before income taxes	232.5			247.8			502.5			578.1
Income taxes	28.0			40.7			57.7			115.0
Net income	$	204.5		$	207.1		$	444.8		$	463.1

See Notes to Consolidated Financial Statements

4

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED)

(amounts in millions)

	Three Months Ended Sept. 30					Nine Months Ended Sept. 30
	2019		2018			2019		2018
Net income	$	204.5	$	207.1		$	444.8	$	463.1
Other comprehensive income
Pension and retiree medical benefits:
Net pension and retiree medical losses arising during the period, net of tax of $0, $(0.1), $0 and $(0.1), respectively	—		(0.2		)	—		(0.2		)
Amortization of losses included in net periodic benefit cost, net of tax of $0, $0.1, $0 and $0.1, respectively	—		0.2			—		0.2
	—		—			—		—
Derivative instruments:
Reclassification of losses to net income, net of tax of $0.1, $0.1, $0.3 and $0.3, respectively	0.3		0.3			0.9		0.9
Other comprehensive income	0.3		0.3			0.9		0.9
Comprehensive income	$	204.8	$	207.4		$	445.7	$	464.0

See Notes to Consolidated Financial Statements

5

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(amounts in millions)

	Nine Months Ended Sept. 30
	2019			2018
Operating activities
Net income	$	444.8		$	463.1
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	452.2			409.8
Deferred income taxes	24.1			66.6
Amortization of investment tax credits	(1.9		)	(2.1		)
Allowance for equity funds used during construction	(12.9		)	(40.9		)
Net realized and unrealized hedging and derivative transactions	64.5			(9.9		)
Changes in operating assets and liabilities:
Accounts receivable	13.1			(0.7		)
Accrued unbilled revenues	84.8			60.1
Inventories	(15.1		)	13.6
Prepayments and other	(12.4		)	12.6
Accounts payable	(96.0		)	25.3
Net regulatory assets and liabilities	72.3			(23.6		)
Other current liabilities	(66.3		)	(87.7		)
Pension and other employee benefit obligations	(44.4		)	(29.0		)
Other, net	(72.4		)	(19.8		)
Net cash provided by operating activities	834.4			837.4
Investing activities
Utility capital/construction expenditures	(1,098.6		)	(1,190.7		)
Investments in utility money pool arrangement	(397.0		)	(578.0		)
Repayments from utility money pool arrangement	397.0			575.0
Net cash used in investing activities	(1,098.6		)	(1,193.7		)
Financing activities
Repayments of short-term borrowings, net	(307.0		)	—
Borrowings under utility money pool arrangement	58.0			526.0
Repayments under utility money pool arrangement	(58.0		)	(526.0		)
Proceeds from issuance of long-term debt	928.6			691.4
Repayments of long-term debt	(400.0		)	(300.0		)
Capital contributions from parent	632.7			246.8
Dividends paid to parent	(295.4		)	(271.9		)
Other, net	—			(0.1		)
Net cash provided by financing activities	558.9			366.2
Net change in cash and cash equivalents	294.7			9.9
Cash and cash equivalents at beginning of period	33.4			7.5
Cash and cash equivalents at end of period	$	328.1		$	17.4
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	$	(173.4	)	$	(145.3	)
Cash paid for income taxes, net	(43.7		)	(86.4		)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	$	228.5		$	135.0
Inventory transfers to property, plant and equipment	24.4			29.8
Operating lease right-of-use assets	653.8			—
Allowance for equity funds used during construction	12.9			40.9

See Notes to Consolidated Financial Statements

6

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS (UNAUDITED)

(amounts in millions, except share and per share data)

	Sept. 30, 2019			Dec. 31, 2018
Assets
Current assets
Cash and cash equivalents	$	328.1		$	33.4
Accounts receivable, net	294.2			310.3
Accounts receivable from affiliates	13.6			80.8
Accrued unbilled revenues	228.8			313.5
Inventories	188.1			197.4
Regulatory assets	70.5			120.6
Derivative instruments	10.0			42.6
Prepayments and other	39.3			23.8
Total current assets	1,172.6			1,122.4
Property, plant and equipment, net	15,786.4			15,120.0
Other assets
Regulatory assets	1,063.3			1,010.7
Derivative instruments	0.7			1.2
Operating lease right-of-use assets	594.4			—
Other	248.9			37.2
Total other assets	1,907.3			1,049.1
Total assets	$	18,866.3		$	17,291.5
Liabilities and Equity
Current liabilities
Current portion of long-term debt	$	—		$	406.2
Short-term debt	—			307.0
Accounts payable	514.0			503.4
Accounts payable to affiliates	44.5			46.0
Regulatory liabilities	116.5			67.3
Taxes accrued	159.7			202.0
Accrued interest	36.0			43.2
Dividends payable to parent	97.3			91.5
Derivative instruments	11.7			34.6
Other	179.5			101.5
Total current liabilities	1,159.2			1,802.7
Deferred credits and other liabilities
Deferred income taxes	1,772.0			1,719.3
Deferred investment tax credits	23.5			25.3
Regulatory liabilities	2,022.3			2,021.5
Asset retirement obligations	350.1			338.7
Derivative instruments	54.8			0.6
Customer advances	172.8			168.1
Pension and employee benefit obligations	230.5			275.3
Operating lease liabilities	539.5			—
Other	152.0			50.4
Total deferred credits and other liabilities	5,317.5			4,599.2
Commitments and contingencies
Capitalization
Long-term debt	5,384.0			4,591.4
Common stock — 100 shares authorized at $0.01 par value; 100 shares outstanding at Sept. 30, 2019 and Dec. 31, 2018, respectively	—			—
Additional paid in capital	4,903.3			4,340.5
Retained earnings	2,126.9			1,983.2
Accumulated other comprehensive loss	(24.6		)	(25.5		)
Total common stockholder’s equity	7,005.6			6,298.2
Total liabilities and equity	$	18,866.3		$	17,291.5

See Notes to Consolidated Financial Statements

7

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER’S EQUITY (UNAUDITED)

(amounts in millions, except share data)

	Common Stock Issued					Retained Earnings			Accumulated Other Comprehensive Loss			Total Common Stockholder’s Equity
	Shares	Par Value		Additional Paid In Capital
Three Months Ended Sept. 30, 2019 and 2018
Balance at June 30, 2018	100	$	—	$	4,273.1	$	1,882.6		$	(26.1	)	$	6,129.6
Net income						207.1						207.1
Other comprehensive income									0.3			0.3
Dividends declared to parent						(103.5		)				(103.5		)
Contribution of capital by parent				5.3								5.3
Balance at Sept. 30, 2018	100	$	—	$	4,278.4	$	1,986.2		$	(25.8	)	$	6,238.8
Balance at June 30, 2019	100	$	—	$	4,618.3	$	2,019.7		$	(24.9	)	$	6,613.1
Net income						204.5						204.5
Other comprehensive income									0.3			0.3
Dividends declared to parent						(97.3		)				(97.3		)
Contribution of capital by parent				285.0								285.0
Balance at Sept. 30, 2019	100	$	—	$	4,903.3	$	2,126.9		$	(24.6	)	$	7,005.6
See Notes to Consolidated Financial Statements

8

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER’S EQUITY (UNAUDITED)

(amounts in millions, except share data)

	Common Stock Issued					Retained Earnings			Accumulated Other Comprehensive Loss			Total Common Stockholder’s Equity
	Shares	Par Value		Additional Paid In Capital
Nine Months Ended Sept. 30, 2019 and 2018
Balance at Dec. 31, 2017	100	$	—	$	4,032.8	$	1,822.2		$	(26.7	)	$	5,828.3
Net income						463.1						463.1
Other comprehensive income									0.9			0.9
Dividends declared to parent						(299.1		)				(299.1		)
Contribution of capital by parent				245.6								245.6
Balance at Sept. 30, 2018	100	$	—	$	4,278.4	$	1,986.2		$	(25.8	)	$	6,238.8
Balance at Dec. 31, 2018	100	$	—	$	4,340.5	$	1,983.2		$	(25.5	)	$	6,298.2
Net income						444.8						444.8
Other comprehensive income									0.9			0.9
Dividends declared to parent						(301.1		)				(301.1		)
Contribution of capital by parent				562.8								562.8
Balance at Sept. 30, 2019	100	$	—	$	4,903.3	$	2,126.9		$	(24.6	)	$	7,005.6
See Notes to Consolidated Financial Statements

9

PUBLIC SERVICE CO. OF COLORADO AND SUBSIDIARIES

Notes to Consolidated Financial Statements (UNAUDITED)

In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with U.S. GAAP, the financial position of PSCo and its subsidiaries as of Sept. 30, 2019 and Dec. 31, 2018; the results of its operations, including the components of net income and comprehensive income, and changes in stockholders’ equity for the three and nine months ended Sept. 30, 2019 and 2018; and its cash flows for the nine months ended Sept. 30, 2019 and 2018. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after Sept. 30, 2019 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2018 balance sheet information has been derived from the audited 2018 consolidated financial statements included in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2018. These notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto, included in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2018, filed with the SEC on Feb. 22, 2019. Due to the seasonality of PSCo’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

1. Summary of Significant Accounting Policies

The significant accounting policies set forth in Note 1 to the consolidated financial statements in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2018, appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

2. Accounting Pronouncements

Recently Issued

Credit Losses — In 2016, the FASB issued Financial Instruments - Credit Losses, Topic 326 (ASC Topic 326), which changes how entities account for losses on receivables and certain other assets. The guidance requires use of a current expected credit loss model, which may result in earlier recognition of credit losses than under previous accounting standards. ASC Topic 326 is effective for interim and annual periods beginning on or after Dec. 15, 2019, and will be applied on a modified-retrospective approach through a cumulative-effect adjustment to retained earnings as of Jan. 1, 2020. PSCo expects the impact of adoption of the new standard to include first-time recognition of expected credit losses (i.e., bad debt expense) on unbilled revenues, with the initial allowance established at Jan. 1, 2020 charged to retained earnings.

Recently Adopted

Leases — In 2016, the FASB issued Leases, Topic 842 (ASC Topic 842), which provides new accounting and disclosure guidance for leasing activities, most significantly requiring that operating leases be recognized on the balance sheet. PSCo adopted the guidance on Jan. 1, 2019 utilizing the package of transition practical expedients provided by the new standard, including carrying forward prior conclusions on whether agreements existing before the adoption date contain leases and whether existing leases are operating or finance leases; ASC Topic 842 refers to capital leases as finance leases.

Specifically for land easement contracts, PSCo has elected the practical expedient provided by ASU No. 2018-01 Leases: Land Easement Practical Expedient for Transition to Topic 842, and as a result, only those easement contracts entered on or after Jan. 1, 2019 will be evaluated to determine if lease treatment is appropriate.

PSCo also utilized the transition practical expedient offered by ASU No. 2018-11 Leases: Targeted Improvements to implement the standard on a prospective basis. As a result, reporting periods in the consolidated financial statements beginning Jan. 1, 2019 reflect the implementation of ASC Topic 842, while prior periods continue to be reported in accordance with Leases, Topic 840 (ASC Topic 840). Other than first-time recognition of operating leases on its consolidated balance sheet, the implementation of ASC Topic 842 did not have a significant impact on PSCo’s consolidated financial statements. Adoption resulted in recognition of approximately $0.7 billion of operating lease ROU assets and current/noncurrent operating lease liabilities. See Note 9 to the consolidated financial statements for leasing disclosures.

3. Selected Balance Sheet Data

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
Accounts receivable, net
Accounts receivable	$	315.1		$	330.8
Less allowance for bad debts	(20.9		)	(20.5		)
Accounts receivable, net	$	294.2		$	310.3

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Inventories
Materials and supplies	$	61.8	$	61.9
Fuel	75.3		69.5
Natural gas	51.0		66.0
Total inventories	$	188.1	$	197.4

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
Property, plant and equipment, net
Electric plant	$	14,070.5		$	13,604.5
Natural gas plant	4,526.5			4,387.6
Common and other property	1,070.2			1,023.7
Plant to be retired (a)	275.5			321.9
Construction work in progress	928.8			573.3
Total property, plant and equipment	20,871.5			19,911.0
Less accumulated depreciation	(5,085.1		)	(4,791.0		)
Property, plant and equipment, net	$	15,786.4		$	15,120.0

^(a)  In 2018, the CPUC approved early retirement of PSCo’s Comanche Units 1 and 2 in approximately 2022 and 2025, respectively. PSCo also expects Craig Unit 1 to be retired early in 2025. Amounts are presented net of accumulated depreciation.

10

4. Borrowings and Other Financing Instruments

Short-Term Borrowings

PSCo meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility and the money pool.

Money Pool — Xcel Energy Inc. and its utility subsidiaries have established a money pool arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Xcel Energy Inc. may make investments in the utility subsidiaries at market-based interest rates; however, the money pool arrangement does not allow the utility subsidiaries to make investments in Xcel Energy Inc. Money pool borrowings for PSCo were as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2019			Year Ended Dec. 31, 2018
Borrowing limit	$	250		$	250
Amount outstanding at period end	—			—
Average amount outstanding	23			25
Maximum amount outstanding	50			156
Weighted average interest rate, computed on a daily basis	2.29		%	1.93		%
Weighted average interest rate at period end	N/A			N/A

Commercial Paper — Commercial paper outstanding for PSCo was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2019			Year Ended Dec. 31, 2018
Borrowing limit	$	700		$	700
Amount outstanding at period end	—			307
Average amount outstanding	129			55
Maximum amount outstanding	379			309
Weighted average interest rate, computed on a daily basis	2.52		%	2.28		%
Weighted average interest rate at period end	N/A			2.95

Letters of Credit — PSCo uses letters of credit, generally with terms of one year, to provide financial guarantees for certain operating obligations. There were $9 million and $10 million of letters of credit outstanding under the credit facility at Sept. 30, 2019 and Dec. 31, 2018, respectively. The contract amounts of these letters of credit approximate their fair value and are subject to fees.

Credit Facility — In order to use its commercial paper program to fulfill short-term funding needs, PSCo must have a revolving credit facility in place at least equal to the amount of its commercial paper borrowing limit and cannot issue commercial paper in an aggregate amount exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

Amended Credit Agreement — In June 2019, PSCo entered into an amended five-year credit agreement with a syndicate of banks. The amended credit agreements have substantially the same terms and conditions as the prior credit agreements with the exception of the maturity, which was extended from June 2021 to June 2024.

PSCo has the right to request an extension of the revolving credit facility termination date for two additional one year periods. All extension requests are subject to majority bank group approval.

At Sept. 30, 2019, PSCo had the following committed credit facility available (in millions of dollars):

Credit Facility (a)		Outstanding (b)		Available
$	700	$	9	$	691

^(a)    This credit facility expires in June 2024.

^(b)    Includes outstanding commercial paper and letters of credit.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. PSCo had no direct advances on the credit facility outstanding at Sept. 30, 2019 and Dec. 31, 2018.

Long-Term Borrowings

During the nine months ended Sept. 30, 2019, PSCo issued the following:

– $400 million of 4.05% first mortgage bonds due Sept. 15, 2049.

– $550 million of 3.20% first mortgage green bonds due March 1, 2050.

5. Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. PSCo’s operating revenues consists of the following:

	Three Months Ended Sept. 30, 2019
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	315.3	$	94.1	$	3.1	$	412.5
C&I	452.4		32.9		5.5		490.8
Other	11.8		—		—		11.8
Total retail	779.5		127.0		8.6		915.1
Wholesale	40.3		—		—		40.3
Transmission	16.4		—		—		16.4
Other	8.3		21.4		—		29.7
Total revenue from contracts with customers	844.5		148.4		8.6		1,001.5
Alternative revenue and other	36.2		5.5		1.1		42.8
Total revenues	$	880.7	$	153.9	$	9.7	$	1,044.3

	Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	315.7	$	84.4	$	2.7	$	402.8
C&I	458.5		29.1		4.9		492.5
Other	11.8		—		—		11.8
Total retail	786.0		113.5		7.6		907.1
Wholesale	41.2		—		—		41.2
Transmission	16.3		—		—		16.3
Other	10.6		18.4		—		29.0
Total revenue from contracts with customers	854.1		131.9		7.6		993.6
Alternative revenue and other	40.7		25.3		1.1		67.1
Total revenues	$	894.8	$	157.2	$	8.7	$	1,060.7

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	Nine Months Ended Sept. 30, 2019
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	771.9	$	535.6	$	8.4	$	1,315.9
C&I	1,204.7		202.6		20.0		1,427.3
Other	36.1		—		—		36.1
Total retail	2,012.7		738.2		28.4		2,779.3
Wholesale	126.7		—		—		126.7
Transmission	41.4		—		—		41.4
Other	26.4		76.3		—		102.7
Total revenue from contracts with customers	2,207.2		814.5		28.4		3,050.1
Alternative revenue and other	107.6		16.2		3.4		127.2
Total revenues	$	2,314.8	$	830.7	$	31.8	$	3,177.3

	Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	766.1	$	416.2	$	7.9	$	1,190.2
C&I	1,185.4		154.0		17.4		1,356.8
Other	35.4		—		0.1		35.5
Total retail	1,986.9		570.2		25.4		2,582.5
Wholesale	125.3		—		—		125.3
Transmission	41.7		—		—		41.7
Other	44.1		62.1		—		106.2
Total revenue from contracts with customers	2,198.0		632.3		25.4		2,855.7
Alternative revenue and other	111.3		75.5		3.3		190.1
Total revenues	$	2,309.3	$	707.8	$	28.7	$	3,045.8

6. Income Taxes

Note 8 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2018 represents, in all material respects, the current status of other income tax matters except to the extent noted below, and are incorporated herein by reference.

The following table reconciles the difference between the statutory rate and the ETR:

	Nine Months Ended Sept. 30
	2019		2018
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	3.7		3.7
Decreases in tax from:
Wind PTCs	(7.7	)	—
Plant regulatory differences (a)	(3.6	)	(3.1	)
Other tax credits and tax credit and NOL allowances (net)	(1.3	)	(0.7	)
Other (net)	(0.6	)	(1.0	)
Effective income tax rate	11.5	%	19.9	%

^(a) Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method and the timing of regulatory decisions regarding the return of excess deferred taxes. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions and additional prepaid pension asset amortization.

Federal Audits — PSCO is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s federal income tax returns expire as follows:

Tax Year(s)	Expiration
2009 - 2013	June 2020
2014 - 2016	September 2020

In 2015, the IRS commenced an examination of tax years 2012 and 2013. In 2017, the IRS concluded the audit of tax years 2012 and 2013 and proposed an adjustment that would impact Xcel Energy’s NOL and ETR. Xcel Energy filed a protest with the IRS. As of Sept. 30, 2019, the case has been forwarded to Office of Appeals and Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of this issue; however, the outcome and timing of a resolution is unknown.

In 2018, the IRS began an audit of tax years 2014 - 2016. As of Sept. 30, 2019 no adjustments have been proposed.

State Audits — PSCo is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of Sept. 30, 2019, PSCo’s earliest open tax year subject to examination by state taxing authorities under applicable statutes of limitations is 2009. There are currently no state income tax audits in progress.

Unrecognized Benefits — Unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which ultimate deductibility is highly certain, but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR but would accelerate the payment to the taxing authority to an earlier period.

Unrecognized tax benefits — permanent vs temporary:

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Unrecognized tax benefit — Permanent tax positions	$	7.0	$	5.4
Unrecognized tax benefit — Temporary tax positions	4.7		4.9
Total unrecognized tax benefit	$	11.7	$	10.3

12

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
NOL and tax credit carryforwards	$	(8.3	)	$	(5.6	)

Net deferred tax liability associated with the unrecognized tax benefit amounts and related NOLs and tax credits carryforwards were $4.9 million and $2.0 million for Sept. 30, 2019 and Dec. 31, 2018, respectively.

As the IRS Appeals and federal audit progresses, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $8.7 million in the next 12 months.

Payables for interest related to unrecognized tax benefits were not material and no amounts were accrued for penalties related to unrecognized tax benefits as of Sept. 30, 2019 or Dec. 31, 2018.

7. Fair Value of Financial Assets and Liabilities

Fair Value Measurements

The accounting guidance for fair value measurements and disclosures provides a single definition of fair value, hierarchical framework for measuring assets and liabilities and requires disclosure about assets and liabilities measured at fair value.

Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are highly liquid and actively traded instruments with quoted prices.

Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, or priced with models using highly observable inputs.

Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 are those valued with models requiring significant management judgment or estimation.

Specific valuation methods include:

Cash equivalents — The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted net asset value.

Interest rate derivatives — The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts.

Commodity derivatives — The methods used to measure the fair value of commodity derivative forwards and options generally utilize observable forward prices and volatilities, as well as observable pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. When contractual settlements relate to delivery locations for which pricing is relatively unobservable, or extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable inputs on a valuation is evaluated, and may result in Level 3 classification.

Derivative Instruments Fair Value Measurements

PSCo enters into derivative instruments, including forward contracts, futures, swaps and options, for trading purposes and to manage risk in connection with changes in interest rates, utility commodity prices and vehicle fuel prices.

Interest Rate Derivatives — PSCo enters into various instruments that effectively fix the yield or price on a specified benchmark interest rate for an anticipated debt issuance for a specific period. These derivative instruments are generally designated as cash flow hedges for accounting purposes.

At Sept. 30, 2019, accumulated other comprehensive loss related to interest rate derivatives included $1.2 million of net losses expected to be reclassified into earnings during the next 12 months as the related hedged interest rate transactions impact earnings, including forecasted amounts for unsettled hedges, as applicable.

Wholesale and Commodity Trading Risk — PSCo conducts various wholesale and commodity trading activities, including the purchase and sale of electric capacity, energy, energy-related instruments and natural gas-related instruments, including derivatives. PSCo is allowed to conduct these activities within guidelines and limitations as approved by its risk management committee, comprised of management personnel not directly involved in activities governed by this policy.

Commodity Derivatives — PSCo enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations, as well as for trading purposes. This could include the purchase or sale of energy or energy-related products, natural gas to generate electric energy, natural gas for resale, and vehicle fuel.

PSCo may enter into derivative instruments that mitigate commodity price risk on behalf of electric and natural gas customers but may not be designated as qualifying hedging transactions. Changes in the fair value of non-trading commodity derivative instruments are recorded as other comprehensive income or deferred as a regulatory asset or liability. The classification as a regulatory asset or liability is based on approved regulatory recovery mechanisms.

As of Sept. 30, 2019, PSCo had no commodity contracts designated as cash flow hedges.

PSCo also enters into commodity derivative instruments for trading purposes not directly related to commodity price risks associated with serving its electric and natural gas customers. Changes in the fair value of these commodity derivatives are recorded in electric operating revenues, net of amounts credited to customers under margin-sharing mechanisms.

Gross notional amounts of commodity forwards and options:

(Amounts in Millions) (a)(b)	Sept. 30, 2019	Dec. 31, 2018
Megawatt hours of electricity	15.5	24.4
Million British thermal units of natural gas	58.8	48.4

^(a)  Amounts are not reflective of net positions in the underlying commodities.

^(b)  Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

Consideration of Credit Risk and Concentrations — PSCo continuously monitors the creditworthiness of the counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. The impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented in the consolidated balance sheets. PSCo’s most significant concentrations of credit risk with particular entities or industries are contracts with counterparties to its wholesale, trading and non-trading commodity activities.

13

At Sept. 30, 2019, six of PSCo’s 10 most significant counterparties for these activities, comprising $124.6 million or 74% of this credit exposure, had investment grade credit ratings from S&P Global Ratings, Moody’s Investor Services or Fitch Ratings. Three of the 10 most significant counterparties, comprising $14.9 million or 9% of this credit exposure, were not rated by these external agencies, but based on PSCo’s internal analysis, had credit quality consistent with investment grade. One of these significant counterparties, comprising $8.0 million or 5% of this credit exposure, had credit quality less than investment grade, based on external analysis. Seven of these significant counterparties are independent system operators, municipal or cooperative electric entities, or other utilities.

Impact of derivative activity:

	Pre-Tax Fair Value Losses Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss		Regulatory (Assets) and Liabilities
Three Months Ended Sept. 30, 2019
Other derivative instruments
Natural gas commodity	$	—	$	(2.2	)
Total	$	—	$	(2.2	)
Nine Months Ended Sept. 30, 2019
Other derivative instruments
Natural gas commodity	$	—	$	(3.7	)
Total	$	—	$	(3.7	)
Three Months Ended Sept. 30, 2018
Other derivative instruments
Natural gas commodity	$	—	$	(1.2	)
Total	$	—	$	(1.2	)
Nine Months Ended Sept. 30, 2018
Other derivative instruments
Natural gas commodity	$	—	$	(1.6	)
Total	$	—	$	(1.6	)

	Pre-Tax (Gains) Losses Reclassified into Income During the Period from:							Pre-Tax Gains (Losses) Recognized During the Period in Income
(Millions of Dollars)	Accumulated Other Comprehensive Loss			Regulatory Assets and (Liabilities)
Three Months Ended Sept. 30, 2019
Derivatives designated as cash flow hedges
Interest rate	$	0.4	(a)	$	—			$	—
Total	$	0.4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	0.6		(b)
Total	$	—		$	—			$	0.6
Nine Months Ended Sept. 30, 2019
Derivatives designated as cash flow hedges
Interest rate	$	1.2	(a)	$	—			$	—
Total	$	1.2		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	5.3		(b)
Natural gas commodity	—			(1.3		)	(c)	(2.1		)	(c)
Total	$	—		$	(1.3	)		$	3.2
Three Months Ended Sept. 30, 2018
Derivatives designated as cash flow hedges
Interest rate	$	0.4	(a)	$	—			$	—
Total	$	0.4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2.0		(b)
Total	$	—		$	—			$	2.0
Nine Months Ended Sept. 30, 2018
Derivatives designated as cash flow hedges
Interest rate	$	1.2	(a)	$	—			$	—
Total	$	1.2		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2.7		(b)
Natural gas commodity	—			2.7			(c)	(1.6		)	(c)
Total	$	—		$	2.7			$	1.1

^(a)  Amounts are recorded to interest charges.

^(b)  Amounts are recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue as appropriate.

^(c)  Amounts for both the three and nine months ended Sept. 30, 2019 included no settlement gain or losses on derivatives entered to mitigate natural gas price risk for electric generation recorded to electric fuel and purchased power, subject to cost-recovery mechanisms and reclassified to a regulatory asset, as appropriate. Amounts for the three and nine months ended Sept. 30, 2018 included no such settlement gains or losses and $1.2 million of such settlement losses, respectively. Remaining derivative settlement losses for the three and nine months ended Sept. 30, 2019 and 2018 relate to natural gas operations and are recorded to cost of natural gas sold and transported. These gains and losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset or liability, as appropriate.

PSCo had no derivative instruments designated as fair value hedges during the three and nine months ended Sept. 30, 2019 and 2018.

14

Credit Related Contingent Features — Contract provisions for derivative instruments that PSCo enters into, including those accounted for as normal purchase-normal sale contracts and therefore not reflected on the consolidated balance sheets, may require the posting of collateral or settlement of the contracts for various reasons, including if PSCo’s credit ratings are downgraded below its investment grade credit rating by any of the major credit rating agencies, or for cross-default contractual provisions if there was a failure under other financing arrangements related to payment terms or other covenants. At Sept. 30, 2019 and Dec. 31, 2018, there were no derivative instruments in a liability position with such underlying contract provisions, with no offsetting positions or posted collateral.

Certain derivative instruments are also subject to contract provisions that contain adequate assurance clauses. These provisions allow counterparties to seek performance assurance, including cash collateral, in the event that PSCo’s ability to fulfill its contractual obligations is reasonably expected to be impaired. PSCo had no collateral posted related to adequate assurance clauses in derivative contracts as of Sept. 30, 2019 and Dec. 31, 2018.

Recurring Fair Value Measurements — PSCo’s assets and liabilities measured at fair value on a recurring basis:

	Sept. 30, 2019													Dec. 31, 2018
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative assets
Other derivative instruments:
Commodity trading	$	1.4	$	13.6	$	0.2	$	15.2	$	(10.0	)	$	5.2	$	2.3	$	65.0	$	0.1	$	67.4	$	(28.2	)	$	39.2
Natural gas commodity	—		4.8		—		4.8		—			4.8		—		3.4		—		3.4		—			3.4
Total current derivative assets	$	1.4	$	18.4	$	0.2	$	20.0	$	(10.0	)	$	10.0	$	2.3	$	68.4	$	0.1	$	70.8	$	(28.2	)	$	42.6
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	0.5	$	5.7	$	0.1	$	6.3	$	(5.6	)	$	0.7	$	—	$	1.6	$	—	$	1.6	$	(0.4	)	$	1.2
Total noncurrent derivative assets	$	0.5	$	5.7	$	0.1	$	6.3	$	(5.6	)	$	0.7	$	—	$	1.6	$	—	$	1.6	$	(0.4	)	$	1.2

	Sept. 30, 2019													Dec. 31, 2018
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative liabilities
Other derivative instruments:
Commodity trading	$	1.4	$	19.1	$	0.1	$	20.6	$	(13.3	)	$	7.3	$	2.4	$	64.2	$	—	$	66.6	$	(34.7	)	$	31.9
Natural gas commodity	—		4.4		—		4.4		—			4.4		—		—		—		—		—			—
Total current derivative liabilities	$	1.4	$	23.5	$	0.1	$	25.0	$	(13.3	)	11.7		$	2.4	$	64.2	$	—	$	66.6	$	(34.7	)	31.9
PPAs (b)												—													2.7
Current derivative instruments												$	11.7												$	34.6
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	0.4	$	60.0	$	—	$	60.4	$	(5.6	)	$	54.8	$	—	$	1.1	$	—	$	1.1	$	(0.5	)	$	0.6
Total noncurrent derivative liabilities	$	0.4	$	60.0	$	—	$	60.4	$	(5.6	)	$	54.8	$	—	$	1.1	$	—	$	1.1	$	(0.5	)	$	0.6

^(a)  PSCo nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Sept. 30, 2019 and Dec. 31, 2018. At both Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include no obligations to return cash collateral. At Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include the rights to reclaim cash collateral of $3.2 million and $6.5 million, respectively. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

^(b)  During 2006, PSCo qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts will be amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.

There were $0.5 million and $1.5 million of losses recognized in earnings for Level 3 commodity trading derivatives in the three and nine months ended Sept. 30, 2019, respectively. There were immaterial gains and losses recognized in earnings for Level 3 commodity trading derivatives in both the three and nine months ended Sept. 30, 2018.

PSCo recognizes transfers between fair value hierarchy levels as of the beginning of each period. There were no transfers of amounts between levels for derivative instruments for the three and nine months ended Sept. 30, 2019 and 2018.

15

Fair Value of Long-Term Debt

Other financial instruments for which the carrying amount did not equal fair value:

	Sept. 30, 2019				Dec. 31, 2018
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	5,384.0	$	6,139.2	$	4,997.6	$	5,123.2

Fair value of PSCo’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of Sept. 30, 2019 and Dec. 31, 2018, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

8. Benefit Plans and Other Postretirement Benefits

Components of Net Periodic Benefit Cost (Credit)

	Three Months Ended Sept. 30
	2019			2018			2019			2018
(Millions of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	6.4		$	7.3		$	0.1		$	0.2
Interest cost (a)	12.9			11.8			3.9			3.8
Expected return on plan assets (a)	(17.1		)	(17.1		)	(4.7		)	(5.7		)
Amortization of prior service credit (a)	(0.8		)	(0.9		)	(1.3		)	(1.6		)
Amortization of net loss (a)	6.3			7.8			0.7			1.0
Net periodic benefit cost (credit)	7.7			8.9			(1.3		)	(2.3		)
Credits (costs) not recognized due to the effects of regulation	0.8			(4.1		)	0.4			1.4
Net benefit cost (credit) recognized for financial reporting	$	8.5		$	4.8		$	(0.9	)	$	(0.9	)

	Nine Months Ended Sept. 30
	2019			2018			2019			2018
(Millions of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	19.2		$	21.8		$	0.4		$	0.5
Interest cost (a)	38.7			35.5			11.7			11.2
Expected return on plan assets (a)	(51.4		)	(51.4		)	(14.2		)	(17.0		)
Amortization of prior service credit (a)	(2.5		)	(2.5		)	(4.1		)	(4.7		)
Amortization of net loss (a)	19.1			23.4			2.2			3.1
Net periodic benefit cost (credit)	23.1			26.8			(4.0		)	(6.9		)
Credits (costs) not recognized due to the effects of regulation	4.4			(1.7		)	0.9			1.4
Net benefit cost (credit) recognized for financial reporting	$	27.5		$	25.1		$	(3.1	)	$	(5.5	)

^(a)   The components of net periodic cost other than the service cost component are included in the line item “other income, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.

In January 2019, contributions of $150.0 million were made across four of Xcel Energy’s pension plans, of which $43.0 million was attributable to PSCo. In July 2019, Xcel Energy made a $4.0 million contribution to the Xcel Energy Inc. Non-Bargaining Pension Plan (South), of which $2.7 million was attributable to PSCo. Xcel Energy does not expect additional pension contributions during 2019.

9. Commitments and Contingencies

The following include commitments, contingencies and unresolved contingencies that are material to PSCo’s financial position.

Legal

PSCo is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation.

Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to, when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on PSCo’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003.  Multiple lawsuits seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada.

Two cases remain active which include an MDL matter consisting of a Colorado purported class (Breckenridge) and a Wisconsin purported class (Arandell Corp.).

Breckenridge/Colorado — In February 2019, the MDL panel remanded Breckenridge back to the U.S. District Court in Colorado.

Arandell Corp. — In February 2019, the case was remanded back to the U.S. District Court in Wisconsin.

Xcel Energy has concluded that a loss is remote for both remaining lawsuits.

Line Extension Disputes — In December 2015, the DRC filed a lawsuit seeking monetary damages in the Denver District Court, stating PSCo failed to award proper allowances and refunds for line extensions to new developments pursuant to the terms of electric and gas service agreements. The dispute involves claims by over fifty developers. In February 2018, the Colorado Supreme Court denied DRC’s petition to appeal the Denver District Court’s dismissal of the lawsuit, effectively terminating this litigation. However, in January 2018, DRC filed a new lawsuit in Boulder County District Court, asserting a single claim that PSCo was required to file its line extension agreements with the CPUC but failed to do so.

This claim is similar to the arguments previously raised by DRC. PSCo filed a motion to dismiss this claim, which was granted in May 2018. DRC subsequently filed an appeal to the Colorado Court of Appeals. It is uncertain when a decision will be rendered.

PSCo has concluded that a loss is remote with respect to both of these matters as the service agreements were developed to implement CPUC approved tariffs and PSCo has complied with the tariff provisions. If a loss were sustained, PSCo believes it would be allowed to recover costs through traditional regulatory mechanisms. Amount or range in dispute is presently unknown and no accrual has been recorded for this matter.

16

Environmental

MGP, Landfill or Disposal Sites — PSCo is cooperating with the City of Denver on an environmental investigation of the Rice Yards Site in Denver, Colorado, which had various historic industrial uses by multiple parties, including railroad, maintenance shop, scrap metal yard, and MGP operations.

The area is being redeveloped into residential and commercial mixed uses, and PSCo is in discussions with the current property owner regarding legal claims related to the Rice Yards Site.

In addition, PSCo is currently investigating or remediating two other MGP, landfill or other disposal sites across its service territories.

PSCo has recognized its best estimate of costs/liabilities that will result from final resolution of these issues, however, the outcome and timing is unknown.  In addition, there may be insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of the costs incurred.

Environmental Requirements — Water and Waste

Coal Ash Regulation — PSCo’s operations are subject to federal and state laws that impose requirements for handling, storage, treatment and disposal of solid waste.

Under the CCR Rule, utilities are required to complete groundwater sampling around their CCR landfills and surface impoundments. By the end of 2019, only six of PSCo’s regulated ash units are expected to be in operation. PSCo is conducting groundwater sampling and where appropriate, initiating the assessment of corrective measures and evaluating whether corrective action is required at any CCR landfills or surface impoundments.

Until PSCo completes its assessment, it is uncertain what impact, if any, there will be on the operations, financial condition or cash flows.

Leases

PSCo evaluates contracts that may contain leases, including PPAs and arrangements for the use of office space and other facilities, vehicles and equipment. Under ASC Topic 842, adopted by PSCo on Jan. 1, 2019, a contract contains a lease if it conveys the exclusive right to control the use of a specific asset. A contract determined to contain a lease is evaluated further to determine if the arrangement is a finance lease.

ROU assets represent PSCo's rights to use leased assets. Starting in 2019, the present value of future operating lease payments is recognized in other current liabilities and noncurrent operating lease liabilities. These amounts, adjusted for any prepayments or incentives, are recognized as operating lease ROU assets.

Most of PSCo’s leases do not contain a readily determinable discount rate. Therefore, the present value of future lease payments is calculated using the estimated incremental borrowing rate (weighted-average of 4.1%). PSCo has elected to utilize the practical expedient under which non-lease components, such as asset maintenance costs included in payments, are not deducted from minimum lease payments for the purposes of lease accounting and disclosure.

Leases with an initial term of 12 months or less are classified as short-term leases and are not recognized on the consolidated balance sheet.

Operating lease ROU assets:

(Millions of Dollars)	Sept. 30, 2019
PPAs	$	585.1
Other	68.7
Gross operating lease ROU assets	653.8
Accumulated amortization	(59.4		)
Net operating lease ROU assets	$	594.4

In 2019, ROU assets for finance leases are included in other noncurrent assets, and the present value of future finance lease payments is included in other current liabilities and other noncurrent liabilities. Prior to 2019, finance leases were included in property, plant and equipment, the current portion of long-term debt and long-term debt.

PSCo’s most significant finance lease activities are related to WYCO, a joint venture with CIG, to develop and lease natural gas pipeline, storage and compression facilities. Xcel Energy Inc. has a 50% ownership interest in WYCO. WYCO leases its facilities to CIG, and CIG operates the facilities, providing natural gas storage and transportation services to PSCo under separate service agreements.

PSCo accounts for its Totem natural gas storage service and Front Range pipeline arrangements with CIG and WYCO, respectively, as finance leases.

Finance lease ROU assets:

(Millions of Dollars)	Sept. 30, 2019
Gas storage facilities	$	200.5
Gas pipeline	20.7
Gross finance lease ROU assets	221.2
Accumulated amortization	(80.8		)
Net finance lease ROU assets	$	140.4

Components of lease expense:

(Millions of Dollars)	Three Months Ended Sept. 30, 2019		Nine Months Ended Sept. 30, 2019
Operating leases
PPA capacity payments	$	24.6	$	73.6
Other operating leases (a)	4.3		11.5
Total operating lease expense (b)	$	28.9	$	85.1
Finance leases
Amortization of ROU assets	$	1.6	$	4.6
Interest expense on lease liability	4.7		14.2
Total finance lease expense	$	6.3	$	18.8

^(a)  Includes short-term lease expense of $0.3 million for the three months ended Sept. 30, 2019 and $1.0 million for the nine months ended Sept. 30, 2019.

^(b)  PPA capacity payments are included in electric fuel and purchased power on the consolidated statements of income. Expense for other operating leases is included in O&M expense and electric fuel and purchased power.

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Future commitments under operating and finance leases as of Sept. 30, 2019:

(Millions of Dollars)	PPA (a) (b) Operating Leases			Other Operating Leases			Total Operating Leases			Finance Leases
2019	$	23.9		$	3.3		$	27.2		$	6.2
2020	95.9			13.2			109.1			24.8
2021	96.4			12.6			109.0			23.6
2022	82.6			11.6			94.2			20.5
2023	70.0			10.9			80.9			20.3
Thereafter	288.6			29.2			317.8			419.8
Total minimum obligation	657.4			80.8			738.2			515.2
Interest component of obligation	(100.6		)	(13.1		)	(113.7		)	(374.8		)
Present value of minimum obligation	$	556.8		$	67.7		624.5			140.4
Less current portion							(85.0		)	(6.7		)
Noncurrent operating and finance lease liabilities							$	539.5		$	133.7
Weighted-average remaining lease term in years							8.1			38.9

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b)  PPA operating leases contractually expire at various dates through 2032.

Future commitments under operating and finance leases as of Dec. 31, 2018:

(Millions of Dollars)	PPA (a) (b) Operating Leases		Other Operating Leases		Total Operating Leases		Finance Leases
2019	$	95.5	$	10.8	$	106.3	$	24.9
2020	95.9		10.7		106.6		24.8
2021	96.4		9.5		105.9		23.6
2022	82.6		8.4		91.0		20.5
2023	70.0		8.1		78.1		20.3
Thereafter	288.6		53.4		342.0		420.4
Total minimum obligation							534.5
Interest component of obligation							(389.5		)
Present value of minimum obligation							$	145.0

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b)  PPA operating leases contractually expire at various dates through 2032.

Variable Interest Entities 

Under certain PPAs, PSCo purchases power from IPPs and is required to reimburse the IPPs for fuel costs, or to participate in tolling arrangements under which PSCo procures the natural gas required to produce the energy that it purchases. These specific PPAs create a variable interest in the associated IPP.

PSCo had approximately 1,442 MW and 1,571 MW of capacity under long-term PPAs as of Sept. 30, 2019 and Dec. 31, 2018, respectively, with entities that have been determined to be VIEs. PSCo concluded that these entities are not required to be consolidated in its financial statements because it does not have the power to direct the activities that significantly impact the entities’ economic performance. These agreements have various expiration dates through 2032.

10. Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive loss, net of tax, for the three and nine months ended Sept. 30, 2019 and 2018:

	Three Months Ended Sept. 30, 2019									Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at July 1	$	(24.7	)	$	(0.2	)	$	(24.9	)	$	(25.8	)	$	(0.3	)	$	(26.1	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively)	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.1, $0, $0.1 and $0, respectively) (a)	0.3			—			0.3			0.3			—			0.3
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.3			—			0.3			0.3			—			0.3
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

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	Nine Months Ended Sept. 30, 2019									Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at Jan. 1	$	(25.3	)	$	(0.2	)	$	(25.5	)	$	(26.4	)	$	(0.3	)	$	(26.7	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.3, $0, $0.3 and $0, respectively) (a)	0.9			—			0.9			0.9			—			0.9
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.9			—			0.9			0.9			—			0.9
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

^(a)  Included in interest charges.

11. Segment Information

Operating results from the regulated electric utility and regulated natural gas utility are each separately and regularly reviewed by PSCo’s chief operating decision maker. PSCo evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

PSCo has the following reportable segments: regulated electric utility, regulated natural gas utility and all other.

• Regulated Electric - The regulated electric utility segment generates electricity which is transmitted and distributed in Colorado. This segment includes sales for resale and provides wholesale transmission service to various entities in the United States. Regulated electric utility also includes PSCo’s wholesale commodity and trading operations.

• Regulated Natural Gas - The regulated natural gas utility segment transports, stores and distributes natural gas in portions of Colorado.

• All Other - Revenues from operating segments not included above are below the necessary quantitative thresholds are included in the all other category. Those primarily include steam revenue, appliance repair services and nonutility real estate activities.

Asset and capital expenditure information is not provided for PSCo’s reportable segments. As an integrated electric and natural gas utility, PSCo operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis.

Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.

PSCo’s segment information for the three and nine months ended Sept. 30:

	Three Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Regulated Electric
Operating revenues	$	880.7		$	894.8
Intersegment revenues	0.1			—
Total revenue	880.8			894.8
Net income	204.7			191.7
Regulated Natural Gas
Operating revenues	$	153.9		$	157.2
Intersegment revenues	0.1			0.3
Total revenue	154.0			157.5
Net income	0.7			15.1
All Other
Operating revenues (a)	$	9.7		$	8.7
Net (loss) income	(0.9		)	0.3
Consolidated Total
Operating revenues (a)	$	1,044.5		$	1,061.0
Reconciling eliminations	(0.2		)	(0.3		)
Total revenue	$	1,044.3		$	1,060.7
Net income	204.5			207.1

^(a)  Operating revenues include $1.1 million of other affiliate revenue for the three months ended Sept. 30, 2019 and 2018.

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	Nine Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Regulated Electric
Operating revenues	$	2,314.8		$	2,309.3
Intersegment revenues	0.3			0.2
Total revenue	2,315.1			2,309.5
Net income	371.9			373.3
Regulated Natural Gas
Operating revenues	$	830.7		$	707.8
Intersegment revenues	0.2			0.4
Total revenue	830.9			708.2
Net income	77.5			89.7
All Other
Operating revenues (a)	$	31.8		$	28.7
Net (loss) income	(4.6		)	0.1
Consolidated Total
Operating revenues (a)	$	3,177.8		$	3,046.4
Reconciling eliminations	(0.5		)	(0.6		)
Total revenue	$	3,177.3		$	3,045.8
Net income	444.8			463.1

^(a)  Operating revenues include $3.3 million of other affiliate revenue for the nine months ended Sept. 30, 2019 and 2018.

Item 2 — MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Discussion of financial condition and liquidity for PSCo is omitted per conditions set forth in general instructions H(1)(a) and (b) of Form 10-Q for wholly owned subsidiaries. It is replaced with management’s narrative analysis of the results of operations set forth in general instructions H(2)(a) of Form 10-Q for wholly owned subsidiaries (reduced disclosure format).

Non-GAAP Financial Measures

The following discussion includes financial information prepared in accordance with GAAP, as well as certain non-GAAP financial measures such as electric margin, natural gas margin and ongoing earnings. Generally, a non-GAAP financial measure is a measure of a company’s financial performance, financial position or cash flows that excludes (or includes) amounts that are adjusted from measures calculated and presented in accordance with GAAP. PSCo’s management uses non-GAAP measures for financial planning and analysis, for reporting of results, in determining performance-based compensation and communicating its earnings outlook to analysts and investors. Non-GAAP financial measures are intended to supplement investors’ understanding of our performance and should not be considered alternatives for financial measures presented in accordance with GAAP. These measures are discussed in more detail below and may not be comparable to other companies’ similarly titled non-GAAP financial measures.

Electric and Natural Gas Margins

Electric margin is presented as electric revenues less electric fuel and purchased power expenses. Natural gas margin is presented as natural gas revenues less the cost of natural gas sold and transported. Expenses incurred for electric fuel and purchased power and the cost of natural gas are generally recovered through various regulatory recovery mechanisms. As a result, changes in these expenses are generally offset in operating revenues.

Management believes electric and natural gas margins provide the most meaningful basis for evaluating our operations because they exclude the revenue impact of fluctuations in these expenses. These margins can be reconciled to operating income, a GAAP measure, by including other operating revenues, cost of sales-other, O&M expenses, conservation and DSM expenses, depreciation and amortization and taxes (other than income taxes).

Results of Operations

PSCo’s net income was approximately $444.8 million for the nine months ended Sept. 30, 2019 compared with approximately $463.1 million for the prior year. The decrease in year-to-date earnings was driven by higher depreciation, O&M, interest expense and lower AFUDC, which offsets higher natural gas and electric margin. Changes in depreciation and AFUDC are primarily driven by the Rush Creek wind project that was placed in service in 2018.

Electric Margin

Electric revenues and fuel and purchased power expenses are impacted by fluctuations in the price of natural gas and coal used in the generation of electricity. However, these price fluctuations have minimal impact on electric margin due to fuel recovery mechanisms that recover fuel expenses. In addition, electric customers receive a credit for PTCs that are generated in a particular period.

Electric revenues and margin:

	Nine Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Electric revenues	$	2,314.8		$	2,309.3
Electric fuel and purchased power	(829.5		)	(841.7		)
Electric margin	$	1,485.3		$	1,467.6

Changes in electric margin:

(Millions of Dollars)	2019 vs. 2018
Non-fuel riders	$	50.2
Finance leases (offset in interest expense and amortization)	16.4
Timing of tax reform regulatory decisions (offset in income tax and amortization)	(19.7		)
Conservation and DSM riders (offset in expense)	(3.8		)
Estimated impact of weather	(2.6		)
Wholesale transmission revenue (net)	(2.4		)
Sales decline	(1.9		)
Other, net	(18.5		)
Total increase in electric margin	$	17.7

Natural Gas Margin

Natural gas expense varies with changing sales and the cost of natural gas. However, fluctuations in the cost of natural gas have minimal impact on natural gas margin due to natural gas cost recovery mechanisms.

Natural gas revenues and margin:

	Nine Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Natural gas revenues	$	830.7		$	707.8
Cost of natural gas sold and transported	(376.7		)	(282.1		)
Natural gas margin	$	454.0		$	425.7

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Changes in natural gas margin:

(Millions of Dollars)	2019 vs. 2018
Estimated impact of weather	$	8.5
Infrastructure and integrity riders	8.5
Transport sales	4.6
Retail sales growth (excluding weather impact)	4.4
Retail rate increase	3.5
Other, net	(1.2		)
Total increase in natural gas margin	$	28.3

Non-Fuel Operating Expenses and Other Items

O&M Expenses — O&M expenses increased $24.4 million, or 4.3%, for the nine months ended Sept. 30, 2019 compared with the prior year. Increase was driven by distribution costs, plant generation costs and gas operations. Distribution costs were higher due to storms, meters and vegetation management. Plant generation costs increased due to in-servicing the Rush Creek wind project and timing of planned maintenance and overhauls. Gas operation expenses increased due to pipeline maintenance.

Depreciation and Amortization — Depreciation and amortization expense increased $42.5 million, or 10.5%, for the nine months ended Sept. 30, 2019 compared with the prior year. Increase was primarily driven by the in-servicing of the Rush Creek wind farm, as well as other capital investments, partially offset by accelerated amortization of the prepaid pension asset in the third quarter of 2018.

AFUDC, Equity and Debt — AFUDC decreased $37.1 million for the nine months ended Sept. 30, 2019 compared with the prior year. Decrease was primarily due to the Rush Creek wind project being placed in-service in 2018.

Interest Charges — Interest charges increased $22.0 million, or 14.3%, for the nine months ended Sept. 30, 2019 compared with the prior year. Increase was primarily due to higher debt levels to fund capital investments, changes in short-term interest rates and implementation of lease accounting standard (offset in electric margin).

Income Taxes — Income tax expense decreased $57.3 million for the nine months ended Sept. 30, 2019 compared with the prior year. Decrease was primarily driven by wind PTCs and lower pre-tax earnings. Wind PTCs are credited to customers (recorded as a reduction to revenue) and do not have a material impact on net income. ETR was 11.5% for the nine months ended Sept. 30, 2019 compared with 19.9% for the prior year, largely due to the items referenced above. See Note 6 to the consolidated financial statements.

Regulation

FERC and State Regulation — The FERC has jurisdiction over rates for electric transmission service in interstate commerce and electricity sold at wholesale, hydro facility licensing, natural gas transportation, asset transactions and mergers, accounting practices and certain other activities of PSCo, including enforcement of North American Electric Reliability Corporation mandatory electric reliability standards. State and local agencies have jurisdiction over many of PSCo’s activities, including regulation of retail rates and environmental matters.

Xcel Energy, which includes PSCo, attempts to mitigate the risk of regulatory penalties through formal training on prohibited practices and a compliance function that reviews interaction with the markets under FERC and Commodity Futures Trading Commission jurisdictions.

Public campaigns are conducted to raise awareness of public safety issues of interacting with our electric systems.

While programs to comply with regulatory requirements are in place, there is no guarantee compliance programs or other measures will be sufficient to ensure against violations. Decisions by these regulators can significantly impact PSCo’s results of operations.

PSCo — Colorado 2019 Electric Rate Case — In May 2019, PSCo filed a request with the CPUC seeking a net rate increase of approximately $158.3 million, or 5.7%. The filing also requests the transfer of $249.4 million of rider revenue to base rates, which will not impact overall customer bills as the revenue is currently being recovered through various riders. The request is based on a ROE of 10.35%, an equity ratio of 56.46%, a rate base of approximately $8.2 billion, a historic test year ended Dec. 31, 2018 (adjusted for 2019 capital investment) and incorporates the full impact of tax reform.

In October 2019, PSCo filed rebuttal testimony and revised its request seeking a net increase to retail electric base rate revenue of $108.3 million, reflecting a $353.3 million increase offset by $245.0 million of previously authorized costs (currently recovered through various rider mechanisms). The rebuttal includes certain forecasted plant additions through June 2019 based on a 13-month average rate base convention, a ROE of 10.20%, an equity ratio of 55.61% (based on a 13-month average equity ending Aug. 31, 2019) and inclusion of short-term debt in the capital structure and CWIP in rate base.

The procedural schedule is as follows:

• Settlement deadline — Oct. 30, 2019

• Evidentiary hearing — Nov. 4-13, 2019

• A CPUC decision is anticipated in December 2019 with implementation of final rates on Jan. 1, 2020.

In September 2019, the CPUC Staff, FEA, OCC and CEC filed comprehensive answer testimony. Several other parties filed additional testimony.

Recommendations and the estimated impact on PSCo’s filed electric rate request as calculated by the filing parties, but with our estimate of the impact of their recommendations on riders are as follows:

(Millions of Dollars)	Filed base revenue request		Less: Previously authorized costs (existing riders) (b)		Filed net change to revenue
PSCo	$	407.7	$	249.4	$	158.3
CPUC Staff (a)	234.6		226.9		7.7
FEA	245.8		238.9		6.9
OCC (a)	207.4		216.3		(8.9		)
CEC (a)	186.9		213.0		(26.1		)

^(a)  Staff, OCC and CEC have incorporated corrections to the filed case of ($4.3) million identified by PSCo.

^(b)  Amounts derived from intervenors’ positions attributable to previously authorized costs (existing riders), impacted by proposed differences in weighted average cost of capital.

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Recommended positions on PSCo’s filed electric rate request are as follows:

Position	Staff			FEA			OCC			CEC
ROE	9.00	%		9.20	%		8.80	%		8.90	%
Equity	55.57	%		56.11	%		54.60	%		54.27	%
Test Year	2019 Current		(a)	2018 Historic		(b)	2018 Historic		(c)	2018 Historic		(d)

^(a)  Incorporated 13-month average of proposed forecasted plant additions and rejected adjustments for wildfire mitigation improvements.

^(b)  Incorporated year-end rate base and rejected proposed forecasted plant additions. Except for the transmission portion, the FEA supported portions of wildfire mitigation improvements and included 2019 distribution capital and O&M in its cost of service amount.

^(c)  Incorporated proposed 13-month average rate base while rejecting the proposed forecasted plant additions including amounts requested for AGIS and wildfire mitigation improvements.

^(d)  Rejected proposed forecasted plant additions and the majority of the adjustment for wildfire mitigation improvements.

Other Pending and Recently Concluded Regulatory Proceedings

Mechanism	Utility Service	Amount Requested (in millions)	Filing Date	Approval	Additional Information
CPUC
Rate Case	Steam	$7	May 2019	Received	In May 2019, PSCo filed an unopposed Settlement Agreement with CPUC Staff and the City of Denver. The settlement reflects a ROE of 9.67% for AFUDC purposes, an equity ratio of 56.04% and utilization of tax reform benefits. The CPUC approved the Settlement Agreement without modification on Sept. 5, 2019. The first stepped increase went into effect Oct. 1, 2019, with full rates effective Oct. 1, 2020.
Rate Case Appeal	Natural Gas	N/A	April 2019	Pending	In April 2019, PSCo filed an appeal seeking judicial review of the CPUC’s prior ruling regarding PSCo’s last natural gas rate case (approved in December 2018). Appeal requests review of the following: denial of a return on the prepaid pension and retiree medical assets; the use of a capital structure that is not based on the actual historical test year level; and the use of an average rate base methodology rather than a year-end rate base methodology. The District Court of Denver County has adopted a briefing schedule that will conclude in October 2019. Timeline on a final ruling is unknown.

Public Utility Regulation

Except to the extent noted in Regulation above, the circumstances set forth in Public Utility Regulation included in Item 1 of PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2018 and in Item 2 of PSCo's Quarterly Report on Form 10-Q for the quarterly periods ended March 31, 2019 and June 30, 2019, appropriately represent, in all material respects, the current status of public utility regulation and are incorporated by reference.

Environmental Matters

In June 2019, the EPA issued the final ACE rule to replace the Obama-era Clean Power Plan. The final ACE rule may require implementation of heat rate improvement projects at some of our coal-fired power plants. It is not known what the costs associated with the final rule might be until state plans are developed to implement the final regulation. PSCo believes the costs would be recoverable through rates based on prior state commission practice.

Item 4 — CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

PSCo maintains a set of disclosure controls and procedures designed to ensure that information required to be disclosed in reports that it files or submits under the Securities Exchange Act of 1934 is recorded, processed, summarized, and reported within the time periods specified in SEC rules and forms. In addition, the disclosure controls and procedures ensure that information required to be disclosed is accumulated and communicated to management, including the CEO and CFO, allowing timely decisions regarding required disclosure. As of Sept. 30, 2019, based on an evaluation carried out under the supervision and with the participation of PSCo’s management, including the CEO and CFO, of the effectiveness of its disclosure controls and the procedures, the CEO and CFO have concluded that PSCo’s disclosure controls and procedures were effective.

Internal Control Over Financial Reporting

No changes in PSCo’s internal control over financial reporting occurred during the most recent fiscal quarter that materially affected, or are reasonably likely to materially affect, PSCo’s internal control over financial reporting.

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Part II — OTHER INFORMATION

Item 1 — Legal Proceedings

PSCo is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation.

Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to, when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on PSCo’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

See Note 9 to the consolidated financial statements and Part I Item 2 for further information.

Item 1A — RISK FACTORS

PSCo’s risk factors are documented in Item 1A of Part I of its Annual Report on Form 10-K for the year ended Dec. 31, 2018, which is incorporated herein by reference. There have been no material changes from the risk factors previously disclosed in the Form 10-K.

Item 6 — EXHIBITS

* Indicates incorporation by reference

+ Executive Compensation Arrangements and Benefit Plans Covering Executive Officers and Directors

Exhibit Number	Description	Report or Registration Statement	SEC File or Registration Number	Exhibit Reference
3.01*	Amended and Restated Articles of Incorporation dated July 15, 1998	PSCo Form 10-Q for the quarter ended Sept. 30, 2017	001-03280	3.01
3.02*	By-Laws of PSCo as Amended and Restated on Jan. 25, 2019	PSCo Form 10-K for the year ended Dec. 31, 2018	001-03280	3.02
4.02*	Supplemental Indenture dated as of August 1, 2019, between Public Service Company of Colorado and U.S. Bank National Association, as successor Trustee, creating 3.20% First Mortgage Bonds, Series No. 34 due March 1, 2050.	PSCo Form 8-K dated August 13, 2019	001-3280	4.01
31.01	Principal Executive Officer’s certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
31.02	Principal Financial Officer’s certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32.01	Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS	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	XBRL Schema
101.CAL	XBRL Calculation
101.DEF	XBRL Definition
101.LAB	XBRL Label
101.PRE	XBRL Presentation
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

23

SIGNATURES

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

		Public Service Company of Colorado
Oct. 25, 2019	By:	/s/ JEFFREY S. SAVAGE
		Jeffrey S. Savage
		Senior Vice President, Controller
		(Principal Accounting Officer)
		/s/ ROBERT C. FRENZEL
		Robert C. Frenzel
		Executive Vice President, Chief Financial Officer and Director
		(Principal Financial Officer)

24

EX-31.01

Exhibit 31.01

CERTIFICATION

I, Ben Fowke, certify that:

1. I have reviewed this report on Form 10-Q of Public Service Company of Colorado;

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: Oct. 25, 2019

/s/ BEN FOWKE

Ben Fowke

Chairman, Chief Executive Officer and Director

(Principal Executive Officer)

1

EX-31.02

Exhibit 31.02

CERTIFICATION

I, Robert C. Frenzel, certify that:

1. I have reviewed this report on Form 10-Q of Public Service Company of Colorado;

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: Oct. 25, 2019

/s/ ROBERT C. FRENZEL

Robert C. Frenzel

Executive Vice President, Chief Financial Officer and Director

(Principal Financial Officer)

2

EX-32.01

Exhibit 32.01

OFFICER CERTIFICATION

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Public Service Company of Colorado (PSCo) on Form 10-Q for the quarter ended Sept. 30, 2019, as filed with the SEC on the date hereof (Form 10-Q), each of the undersigned officers of PSCo certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer’s knowledge:

(1) The Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of PSCo as of the dates and for the periods expressed in the Form 10-Q.

Date: Oct. 25, 2019

/s/ BEN FOWKE

Ben Fowke

Chairman, Chief Executive Officer and Director

(Principal Executive Officer)

/s/ ROBERT C. FRENZEL

Robert C. Frenzel

Executive Vice President, Chief Financial Officer and Director

(Principal Financial Officer)

The foregoing certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of the Report or as a separate disclosure document.

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to PSCo and will be retained by PSCo and furnished to the SEC or its staff upon request.

1

XML

Long-Term Borrowings (Details) - Bonds [Member] $ in Millions	Sep. 30, 2019 USD ($)
Series Due September 15, 2049 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 400
Debt Instrument, Interest Rate, Stated Percentage	4.05%
Series Due March 1, 2050 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 550
Debt Instrument, Interest Rate, Stated Percentage	3.20%

XML

Selected Balance Sheet Data (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Accounts receivable, net
Accounts receivable	$ 315.1	$ 330.8
Less allowance for bad debts	(20.9)	(20.5)
Accounts receivable, net	$ 294.2	$ 310.3

XML

Money Pool (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Amount outstanding at period end	$ 0	$ 307,000,000.0
Money Pool
Short-term Debt [Line Items]
Borrowing limit	250,000,000	250,000,000
Amount outstanding at period end	0	0
Average amount outstanding	23,000,000	25,000,000
Maximum amount outstanding	$ 50,000,000	$ 156,000,000
Weighted average interest rate, computed on a daily basis	2.29%	1.93%

XML

Income Taxes

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

Note 8 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2018 represents, in all material respects, the current status of other income tax matters except to the extent noted below, and are incorporated herein by reference.

The following table reconciles the difference between the statutory rate and the ETR:

	Nine Months Ended Sept. 30
	2019		2018
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	3.7		3.7
Decreases in tax from:
Wind PTCs	(7.7	)	—
Plant regulatory differences (a)	(3.6	)	(3.1	)
Other tax credits and tax credit and NOL allowances (net)	(1.3	)	(0.7	)
Other (net)	(0.6	)	(1.0	)
Effective income tax rate	11.5	%	19.9	%

^(a) Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method and the timing of regulatory decisions regarding the return of excess deferred taxes. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions and additional prepaid pension asset amortization.

Federal Audits — PSCO is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s federal income tax returns expire as follows:

Tax Year(s)	Expiration
2009 - 2013	June 2020
2014 - 2016	September 2020

In 2015, the IRS commenced an examination of tax years 2012 and 2013. In 2017, the IRS concluded the audit of tax years 2012 and 2013 and proposed an adjustment that would impact Xcel Energy’s NOL and ETR. Xcel Energy filed a protest with the IRS. As of Sept. 30, 2019, the case has been forwarded to Office of Appeals and Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of this issue; however, the outcome and timing of a resolution is unknown.

In 2018, the IRS began an audit of tax years 2014 - 2016. As of Sept. 30, 2019 no adjustments have been proposed.

State Audits — PSCo is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of Sept. 30, 2019, PSCo’s earliest open tax year subject to examination by state taxing authorities under applicable statutes of limitations is 2009. There are currently no state income tax audits in progress.

Unrecognized Benefits — Unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which ultimate deductibility is highly certain, but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR but would accelerate the payment to the taxing authority to an earlier period.

Unrecognized tax benefits — permanent vs temporary:

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Unrecognized tax benefit — Permanent tax positions	$	7.0	$	5.4
Unrecognized tax benefit — Temporary tax positions	4.7		4.9
Total unrecognized tax benefit	$	11.7	$	10.3

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
NOL and tax credit carryforwards	$	(8.3	)	$	(5.6	)

Net deferred tax liability associated with the unrecognized tax benefit amounts and related NOLs and tax credits carryforwards were $4.9 million and $2.0 million for Sept. 30, 2019 and Dec. 31, 2018, respectively.

As the IRS Appeals and federal audit progresses, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $8.7 million in the next 12 months.

Payables for interest related to unrecognized tax benefits were not material and no amounts were accrued for penalties related to unrecognized tax benefits as of Sept. 30, 2019 or Dec. 31, 2018.

XML

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

The significant accounting policies set forth in Note 1 to the consolidated financial statements in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2018, appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

XML

Commitments and Contingencies Coal Ash Regulation (Details)	Sep. 30, 2019
Federal Coal Ash Regulation [Domain]
Site Contingency [Line Items]
Number of sites where regulated ash units will still be in operation at a specified date	6

XML

Benefit Plans and Other Postretirement Benefits (Details) $ in Millions			1 Months Ended	3 Months Ended		9 Months Ended
		Jul. 01, 2019 USD ($)	Jan. 31, 2019 USD ($) Plan	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Pension Plan [Member]
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				$ 6.4	$ 7.3	$ 19.2	$ 21.8
Interest cost	[1]			12.9	11.8	38.7	35.5
Expected return on plan assets	[1]			(17.1)	(17.1)	(51.4)	(51.4)
Amortization of prior service credit	[1]			(0.8)	(0.9)	(2.5)	(2.5)
Amortization of net loss	[1]			6.3	7.8	19.1	23.4
Net periodic benefit cost (credit)				7.7	8.9	23.1	26.8
Credits (costs) not recognized due to the effects of regulation				0.8	(4.1)	4.4	(1.7)
Net benefit cost (credit) recognized for financial reporting				8.5	4.8	27.5	25.1
Contributions to pension plans		$ 2.7	$ 43.0
Pension Plan [Member] | Xcel Energy Inc.
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to pension plans		$ 4.0	$ 150.0
Number of Xcel Energy's pension plans to which contributions were made | Plan			4
Other Postretirement Benefits Plan [Member]
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				0.1	0.2	0.4	0.5
Interest cost	[1]			3.9	3.8	11.7	11.2
Expected return on plan assets	[1]			(4.7)	(5.7)	(14.2)	(17.0)
Amortization of prior service credit	[1]			(1.3)	(1.6)	(4.1)	(4.7)
Amortization of net loss	[1]			0.7	1.0	2.2	3.1
Net periodic benefit cost (credit)				(1.3)	(2.3)	(4.0)	(6.9)
Credits (costs) not recognized due to the effects of regulation				0.4	1.4	0.9	1.4
Net benefit cost (credit) recognized for financial reporting				$ (0.9)	$ (0.9)	$ (3.1)	$ (5.5)

[1] The components of net periodic cost other than the service cost component are included in the line item “other income, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.

XML

Segment Information (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Segment Reporting Information [Line Items]
Net income	$ 204.5		$ 207.1		$ 444.8		$ 463.1
Gas	153.9		157.2		830.7		707.8
Unregulated Operating Revenue	9.7		8.7		31.8		28.7
Regulated and Unregulated Operating Revenue	1,044.3		1,060.7		3,177.3		3,045.8
Affiliate Revenue	1.1		1.1		3.3		3.3
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues	880.8		894.8		2,315.1		2,309.5
Net income	204.7		191.7		371.9		373.3
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues	154.0		157.5		830.9		708.2
Net income	0.7		15.1		77.5		89.7
All Other
Segment Reporting Information [Line Items]
Net income	(0.9)		0.3		(4.6)		0.1
Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	880.7		894.8		2,314.8		2,309.3
Gas	153.9		157.2		830.7		707.8
Unregulated Operating Revenue	9.7	[1]	8.7	[1]	31.8	[2]	28.7	[2]
Regulated and Unregulated Operating Revenue	1,044.5	[1]	1,061.0	[1]	3,177.8	[2]	3,046.4	[2]
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	0.1		0.0		0.3		0.2
Gas	0.1		0.3		0.2		0.4
Regulated and Unregulated Operating Revenue	$ (0.2)		$ (0.3)		$ (0.5)		$ (0.6)

[1] Operating revenues include $1.1 million of other affiliate revenue for the three months ended Sept. 30, 2019 and 2018.

[2] Operating revenues include $3.3 million of other affiliate revenue for the nine months ended Sept. 30, 2019 and 2018.

XML

Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt, Carrying Amount	$ 5,384.0	$ 4,997.6
Level 2
Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt, fair value	$ 6,139.2	$ 5,123.2

XML

Income Taxes (Details)		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate		21.00%	21.00%
State tax (net of federal tax effect)		3.70%	3.70%
Wind PTCs		(7.70%)	0.00%
Plant regulatory differences	[1]	(3.60%)	(3.10%)
Other tax credits and tax credit and NOL allowances (net)		(1.30%)	(0.70%)
Other (net)		(0.60%)	(1.00%)
Effective income tax rate		11.50%	19.90%

[1] Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method and the timing of regulatory decisions regarding the return of excess deferred taxes. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions and additional prepaid pension asset amortization.

XML

Fair Value of Financial Assets and Liabilities Commodity Derivatives (Details) MWh in Millions, MMBTU in Millions, $ in Millions		Sep. 30, 2019 USD ($) MMBTU MWh	Dec. 31, 2018 MMBTU MWh
Cash flow hedge commodity [Member]
Derivative [Line Items]
Commodity contracts designated as cash flow hedges | $		$ 0.0
Electric Commodity [Member]
Gross Notional Amounts of Commodity Forwards and Options [Abstract]
Derivative, Nonmonetary Notional amount | MWh	[1],[2]	15.5	24.4
Natural Gas Commodity [Member]
Gross Notional Amounts of Commodity Forwards and Options [Abstract]
Derivative, Nonmonetary Notional amount | MMBTU	[1],[2]	58.8	48.4

[1] Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

[2] Amounts are not reflective of net positions in the underlying commodities.

XML

Revenues (Tables)

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

PSCo’s operating revenues consists of the following:

	Three Months Ended Sept. 30, 2019
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	315.3	$	94.1	$	3.1	$	412.5
C&I	452.4		32.9		5.5		490.8
Other	11.8		—		—		11.8
Total retail	779.5		127.0		8.6		915.1
Wholesale	40.3		—		—		40.3
Transmission	16.4		—		—		16.4
Other	8.3		21.4		—		29.7
Total revenue from contracts with customers	844.5		148.4		8.6		1,001.5
Alternative revenue and other	36.2		5.5		1.1		42.8
Total revenues	$	880.7	$	153.9	$	9.7	$	1,044.3

	Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	315.7	$	84.4	$	2.7	$	402.8
C&I	458.5		29.1		4.9		492.5
Other	11.8		—		—		11.8
Total retail	786.0		113.5		7.6		907.1
Wholesale	41.2		—		—		41.2
Transmission	16.3		—		—		16.3
Other	10.6		18.4		—		29.0
Total revenue from contracts with customers	854.1		131.9		7.6		993.6
Alternative revenue and other	40.7		25.3		1.1		67.1
Total revenues	$	894.8	$	157.2	$	8.7	$	1,060.7

	Nine Months Ended Sept. 30, 2019
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	771.9	$	535.6	$	8.4	$	1,315.9
C&I	1,204.7		202.6		20.0		1,427.3
Other	36.1		—		—		36.1
Total retail	2,012.7		738.2		28.4		2,779.3
Wholesale	126.7		—		—		126.7
Transmission	41.4		—		—		41.4
Other	26.4		76.3		—		102.7
Total revenue from contracts with customers	2,207.2		814.5		28.4		3,050.1
Alternative revenue and other	107.6		16.2		3.4		127.2
Total revenues	$	2,314.8	$	830.7	$	31.8	$	3,177.3

	Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	766.1	$	416.2	$	7.9	$	1,190.2
C&I	1,185.4		154.0		17.4		1,356.8
Other	35.4		—		0.1		35.5
Total retail	1,986.9		570.2		25.4		2,582.5
Wholesale	125.3		—		—		125.3
Transmission	41.7		—		—		41.7
Other	44.1		62.1		—		106.2
Total revenue from contracts with customers	2,198.0		632.3		25.4		2,855.7
Alternative revenue and other	111.3		75.5		3.3		190.1
Total revenues	$	2,309.3	$	707.8	$	28.7	$	3,045.8

XML

Other Comprehensive Income

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Other Comprehensive Income

Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive loss, net of tax, for the three and nine months ended Sept. 30, 2019 and 2018:

	Three Months Ended Sept. 30, 2019									Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at July 1	$	(24.7	)	$	(0.2	)	$	(24.9	)	$	(25.8	)	$	(0.3	)	$	(26.1	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively)	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.1, $0, $0.1 and $0, respectively) (a)	0.3			—			0.3			0.3			—			0.3
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.3			—			0.3			0.3			—			0.3
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

	Nine Months Ended Sept. 30, 2019									Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at Jan. 1	$	(25.3	)	$	(0.2	)	$	(25.5	)	$	(26.4	)	$	(0.3	)	$	(26.7	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.3, $0, $0.3 and $0, respectively) (a)	0.9			—			0.9			0.9			—			0.9
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.9			—			0.9			0.9			—			0.9
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

^(a) 

Included in interest charges.

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CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 328.1	$ 33.4
Accounts receivable, net	294.2	310.3
Accounts receivable from affiliates	13.6	80.8
Accrued unbilled revenues	228.8	313.5
Inventories	188.1	197.4
Regulatory assets	70.5	120.6
Derivative instruments	10.0	42.6
Prepayments and other	39.3	23.8
Total current assets	1,172.6	1,122.4
Property, plant and equipment, net	15,786.4	15,120.0
Other assets
Regulatory assets	1,063.3	1,010.7
Derivative instruments	0.7	1.2
Operating lease right-of-use assets	594.4	0.0
Other	248.9	37.2
Total other assets	1,907.3	1,049.1
Total assets	18,866.3	17,291.5
Current liabilities
Current portion of long-term debt	0.0	406.2
Short-term debt	0.0	307.0
Accounts payable	514.0	503.4
Accounts payable to affiliates	44.5	46.0
Regulatory liabilities	116.5	67.3
Taxes accrued	159.7	202.0
Accrued interest	36.0	43.2
Dividends payable to parent	97.3	91.5
Derivative instruments	11.7	34.6
Other	179.5	101.5
Total current liabilities	1,159.2	1,802.7
Deferred credits and other liabilities
Deferred income taxes	1,772.0	1,719.3
Deferred investment tax credits	23.5	25.3
Regulatory liabilities	2,022.3	2,021.5
Asset retirement obligations	350.1	338.7
Derivative instruments	54.8	0.6
Customer advances	172.8	168.1
Pension and employee benefit obligations	230.5	275.3
Operating lease liabilities	539.5	0.0
Other	152.0	50.4
Total deferred credits and other liabilities	5,317.5	4,599.2
Capitalization
Long-term debt	5,384.0	4,591.4
Common stock — 100 shares authorized at $0.01 par value; 100 shares outstanding at Sept. 30, 2019 and Dec. 31, 2018, respectively	0.0	0.0
Additional paid in capital	4,903.3	4,340.5
Retained earnings	2,126.9	1,983.2
Accumulated other comprehensive loss	(24.6)	(25.5)
Total common stockholder’s equity	7,005.6	6,298.2
Total liabilities and equity	$ 18,866.3	$ 17,291.5

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Commitments and Contingencies Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Schedule of Operating and Finance Lease Right-of-Use Assets

Operating lease ROU assets:

(Millions of Dollars)	Sept. 30, 2019
PPAs	$	585.1
Other	68.7
Gross operating lease ROU assets	653.8
Accumulated amortization	(59.4		)
Net operating lease ROU assets	$	594.4

Finance lease ROU assets:

(Millions of Dollars)	Sept. 30, 2019
Gas storage facilities	$	200.5
Gas pipeline	20.7
Gross finance lease ROU assets	221.2
Accumulated amortization	(80.8		)
Net finance lease ROU assets	$	140.4

Schedule of Components of Lease Expense

Components of lease expense:

(Millions of Dollars)	Three Months Ended Sept. 30, 2019		Nine Months Ended Sept. 30, 2019
Operating leases
PPA capacity payments	$	24.6	$	73.6
Other operating leases (a)	4.3		11.5
Total operating lease expense (b)	$	28.9	$	85.1
Finance leases
Amortization of ROU assets	$	1.6	$	4.6
Interest expense on lease liability	4.7		14.2
Total finance lease expense	$	6.3	$	18.8

^(a)  Includes short-term lease expense of $0.3 million for the three months ended Sept. 30, 2019 and $1.0 million for the nine months ended Sept. 30, 2019.

^(b) 

PPA capacity payments are included in electric fuel and purchased power on the consolidated statements of income. Expense for other operating leases is included in O&M expense and electric fuel and purchased power.

Schedule of Future Commitments under Finance Leases

Future commitments under operating and finance leases as of Sept. 30, 2019:

(Millions of Dollars)	PPA (a) (b) Operating Leases			Other Operating Leases			Total Operating Leases			Finance Leases
2019	$	23.9		$	3.3		$	27.2		$	6.2
2020	95.9			13.2			109.1			24.8
2021	96.4			12.6			109.0			23.6
2022	82.6			11.6			94.2			20.5
2023	70.0			10.9			80.9			20.3
Thereafter	288.6			29.2			317.8			419.8
Total minimum obligation	657.4			80.8			738.2			515.2
Interest component of obligation	(100.6		)	(13.1		)	(113.7		)	(374.8		)
Present value of minimum obligation	$	556.8		$	67.7		624.5			140.4
Less current portion							(85.0		)	(6.7		)
Noncurrent operating and finance lease liabilities							$	539.5		$	133.7
Weighted-average remaining lease term in years							8.1			38.9

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b)  PPA operating leases contractually expire at various dates through 2032.

Future commitments under operating and finance leases as of Dec. 31, 2018:

(Millions of Dollars)	PPA (a) (b) Operating Leases		Other Operating Leases		Total Operating Leases		Finance Leases
2019	$	95.5	$	10.8	$	106.3	$	24.9
2020	95.9		10.7		106.6		24.8
2021	96.4		9.5		105.9		23.6
2022	82.6		8.4		91.0		20.5
2023	70.0		8.1		78.1		20.3
Thereafter	288.6		53.4		342.0		420.4
Total minimum obligation							534.5
Interest component of obligation							(389.5		)
Present value of minimum obligation							$	145.0

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b) 

PPA operating leases contractually expire at various dates through 2032.

Schedule of Future Commitments under Operating Leases

Future commitments under operating and finance leases as of Sept. 30, 2019:

(Millions of Dollars)	PPA (a) (b) Operating Leases			Other Operating Leases			Total Operating Leases			Finance Leases
2019	$	23.9		$	3.3		$	27.2		$	6.2
2020	95.9			13.2			109.1			24.8
2021	96.4			12.6			109.0			23.6
2022	82.6			11.6			94.2			20.5
2023	70.0			10.9			80.9			20.3
Thereafter	288.6			29.2			317.8			419.8
Total minimum obligation	657.4			80.8			738.2			515.2
Interest component of obligation	(100.6		)	(13.1		)	(113.7		)	(374.8		)
Present value of minimum obligation	$	556.8		$	67.7		624.5			140.4
Less current portion							(85.0		)	(6.7		)
Noncurrent operating and finance lease liabilities							$	539.5		$	133.7
Weighted-average remaining lease term in years							8.1			38.9

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b)  PPA operating leases contractually expire at various dates through 2032.

Future commitments under operating and finance leases as of Dec. 31, 2018:

(Millions of Dollars)	PPA (a) (b) Operating Leases		Other Operating Leases		Total Operating Leases		Finance Leases
2019	$	95.5	$	10.8	$	106.3	$	24.9
2020	95.9		10.7		106.6		24.8
2021	96.4		9.5		105.9		23.6
2022	82.6		8.4		91.0		20.5
2023	70.0		8.1		78.1		20.3
Thereafter	288.6		53.4		342.0		420.4
Total minimum obligation							534.5
Interest component of obligation							(389.5		)
Present value of minimum obligation							$	145.0

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b) 

PPA operating leases contractually expire at various dates through 2032.

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CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest charges and financing costs
Other financing costs	$ 1.6	$ 1.7	$ 4.9	$ 4.9

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Revenues (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,044.3	$ 1,060.7	$ 3,177.3	$ 3,045.8
Regulated Electric
Disaggregation of Revenue [Line Items]
Total revenues	880.7	894.8	2,314.8	2,309.3
Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues	153.9	157.2	830.7	707.8
All Other
Disaggregation of Revenue [Line Items]
Total revenues	9.7	8.7	31.8	28.7
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,001.5	993.6	3,050.1	2,855.7
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	844.5	854.1	2,207.2	2,198.0
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	148.4	131.9	814.5	632.3
Total revenue from contracts with customers | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	8.6	7.6	28.4	25.4
Retail
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	915.1	907.1	2,779.3	2,582.5
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	412.5	402.8	1,315.9	1,190.2
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	490.8	492.5	1,427.3	1,356.8
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11.8	11.8	36.1	35.5
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	779.5	786.0	2,012.7	1,986.9
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	315.3	315.7	771.9	766.1
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	452.4	458.5	1,204.7	1,185.4
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11.8	11.8	36.1	35.4
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	127.0	113.5	738.2	570.2
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	94.1	84.4	535.6	416.2
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	32.9	29.1	202.6	154.0
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.0
Retail | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	8.6	7.6	28.4	25.4
Retail | All Other | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3.1	2.7	8.4	7.9
Retail | All Other | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.5	4.9	20.0	17.4
Retail | All Other | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.1
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	40.3	41.2	126.7	125.3
Wholesale | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	40.3	41.2	126.7	125.3
Wholesale | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.0
Wholesale | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.0
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16.4	16.3	41.4	41.7
Transmission | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16.4	16.3	41.4	41.7
Transmission | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.0
Transmission | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	29.7	29.0	102.7	106.2
Other | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	8.3	10.6	26.4	44.1
Other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	21.4	18.4	76.3	62.1
Other | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	0.0	0.0	0.0
Alternative and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	42.8	67.1	127.2	190.1
Alternative and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	36.2	40.7	107.6	111.3
Alternative and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	5.5	25.3	16.2	75.5
Alternative and other | All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 1.1	$ 1.1	$ 3.4	$ 3.3

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Fair Value of Financial Assets and Liabilities Interest Rate Derivatives (Details) $ in Millions	Sep. 30, 2019 USD ($)
Interest Rate Swap [Member]
Derivative [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1.2

XML

Recurring Fair Value Measures (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative Asset, Collateral, Obligation to Return Cash, Offset		$ 0		$ 0		$ 0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		3,200,000		3,200,000		6,500,000
Commodity Trading
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings		500,000		1,500,000
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3		0	$ 0	0	$ 0
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability		11,700,000		11,700,000		34,600,000
Fair Value Measured on a Recurring Basis | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		20,000,000.0		20,000,000.0		70,800,000
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	[1]	(10,000,000.0)		(10,000,000.0)		(28,200,000)
Derivative Asset		10,000,000.0		10,000,000.0		42,600,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1,400,000		1,400,000		2,300,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		18,400,000		18,400,000		68,400,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		200,000		200,000		100,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		6,300,000		6,300,000		1,600,000
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	[1]	(5,600,000)		(5,600,000)		(400,000)
Derivative Asset		700,000		700,000		1,200,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		500,000		500,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		5,700,000		5,700,000		1,600,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		100,000		100,000		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		25,000,000.0		25,000,000.0		66,600,000
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1]	(13,300,000)		(13,300,000)		(34,700,000)
Derivative Liability		11,700,000		11,700,000		31,900,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		1,400,000		1,400,000		2,400,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		23,500,000		23,500,000		64,200,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		100,000		100,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		60,400,000		60,400,000		1,100,000
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1]	(5,600,000)		(5,600,000)		(500,000)
Derivative Liability		54,800,000		54,800,000		600,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		400,000		400,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		60,000,000.0		60,000,000.0		1,100,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		15,200,000		15,200,000		67,400,000
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	[1]	(10,000,000.0)		(10,000,000.0)		(28,200,000)
Derivative Asset		5,200,000		5,200,000		39,200,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Commodity Trading | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1,400,000		1,400,000		2,300,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Commodity Trading | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		13,600,000		13,600,000		65,000,000.0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Commodity Trading | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		200,000		200,000		100,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		4,800,000		4,800,000		3,400,000
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	[1]	0		0		0
Derivative Asset		4,800,000		4,800,000		3,400,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Natural Gas Commodity | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Natural Gas Commodity | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		4,800,000		4,800,000		3,400,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Assets | Natural Gas Commodity | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Assets | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		6,300,000		6,300,000		1,600,000
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	[1]	(5,600,000)		(5,600,000)		(400,000)
Derivative Asset		700,000		700,000		1,200,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Assets | Commodity Trading | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		500,000		500,000		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Assets | Commodity Trading | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		5,700,000		5,700,000		1,600,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Assets | Commodity Trading | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		100,000		100,000		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		20,600,000		20,600,000		66,600,000
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1]	(13,300,000)		(13,300,000)		(34,700,000)
Derivative Liability		7,300,000		7,300,000		31,900,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Commodity Trading | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		1,400,000		1,400,000		2,400,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Commodity Trading | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		19,100,000		19,100,000		64,200,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Commodity Trading | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		100,000		100,000		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		4,400,000		4,400,000		0
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1]	0		0		0
Derivative Liability		4,400,000		4,400,000		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Natural Gas Commodity | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Natural Gas Commodity | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		4,400,000		4,400,000		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Current Liabilities | Natural Gas Commodity | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Liabilities | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		60,400,000		60,400,000		1,100,000
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1]	(5,600,000)		(5,600,000)		(500,000)
Derivative Liability		54,800,000		54,800,000		600,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Liabilities | Commodity Trading | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		400,000		400,000		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Liabilities | Commodity Trading | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		60,000,000.0		60,000,000.0		1,100,000
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Other Noncurrent Liabilities | Commodity Trading | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0		0
Fair Value, Measurements, Nonrecurring | Other Current Liabilities | PPAs
Derivatives, Fair Value [Line Items]
Derivative Liability	[2]	$ 0		$ 0		$ 2,700,000

[1] PSCo nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Sept. 30, 2019 and Dec. 31, 2018. At both Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include no obligations to return cash collateral. At Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include the rights to reclaim cash collateral of $3.2 million and $6.5 million, respectively. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[2] During 2006, PSCo qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts will be amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.

XML

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 25, 2019
Cover page.
Entity Registrant Name	PUBLIC SERVICE CO OF COLORADO
Entity Central Index Key	0000081018
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-03280
Entity Tax Identification Number	84-0296600
Entity Incorporation, State or Country Code	CO
Entity Address, Address Line One	1800 Larimer, Suite 1100
Entity Address, City or Town	Denver
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80202
City Area Code	303
Local Phone Number	571-7511
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		100

XML

Other Comprehensive Income (Tables)

9 Months Ended

Sep. 30, 2019

Stockholders' Equity Note [Abstract]

Changes in Accumulated Other Comprehensive Loss, Net of Tax

Changes in accumulated other comprehensive loss, net of tax, for the three and nine months ended Sept. 30, 2019 and 2018:

	Three Months Ended Sept. 30, 2019									Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at July 1	$	(24.7	)	$	(0.2	)	$	(24.9	)	$	(25.8	)	$	(0.3	)	$	(26.1	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively)	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.1, $0, $0.1 and $0, respectively) (a)	0.3			—			0.3			0.3			—			0.3
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.3			—			0.3			0.3			—			0.3
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

	Nine Months Ended Sept. 30, 2019									Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at Jan. 1	$	(25.3	)	$	(0.2	)	$	(25.5	)	$	(26.4	)	$	(0.3	)	$	(26.7	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.3, $0, $0.3 and $0, respectively) (a)	0.9			—			0.9			0.9			—			0.9
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.9			—			0.9			0.9			—			0.9
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

^(a) 

Included in interest charges.

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive income:
Net income	$ 204.5	$ 207.1	$ 444.8	$ 463.1
Pension and retiree medical benefits:
Net pension and retiree medical losses arising during the period, net of tax of $0, $(0.1), $0 and $(0.1), respectively	0.0	(0.2)	0.0	(0.2)
Amortization of losses included in net periodic benefit cost, net of tax of $0, $0.1, $0 and $0.1, respectively	0.0	0.2	0.0	0.2
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax	0.0	0.0	0.0	0.0
Derivative instruments:
Reclassification of losses to net income, net of tax of $0.1, $0.1, $0.3 and $0.3, respectively	0.3	0.3	0.9	0.9
Other comprehensive income	0.3	0.3	0.9	0.9
Comprehensive income	$ 204.8	$ 207.4	$ 445.7	$ 464.0

XML

Income Taxes (Tables)

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following table reconciles the difference between the statutory rate and the ETR:

	Nine Months Ended Sept. 30
	2019		2018
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	3.7		3.7
Decreases in tax from:
Wind PTCs	(7.7	)	—
Plant regulatory differences (a)	(3.6	)	(3.1	)
Other tax credits and tax credit and NOL allowances (net)	(1.3	)	(0.7	)
Other (net)	(0.6	)	(1.0	)
Effective income tax rate	11.5	%	19.9	%

^(a) Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method and the timing of regulatory decisions regarding the return of excess deferred taxes. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions and additional prepaid pension asset amortization.

Summary of Statute of Limitations Applicable to Open Tax Years [Table Text Block]

Federal Audits — PSCO is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s federal income tax returns expire as follows:

Tax Year(s)	Expiration
2009 - 2013	June 2020
2014 - 2016	September 2020

Reconciliation of Unrecognized Tax Benefits

Unrecognized tax benefits — permanent vs temporary:

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Unrecognized tax benefit — Permanent tax positions	$	7.0	$	5.4
Unrecognized tax benefit — Temporary tax positions	4.7		4.9
Total unrecognized tax benefit	$	11.7	$	10.3

Tax Benefits Associated with NOL and Tax Credit Carryforwards

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
NOL and tax credit carryforwards	$	(8.3	)	$	(5.6	)

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Segment Information

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Segment Information

Segment Information

Operating results from the regulated electric utility and regulated natural gas utility are each separately and regularly reviewed by PSCo’s chief operating decision maker. PSCo evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

PSCo has the following reportable segments: regulated electric utility, regulated natural gas utility and all other.

• Regulated Electric - The regulated electric utility segment generates electricity which is transmitted and distributed in Colorado. This segment includes sales for resale and provides wholesale transmission service to various entities in the United States. Regulated electric utility also includes PSCo’s wholesale commodity and trading operations.

• Regulated Natural Gas - The regulated natural gas utility segment transports, stores and distributes natural gas in portions of Colorado.

• All Other - Revenues from operating segments not included above are below the necessary quantitative thresholds are included in the all other category. Those primarily include steam revenue, appliance repair services and nonutility real estate activities.

Asset and capital expenditure information is not provided for PSCo’s reportable segments. As an integrated electric and natural gas utility, PSCo operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis.

Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.

PSCo’s segment information for the three and nine months ended Sept. 30:

	Three Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Regulated Electric
Operating revenues	$	880.7		$	894.8
Intersegment revenues	0.1			—
Total revenue	880.8			894.8
Net income	204.7			191.7
Regulated Natural Gas
Operating revenues	$	153.9		$	157.2
Intersegment revenues	0.1			0.3
Total revenue	154.0			157.5
Net income	0.7			15.1
All Other
Operating revenues (a)	$	9.7		$	8.7
Net (loss) income	(0.9		)	0.3
Consolidated Total
Operating revenues (a)	$	1,044.5		$	1,061.0
Reconciling eliminations	(0.2		)	(0.3		)
Total revenue	$	1,044.3		$	1,060.7
Net income	204.5			207.1

^(a)  Operating revenues include $1.1 million of other affiliate revenue for the three months ended Sept. 30, 2019 and 2018.

	Nine Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Regulated Electric
Operating revenues	$	2,314.8		$	2,309.3
Intersegment revenues	0.3			0.2
Total revenue	2,315.1			2,309.5
Net income	371.9			373.3
Regulated Natural Gas
Operating revenues	$	830.7		$	707.8
Intersegment revenues	0.2			0.4
Total revenue	830.9			708.2
Net income	77.5			89.7
All Other
Operating revenues (a)	$	31.8		$	28.7
Net (loss) income	(4.6		)	0.1
Consolidated Total
Operating revenues (a)	$	3,177.8		$	3,046.4
Reconciling eliminations	(0.5		)	(0.6		)
Total revenue	$	3,177.3		$	3,045.8
Net income	444.8			463.1

^(a) 

Operating revenues include $3.3 million of other affiliate revenue for the nine months ended Sept. 30, 2019 and 2018.

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CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Capitalization, Long-term Debt and Equity [Abstract]
Common stock, shares authorized (in shares)	100	100
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares outstanding (in shares)	100	100

XML

Segment Information (Tables)

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Results from Operations by Reportable Segment

	Nine Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Regulated Electric
Operating revenues	$	2,314.8		$	2,309.3
Intersegment revenues	0.3			0.2
Total revenue	2,315.1			2,309.5
Net income	371.9			373.3
Regulated Natural Gas
Operating revenues	$	830.7		$	707.8
Intersegment revenues	0.2			0.4
Total revenue	830.9			708.2
Net income	77.5			89.7
All Other
Operating revenues (a)	$	31.8		$	28.7
Net (loss) income	(4.6		)	0.1
Consolidated Total
Operating revenues (a)	$	3,177.8		$	3,046.4
Reconciling eliminations	(0.5		)	(0.6		)
Total revenue	$	3,177.3		$	3,045.8
Net income	444.8			463.1

^(a) 

Operating revenues include $3.3 million of other affiliate revenue for the nine months ended Sept. 30, 2019 and 2018.

PSCo’s segment information for the three and nine months ended Sept. 30:

	Three Months Ended Sept. 30
(Millions of Dollars)	2019			2018
Regulated Electric
Operating revenues	$	880.7		$	894.8
Intersegment revenues	0.1			—
Total revenue	880.8			894.8
Net income	204.7			191.7
Regulated Natural Gas
Operating revenues	$	153.9		$	157.2
Intersegment revenues	0.1			0.3
Total revenue	154.0			157.5
Net income	0.7			15.1
All Other
Operating revenues (a)	$	9.7		$	8.7
Net (loss) income	(0.9		)	0.3
Consolidated Total
Operating revenues (a)	$	1,044.5		$	1,061.0
Reconciling eliminations	(0.2		)	(0.3		)
Total revenue	$	1,044.3		$	1,060.7
Net income	204.5			207.1

^(a) 

Operating revenues include $1.1 million of other affiliate revenue for the three months ended Sept. 30, 2019 and 2018.

XML

Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 594.4		$ 0.0
Operating Lease, Liability	$ 624.5
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset		$ 700.0
Operating Lease, Liability		$ 700.0

XML

Amended Credit Agreement (Details) - Credit Facility		9 Months Ended
		Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Line of Credit Facility [Line Items]
Number of extension you can request		2
Credit Facility	[1]	$ 700,000,000
Outstanding	[2]	9,000,000
Available		691,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0

[1] This credit facility expires in June 2024.

[2] Includes outstanding commercial paper and letters of credit.

XML

Fair Value of Financial Assets and Liabilities

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

Fair Value of Financial Assets and Liabilities

Fair Value Measurements

The accounting guidance for fair value measurements and disclosures provides a single definition of fair value, hierarchical framework for measuring assets and liabilities and requires disclosure about assets and liabilities measured at fair value.

Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are highly liquid and actively traded instruments with quoted prices.

Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts, or priced with models using highly observable inputs.

Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 are those valued with models requiring significant management judgment or estimation.

Specific valuation methods include:

Cash equivalents — The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted net asset value.

Interest rate derivatives — The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts.

Commodity derivatives — The methods used to measure the fair value of commodity derivative forwards and options generally utilize observable forward prices and volatilities, as well as observable pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. When contractual settlements relate to delivery locations for which pricing is relatively unobservable, or extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable inputs on a valuation is evaluated, and may result in Level 3 classification.

Derivative Instruments Fair Value Measurements

PSCo enters into derivative instruments, including forward contracts, futures, swaps and options, for trading purposes and to manage risk in connection with changes in interest rates, utility commodity prices and vehicle fuel prices.

Interest Rate Derivatives — PSCo enters into various instruments that effectively fix the yield or price on a specified benchmark interest rate for an anticipated debt issuance for a specific period. These derivative instruments are generally designated as cash flow hedges for accounting purposes.

At Sept. 30, 2019, accumulated other comprehensive loss related to interest rate derivatives included $1.2 million of net losses expected to be reclassified into earnings during the next 12 months as the related hedged interest rate transactions impact earnings, including forecasted amounts for unsettled hedges, as applicable.

Wholesale and Commodity Trading Risk — PSCo conducts various wholesale and commodity trading activities, including the purchase and sale of electric capacity, energy, energy-related instruments and natural gas-related instruments, including derivatives. PSCo is allowed to conduct these activities within guidelines and limitations as approved by its risk management committee, comprised of management personnel not directly involved in activities governed by this policy.

Commodity Derivatives — PSCo enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations, as well as for trading purposes. This could include the purchase or sale of energy or energy-related products, natural gas to generate electric energy, natural gas for resale, and vehicle fuel.

PSCo may enter into derivative instruments that mitigate commodity price risk on behalf of electric and natural gas customers but may not be designated as qualifying hedging transactions. Changes in the fair value of non-trading commodity derivative instruments are recorded as other comprehensive income or deferred as a regulatory asset or liability. The classification as a regulatory asset or liability is based on approved regulatory recovery mechanisms.

As of Sept. 30, 2019, PSCo had no commodity contracts designated as cash flow hedges.

PSCo also enters into commodity derivative instruments for trading purposes not directly related to commodity price risks associated with serving its electric and natural gas customers. Changes in the fair value of these commodity derivatives are recorded in electric operating revenues, net of amounts credited to customers under margin-sharing mechanisms.

Gross notional amounts of commodity forwards and options:

(Amounts in Millions) (a)(b)	Sept. 30, 2019	Dec. 31, 2018
Megawatt hours of electricity	15.5	24.4
Million British thermal units of natural gas	58.8	48.4

^(a)  Amounts are not reflective of net positions in the underlying commodities.

^(b)  Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

Consideration of Credit Risk and Concentrations — PSCo continuously monitors the creditworthiness of the counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. The impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented in the consolidated balance sheets. PSCo’s most significant concentrations of credit risk with particular entities or industries are contracts with counterparties to its wholesale, trading and non-trading commodity activities.

At Sept. 30, 2019, six of PSCo’s 10 most significant counterparties for these activities, comprising $124.6 million or 74% of this credit exposure, had investment grade credit ratings from S&P Global Ratings, Moody’s Investor Services or Fitch Ratings. Three of the 10 most significant counterparties, comprising $14.9 million or 9% of this credit exposure, were not rated by these external agencies, but based on PSCo’s internal analysis, had credit quality consistent with investment grade. One of these significant counterparties, comprising $8.0 million or 5% of this credit exposure, had credit quality less than investment grade, based on external analysis. Seven of these significant counterparties are independent system operators, municipal or cooperative electric entities, or other utilities.

Impact of derivative activity:

	Pre-Tax Fair Value Losses Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss		Regulatory (Assets) and Liabilities
Three Months Ended Sept. 30, 2019
Other derivative instruments
Natural gas commodity	$	—	$	(2.2	)
Total	$	—	$	(2.2	)
Nine Months Ended Sept. 30, 2019
Other derivative instruments
Natural gas commodity	$	—	$	(3.7	)
Total	$	—	$	(3.7	)
Three Months Ended Sept. 30, 2018
Other derivative instruments
Natural gas commodity	$	—	$	(1.2	)
Total	$	—	$	(1.2	)
Nine Months Ended Sept. 30, 2018
Other derivative instruments
Natural gas commodity	$	—	$	(1.6	)
Total	$	—	$	(1.6	)

	Pre-Tax (Gains) Losses Reclassified into Income During the Period from:							Pre-Tax Gains (Losses) Recognized During the Period in Income
(Millions of Dollars)	Accumulated Other Comprehensive Loss			Regulatory Assets and (Liabilities)
Three Months Ended Sept. 30, 2019
Derivatives designated as cash flow hedges
Interest rate	$	0.4	(a)	$	—			$	—
Total	$	0.4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	0.6		(b)
Total	$	—		$	—			$	0.6
Nine Months Ended Sept. 30, 2019
Derivatives designated as cash flow hedges
Interest rate	$	1.2	(a)	$	—			$	—
Total	$	1.2		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	5.3		(b)
Natural gas commodity	—			(1.3		)	(c)	(2.1		)	(c)
Total	$	—		$	(1.3	)		$	3.2
Three Months Ended Sept. 30, 2018
Derivatives designated as cash flow hedges
Interest rate	$	0.4	(a)	$	—			$	—
Total	$	0.4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2.0		(b)
Total	$	—		$	—			$	2.0
Nine Months Ended Sept. 30, 2018
Derivatives designated as cash flow hedges
Interest rate	$	1.2	(a)	$	—			$	—
Total	$	1.2		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2.7		(b)
Natural gas commodity	—			2.7			(c)	(1.6		)	(c)
Total	$	—		$	2.7			$	1.1

^(a)  Amounts are recorded to interest charges.

^(b)  Amounts are recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue as appropriate.

^(c)  Amounts for both the three and nine months ended Sept. 30, 2019 included no settlement gain or losses on derivatives entered to mitigate natural gas price risk for electric generation recorded to electric fuel and purchased power, subject to cost-recovery mechanisms and reclassified to a regulatory asset, as appropriate. Amounts for the three and nine months ended Sept. 30, 2018 included no such settlement gains or losses and $1.2 million of such settlement losses, respectively. Remaining derivative settlement losses for the three and nine months ended Sept. 30, 2019 and 2018 relate to natural gas operations and are recorded to cost of natural gas sold and transported. These gains and losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset or liability, as appropriate.

PSCo had no derivative instruments designated as fair value hedges during the three and nine months ended Sept. 30, 2019 and 2018.

Credit Related Contingent Features — Contract provisions for derivative instruments that PSCo enters into, including those accounted for as normal purchase-normal sale contracts and therefore not reflected on the consolidated balance sheets, may require the posting of collateral or settlement of the contracts for various reasons, including if PSCo’s credit ratings are downgraded below its investment grade credit rating by any of the major credit rating agencies, or for cross-default contractual provisions if there was a failure under other financing arrangements related to payment terms or other covenants. At Sept. 30, 2019 and Dec. 31, 2018, there were no derivative instruments in a liability position with such underlying contract provisions, with no offsetting positions or posted collateral.

Certain derivative instruments are also subject to contract provisions that contain adequate assurance clauses. These provisions allow counterparties to seek performance assurance, including cash collateral, in the event that PSCo’s ability to fulfill its contractual obligations is reasonably expected to be impaired. PSCo had no collateral posted related to adequate assurance clauses in derivative contracts as of Sept. 30, 2019 and Dec. 31, 2018.

Recurring Fair Value Measurements — PSCo’s assets and liabilities measured at fair value on a recurring basis:

	Sept. 30, 2019													Dec. 31, 2018
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative assets
Other derivative instruments:
Commodity trading	$	1.4	$	13.6	$	0.2	$	15.2	$	(10.0	)	$	5.2	$	2.3	$	65.0	$	0.1	$	67.4	$	(28.2	)	$	39.2
Natural gas commodity	—		4.8		—		4.8		—			4.8		—		3.4		—		3.4		—			3.4
Total current derivative assets	$	1.4	$	18.4	$	0.2	$	20.0	$	(10.0	)	$	10.0	$	2.3	$	68.4	$	0.1	$	70.8	$	(28.2	)	$	42.6
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	0.5	$	5.7	$	0.1	$	6.3	$	(5.6	)	$	0.7	$	—	$	1.6	$	—	$	1.6	$	(0.4	)	$	1.2
Total noncurrent derivative assets	$	0.5	$	5.7	$	0.1	$	6.3	$	(5.6	)	$	0.7	$	—	$	1.6	$	—	$	1.6	$	(0.4	)	$	1.2

	Sept. 30, 2019													Dec. 31, 2018
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative liabilities
Other derivative instruments:
Commodity trading	$	1.4	$	19.1	$	0.1	$	20.6	$	(13.3	)	$	7.3	$	2.4	$	64.2	$	—	$	66.6	$	(34.7	)	$	31.9
Natural gas commodity	—		4.4		—		4.4		—			4.4		—		—		—		—		—			—
Total current derivative liabilities	$	1.4	$	23.5	$	0.1	$	25.0	$	(13.3	)	11.7		$	2.4	$	64.2	$	—	$	66.6	$	(34.7	)	31.9
PPAs (b)												—													2.7
Current derivative instruments												$	11.7												$	34.6
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	0.4	$	60.0	$	—	$	60.4	$	(5.6	)	$	54.8	$	—	$	1.1	$	—	$	1.1	$	(0.5	)	$	0.6
Total noncurrent derivative liabilities	$	0.4	$	60.0	$	—	$	60.4	$	(5.6	)	$	54.8	$	—	$	1.1	$	—	$	1.1	$	(0.5	)	$	0.6

^(a)  PSCo nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Sept. 30, 2019 and Dec. 31, 2018. At both Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include no obligations to return cash collateral. At Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include the rights to reclaim cash collateral of $3.2 million and $6.5 million, respectively. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

^(b)  During 2006, PSCo qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts will be amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.

There were $0.5 million and $1.5 million of losses recognized in earnings for Level 3 commodity trading derivatives in the three and nine months ended Sept. 30, 2019, respectively. There were immaterial gains and losses recognized in earnings for Level 3 commodity trading derivatives in both the three and nine months ended Sept. 30, 2018.

PSCo recognizes transfers between fair value hierarchy levels as of the beginning of each period. There were no transfers of amounts between levels for derivative instruments for the three and nine months ended Sept. 30, 2019 and 2018.

Fair Value of Long-Term Debt

Other financial instruments for which the carrying amount did not equal fair value:

	Sept. 30, 2019				Dec. 31, 2018
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	5,384.0	$	6,139.2	$	4,997.6	$	5,123.2

Fair value of PSCo’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of Sept. 30, 2019 and Dec. 31, 2018, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

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Accounting Pronouncements

9 Months Ended

Sep. 30, 2019

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

Accounting Pronouncements

Accounting Pronouncements

Recently Issued

Credit Losses — In 2016, the FASB issued Financial Instruments - Credit Losses, Topic 326 (ASC Topic 326), which changes how entities account for losses on receivables and certain other assets. The guidance requires use of a current expected credit loss model, which may result in earlier recognition of credit losses than under previous accounting standards. ASC Topic 326 is effective for interim and annual periods beginning on or after Dec. 15, 2019, and will be applied on a modified-retrospective approach through a cumulative-effect adjustment to retained earnings as of Jan. 1, 2020. PSCo expects the impact of adoption of the new standard to include first-time recognition of expected credit losses (i.e., bad debt expense) on unbilled revenues, with the initial allowance established at Jan. 1, 2020 charged to retained earnings.

Recently Adopted

Leases — In 2016, the FASB issued Leases, Topic 842 (ASC Topic 842), which provides new accounting and disclosure guidance for leasing activities, most significantly requiring that operating leases be recognized on the balance sheet. PSCo adopted the guidance on Jan. 1, 2019 utilizing the package of transition practical expedients provided by the new standard, including carrying forward prior conclusions on whether agreements existing before the adoption date contain leases and whether existing leases are operating or finance leases; ASC Topic 842 refers to capital leases as finance leases.

Specifically for land easement contracts, PSCo has elected the practical expedient provided by ASU No. 2018-01 Leases: Land Easement Practical Expedient for Transition to Topic 842, and as a result, only those easement contracts entered on or after Jan. 1, 2019 will be evaluated to determine if lease treatment is appropriate.

PSCo also utilized the transition practical expedient offered by ASU No. 2018-11 Leases: Targeted Improvements to implement the standard on a prospective basis. As a result, reporting periods in the consolidated financial statements beginning Jan. 1, 2019 reflect the implementation of ASC Topic 842, while prior periods continue to be reported in accordance with Leases, Topic 840 (ASC Topic 840). Other than first-time recognition of operating leases on its consolidated balance sheet, the implementation of ASC Topic 842 did not have a significant impact on PSCo’s consolidated financial statements. Adoption resulted in recognition of approximately $0.7 billion of operating lease ROU assets and current/noncurrent operating lease liabilities. See Note 9 to the consolidated financial statements for leasing disclosures.

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Commitments and Contingencies Leases (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended	9 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Discount Rate, Percent		4.10%		4.10%
Maximum lease term for short-term lease classification			12 months
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset, Gross		$ 653.8		$ 653.8
Operating Lease, Right-of-Use Asset, Accumulated Depreciation		(59.4)		(59.4)
Operating Lease, Right-of-Use Asset		594.4		594.4	$ 0.0
Finance Lease, Assets and Liabilities, Lessee [Abstract]
Finance Lease, Right-of-Use Asset, Gross		221.2		221.2
Finance Lease, Right-of-Use Asset, Accumulated Depreciation		(80.8)		(80.8)
Finance Lease, Right-of-Use Asset		140.4		140.4
Operating Lease, Cost [Abstract]
Operating Lease, Cost	[1]	28.9		85.1
Payments of Financing Costs [Abstract]
Finance Lease, Right-of-Use Asset, Amortization		1.6		4.6
Finance Lease, Interest Expense		4.7		14.2
Finance Lease, Cost		6.3		18.8
Short-term Lease, Cost		0.3		1.0
Operating Leases after Adoption of ASC Topic 842
2019		27.2		27.2
2020		109.1		109.1
2021		109.0		109.0
2022		94.2		94.2
2023		80.9		80.9
Thereafter		317.8		317.8
Total minimum obligation		738.2		738.2
Interest component of obligation		(113.7)		(113.7)
Present value of minimum obligation		624.5		624.5
Less current portion		(85.0)		(85.0)
Operating lease liabilities		$ 539.5		$ 539.5	0.0
Weighted-average remaining lease term in years		8 years 1 month		8 years 1 month
Finance Leases after Adoption of ASC Topic 842
2019		$ 6.2		$ 6.2
2020		24.8		24.8
2021		23.6		23.6
2022		20.5		20.5
2023		20.3		20.3
Thereafter		419.8		419.8
Total minimum obligation		515.2		515.2
Interest component of obligation		(374.8)		(374.8)
Present value of minimum obligation		140.4		140.4
Less current portion		(6.7)		(6.7)
Noncurrent operating and finance lease liabilities		$ 133.7		$ 133.7
Weighted-average remaining lease term in years		38 years 11 months		38 years 11 months
Operating Leases before Adoption of ASC Topic 842
2019					106.3
2020					106.6
2021					105.9
2022					91.0
2023					78.1
Thereafter					342.0
Finance Leases before Adoption of ASC Topic 842
2019					24.9
2020					24.8
2021					23.6
2022					20.5
2023					20.3
Thereafter					420.4
Total minimum obligation					534.5
Interest component of obligation					(389.5)
Present value of minimum obligation					145.0
WYCO
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Equity Method Investment, Ownership Percentage		50.00%		50.00%
Gas Storage Facilities [Member]
Finance Lease, Assets and Liabilities, Lessee [Abstract]
Finance Lease, Right-of-Use Asset, Gross		$ 200.5		$ 200.5
Purchased Power Agreements [Member]
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset, Gross		585.1		585.1
Operating Lease, Cost [Abstract]
Operating Lease, Cost		24.6		73.6
Operating Leases after Adoption of ASC Topic 842
2019	[2],[3]	23.9		23.9
2020	[2],[3]	95.9		95.9
2021	[2],[3]	96.4		96.4
2022	[2],[3]	82.6		82.6
2023	[2],[3]	70.0		70.0
Thereafter	[2],[3]	288.6		288.6
Total minimum obligation	[2],[3]	657.4		657.4
Interest component of obligation	[2],[3]	(100.6)		(100.6)
Present value of minimum obligation	[2],[3]	556.8		556.8
Operating Leases before Adoption of ASC Topic 842
2019	[4],[5]				95.5
2020	[4],[5]				95.9
2021	[4],[5]				96.4
2022	[4],[5]				82.6
2023	[4],[5]				70.0
Thereafter	[4],[5]				288.6
Property, Plant and Equipment, Other Types [Member]
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset, Gross		68.7		68.7
Operating Lease, Cost [Abstract]
Operating Lease, Cost	[6]	4.3		11.5
Operating Leases after Adoption of ASC Topic 842
2019		3.3		3.3
2020		13.2		13.2
2021		12.6		12.6
2022		11.6		11.6
2023		10.9		10.9
Thereafter		29.2		29.2
Total minimum obligation		80.8		80.8
Interest component of obligation		(13.1)		(13.1)
Present value of minimum obligation		67.7		67.7
Operating Leases before Adoption of ASC Topic 842
2019					10.8
2020					10.7
2021					9.5
2022					8.4
2023					8.1
Thereafter					$ 53.4
Pipelines [Member]
Finance Lease, Assets and Liabilities, Lessee [Abstract]
Finance Lease, Right-of-Use Asset, Gross		$ 20.7		$ 20.7

[1] PPA capacity payments are included in electric fuel and purchased power on the consolidated statements of income. Expense for other operating leases is included in O&M expense and electric fuel and purchased power.

[2] Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

[3] PPA operating leases contractually expire at various dates through 2032.

[4] Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

[5] PPA operating leases contractually expire at various dates through 2032.

[6] Includes short-term lease expense of $0.3 million for the three months ended Sept. 30, 2019 and $1.0 million for the nine months ended Sept. 30, 2019.

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Gas Trading Litigation (Details)	Dec. 31, 2018
Gas Trading Litigation [Member]
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	2

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Income Taxes Federal Audits (Details)	9 Months Ended
	Sep. 30, 2019 USD ($)
Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Potential Tax Adjustments	$ 0

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Fair Value of Financial Assets and Liabilities Consideration of Credit Risk and Concentrations (Details)		3 Months Ended		9 Months Ended
		Sep. 30, 2019 USD ($) Counterparty	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Counterparty	Sep. 30, 2018 USD ($)
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Derivative instruments designated as fair value hedges		$ 0	$ 0	$ 0	$ 0
Not Designated as Hedging Instrument [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0	0
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		(2,200,000)	(1,200,000)	(3,700,000)	(1,600,000)
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss		0	0	0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		0	0	(1,300,000)	2,700,000
Pre-tax gains (losses) recognized during the period in income		600,000	2,000,000.0	3,200,000	1,100,000
Not Designated as Hedging Instrument [Member] | Natural Gas Commodity for Electric Generation [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		0	0	0	1,200,000
Not Designated as Hedging Instrument [Member] | Natural Gas Commodity Contract [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		0	0	0	0
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		(2,200,000)	(1,200,000)	(3,700,000)	(1,600,000)
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss				0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	[1]			(1,300,000)	2,700,000
Pre-tax gains (losses) recognized during the period in income	[1]			(2,100,000)	(1,600,000)
Not Designated as Hedging Instrument [Member] | Commodity Trading Contract [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss		0	0	0	0
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		0	0	0	0
Pre-tax gains (losses) recognized during the period in income	[2]	600,000	2,000,000.0	5,300,000	2,700,000
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss		400,000	400,000	1,200,000	1,200,000
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		0	0	0	0
Pre-tax gains (losses) recognized during the period in income		0	0	0	0
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-tax (gains) losses reclassified into income during the period from accumulated other comprehensive loss	[3]	400,000	400,000	1,200,000	1,200,000
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		0	0	0	0
Pre-tax gains (losses) recognized during the period in income		$ 0	$ 0	$ 0	$ 0
Credit Concentration Risk [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		10		10
Credit Concentration Risk [Member] | Municipal or Cooperative Entities or Other Utilities [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		7		7
Credit Concentration Risk [Member] | External Credit Rating, Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		6		6
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 124,600,000		$ 124,600,000
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		74.00%		74.00%
Credit Concentration Risk [Member] | Internal Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		3		3
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 14,900,000		$ 14,900,000
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		9.00%		9.00%
Credit Concentration Risk [Member] | External Credit Rating, Non Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		1		1
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 8,000,000.0		$ 8,000,000.0
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		5.00%		5.00%

[1] Amounts for both the three and nine months ended Sept. 30, 2019 included no settlement gain or losses on derivatives entered to mitigate natural gas price risk for electric generation recorded to electric fuel and purchased power, subject to cost-recovery mechanisms and reclassified to a regulatory asset, as appropriate. Amounts for the three and nine months ended Sept. 30, 2018 included no such settlement gains or losses and $1.2 million of such settlement losses, respectively. Remaining derivative settlement losses for the three and nine months ended Sept. 30, 2019 and 2018 relate to natural gas operations and are recorded to cost of natural gas sold and transported. These gains and losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset or liability, as appropriate.

[2] Amounts are recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue as appropriate.

[3] Amounts are recorded to interest charges.

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CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating revenues
Electric	$ 880.7	$ 894.8	$ 2,314.8	$ 2,309.3
Gas	153.9	157.2	830.7	707.8
Steam and other	9.7	8.7	31.8	28.7
Total operating revenues	1,044.3	1,060.7	3,177.3	3,045.8
Operating expenses
Electric fuel and purchased power	284.7	288.6	829.5	841.7
Cost of natural gas sold and transported	34.3	32.3	376.7	282.1
Cost of sales — steam and other	3.5	3.3	11.9	10.9
Operating and maintenance expenses	198.4	201.4	597.9	573.5
Demand side management expenses	36.6	39.4	100.9	105.3
Depreciation and amortization	153.5	168.0	448.6	406.1
Taxes (other than income taxes)	49.0	50.8	154.8	153.2
Total operating expenses	760.0	783.8	2,520.3	2,372.8
Operating income	284.3	276.9	657.0	673.0
Other income, net	1.4	1.3	1.9	2.4
Allowance for funds used during construction — equity	3.8	16.4	12.9	40.9
Interest charges and financing costs
Interest charges — includes other financing costs of $1.6, $1.7, $4.9 and $4.9, respectively	59.2	53.2	176.3	154.3
Allowance for funds used during construction — debt	(2.2)	(6.4)	(7.0)	(16.1)
Total interest charges and financing costs	57.0	46.8	169.3	138.2
Income before income taxes	232.5	247.8	502.5	578.1
Income taxes	28.0	40.7	57.7	115.0
Net income	$ 204.5	$ 207.1	$ 444.8	$ 463.1

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CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net income	$ 444.8	$ 463.1
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	452.2	409.8
Deferred income taxes	24.1	66.6
Amortization of investment tax credits	(1.9)	(2.1)
Allowance for equity funds used during construction	(12.9)	(40.9)
Net realized and unrealized hedging and derivative transactions	64.5	(9.9)
Changes in operating assets and liabilities:
Accounts receivable	13.1	(0.7)
Accrued unbilled revenues	84.8	60.1
Inventories	(15.1)	13.6
Prepayments and other	(12.4)	12.6
Accounts payable	(96.0)	25.3
Net regulatory assets and liabilities	72.3	(23.6)
Other current liabilities	(66.3)	(87.7)
Pension and other employee benefit obligations	(44.4)	(29.0)
Other, net	(72.4)	(19.8)
Net cash provided by operating activities	834.4	837.4
Investing activities
Utility capital/construction expenditures	(1,098.6)	(1,190.7)
Investments in utility money pool arrangement	(397.0)	(578.0)
Repayments from utility money pool arrangement	397.0	575.0
Net cash used in investing activities	(1,098.6)	(1,193.7)
Financing activities
Repayments of short-term borrowings, net	(307.0)	0.0
Borrowings under utility money pool arrangement	58.0	526.0
Repayments under utility money pool arrangement	(58.0)	(526.0)
Proceeds from issuance of long-term debt	928.6	691.4
Repayments of long-term debt	400.0	300.0
Capital contributions from parent	632.7	246.8
Dividends paid to parent	(295.4)	(271.9)
Other, net	0.0	(0.1)
Net cash provided by financing activities	558.9	366.2
Net change in cash and cash equivalents	294.7	9.9
Cash and cash equivalents at beginning of period	33.4	7.5
Cash and cash equivalents at end of period	328.1	17.4
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(173.4)	(145.3)
Cash paid for income taxes, net	(43.7)	(86.4)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	228.5	135.0
Inventory transfers to property, plant and equipment	24.4	29.8
Operating lease right-of-use assets	653.8	0.0
Allowance for equity funds used during construction	$ 12.9	$ 40.9

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Benefit Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2019

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Credit)

Components of Net Periodic Benefit Cost (Credit)

	Three Months Ended Sept. 30
	2019			2018			2019			2018
(Millions of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	6.4		$	7.3		$	0.1		$	0.2
Interest cost (a)	12.9			11.8			3.9			3.8
Expected return on plan assets (a)	(17.1		)	(17.1		)	(4.7		)	(5.7		)
Amortization of prior service credit (a)	(0.8		)	(0.9		)	(1.3		)	(1.6		)
Amortization of net loss (a)	6.3			7.8			0.7			1.0
Net periodic benefit cost (credit)	7.7			8.9			(1.3		)	(2.3		)
Credits (costs) not recognized due to the effects of regulation	0.8			(4.1		)	0.4			1.4
Net benefit cost (credit) recognized for financial reporting	$	8.5		$	4.8		$	(0.9	)	$	(0.9	)

	Nine Months Ended Sept. 30
	2019			2018			2019			2018
(Millions of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	19.2		$	21.8		$	0.4		$	0.5
Interest cost (a)	38.7			35.5			11.7			11.2
Expected return on plan assets (a)	(51.4		)	(51.4		)	(14.2		)	(17.0		)
Amortization of prior service credit (a)	(2.5		)	(2.5		)	(4.1		)	(4.7		)
Amortization of net loss (a)	19.1			23.4			2.2			3.1
Net periodic benefit cost (credit)	23.1			26.8			(4.0		)	(6.9		)
Credits (costs) not recognized due to the effects of regulation	4.4			(1.7		)	0.9			1.4
Net benefit cost (credit) recognized for financial reporting	$	27.5		$	25.1		$	(3.1	)	$	(5.5	)

^(a)  

The components of net periodic cost other than the service cost component are included in the line item “other income, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.

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Borrowings and Other Financing Instruments (Tables)

9 Months Ended

Sep. 30, 2019

Borrowings and Other Financing Instruments [Abstract]

Credit Facilities

At Sept. 30, 2019, PSCo had the following committed credit facility available (in millions of dollars):

Credit Facility (a)		Outstanding (b)		Available
$	700	$	9	$	691

^(a)    This credit facility expires in June 2024.

^(b)    Includes outstanding commercial paper and letters of credit.

Money Pool

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Money pool borrowings for PSCo were as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2019			Year Ended Dec. 31, 2018
Borrowing limit	$	250		$	250
Amount outstanding at period end	—			—
Average amount outstanding	23			25
Maximum amount outstanding	50			156
Weighted average interest rate, computed on a daily basis	2.29		%	1.93		%
Weighted average interest rate at period end	N/A			N/A

Commercial Paper

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Commercial paper outstanding for PSCo was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2019			Year Ended Dec. 31, 2018
Borrowing limit	$	700		$	700
Amount outstanding at period end	—			307
Average amount outstanding	129			55
Maximum amount outstanding	379			309
Weighted average interest rate, computed on a daily basis	2.52		%	2.28		%
Weighted average interest rate at period end	N/A			2.95

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Revenues

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Revenues

Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. PSCo’s operating revenues consists of the following:

	Three Months Ended Sept. 30, 2019
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	315.3	$	94.1	$	3.1	$	412.5
C&I	452.4		32.9		5.5		490.8
Other	11.8		—		—		11.8
Total retail	779.5		127.0		8.6		915.1
Wholesale	40.3		—		—		40.3
Transmission	16.4		—		—		16.4
Other	8.3		21.4		—		29.7
Total revenue from contracts with customers	844.5		148.4		8.6		1,001.5
Alternative revenue and other	36.2		5.5		1.1		42.8
Total revenues	$	880.7	$	153.9	$	9.7	$	1,044.3

	Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	315.7	$	84.4	$	2.7	$	402.8
C&I	458.5		29.1		4.9		492.5
Other	11.8		—		—		11.8
Total retail	786.0		113.5		7.6		907.1
Wholesale	41.2		—		—		41.2
Transmission	16.3		—		—		16.3
Other	10.6		18.4		—		29.0
Total revenue from contracts with customers	854.1		131.9		7.6		993.6
Alternative revenue and other	40.7		25.3		1.1		67.1
Total revenues	$	894.8	$	157.2	$	8.7	$	1,060.7

	Nine Months Ended Sept. 30, 2019
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	771.9	$	535.6	$	8.4	$	1,315.9
C&I	1,204.7		202.6		20.0		1,427.3
Other	36.1		—		—		36.1
Total retail	2,012.7		738.2		28.4		2,779.3
Wholesale	126.7		—		—		126.7
Transmission	41.4		—		—		41.4
Other	26.4		76.3		—		102.7
Total revenue from contracts with customers	2,207.2		814.5		28.4		3,050.1
Alternative revenue and other	107.6		16.2		3.4		127.2
Total revenues	$	2,314.8	$	830.7	$	31.8	$	3,177.3

	Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	766.1	$	416.2	$	7.9	$	1,190.2
C&I	1,185.4		154.0		17.4		1,356.8
Other	35.4		—		0.1		35.5
Total retail	1,986.9		570.2		25.4		2,582.5
Wholesale	125.3		—		—		125.3
Transmission	41.7		—		—		41.7
Other	44.1		62.1		—		106.2
Total revenue from contracts with customers	2,198.0		632.3		25.4		2,855.7
Alternative revenue and other	111.3		75.5		3.3		190.1
Total revenues	$	2,309.3	$	707.8	$	28.7	$	3,045.8

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Selected Balance Sheet Data

9 Months Ended

Sep. 30, 2019

Balance Sheet Related Disclosures [Abstract]

Selected Balance Sheet Data

Selected Balance Sheet Data

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
Accounts receivable, net
Accounts receivable	$	315.1		$	330.8
Less allowance for bad debts	(20.9		)	(20.5		)
Accounts receivable, net	$	294.2		$	310.3

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Inventories
Materials and supplies	$	61.8	$	61.9
Fuel	75.3		69.5
Natural gas	51.0		66.0
Total inventories	$	188.1	$	197.4

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
Property, plant and equipment, net
Electric plant	$	14,070.5		$	13,604.5
Natural gas plant	4,526.5			4,387.6
Common and other property	1,070.2			1,023.7
Plant to be retired (a)	275.5			321.9
Construction work in progress	928.8			573.3
Total property, plant and equipment	20,871.5			19,911.0
Less accumulated depreciation	(5,085.1		)	(4,791.0		)
Property, plant and equipment, net	$	15,786.4		$	15,120.0

^(a) 

In 2018, the CPUC approved early retirement of PSCo’s Comanche Units 1 and 2 in approximately 2022 and 2025, respectively. PSCo also expects Craig Unit 1 to be retired early in 2025. Amounts are presented net of accumulated depreciation.

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Commitments and Contingencies

9 Months Ended

Sep. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments and Contingencies

The following include commitments, contingencies and unresolved contingencies that are material to PSCo’s financial position.

Legal

PSCo is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation.

Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to, when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on PSCo’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003.  Multiple lawsuits seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada.

Two cases remain active which include an MDL matter consisting of a Colorado purported class (Breckenridge) and a Wisconsin purported class (Arandell Corp.).

Breckenridge/Colorado — In February 2019, the MDL panel remanded Breckenridge back to the U.S. District Court in Colorado.

Arandell Corp. — In February 2019, the case was remanded back to the U.S. District Court in Wisconsin.

Xcel Energy has concluded that a loss is remote for both remaining lawsuits.

Line Extension Disputes — In December 2015, the DRC filed a lawsuit seeking monetary damages in the Denver District Court, stating PSCo failed to award proper allowances and refunds for line extensions to new developments pursuant to the terms of electric and gas service agreements. The dispute involves claims by over fifty developers. In February 2018, the Colorado Supreme Court denied DRC’s petition to appeal the Denver District Court’s dismissal of the lawsuit, effectively terminating this litigation. However, in January 2018, DRC filed a new lawsuit in Boulder County District Court, asserting a single claim that PSCo was required to file its line extension agreements with the CPUC but failed to do so.

This claim is similar to the arguments previously raised by DRC. PSCo filed a motion to dismiss this claim, which was granted in May 2018. DRC subsequently filed an appeal to the Colorado Court of Appeals. It is uncertain when a decision will be rendered.

PSCo has concluded that a loss is remote with respect to both of these matters as the service agreements were developed to implement CPUC approved tariffs and PSCo has complied with the tariff provisions. If a loss were sustained, PSCo believes it would be allowed to recover costs through traditional regulatory mechanisms. Amount or range in dispute is presently unknown and no accrual has been recorded for this matter.

Environmental

MGP, Landfill or Disposal Sites — PSCo is cooperating with the City of Denver on an environmental investigation of the Rice Yards Site in Denver, Colorado, which had various historic industrial uses by multiple parties, including railroad, maintenance shop, scrap metal yard, and MGP operations.

The area is being redeveloped into residential and commercial mixed uses, and PSCo is in discussions with the current property owner regarding legal claims related to the Rice Yards Site.

In addition, PSCo is currently investigating or remediating two other MGP, landfill or other disposal sites across its service territories.

PSCo has recognized its best estimate of costs/liabilities that will result from final resolution of these issues, however, the outcome and timing is unknown.  In addition, there may be insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of the costs incurred.

Environmental Requirements — Water and Waste

Coal Ash Regulation — PSCo’s operations are subject to federal and state laws that impose requirements for handling, storage, treatment and disposal of solid waste.

Under the CCR Rule, utilities are required to complete groundwater sampling around their CCR landfills and surface impoundments. By the end of 2019, only six of PSCo’s regulated ash units are expected to be in operation. PSCo is conducting groundwater sampling and where appropriate, initiating the assessment of corrective measures and evaluating whether corrective action is required at any CCR landfills or surface impoundments.

Until PSCo completes its assessment, it is uncertain what impact, if any, there will be on the operations, financial condition or cash flows.

Leases

PSCo evaluates contracts that may contain leases, including PPAs and arrangements for the use of office space and other facilities, vehicles and equipment. Under ASC Topic 842, adopted by PSCo on Jan. 1, 2019, a contract contains a lease if it conveys the exclusive right to control the use of a specific asset. A contract determined to contain a lease is evaluated further to determine if the arrangement is a finance lease.

ROU assets represent PSCo's rights to use leased assets. Starting in 2019, the present value of future operating lease payments is recognized in other current liabilities and noncurrent operating lease liabilities. These amounts, adjusted for any prepayments or incentives, are recognized as operating lease ROU assets.

Most of PSCo’s leases do not contain a readily determinable discount rate. Therefore, the present value of future lease payments is calculated using the estimated incremental borrowing rate (weighted-average of 4.1%). PSCo has elected to utilize the practical expedient under which non-lease components, such as asset maintenance costs included in payments, are not deducted from minimum lease payments for the purposes of lease accounting and disclosure.

Leases with an initial term of 12 months or less are classified as short-term leases and are not recognized on the consolidated balance sheet.

Operating lease ROU assets:

(Millions of Dollars)	Sept. 30, 2019
PPAs	$	585.1
Other	68.7
Gross operating lease ROU assets	653.8
Accumulated amortization	(59.4		)
Net operating lease ROU assets	$	594.4

In 2019, ROU assets for finance leases are included in other noncurrent assets, and the present value of future finance lease payments is included in other current liabilities and other noncurrent liabilities. Prior to 2019, finance leases were included in property, plant and equipment, the current portion of long-term debt and long-term debt.

PSCo’s most significant finance lease activities are related to WYCO, a joint venture with CIG, to develop and lease natural gas pipeline, storage and compression facilities. Xcel Energy Inc. has a 50% ownership interest in WYCO. WYCO leases its facilities to CIG, and CIG operates the facilities, providing natural gas storage and transportation services to PSCo under separate service agreements.

PSCo accounts for its Totem natural gas storage service and Front Range pipeline arrangements with CIG and WYCO, respectively, as finance leases.

Finance lease ROU assets:

(Millions of Dollars)	Sept. 30, 2019
Gas storage facilities	$	200.5
Gas pipeline	20.7
Gross finance lease ROU assets	221.2
Accumulated amortization	(80.8		)
Net finance lease ROU assets	$	140.4

Components of lease expense:

(Millions of Dollars)	Three Months Ended Sept. 30, 2019		Nine Months Ended Sept. 30, 2019
Operating leases
PPA capacity payments	$	24.6	$	73.6
Other operating leases (a)	4.3		11.5
Total operating lease expense (b)	$	28.9	$	85.1
Finance leases
Amortization of ROU assets	$	1.6	$	4.6
Interest expense on lease liability	4.7		14.2
Total finance lease expense	$	6.3	$	18.8

^(a)  Includes short-term lease expense of $0.3 million for the three months ended Sept. 30, 2019 and $1.0 million for the nine months ended Sept. 30, 2019.

^(b)  PPA capacity payments are included in electric fuel and purchased power on the consolidated statements of income. Expense for other operating leases is included in O&M expense and electric fuel and purchased power.

Future commitments under operating and finance leases as of Sept. 30, 2019:

(Millions of Dollars)	PPA (a) (b) Operating Leases			Other Operating Leases			Total Operating Leases			Finance Leases
2019	$	23.9		$	3.3		$	27.2		$	6.2
2020	95.9			13.2			109.1			24.8
2021	96.4			12.6			109.0			23.6
2022	82.6			11.6			94.2			20.5
2023	70.0			10.9			80.9			20.3
Thereafter	288.6			29.2			317.8			419.8
Total minimum obligation	657.4			80.8			738.2			515.2
Interest component of obligation	(100.6		)	(13.1		)	(113.7		)	(374.8		)
Present value of minimum obligation	$	556.8		$	67.7		624.5			140.4
Less current portion							(85.0		)	(6.7		)
Noncurrent operating and finance lease liabilities							$	539.5		$	133.7
Weighted-average remaining lease term in years							8.1			38.9

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b)  PPA operating leases contractually expire at various dates through 2032.

Future commitments under operating and finance leases as of Dec. 31, 2018:

(Millions of Dollars)	PPA (a) (b) Operating Leases		Other Operating Leases		Total Operating Leases		Finance Leases
2019	$	95.5	$	10.8	$	106.3	$	24.9
2020	95.9		10.7		106.6		24.8
2021	96.4		9.5		105.9		23.6
2022	82.6		8.4		91.0		20.5
2023	70.0		8.1		78.1		20.3
Thereafter	288.6		53.4		342.0		420.4
Total minimum obligation							534.5
Interest component of obligation							(389.5		)
Present value of minimum obligation							$	145.0

^(a)  Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

^(b) 

PPA operating leases contractually expire at various dates through 2032.

Variable Interest Entities 

Under certain PPAs, PSCo purchases power from IPPs and is required to reimburse the IPPs for fuel costs, or to participate in tolling arrangements under which PSCo procures the natural gas required to produce the energy that it purchases. These specific PPAs create a variable interest in the associated IPP.

PSCo had approximately 1,442 MW and 1,571 MW of capacity under long-term PPAs as of Sept. 30, 2019 and Dec. 31, 2018, respectively, with entities that have been determined to be VIEs. PSCo concluded that these entities are not required to be consolidated in its financial statements because it does not have the power to direct the activities that significantly impact the entities’ economic performance. These agreements have various expiration dates through 2032.

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Selected Balance Sheet Data Balance Sheet Related Disclosures, Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Public Utilities, Inventory [Line Items]
Total Inventories	$ 188.1	$ 197.4
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventories	61.8	61.9
Fuel
Public Utilities, Inventory [Line Items]
Inventories	75.3	69.5
Natural gas
Public Utilities, Inventory [Line Items]
Inventories	$ 51.0	$ 66.0

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Borrowings and Other Financing Instruments Commercial Paper (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Amount outstanding at period end	$ 0	$ 307,000,000.0
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	700,000,000	700,000,000
Amount outstanding at period end	0	307,000,000
Average amount outstanding	129,000,000	55,000,000
Maximum amount outstanding	$ 379,000,000	$ 309,000,000
Weighted average interest rate, computed on a daily basis	2.52%	2.28%
Weighted average interest rate at period end		2.95%

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Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period				$ 6,298.2
Accumulated other comprehensive loss at end of period		$ 7,005.6		7,005.6
Interest rate derivatives, tax		28.0	$ 40.7	57.7	$ 115.0
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(24.7)	(25.8)	(25.3)	(26.4)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		0.0	0.0	0.0	0.0
Losses reclassified from net accumulated other comprehensive loss		0.0	0.0	0.0	0.0
Net current period other comprehensive loss		0.3	0.3	0.9	0.9
Accumulated other comprehensive loss at end of period		(24.4)	(25.5)	(24.4)	(25.5)
Gains and Losses on Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income (loss), tax		0.0	0.0	0.0	0.0
Interest rate derivatives, tax		0.1	0.1	0.3	0.3
Amortization of net actuarial loss, tax		0.0	0.0	0.0	0.0
Gains and Losses on Cash Flow Hedges | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Losses reclassified from net accumulated other comprehensive loss	[1]	(0.3)	(0.3)	(0.9)	(0.9)
Defined Benefit and Postretirement Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(0.2)	(0.3)	(0.2)	(0.3)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		0.0	(0.2)	0.0	(0.2)
Losses reclassified from net accumulated other comprehensive loss		0.0	(0.2)	0.0	(0.2)
Net current period other comprehensive loss		0.0	0.0	0.0	0.0
Accumulated other comprehensive loss at end of period		(0.2)	(0.3)	(0.2)	(0.3)
Defined Benefit and Postretirement Items | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income (loss), tax		0.0	(0.1)	0.0	(0.1)
Interest rate derivatives, tax		0.0	0.0	0.0	0.0
Amortization of net actuarial loss, tax		0.0	0.1	0.0	0.1
Defined Benefit and Postretirement Items | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Losses reclassified from net accumulated other comprehensive loss	[1]	0.0	0.0	0.0	0.0
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(24.9)	(26.1)	(25.5)	(26.7)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		0.0	(0.2)	0.0	(0.2)
Losses reclassified from net accumulated other comprehensive loss		0.0	(0.2)	0.0	(0.2)
Net current period other comprehensive loss		0.3	0.3	0.9	0.9
Accumulated other comprehensive loss at end of period		(24.6)	(25.8)	(24.6)	(25.8)
Total | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Losses reclassified from net accumulated other comprehensive loss	[1]	$ (0.3)	$ (0.3)	$ (0.9)	$ (0.9)

[1] Included in interest charges.

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MGP, Landfill or Disposal Sites (Details)	Sep. 30, 2019
Other MGP, Landfill, or Disposal Sites [Domain]
Site Contingency [Line Items]
Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation	2

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Benefit Plans and Other Postretirement Benefits

9 Months Ended

Sep. 30, 2019

Retirement Benefits [Abstract]

Benefit Plans and Other Postretirement Benefits

Benefit Plans and Other Postretirement Benefits

Components of Net Periodic Benefit Cost (Credit)

	Three Months Ended Sept. 30
	2019			2018			2019			2018
(Millions of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	6.4		$	7.3		$	0.1		$	0.2
Interest cost (a)	12.9			11.8			3.9			3.8
Expected return on plan assets (a)	(17.1		)	(17.1		)	(4.7		)	(5.7		)
Amortization of prior service credit (a)	(0.8		)	(0.9		)	(1.3		)	(1.6		)
Amortization of net loss (a)	6.3			7.8			0.7			1.0
Net periodic benefit cost (credit)	7.7			8.9			(1.3		)	(2.3		)
Credits (costs) not recognized due to the effects of regulation	0.8			(4.1		)	0.4			1.4
Net benefit cost (credit) recognized for financial reporting	$	8.5		$	4.8		$	(0.9	)	$	(0.9	)

	Nine Months Ended Sept. 30
	2019			2018			2019			2018
(Millions of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	19.2		$	21.8		$	0.4		$	0.5
Interest cost (a)	38.7			35.5			11.7			11.2
Expected return on plan assets (a)	(51.4		)	(51.4		)	(14.2		)	(17.0		)
Amortization of prior service credit (a)	(2.5		)	(2.5		)	(4.1		)	(4.7		)
Amortization of net loss (a)	19.1			23.4			2.2			3.1
Net periodic benefit cost (credit)	23.1			26.8			(4.0		)	(6.9		)
Credits (costs) not recognized due to the effects of regulation	4.4			(1.7		)	0.9			1.4
Net benefit cost (credit) recognized for financial reporting	$	27.5		$	25.1		$	(3.1	)	$	(5.5	)

^(a)   The components of net periodic cost other than the service cost component are included in the line item “other income, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.

In January 2019, contributions of $150.0 million were made across four of Xcel Energy’s pension plans, of which $43.0 million was attributable to PSCo. In July 2019, Xcel Energy made a $4.0 million contribution to the Xcel Energy Inc. Non-Bargaining Pension Plan (South), of which $2.7 million was attributable to PSCo. Xcel Energy does not expect additional pension contributions during 2019.

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Borrowings and Other Financing Instruments

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Borrowings and Other Financing Instruments

Borrowings and Other Financing Instruments

Short-Term Borrowings

PSCo meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility and the money pool.

Money Pool — Xcel Energy Inc. and its utility subsidiaries have established a money pool arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Xcel Energy Inc. may make investments in the utility subsidiaries at market-based interest rates; however, the money pool arrangement does not allow the utility subsidiaries to make investments in Xcel Energy Inc. Money pool borrowings for PSCo were as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2019			Year Ended Dec. 31, 2018
Borrowing limit	$	250		$	250
Amount outstanding at period end	—			—
Average amount outstanding	23			25
Maximum amount outstanding	50			156
Weighted average interest rate, computed on a daily basis	2.29		%	1.93		%
Weighted average interest rate at period end	N/A			N/A

Commercial Paper — Commercial paper outstanding for PSCo was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2019			Year Ended Dec. 31, 2018
Borrowing limit	$	700		$	700
Amount outstanding at period end	—			307
Average amount outstanding	129			55
Maximum amount outstanding	379			309
Weighted average interest rate, computed on a daily basis	2.52		%	2.28		%
Weighted average interest rate at period end	N/A			2.95

Letters of Credit — PSCo uses letters of credit, generally with terms of one year, to provide financial guarantees for certain operating obligations. There were $9 million and $10 million of letters of credit outstanding under the credit facility at Sept. 30, 2019 and Dec. 31, 2018, respectively. The contract amounts of these letters of credit approximate their fair value and are subject to fees.

Credit Facility — In order to use its commercial paper program to fulfill short-term funding needs, PSCo must have a revolving credit facility in place at least equal to the amount of its commercial paper borrowing limit and cannot issue commercial paper in an aggregate amount exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

Amended Credit Agreement — In June 2019, PSCo entered into an amended five-year credit agreement with a syndicate of banks. The amended credit agreements have substantially the same terms and conditions as the prior credit agreements with the exception of the maturity, which was extended from June 2021 to June 2024.

PSCo has the right to request an extension of the revolving credit facility termination date for two additional one year periods. All extension requests are subject to majority bank group approval.

At Sept. 30, 2019, PSCo had the following committed credit facility available (in millions of dollars):

Credit Facility (a)		Outstanding (b)		Available
$	700	$	9	$	691

^(a)    This credit facility expires in June 2024.

^(b)    Includes outstanding commercial paper and letters of credit.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. PSCo had no direct advances on the credit facility outstanding at Sept. 30, 2019 and Dec. 31, 2018.

Long-Term Borrowings

During the nine months ended Sept. 30, 2019, PSCo issued the following:

– $400 million of 4.05% first mortgage bonds due Sept. 15, 2049.

–

$550 million of 3.20% first mortgage green bonds due March 1, 2050.

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Management's Opinion

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Management's Opinion

In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with U.S. GAAP, the financial position of PSCo and its subsidiaries as of Sept. 30, 2019 and Dec. 31, 2018; the results of its operations, including the components of net income and comprehensive income, and changes in stockholders’ equity for the three and nine months ended Sept. 30, 2019 and 2018; and its cash flows for the nine months ended Sept. 30, 2019 and 2018. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after Sept. 30, 2019 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2018 balance sheet information has been derived from the audited 2018 consolidated financial statements included in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2018. These notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto, included in the PSCo Annual Report on Form 10-K for the year ended Dec. 31, 2018, filed with the SEC on Feb. 22, 2019. Due to the seasonality of PSCo’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

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Selected Balance Sheet Data Balance Sheet Related Disclosures, Property, Plant and Equipment (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 20,871.5	$ 19,911.0
Less accumulated depreciation		(5,085.1)	(4,791.0)
Property, plant and equipment, net		15,786.4	15,120.0
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		14,070.5	13,604.5
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		4,526.5	4,387.6
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,070.2	1,023.7
Plant to be retired
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	[1]	275.5	321.9
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 928.8	$ 573.3

[1] In 2018, the CPUC approved early retirement of PSCo’s Comanche Units 1 and 2 in approximately 2022 and 2025, respectively. PSCo also expects Craig Unit 1 to be retired early in 2025. Amounts are presented net of accumulated depreciation.

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Letters of Credit (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 0.0	$ 307.0
Letter of Credit
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 9.0	$ 10.0
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Letters of Credit, Term	1 year

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Variable Interest Entities (Details) - MW	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	8 years 1 month
Purchased Power Agreements [Abstract]
Finance Lease, Weighted Average Remaining Lease Term	38 years 11 months
Independent Power Producing Entities
Purchased Power Agreements [Abstract]
Generating capacity under long term purchased power agreements (in MW)	1,442	1,571

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Commitments and Contingencies Line Extension Disputes (Details) - Line Extension Disputes [Member] - Minimum [Member] $ in Millions	1 Months Ended
	Dec. 31, 2015	Mar. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs	50
PSCo [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual		$ 0.0

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Income Taxes Unrecognized Tax Benefits (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Unrecognized tax benefit — Permanent tax positions	$ 7,000,000.0	$ 5,400,000
Unrecognized tax benefit — Temporary tax positions	4,700,000	4,900,000
Total unrecognized tax benefit	11,700,000	10,300,000
NOL and tax credit carryforwards	8,300,000	5,600,000
Net Deferred Tax Liability associated with the Unrecognized Tax Benefit Amounts and Related NOLs and Tax Credit Carryforwards	(4,900,000)	(2,000,000.0)
Decrease in Unrecognized Tax Benefits is Reasonably Possible	8,700,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	$ 0	$ 0

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Credit Related Contingent Features (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Collateral posted on derivative instruments	$ 0	$ 0
Derivative instruments in a gross liability position	0	0
Collateral posted related to adequate assurance clauses in derivative contracts	$ 0	$ 0

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Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Gross Notional Amounts of Commodity Forwards and Options

Gross notional amounts of commodity forwards and options:

(Amounts in Millions) (a)(b)	Sept. 30, 2019	Dec. 31, 2018
Megawatt hours of electricity	15.5	24.4
Million British thermal units of natural gas	58.8	48.4

^(a)  Amounts are not reflective of net positions in the underlying commodities.

^(b) 

Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income

Impact of derivative activity:

	Pre-Tax Fair Value Losses Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss		Regulatory (Assets) and Liabilities
Three Months Ended Sept. 30, 2019
Other derivative instruments
Natural gas commodity	$	—	$	(2.2	)
Total	$	—	$	(2.2	)
Nine Months Ended Sept. 30, 2019
Other derivative instruments
Natural gas commodity	$	—	$	(3.7	)
Total	$	—	$	(3.7	)
Three Months Ended Sept. 30, 2018
Other derivative instruments
Natural gas commodity	$	—	$	(1.2	)
Total	$	—	$	(1.2	)
Nine Months Ended Sept. 30, 2018
Other derivative instruments
Natural gas commodity	$	—	$	(1.6	)
Total	$	—	$	(1.6	)

	Pre-Tax (Gains) Losses Reclassified into Income During the Period from:							Pre-Tax Gains (Losses) Recognized During the Period in Income
(Millions of Dollars)	Accumulated Other Comprehensive Loss			Regulatory Assets and (Liabilities)
Three Months Ended Sept. 30, 2019
Derivatives designated as cash flow hedges
Interest rate	$	0.4	(a)	$	—			$	—
Total	$	0.4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	0.6		(b)
Total	$	—		$	—			$	0.6
Nine Months Ended Sept. 30, 2019
Derivatives designated as cash flow hedges
Interest rate	$	1.2	(a)	$	—			$	—
Total	$	1.2		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	5.3		(b)
Natural gas commodity	—			(1.3		)	(c)	(2.1		)	(c)
Total	$	—		$	(1.3	)		$	3.2
Three Months Ended Sept. 30, 2018
Derivatives designated as cash flow hedges
Interest rate	$	0.4	(a)	$	—			$	—
Total	$	0.4		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2.0		(b)
Total	$	—		$	—			$	2.0
Nine Months Ended Sept. 30, 2018
Derivatives designated as cash flow hedges
Interest rate	$	1.2	(a)	$	—			$	—
Total	$	1.2		$	—			$	—
Other derivative instruments
Commodity trading	$	—		$	—			$	2.7		(b)
Natural gas commodity	—			2.7			(c)	(1.6		)	(c)
Total	$	—		$	2.7			$	1.1

^(a)  Amounts are recorded to interest charges.

^(b)  Amounts are recorded to electric operating revenues. Portions of these gains and losses are subject to sharing with electric customers through margin-sharing mechanisms and deducted from gross revenue as appropriate.

^(c)  Amounts for both the three and nine months ended Sept. 30, 2019 included no settlement gain or losses on derivatives entered to mitigate natural gas price risk for electric generation recorded to electric fuel and purchased power, subject to cost-recovery mechanisms and reclassified to a regulatory asset, as appropriate. Amounts for the three and nine months ended Sept. 30, 2018 included no such settlement gains or losses and $1.2 million of such settlement losses, respectively. Remaining derivative settlement losses for the three and nine months ended Sept. 30, 2019 and 2018 relate to natural gas operations and are recorded to cost of natural gas sold and transported. These gains and losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset or liability, as appropriate.

Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level

Recurring Fair Value Measurements — PSCo’s assets and liabilities measured at fair value on a recurring basis:

	Sept. 30, 2019													Dec. 31, 2018
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative assets
Other derivative instruments:
Commodity trading	$	1.4	$	13.6	$	0.2	$	15.2	$	(10.0	)	$	5.2	$	2.3	$	65.0	$	0.1	$	67.4	$	(28.2	)	$	39.2
Natural gas commodity	—		4.8		—		4.8		—			4.8		—		3.4		—		3.4		—			3.4
Total current derivative assets	$	1.4	$	18.4	$	0.2	$	20.0	$	(10.0	)	$	10.0	$	2.3	$	68.4	$	0.1	$	70.8	$	(28.2	)	$	42.6
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	0.5	$	5.7	$	0.1	$	6.3	$	(5.6	)	$	0.7	$	—	$	1.6	$	—	$	1.6	$	(0.4	)	$	1.2
Total noncurrent derivative assets	$	0.5	$	5.7	$	0.1	$	6.3	$	(5.6	)	$	0.7	$	—	$	1.6	$	—	$	1.6	$	(0.4	)	$	1.2

	Sept. 30, 2019													Dec. 31, 2018
	Fair Value						Fair Value Total		Netting (a)					Fair Value						Fair Value Total		Netting (a)
(Millions of Dollars)	Level 1		Level 2		Level 3							Total		Level 1		Level 2		Level 3							Total
Current derivative liabilities
Other derivative instruments:
Commodity trading	$	1.4	$	19.1	$	0.1	$	20.6	$	(13.3	)	$	7.3	$	2.4	$	64.2	$	—	$	66.6	$	(34.7	)	$	31.9
Natural gas commodity	—		4.4		—		4.4		—			4.4		—		—		—		—		—			—
Total current derivative liabilities	$	1.4	$	23.5	$	0.1	$	25.0	$	(13.3	)	11.7		$	2.4	$	64.2	$	—	$	66.6	$	(34.7	)	31.9
PPAs (b)												—													2.7
Current derivative instruments												$	11.7												$	34.6
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	0.4	$	60.0	$	—	$	60.4	$	(5.6	)	$	54.8	$	—	$	1.1	$	—	$	1.1	$	(0.5	)	$	0.6
Total noncurrent derivative liabilities	$	0.4	$	60.0	$	—	$	60.4	$	(5.6	)	$	54.8	$	—	$	1.1	$	—	$	1.1	$	(0.5	)	$	0.6

^(a)  PSCo nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Sept. 30, 2019 and Dec. 31, 2018. At both Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include no obligations to return cash collateral. At Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include the rights to reclaim cash collateral of $3.2 million and $6.5 million, respectively. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

^(b) 

During 2006, PSCo qualified these contracts under the normal purchase exception. Based on this qualification, the contracts are no longer adjusted to fair value and the previous carrying value of these contracts will be amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.

Carrying Amount and Fair Value of Long-term Debt

Other financial instruments for which the carrying amount did not equal fair value:

	Sept. 30, 2019				Dec. 31, 2018
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	5,384.0	$	6,139.2	$	4,997.6	$	5,123.2

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Selected Balance Sheet Data (Tables)

9 Months Ended

Sep. 30, 2019

Balance Sheet Related Disclosures [Abstract]

Accounts Receivable, Net

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
Accounts receivable, net
Accounts receivable	$	315.1		$	330.8
Less allowance for bad debts	(20.9		)	(20.5		)
Accounts receivable, net	$	294.2		$	310.3

Inventories

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Inventories
Materials and supplies	$	61.8	$	61.9
Fuel	75.3		69.5
Natural gas	51.0		66.0
Total inventories	$	188.1	$	197.4

Property, plant and equipment, net

(Millions of Dollars)	Sept. 30, 2019			Dec. 31, 2018
Property, plant and equipment, net
Electric plant	$	14,070.5		$	13,604.5
Natural gas plant	4,526.5			4,387.6
Common and other property	1,070.2			1,023.7
Plant to be retired (a)	275.5			321.9
Construction work in progress	928.8			573.3
Total property, plant and equipment	20,871.5			19,911.0
Less accumulated depreciation	(5,085.1		)	(4,791.0		)
Property, plant and equipment, net	$	15,786.4		$	15,120.0

^(a) 

In 2018, the CPUC approved early retirement of PSCo’s Comanche Units 1 and 2 in approximately 2022 and 2025, respectively. PSCo also expects Craig Unit 1 to be retired early in 2025. Amounts are presented net of accumulated depreciation.

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CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2017		100
Beginning balance at Dec. 31, 2017	$ 5,828.3	$ 0.0	$ 4,032.8	$ 1,822.2	$ (26.7)
Increase (Decrease) in Stockholder's Equity
Net income	463.1			463.1
Other comprehensive income	0.9
Dividends declared to parent	(299.1)			(299.1)
Contribution of capital by parent	245.6		245.6
Balance (in shares) at Sep. 30, 2018		100
Ending balance at Sep. 30, 2018	6,238.8	$ 0.0	4,278.4	1,986.2	(25.8)
Balance (in shares) at Jun. 30, 2018		100
Beginning balance at Jun. 30, 2018	6,129.6	$ 0.0	4,273.1	1,882.6	(26.1)
Increase (Decrease) in Stockholder's Equity
Net income	207.1			207.1
Other comprehensive income	0.3
Dividends declared to parent	(103.5)			(103.5)
Contribution of capital by parent	5.3		5.3
Balance (in shares) at Sep. 30, 2018		100
Ending balance at Sep. 30, 2018	$ 6,238.8	$ 0.0	4,278.4	1,986.2	(25.8)
Balance (in shares) at Dec. 31, 2018	100	100
Beginning balance at Dec. 31, 2018	$ 6,298.2	$ 0.0	4,340.5	1,983.2	(25.5)
Increase (Decrease) in Stockholder's Equity
Net income	444.8			444.8
Other comprehensive income	0.9
Dividends declared to parent	(301.1)			(301.1)
Contribution of capital by parent	$ 562.8		562.8
Balance (in shares) at Sep. 30, 2019	100	100
Ending balance at Sep. 30, 2019	$ 7,005.6	$ 0.0	4,903.3	2,126.9	(24.6)
Balance (in shares) at Jun. 30, 2019		100
Beginning balance at Jun. 30, 2019	6,613.1	$ 0.0	4,618.3	2,019.7	(24.9)
Increase (Decrease) in Stockholder's Equity
Net income	204.5			204.5
Other comprehensive income	0.3
Dividends declared to parent	(97.3)			(97.3)
Contribution of capital by parent	$ 285.0		285.0
Balance (in shares) at Sep. 30, 2019	100	100
Ending balance at Sep. 30, 2019	$ 7,005.6	$ 0.0	$ 4,903.3	$ 2,126.9	$ (24.6)

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension and retiree medical benefits:
Net pension and retiree medical losses arising during period, tax	$ 0.0	$ (0.1)	$ 0.0	$ (0.1)
Amortization of losses included in net periodic benefit cost, tax	0.0	0.1	0.0	0.1
Derivative instruments:
Reclassification of losses (gains) to net income, tax	$ 0.0	$ 0.0	$ 0.0	$ 0.0