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 March 31, 2021

or

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

For the transition period from to

Commission File Number: 001-31387

Northern States Power Company

Minnesota

(Exact name of registrant as specified in its charter)

Minnesota	41-1967505
(State or Other Jurisdiction of Incorporation or Organization)	(I.R.S. Employer Identification No.)

414 Nicollet Mall	Minneapolis	Minnesota	55401
(Address of Principal Executive Offices)			(Zip Code)

	612	330-5500
(Registrant’s telephone Number, Including Area Code)

N/A

(Former Name, Former Address and Former Fiscal Year, if Changed Since Last Report)

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

Title of each class	Trading Symbol(s)	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, a 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	Outstanding at April 29, 2021
Common Stock, $0.01 par value	1,000,000 shares

Northern States Power Company meets the conditions set forth in General Instructions 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 1 —	Financial Statements (Unaudited)	4
	Consolidated Statements of Income	4
	Consolidated Statements of Comprehensive Income	5
	Consolidated Statements of Cash Flows	6
	Consolidated Balance Sheets	7
	Consolidated Statements of Common Stockholder’s Equity	8
	Notes to Consolidated Financial Statements	9
Item 2 —	Management’s Discussion and Analysis of Financial Condition and Results of Operations	18
Item 4 —	Controls and Procedures	21
PART II	OTHER INFORMATION
Item 1 —	Legal Proceedings	21
Item 1A —	Risk Factors	21
Item 6 —	Exhibits	22
SIGNATURES		23
Certifications Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
Certifications Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

This Form 10-Q is filed by Northern States Power Company, a Minnesota corporation (NSP-Minnesota). NSP-Minnesota is a wholly owned subsidiary of Xcel Energy Inc. Additional information on Xcel Energy is available in various filings with the Securities and Exchange Commission. This report should be read in its entirety.

Definitions of Abbreviations

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
Xcel Energy	Xcel Energy Inc. and its subsidiaries
Federal and State Regulatory Agencies
D.C. Circuit	United States Court of Appeals for the District of Columbia Circuit
DOC	Minnesota Department of Commerce
EPA	United States Environmental Protection Agency
FERC	Federal Energy Regulatory Commission
IRS	Internal Revenue Service
MPUC	Minnesota Public Utilities Commission
NDPSC	North Dakota Public Service Commission
SEC	Securities and Exchange Commission
Electric, Purchased Gas and Resource Adjustment Clauses
FCA	Fuel clause adjustment
GUIC	Gas utility infrastructure cost rider
RES	Renewable energy standard
TCR	Transmission cost recovery adjustment
Other
ASC	FASB Accounting Standards Codification
C&I	Commercial and Industrial
CCR	Coal combustion residuals
CCR Rule	Final rule (40 CFR 257.50 - 257.107) published by the United States EPA regulating the management, storage and disposal of CCRs as nonhazardous waste
CEO	Chief executive officer
CFO	Chief financial officer
COVID-19	Novel coronavirus
ETR	Effective tax rate
FASB	Financial Accounting Standards Board
FTR	Financial transmission right
GAAP	United States generally accepted accounting principles
GE	General Electric Company
IPP	Independent power producing entity
LLC	Limited liability company
MGP	Manufactured gas plant
MISO	Midcontinent Independent System Operator, Inc.
NAV	Net asset value
NOL	Net operating loss
NOPR	Notice of Proposed Rulemaking
O&M	Operating and maintenance
PPA	Power purchase agreement
PTC	Production tax credit
ROE	Return on equity
ROFR	Right-of-first-refusal
RTO	Regional Transmission Organization
SMMPA	Southern Minnesota Municipal Power Agency
TOs	Transmission owners
VIE	Variable interest entity
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, including those relating to future sales, future expenses, future operating performance, estimated base capital expenditures and financing plans, projected capital additions and forecasted annual revenue requirements with respect to rider filings, expected rate increases to customers, expectations and intentions regarding regulatory proceedings, and expected impacts on our results of operations, financial condition and cash flows or resettlement calculations and credit losses relating to certain energy transactions, as well as 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 filings with the SEC (including NSP-Minnesota’s Annual Report on Form 10-K for the fiscal year ended Dec. 31, 2020, and subsequent filings), could cause actual results to differ materially from management expectations as suggested by such forward-looking information: uncertainty around the impacts and duration of the COVID-19 pandemic; operational safety, including our nuclear generation facilities; successful long-term operational planning; commodity risks associated with energy markets and production; rising energy prices and fuel costs; qualified employee work force and third-party contractor factors; ability to recover costs; changes in regulation; 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 NSP-Minnesota 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; effects of geopolitical events, including war and acts of terrorism; cyber security threats and data security breaches; seasonal weather patterns; 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; and costs of potential regulatory penalties.

PART I — FINANCIAL INFORMATION

ITEM 1 — FINANCIAL STATEMENTS

NSP-MINNESOTA AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(amounts in millions)

	Three Months Ended March 31
	2021		2020
Operating revenues
Electric, non-affiliates	$	1,024	$	925
Electric, affiliates	115		110
Natural gas	204		206
Other	9		9
Total operating revenues	1,352		1,250
Operating expenses
Electric fuel and purchased power	433		364
Cost of natural gas sold and transported	125		125
Cost of sales — other	5		6
Operating and maintenance expenses	298		296
Conservation program expenses	34		31
Depreciation and amortization	221		202
Taxes (other than income taxes)	69		69
Total operating expenses	1,185		1,093
Operating income	167		157
Other income (expense), net	2		(5)
Allowance for funds used during construction — equity	7		7
Interest charges and financing costs
Interest charges — includes other financing costs of $2 and $2, respectively	63		61
Allowance for funds used during construction — debt	(3)		(3)
Total interest charges and financing costs	60		58
Income before income taxes	116		101
Income tax benefit	(12)		(6)
Net income	$	128	$	107

See Notes to Consolidated Financial Statements

4

NSP-MINNESOTA AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED)

(amounts in millions)

	Three Months Ended March 31
	2021		2020
Net income	$	128	$	107
Other comprehensive income
Derivative instruments:
Reclassification of losses to net income, net of tax of $— and $—, respectively	1		—
Total other comprehensive income	1		—
Total comprehensive income	$	129	$	107

See Notes to Consolidated Financial Statements

5

NSP-MINNESOTA AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(amounts in millions)

	Three Months Ended March 31
	2021		2020
Operating activities
Net income	$	128	$	107
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	223		204
Nuclear fuel amortization	30		33
Deferred income taxes	(8)		(15)
Allowance for equity funds used during construction	(7)		(7)
Provision for bad debts	6		5
Net realized and unrealized hedging and derivatives transactions	(6)		9
Changes in operating assets and liabilities:
Accounts receivable	(12)		3
Accrued unbilled revenues	43		52
Inventories	38		20
Accounts payable	(38)		(43)
Net regulatory assets and liabilities	(268)		33
Other current liabilities	26		(4)
Pension and other employee benefit obligations	(36)		(48)
Other, net	(2)		(8)
Net cash provided by operating activities	117		341
Investing activities
Capital/construction expenditures	(474)		(274)
Purchase of investment securities	(199)		(835)
Proceeds from the sale of investment securities	194		830
Investments in utility money pool arrangement	—		(305)
Repayments from utility money pool arrangement	—		257
Other, net	(2)		1
Net cash used in investing activities	(481)		(326)
Financing activities
Repayments of short-term borrowings, net	(179)		(30)
Borrowings under utility money pool arrangement	434		118
Repayments under utility money pool arrangement	(434)		(118)
Proceeds from issuance of long-term debt	836		—
Capital contributions from parent	424		114
Dividends paid to parent	(106)		(94)
Other, net	—		(4)
Net cash provided by (used in) financing activities	975		(14)
Net change in cash, cash equivalents and restricted cash	611		1
Cash, cash equivalents and restricted cash at beginning of period	46		126
Cash, cash equivalents and restricted cash at end of period	$	657	$	127
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	$	(72)	$	(75)
Cash received (paid) for income taxes, net	1		(6)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	$	222	$	67
Inventory transfers to property, plant and equipment	5		4
Allowance for equity funds used during construction	7		7

See Notes to Consolidated Financial Statements

6

NSP-MINNESOTA AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS (UNAUDITED)

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

	March 31, 2021		Dec. 31, 2020
Assets
Current assets
Cash and cash equivalents	$	657	$	46
Accounts receivable, net	385		392
Accounts receivable from affiliates	20		32
Accrued unbilled revenues	205		248
Inventories	253		295
Regulatory assets	554		411
Derivative instruments	8		17
Prepayments and other	47		50
Total current assets	2,129		1,491
Property, plant and equipment, net	15,679		15,308
Other assets
Nuclear decommissioning fund and other investments	2,881		2,830
Regulatory assets	1,047		924
Derivative instruments	26		5
Operating lease right-of-use assets	469		488
Other	19		14
Total other assets	4,442		4,261
Total assets	$	22,250	$	21,060
Liabilities and Equity
Current liabilities
Short-term debt	$	—	$	179
Accounts payable	461		438
Accounts payable to affiliates	43		66
Regulatory liabilities	115		123
Taxes accrued	314		263
Accrued interest	58		72
Dividends payable to parent	108		106
Derivative instruments	15		22
Operating lease liabilities	91		85
Other	177		154
Total current liabilities	1,382		1,508
Deferred credits and other liabilities
Deferred income taxes	1,854		1,840
Deferred investment tax credits	18		18
Regulatory liabilities	1,899		1,896
Asset retirement obligations	2,440		2,350
Derivative instruments	84		71
Pension and employee benefit obligations	155		192
Operating lease liabilities	416		443
Other	71		69
Total deferred credits and other liabilities	6,937		6,879
Capitalization
Long-term debt	6,741		5,904
Common stock — 5,000,000 shares authorized of $0.01 par value; 1,000,000 shares outstanding at March 31, 2021 and Dec. 31, 2020, respectively	—		—
Additional paid in capital	4,985		4,585
Retained earnings	2,226		2,206
Accumulated other comprehensive loss	(21)		(22)
Total common stockholder's equity	7,190		6,769
Total liabilities and equity	$	22,250	$	21,060

See Notes to Consolidated Financial Statements

7

NSP-MINNESOTA AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER’S EQUITY (UNAUDITED)

(amounts in millions, except share data)

	Common Stock Issued					Retained Earnings		Accumulated Other Comprehensive Income (Loss)		Total Common Stockholder's Equity
	Shares	Par Value		Additional Paid In Capital
Three Months Ended March 31, 2021 and 2020
Balance at Dec. 31, 2019	1,000,000	$	—	$	4,068	$	2,036	$	(22)	$	6,082
Net income						107				107
Dividends declared to parent						(100)				(100)
Contribution of capital by parent				80						80
Balance at March 31, 2020	1,000,000	$	—	$	4,148	$	2,043	$	(22)	$	6,169
Balance at Dec. 31, 2020	1,000,000	$	—	$	4,585	$	2,206	$	(22)	$	6,769
Net income						128				128
Other comprehensive income								1		1
Dividends declared to parent						(108)				(108)
Contribution of capital by parent				400						400
Balance at March 31, 2021	1,000,000	$	—	$	4,985	$	2,226	$	(21)	$	7,190
See Notes to Consolidated Financial Statements

8

NSP-MINNESOTA 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 GAAP, the financial position of NSP-Minnesota and its subsidiaries as of March 31, 2021 and Dec. 31, 2020; the results of operations, including the components of net income, comprehensive income, cash flows and changes in stockholder’s equity for the three months ended March 31, 2021 and 2020.

All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2021 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, 2020 balance sheet information has been derived from the audited 2020 consolidated financial statements included in the NSP-Minnesota Annual Report on Form 10-K for the year ended Dec. 31, 2020.

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 NSP-Minnesota Annual Report on Form 10-K for the year ended Dec. 31, 2020, filed with the SEC on Feb. 17, 2021. Due to the seasonality of NSP-Minnesota’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 NSP-Minnesota Annual Report on Form 10-K for the year ended Dec. 31, 2020, appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

2. Accounting Pronouncements

Recently Adopted

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.

NSP-Minnesota implemented the guidance using a modified-retrospective approach, recognizing a cumulative effect charge of $1 million (after tax) to retained earnings on Jan. 1, 2020. Other than first-time recognition of an allowance for bad debts on accrued unbilled revenues, the Jan. 1, 2020 adoption of ASC Topic 326 did not have a significant impact on NSP-Minnesota’s consolidated financial statements.

3. Selected Balance Sheet Data

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Accounts receivable, net
Accounts receivable	$	422	$	425
Less allowance for bad debts	(37)		(33)
Accounts receivable, net	$	385	$	392

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Inventories
Materials and supplies	$	181	$	178
Fuel	66		90
Natural gas	6		27
Total inventories	$	253	$	295

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Property, plant and equipment, net
Electric plant	$	19,647	$	18,948
Natural gas plant	1,720		1,707
Common and other property	969		955
Plant to be retired (a)	127		136
Construction work in progress	965		1,150
Total property, plant and equipment	23,428		22,896
Less accumulated depreciation	(8,106)		(7,898)
Nuclear fuel	3,047		2,970
Less accumulated amortization	(2,690)		(2,660)
Property, plant and equipment, net	$	15,679	$	15,308

(a)Includes regulator-approved retirements of Sherco Units 1 and 2.

4. Borrowings and Other Financing Instruments

Short-Term Borrowings

NSP-Minnesota 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 NSP-Minnesota were as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2021			Year Ended Dec. 31, 2020
Borrowing limit	$	250		$	250
Amount outstanding at period end	—			—
Average amount outstanding	24			3
Maximum amount outstanding	236			116
Weighted average interest rate, computed on a daily basis	0.07		%	1.53		%
Weighted average interest rate at period end	N/A			N/A

9

Commercial Paper — Commercial paper outstanding for NSP-Minnesota was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2021			Year Ended Dec. 31, 2020
Borrowing limit	$	500		$	500
Amount outstanding at period end	—			179
Average amount outstanding	104			10
Maximum amount outstanding	317			179
Weighted average interest rate, computed on a daily basis	0.18		%	1.25		%
Weighted average interest rate at period end	N/A			0.18

Letters of Credit — NSP-Minnesota uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At March 31, 2021 and Dec. 31, 2020, there were $10 million of letters of credit outstanding under the credit facility. Amounts approximate their fair value and are subject to fees.

Revolving Credit Facility — In order to issue its commercial paper, NSP-Minnesota 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 exceeding available capacity under this credit facility. The line of credit provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

NSP-Minnesota 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 March 31, 2021, NSP-Minnesota had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Drawn (b)		Available
$	500	$	10	$	490

(a)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. NSP-Minnesota had no direct advances on the credit facility outstanding at March 31, 2021 and Dec. 31, 2020.

Bilateral Credit Agreement — In April 2021, the uncommitted bilateral credit agreement was renewed for an additional one-year term. The credit agreement is limited in use to support letters of credit.

As of March 31, 2021, NSP-Minnesota’s outstanding letters of credit under the Bilateral Credit Agreement were as follows:

(Millions of Dollars)	Limit		Amount Outstanding		Available
NSP-Minnesota	$	75	$	49	$	26

Long-Term Borrowings

During the three months ended March 31, 2021, NSP-Minnesota issued $425 million of 2.25% first mortgage bonds due April 1, 2031 and $425 million of 3.20% first mortgage bonds due April 1, 2052.

5. Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Minnesota’s operating revenues consisted of the following:

	Three Months Ended March 31, 2021
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	326	$	114	$	7	$	447
C&I	416		79		—		495
Other	8		—		2		10
Total retail	750		193		9		952
Wholesale	98		—		—		98
Transmission	57		—		—		57
Interchange	115		—		—		115
Other	2		—		—		2
Total revenue from contracts with customers	1,022		193		9		1,224
Alternative revenue and other	117		11		—		128
Total revenues	$	1,139	$	204	$	9	$	1,352

	Three Months Ended March 31, 2020
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	300	$	114	$	7	$	421
C&I	445		82		—		527
Other	7		—		2		9
Total retail	752		196		9		957
Wholesale	45		—		—		45
Transmission	56		—		—		56
Interchange	110		—		—		110
Other	2		1		—		3
Total revenue from contracts with customers	965		197		9		1,171
Alternative revenue and other	70		9		—		79
Total revenues	$	1,035	$	206	$	9	$	1,250

6.    Income Taxes

Note 7 to the consolidated financial statements included in NSP-Minnesota’s Annual Report on Form 10-K for the year ended Dec. 31, 2020 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.

10

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

	Three Months Ended March 31
	2021		2020 (a)
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	7.0		7.1
Increases (decreases) in tax from:
Wind PTCs	(30.4)		(24.8)
Plant regulatory differences (b)	(7.8)		(8.3)
Other tax credits, net NOL & tax credit allowances	(1.3)		(1.5)
Other (net)	1.2		0.6
Effective income tax rate	(10.3)	%	(5.9)	%

(a)     Prior periods have been restated to conform to current year presentation.

(b) Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reduction.

Federal Audits — NSP-Minnesota 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 Years	Expiration
2014 - 2016	January 2022
2017	September 2021

Additionally, the statute of limitations related to a federal tax loss carryback claim filed in 2020 has been extended. 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.

State Audits — NSP-Minnesota is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of March 31, 2021, NSP-Minnesota’s earliest open tax year subject to examination by state taxing authorities under applicable statutes of limitations is 2013. In July 2020, Minnesota began a review of tax years 2015-2018. In February 2021, Minnesota concluded its review and commenced an audit of the same tax years. As of March 31, 2021, no material adjustments have been proposed.

Unrecognized Benefits — The 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)	March 31, 2021		Dec. 31, 2020
Unrecognized tax benefit — Permanent tax positions	$	21	$	21
Unrecognized tax benefit — Temporary tax positions	3		3
Total unrecognized tax benefit	$	24	$	24

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

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
NOL and tax credit carryforwards	$	(11)	$	(11)

As IRS audits resume and the state audit progresses, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $15 million in the next 12 months.

Payable for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards.

Interest payable related to unrecognized tax benefits:

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Payable for interest related to unrecognized tax benefits at beginning of period	$	(2)	$	(2)
Interest expense related to unrecognized tax benefits	—		—
Payable for interest related to unrecognized tax benefits at end of period	$	(2)	$	(2)

No amounts were accrued for penalties related to unrecognized tax benefits as of March 31, 2021 or Dec. 31, 2020.

7.    Fair Value of Financial Assets and Liabilities

Fair Value Measurements

Accounting guidance for fair value measurements and disclosures provides a single definition of fair value and requires disclosures about assets and liabilities measured at fair value. A hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value is established by this guidance.

•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 NAV.

Investments in equity securities and other funds — Equity securities are valued using quoted prices in active markets. The fair values for commingled funds are measured using NAVs. The investments in commingled funds may be redeemed for NAV with proper notice. Private equity commingled fund investments require approval of the fund for any unscheduled redemption, and such redemptions may be approved or denied by the fund at its sole discretion.

Unscheduled distributions from real estate commingled funds’ investments may be redeemed with proper notice, however, may be delayed or discounted as a result of fund illiquidity.

Investments in debt securities — Fair values for debt securities are determined by a third-party pricing service using recent trades and observable spreads from benchmark interest rates for similar securities.

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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 utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations and are generally assigned a Level 2 classification. When contractual settlements relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable forecasts of forward prices and volatilities on a valuation is evaluated, and may result in Level 3 classification.

Electric commodity derivatives held by NSP-Minnesota include transmission congestion instruments, generally referred to as FTRs. FTRs purchased from a RTO are financial instruments that entitle or obligate the holder to monthly revenues or charges based on transmission congestion across a given transmission path. The value of an FTR is derived from, and designed to offset, the cost of transmission congestion. In addition to overall transmission load, congestion is also influenced by the operating schedules of power plants and the consumption of electricity pertinent to a given transmission path. Unplanned plant outages, scheduled plant maintenance, changes in the relative costs of fuels used in generation, weather and overall changes in demand for electricity can each impact the operating schedules of the power plants on the transmission grid and the value of an FTR.

If forecasted costs of electric transmission congestion increase or decrease for a given FTR path, the value of that particular FTR instrument will likewise increase or decrease. Given the limited observability of certain inputs to the value of FTRs between auction processes, including expected plant operating schedules and retail and wholesale demand, fair value measurements for FTRs have been assigned a Level 3.

Non-trading monthly FTR settlements are included in fuel and purchased energy cost recovery mechanisms, and therefore changes in the fair value of the yet to be settled portions of most FTRs are deferred as a regulatory asset or liability. Given this regulatory treatment and the limited magnitude of NSP-Minnesota’s FTRs relative to its electric utility operations, the numerous unobservable quantitative inputs pertinent to the value of FTRs are immaterial to the consolidated financial statements of NSP-Minnesota.

Non-Derivative Fair Value Measurements

The Nuclear Regulatory Commission requires NSP-Minnesota to maintain a portfolio of investments to fund the costs of decommissioning its nuclear generating plants. Assets of the nuclear decommissioning fund are legally restricted for the purpose of decommissioning these facilities. The fund contains cash equivalents, debt securities, equity securities and other investments. NSP-Minnesota uses the MPUC approved asset allocation for the escrow and investment targets by asset class for both the escrow and qualified trust.

NSP-Minnesota recognizes the costs of funding the decommissioning over the lives of the nuclear plants, assuming rate recovery of all costs. Realized and unrealized gains on fund investments over the life of the fund are deferred as an offset of NSP-Minnesota’s regulatory asset for nuclear decommissioning costs. Consequently, any realized and unrealized gains and losses on securities in the nuclear decommissioning fund are deferred as a component of the regulatory asset.

Unrealized gains for the nuclear decommissioning fund were $1 billion and $981 million as of March 31, 2021 and Dec. 31, 2020, respectively, and unrealized losses were $8 million and $5 million as of March 31, 2021 and Dec. 31, 2020, respectively.

Non-derivative instruments with recurring fair value measurements in the nuclear decommissioning fund:

	March 31, 2021
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	32	$	32	$	—	$	—	$	—	$	32
Commingled funds	795		—		—		—		1,052		1,052
Debt securities	562		—		573		13		—		586
Equity securities	444		1,153		2		—		—		1,155
Total	$	1,833	$	1,185	$	575	$	13	$	1,052	$	2,825

(a)Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $56 million of rabbi trust assets and miscellaneous investments.

	Dec. 31, 2020
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	40	$	40	$	—	$	—	$	—	$	40
Commingled funds	787		—		—		—		1,041		1,041
Debt securities	528		—		572		13		—		585
Equity securities	446		1,109		2		—		—		1,111
Total	$	1,801	$	1,149	$	574	$	13	$	1,041	$	2,777

(a)Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $53 million of rabbi trust assets and miscellaneous investments.

For the three months ended March 31, 2021 and 2020, there were immaterial Level 3 nuclear decommissioning fund investments or transfer of amounts between levels.

Contractual maturity dates of debt securities in the nuclear decommissioning fund as of March 31, 2021:

	Final Contractual Maturity
(Millions of Dollars)	Due in 1 year or Less		Due in 1 to 5 Years		Due in 5 to 10 Years		Due after 10 Years		Total
Debt securities	$	3	$	133	$	202	$	248	$	586

Rabbi Trusts

NSP-Minnesota has established a rabbi trust to provide partial funding for future deferred compensation plan distributions.

Cost and fair value of assets held in rabbi trusts:

	March 31, 2021
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	6	$	6	$	—	$	—	$	6
Mutual funds	10		12		—		—		12
Total	$	16	$	18	$	—	$	—	$	18

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	Dec. 31, 2020
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	1	$	1	$	—	$	—	$	1
Mutual funds	14		16		—		—		16
Total	$	15	$	17	$	—	$	—	$	17

(a)    Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets.

Derivative Instruments Fair Value Measurements

NSP-Minnesota 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 — NSP-Minnesota 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, with changes in fair value prior to settlement recorded as other comprehensive income.

At March 31, 2021, accumulated other comprehensive loss related to settled interest rate derivatives included $1 million of net losses expected to be reclassified into earnings during the next 12 months as the hedged interest rate transactions impact earnings. As of March 31, 2021, NSP-Minnesota had no unsettled interest rate derivatives.

Wholesale and Commodity Trading Risk — NSP-Minnesota 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. NSP-Minnesota 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. Sharing of any margins is determined through state regulatory proceedings as well as the operation of the FERC approved joint operating agreement.

Commodity Derivatives — NSP-Minnesota 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, FTRs, vehicle fuel, and weather derivatives.

At March 31, 2021, NSP-Minnesota had no commodity contracts designated as cash flow hedges. NSP-Minnesota 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. The classification as a regulatory asset or liability, if applicable, is based on approved regulatory recovery mechanisms.

NSP-Minnesota 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, options and FTRs:

(Amounts in Millions) (a)(b)	March 31, 2021	Dec. 31, 2020
Megawatt hours of electricity	49	65
Million British thermal units of natural gas	77	83

(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 — NSP-Minnesota continuously monitors the creditworthiness of 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. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets.

NSP-Minnesota’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.

As of March 31, 2021, six of NSP-Minnesota’s ten most significant counterparties for these activities, comprising $26 million, or 52%, of this credit exposure, had investment grade credit ratings from S&P Global Ratings, Moody’s Investor Services or Fitch Ratings. Three of the ten most significant counterparties, comprising $10 million, or 20%, of this credit exposure, were not rated by these external agencies, but based on NSP-Minnesota’s internal analysis, had credit quality consistent with investment grade. One of these significant counterparties, comprising $8 million or 16% of this credit exposure, had credit quality less than investment grade, based on internal analysis. Eight of these significant counterparties are municipal or cooperative electric entities, RTOs or other utilities.

The impact of derivative activity:

	Pre-Tax Fair Value Gains (Losses) Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss		Regulatory (Assets) and Liabilities
Three Months Ended March 31, 2021
Other derivative instruments
Natural gas commodity	$	—	$	1
Total	$	—	$	1

As of March 31, 2020, NSP-Minnesota had no activity for electric and natural gas commodity derivatives that were recognized in regulatory (assets) and liabilities.

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	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 March 31, 2021
Other derivative instruments
Commodity trading	$	—	$	—		$	31	(a)
Electric commodity	—		(1)		(b)	—
Natural gas commodity	—		1		(c)	(3)		(c)
Total	$	—	$	—		$	28

	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 March 31, 2020
Other derivative instruments
Commodity trading	$	—	$	—		$	4	(a)
Electric commodity	—		(1)		(b)	—
Natural gas commodity	—		1		(c)	(2)		(c)
Total	$	—	$	—		$	2

(a)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.

(b)Amounts are recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

(c)Amounts are recorded to cost of natural gas sold and transported. These derivative settlement gains and losses are shared with natural gas customers through purchased natural gas cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

NSP-Minnesota had no derivative instruments designated as fair value hedges during the three months ended March 31, 2021 and 2020.

Credit Related Contingent Features — Contract provisions for derivative instruments that NSP-Minnesota 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 NSP-Minnesota’s credit ratings are downgraded below its investment grade credit rating by any of the major credit rating agencies. As of both March 31, 2021 and Dec. 31, 2020, there were $4 million derivative liabilities with such underlying contract provisions. Certain contracts also contain cross default provisions that may require the posting of collateral or settlement of the contracts if there was a failure under the other financing arrangements related to payment terms or other covenants. As of March 31, 2021 and Dec. 31, 2020, there were approximately $29 million and $14 million, respectively, of derivative liabilities with such underlying contract provisions.

Certain derivative instruments are also subject to contract provisions that contain adequate assurance clauses. Provisions allow counterparties to seek performance assurance, including cash collateral, in the event that NSP-Minnesota’s ability to fulfill its contractual obligations is reasonably expected to be impaired. NSP-Minnesota had no collateral posted related to adequate assurance clauses in derivative contracts as of March 31, 2021 and Dec. 31, 2020.

Recurring Fair Value Measurements — NSP-Minnesota’s derivative assets and liabilities measured at fair value on a recurring basis:

	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative assets
Other derivative instruments:
Commodity trading	$	1	$	23	$	—	$	24	$	(21)	$	3	$	1	$	26	$	—	$	27	$	(25)	$	2
Electric commodity	—		—		6		6		(1)		5		—		—		13		13		(1)		12
Natural gas commodity	—		—		—		—		—		—		—		3		—		3		—		3
Total current derivative assets	$	1	$	23	$	6	$	30	$	(22)	$	8	$	1	$	29	$	13	$	43	$	(26)	$	17
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	5	$	33	$	28	$	66	$	(40)	$	26	$	7	$	39	$	—	$	46	$	(41)	$	5
Total noncurrent derivative assets	$	5	$	33	$	28	$	66	$	(40)	$	26	$	7	$	39	$	—	$	46	$	(41)	$	5

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	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative liabilities
Other derivative instruments:
Commodity trading	$	4	$	22	$	5	$	31	$	(29)	$	2	$	3	$	18	$	10	$	31	$	(25)	$	6
Electric commodity	—		—		—		—		—		—		—		—		1		1		(1)		—
Natural gas commodity	—		—		—		—		—		—		—		2		—		2		—		2
Total current derivative liabilities	$	4	$	22	$	5	$	31	$	(29)	2		$	3	$	20	$	11	$	34	$	(26)	8
PPAs (b)											13												14
Current derivative instruments											$	15											$	22
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	2	$	50	$	17	$	69	$	(30)	$	39	$	2	$	35	$	13	$	50	$	(27)	$	23
Total noncurrent derivative liabilities	$	2	$	50	$	17	$	69	$	(30)	39		$	2	$	35	$	13	$	50	$	(27)	23
PPAs (b)											45												48
Noncurrent derivative instruments											$	84											$	71

(a)NSP-Minnesota nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at March 31, 2021 and Dec. 31, 2020. At both March 31, 2021 and Dec. 31, 2020, derivative assets and liabilities include $15 million of obligations to return cash collateral. At March 31, 2021 and Dec. 31, 2020 derivative assets and liabilities include rights to reclaim cash collateral of $11 million and $1 million, respectively. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)During 2006, Xcel Energy 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.

Changes in Level 3 commodity derivatives for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Balance at Jan. 1	$	(11)	$	5
Settlements	(7)		(12)
Net transactions recorded during the period:
Gains recognized in earnings (a)	30		6
Net gains recognized as regulatory assets and liabilities	—		3
Balance at March 31	$	12	$	2

(a)Level 3 gains recognized in earnings are subject to offsetting losses of derivative instruments categorized as levels 1 and 2 in the income statement.

NSP-Minnesota recognizes transfers between levels as of the beginning of each period. There were no transfers of amounts between levels for derivative instruments for the three months ended March 31, 2021 and 2020.

Fair Value of Long-Term Debt

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

	March 31, 2021				Dec. 31, 2020
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	6,741	$	7,491	$	5,904	$	7,391

Fair value of NSP-Minnesota’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 March 31, 2021 and Dec. 31, 2020 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

	Three Months Ended March 31
	2021		2020		2021		2020
(Millions of Dollars)	Pension Benefits				Postretirement Health Care Benefits
Service cost	$	7	$	7	$	—	$	—
Interest cost (a)	6		8		1		1
Expected return on plan assets (a)	(13)		(14)		—		—
Amortization of prior service credit (a)	—		—		(1)		(1)
Amortization of net loss (a)	9		8		—		—
Net periodic benefit cost	9		9		—		—
Effects of regulation	(1)		(1)		—		—
Net benefit cost recognized for financial reporting	$	8	$	8	$	—	$	—

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

In January 2021, contributions of $125 million were made across four of Xcel Energy’s pension plans, of which $33 was attributable to NSP-Minnesota. Xcel Energy does not expect additional pension contributions during 2021.

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9. Commitments and Contingencies

The following includes commitments, contingencies and unresolved contingencies that are material to NSP-Minnesota’s financial position.

Legal

NSP-Minnesota 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, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Minnesota’s consolidated financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

Rate Matters and Other

Sherco — In 2018, NSP-Minnesota and SMMPA (Co-owner of Sherco Unit 3) reached a settlement with GE related to a 2011 incident, which damaged the turbine at Sherco Unit 3 and resulted in an extended outage for repair. NSP-Minnesota notified the MPUC of its proposal to refund settlement proceeds to customers through the FCA.

In March 2019, the MPUC approved NSP-Minnesota’s refund proposal. Additionally, the MPUC decided to withhold any decision as to NSP-Minnesota’s prudence in connection with the incident at Sherco Unit 3 until after conclusion of an appeal pending between GE and NSP-Minnesota’s insurers. In February 2020, the Minnesota Court of Appeals affirmed the district court’s judgment in favor of GE. In March 2020, NSP-Minnesota’s insurers filed a petition seeking additional review by the Minnesota Supreme Court.

In April 2020, the Minnesota Supreme Court denied the insurers’ petition for further review, ending the litigation. In accordance with a prior MPUC order, NSP-Minnesota made a compliance filing in August 2020 detailing all costs that resulted from the outage and all insurance recoveries received by NSP-Minnesota in connection with the outage.

In January 2021, the Minnesota Office of the Attorney General and DOC filed comments recommending that NSP-Minnesota refund approximately $17 million of replacement power costs previously recovered through the FCA. On Jan. 27, 2021, NSP-Minnesota filed its response, asserting that it acted prudently in connection with the Sherco Unit 3 outage, the MPUC has previously disallowed $22 million of related costs and no additional refund or disallowance is appropriate. A final decision by the MPUC is pending. A loss related to this matter is deemed remote.

Westmoreland Arbitration — In November 2014, insurers for Westmoreland Coal Company filed an arbitration demand against NSP-Minnesota, SMMPA and Western Fuels Association, seeking recovery of alleged business losses due to a turbine failure at Sherco Unit 3. The Westmoreland insurers claim NSP-Minnesota’s invocation of the force majeure clause to stop the supply of coal was improper because the incident was allegedly caused by NSP-Minnesota’s failure to conform to industry maintenance standards. Westmoreland’s insurers quantified their losses as approximately $36 million.

Arbitration was delayed pending resolution of a separate lawsuit brought by NSP-Minnesota, SMMPA, and their insurers against various GE entities based on the inspection and maintenance advice GE provided for Sherco Unit 3. In July 2020, following the conclusion of the appeal that fully resolved the GE litigation, Westmoreland’s insurers served notice, which triggered the arbitration to resume.

NSP-Minnesota denies the claims asserted by the Westmoreland insurers and believes it properly stopped the supply of coal based upon the force majeure provision. It is uncertain when a final resolution will occur, but it is unlikely an arbitration hearing will take place before the fourth quarter 2021. At this stage of the proceeding, a reasonable estimate of damages or range of damages cannot be determined.

MISO ROE Complaints — In November 2013 and February 2015, customer groups filed two ROE complaints against MISO TOs, which includes NSP-Minnesota and NSP-Wisconsin. The first complaint requested a reduction in base ROE transmission formula rates from 12.38% to 9.15% for the time period of Nov. 12, 2013 to Feb. 11, 2015, and removal of ROE adders (including those for RTO membership). The second complaint requested, for a subsequent time period, a base ROE reduction from 12.38% to 8.67%.

In September 2016, the FERC issued an order (Opinion No. 551) granting a 10.32% base ROE effective for the first complaint period of Nov. 12, 2013 to Feb. 11, 2015 and subsequent to the date of the order. The D.C Circuit subsequently vacated and remanded Opinion No. 551.

In November 2019, the FERC issued an order (Opinion No. 569), which set the MISO base ROE at 9.88%, effective Sept. 28, 2016 and for the first complaint period. The FERC also dismissed the second complaint. In December 2019, MISO TOs filed a request for rehearing regarding the new ROE methodology announced in Opinion No. 569. Customers also filed requests for rehearing claiming, among other points, that the FERC erred by dismissing the second complaint without refunds.

In May 2020, the FERC issued an order (Opinion No. 569-A) which granted rehearing in part to Opinion 569 and further refined the FERC’s ROE methodology, most significantly to incorporate the risk premium model (in addition to the discounted cash flow and capital asset pricing models), resulting in a new base ROE of 10.02%, effective Sept. 28, 2016 and for the first complaint period. The FERC also affirmed its decision in Opinion No. 569 to dismiss the second complaint.

In November 2020, the FERC issued an order (Opinion No. 569-B) in response to rehearing requests. The FERC corrected certain inputs to its ROE calculation model, did not change the ROE effective Sept. 28, 2016, and for the first MISO complaint period and upheld its decision to deny refunds for the second complaint period. NSP-Minnesota has recognized a liability for its best estimate of final refunds to customers. Each 10 basis point reduction in ROE for the first complaint period, second complaint period, and subsequent period relative to amounts accrued would reduce Xcel Energy’s net income by $1 million, $1 million, and $2 million, respectively.

The MISO TOs and various parties have filed petitions for review of Opinion Nos. 569, 569-A and 569-B at the D.C. Circuit with initial briefs filed in March 2021.

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FERC NOPR on ROE Incentive Adders — In April 2021, the FERC issued a NOPR proposing to limit collection of ROE incentive adders for RTO membership to the first three years after an entity begins participation in an RTO. If adopted as a final rule, following a comment period expected to be complete by the end of 2021 or 2022, NSP-Minnesota, NSP-Wisconsin and SPS would prospectively discontinue charging their current 0.5% ROE incentive adders. Amounts related to a discontinuance of the adder would ultimately be offset by an increase in retail rates.

Environmental

MGP, Landfill and Disposal Sites

NSP-Minnesota is currently investigating, remediating or performing post-closure actions at seven MGP, landfill or other disposal sites across its service territories.

NSP-Minnesota 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 costs incurred.

Environmental Requirements — Water and Waste

Coal Ash Regulation — NSP-Minnesota’s operations are subject to federal and state regulations 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. Currently, NSP-Minnesota has three regulated ash units in operation.

NSP-Minnesota is conducting groundwater sampling and monitoring and implementing assessment of corrective measures at certain CCR landfills and surface impoundments. No results above the groundwater protection standards in the rule were identified. Until NSP-Minnesota completes its assessment, it is uncertain what impact, if any, there will be on the operations, financial condition or cash flows.

In August 2020, the EPA published its final rule to implement a cease receipt and initiate a closure date of April 2021 for all CCR impoundments affected by the August 2018 D.C. Circuit ruling. The D.C. Circuit concluded that the EPA cannot allow utilities to continue to use unlined impoundments (including clay lined impoundments) for the storage or disposal of coal ash. This final rule required Xcel Energy to expedite closure plans for one impoundment.

In October 2020, NSP-Minnesota completed construction and placed in service a new impoundment to replace the clay lined impoundment at a cost of $9 million. With the new ash pond in service, NSP-Minnesota has initiated closure activities for the existing ash pond at an estimated cost of $4 million. NSP-Minnesota has five years to complete closure activities.

Closure costs for existing impoundments are included in the calculation of the asset retirement obligation.

Leases

NSP-Minnesota evaluates contracts that may contain leases, including PPAs and arrangements for the use of office space and other facilities, vehicles and equipment. A contract contains a lease if it conveys the exclusive right to control the use of a specific asset.

Components of lease expense:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Operating leases
PPA capacity payments	$	19	$	21
Other operating leases (a)	2		2
Total operating lease expense (b)	$	21	$	23

(a)Includes immaterial short-term lease expense for 2021 and 2020, respectively.

(a)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.

Commitments under operating leases as of March 31, 2021:

(Millions of Dollars)	PPA Operating Leases		Other Operating Leases		Total Operating Leases
Total minimum obligation	$	485	$	79	$	564
Interest component of obligation	(43)		(14)		(57)
Present value of minimum obligation	$	442	$	65	507
Less current portion					(91)
Noncurrent operating lease liabilities					$	416

VIEs

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

NSP-Minnesota had approximately 1,347 MW of capacity under long-term PPAs at both March 31, 2021 and Dec. 31, 2020 with entities that have been determined to be VIEs. NSP-Minnesota concluded that these entities are not required to be consolidated in its consolidated financial statements because it does not have the power to direct the activities that most significantly impact the entities’ economic performance. The PPAs have expiration dates through 2039.

10. Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive income (loss), net of tax, for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31, 2021						Three Months Ended March 31, 2020
(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	$	(19)	$	(3)	$	(22)	$	(19)	$	(3)	$	(22)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives, net of tax of $— and $—, respectively (a)	1		—		1		—		—		—
Accumulated other comprehensive loss at March 31	$	(18)	$	(3)	$	(21)	$	(19)	$	(3)	$	(22)

(a)Included in interest charges.

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11. Segment Information

NSP-Minnesota 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.

NSP-Minnesota has the following reportable segments:

•Regulated Electric — The regulated electric utility segment generates electricity which is transmitted and distributed in Minnesota, North Dakota and South Dakota. In addition, this segment includes sales for resale and provides wholesale transmission service to various entities in the United States. The regulated electric utility segment also includes NSP-Minnesota’s wholesale commodity and trading operations.

•Regulated Natural Gas — The regulated natural gas utility segment transports, stores and distributes natural gas in portions of Minnesota and North Dakota.

NSP-Minnesota also presents All Other, which includes operating segments with revenues below the necessary quantitative thresholds. Those operating segments primarily include appliance repair services, non-utility real estate activities and revenues associated with processing solid waste into refuse-derived fuel.

Asset and capital expenditure information is not provided for NSP-Minnesota’s reportable segments. As an integrated electric and natural gas utility, NSP-Minnesota 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.

NSP-Minnesota’s segment information:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Regulated Electric
Total revenues (a)	$	1,139	$	1,035
Net income	107		86
Regulated Natural Gas
Total revenues (b)	$	204	$	206
Net income	20		23
All Other
Total revenues	$	9	$	9
Net income (loss)	1		(2)
Consolidated Total
Total revenues (a)(b)	$	1,352	$	1,250
Net income	128		107

(a)    Total revenues include $115 million and $110 million of affiliate electric revenue for the three months ended March 31, 2021 and 2020.

(b)    Total revenues include an immaterial amount of affiliate gas revenue for the three months ended March 31, 2021 and 2020.

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

Discussion of financial condition and liquidity for NSP-Minnesota 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. NSP-Minnesota’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 state implementation plan expenses, depreciation and amortization and taxes (other than income taxes).

Results of Operations

NSP-Minnesota’s net income was approximately $128 million for the three months ended March 31, 2021 compared with approximately $107 million for the prior year. The increase reflects higher electric margin (primarily capital investment recovery), partially offset by increased depreciation.

Electric Margin

Electric revenues and fuel and purchased power expenses are impacted by fluctuations in the price of natural gas, coal and uranium. 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.

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Electric revenues and margin:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Electric revenues	$	1,139	$	1,035
Electric fuel and purchased power	(433)		(364)
Electric margin	$	706	$	671

Changes in electric margin:

(Millions of Dollars)	Three Months Ended March 31, 2021 vs. 2020
Non-fuel riders	$	24
Proprietary commodity trading, net of sharing	12
Regulatory rate outcome (ND interim rate increase)	3
PTCs flowed back to customers (offset by lower ETR)	(12)
Other (net)	8
Total increase in electric margin	$	35

Natural Gas Margin

Total 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:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Natural gas revenues	$	204	$	206
Cost of natural gas sold and transported	(125)		(125)
Natural gas margin	$	79	$	81

Changes in natural gas margin:

(Millions of Dollars)	Three Months Ended March 31, 2021 vs. 2020
Retail sales decline (excluding weather impact)	$	(1)
Estimated impact of weather	1
Other (net)	(2)
Total decrease in natural gas margin	$	(2)

Non-Fuel Operating Expenses and Other Items

Depreciation and Amortization — Depreciation and amortization expense increased $19 million, or 9.4% for the first quarter of 2021. The increase was primarily driven by several wind farms going into service and normal system expansion, which is partially offset by lower non-fuel rider amortization.

Income Taxes — Income tax benefit increased $6 million for the first quarter of 2021. The increase was primarily driven by increased wind PTCs. Wind PTCs are credited to customers (recorded as a reduction to revenue) and do not have a material impact on net income. This was partially offset by higher pretax earnings in 2021.

See Note 6 to the consolidated financial statements for further information.

Other

Winter Storm Uri

In mid-February 2021, the central portion of the United States experienced a major winter storm (Winter Storm Uri). Extreme cold temperatures impacted certain operational assets as well as the availability of renewable generation across the region. The cold weather also affected the country’s supply and demand for natural gas. These factors contributed to extremely high market prices for natural gas and electricity. In addition, NSP-Minnesota’s three peak shaving plants, which are used to ensure system reliability under Design Day conditions, have been unavailable since early 2021 due to required repairs to address safety concerns with the units. Despite the extreme conditions, NSP-Minnesota’s customers experienced minimal disruptions as a result of preemptive infrastructure investments and the response of our employees.

As a result of the extremely high market prices, NSP-Minnesota incurred net natural gas, fuel and purchased energy costs of approximately $230 million (largely deferred as regulatory assets). NSP-Minnesota partially mitigated the customer impact by approximately $40 million primarily through sales of excess generation.

Certain energy transactions are subject to final Independent System Operator re-settlement calculations and the impacts of credit losses shared among market participants. Such adjustments are not expected to be material to our results of operations, financial condition or cash flows.

Regulatory Overview — NSP-Minnesota has natural gas, fuel and purchased energy mechanisms in each jurisdiction for the purpose of recovering incurred costs. However, February cost increases were deferred for future recovery and recovery proposed over a period of up to two years in order to significantly mitigate the impact to customer bills. Additionally, NSP-Minnesota is not requesting recovery of associated financing costs in order to further limit the impact to our customers.

The following proceedings have been initiated:

Jurisdiction	Regulatory Status
Minnesota	NSP-Minnesota has filed its report with the MPUC detailing its preparedness and actions during the storm and proposing recovery of incremental costs from natural gas customers over 24 months with no financing charge. Comments are due in May 2021.
South Dakota	In April, NSP-Minnesota filed a letter with the South Dakota Public Utilities Commission noting that we were a net seller in the market, resulting in lower fuel clause costs.
North Dakota	NSP-Minnesota has filed its report with the North Dakota Public Service Commission detailing its preparedness and actions during the storm and proposing recovery of incremental costs from natural gas customers over 24 months with no financing charge.

Public Utility Regulation

The FERC and state and local regulatory commissions regulate NSP-Minnesota. NSP-Minnesota is subject to rate regulation by state utility regulatory agencies, which have jurisdiction with respect to the rates of electric and natural gas distribution companies in Minnesota, North Dakota and South Dakota.

Rates are designed to recover plant investment, operating costs and an allowed return on investment. NSP-Minnesota requests changes in utility rates through commission filings. Changes in operating costs can affect NSP-Minnesota’s financial results, depending on the timing of rate case filings and implementation of final rates. Other factors affecting rate filings are new investments, sales, conservation and demand side management efforts, and the cost of capital.

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In addition, the regulatory commissions authorize the ROE, capital structure and depreciation rates in rate proceedings. Decisions by these regulators can significantly impact NSP-Minnesota’s results of operations.

Except to the extent noted below, the circumstances set forth in Public Utility Regulation included in Item 7 of NSP-Minnesota’s Annual Report on Form 10-K for the year ended Dec. 31, 2020 appropriately represent, in all material respects, the current status of public utility regulation and are incorporated by reference.

Pending and Recently Concluded Regulatory Proceedings

Proceeding	Amount (in millions)	Filing Date	Approval
2020 North Dakota Electric Rate Case	$19	November 2020	Pending
2020 TCR Electric Rider	82	November 2019	Pending
2020 GUIC Natural Gas Rider	21	November 2019	Received
2021 GUIC Natural Gas Rider	27	October 2020	Pending
2020 RES Electric Rider	107	November 2019	Received
2021 RES Electric Rider	189	November 2020	Pending

Additional Information:

2020 Minnesota Electric Rate Case and Stay-Out Alternative — In November 2020, NSP-Minnesota filed an electric rate case seeking a $597 million revenue increase over three years with the MPUC. NSP-Minnesota also filed a stay-out alternative in which it would withdraw its rate case filing.

In December 2020, the MPUC verbally approved the stay-out alternative petition, which includes the extension of the sales, capital and property tax true-up mechanisms and delays any increase to the Nuclear Decommissioning Trust annual accrual until Jan. 1, 2022.

Additionally, NSP-Minnesota agreed to not seek recovery of incremental COVID-19 related expenses, including bad debt expense, and committed to fund $18 million in a Residential Payment Plan Credit Program or other similar customer relief programs, as directed by the MPUC. NSP-Minnesota also agreed to an earnings test in which all earnings above an ROE of 9.06% in 2021 would be refunded to customers.

In February 2021, NSP-Minnesota filed a letter highlighting an error in its calculation of its total deficiency and interim rates included in its November 2020 filing. This error would have reduced the filed deficiency and interim rates by approximately $43 million, should the rate case have proceeded, but has no impact on the stay-out alternative petition.

In April 2021, the MPUC issued an order approving NSP-Minnesota’s proposed true-ups and a requirement to withdraw NSP-Minnesota’s notice of change in rates, as well as establishing a comment period allowing parties to address the true-up discussed in the February letter.

2020 North Dakota Electric Rate Case — In November 2020 and revised in March 2021, NSP-Minnesota filed a rate case with the North Dakota Public Service Commission. NSP-Minnesota is requesting an increase in annual retail electric revenues of approximately $19 million. The rate filing is based on a 2021 forecast test year, a requested ROE of 10.2%, an equity ratio of 52.5% and an electric rate base of approximately $677 million. Interim rates, subject to refund, of approximately $16 million were implemented in January 2021 and subsequently revised to $13 million, effective April 1, 2021.

2020 TCR Electric Rider — In November 2019, NSP-Minnesota filed the TCR Rider based on an ROE of 9.06%. An MPUC decision is pending.

2020 GUIC Natural Gas Rider — In April 2021, the MPUC approved the 2020 GUIC Rider, based on an ROE of 9.04%.

2021 GUIC Natural Gas Rider — In October 2020, NSP-Minnesota filed the GUIC Rider based on an ROE of 9.04%. An MPUC decision is pending.

2020 RES Electric Rider — In November 2019, NSP-Minnesota filed the RES Rider. In March 2021, the MPUC voted to approve revenue requirements of $41 million for 2019 and $66 million for 2020. The filing included an ROE of 9.06%. The new rate will be implemented after the Commission Order is issued.

2021 RES Electric Rider — In November 2020, NSP-Minnesota filed the RES Rider. The requested amount includes a true-up for the 2019 and 2020 rider of $96 million and the 2021 requested amount of $93 million. The filing included an ROE of 9.06%. An MPUC decision is pending.

Minnesota Resource Plan — In July 2019, NSP-Minnesota filed its Minnesota resource plan, which runs through 2034. The plan is expected to result in an 80% carbon reduction by 2030 (from 2005) and puts NSP-Minnesota on a path to achieving its vision of being 100% carbon-free by 2050.

In June 2020, NSP-Minnesota filed a supplement to its resource plan. The updated preferred resource plan reflects the following:

•Retirement of all coal generation by 2030 with reduced operations at some units prior to retirement, including early retirement of the A.S. King coal plant (511 MW) in 2028 and the Sherco 3 coal plant (517 MW) in 2030.

•Extending the life of the Monticello nuclear plant from 2030 to 2040.

•Continuing to run the Prairie Island nuclear generating plant through current end of life (2033 and 2034).

•Construction of the Sherco combined cycle natural gas plant.

•The addition of 3,500 MW of solar.

•The addition of 2,250 MW of wind.

•2,600 MW of firm peaking (combustion turbine, pumped hydro, battery storage, demand response, etc.).

•Achieving 780 gigawatt hours in energy efficiency savings annually through 2034.

•Adding 400 MW of incremental demand response by 2023, and a total of 1,500 MW of demand response by 2034.

Initial comments were submitted Feb. 11, 2021 and reply comments are due June 25, 2021. The MPUC is anticipated to make a final decision during 2021.

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Minnesota Relief and Recovery — In 2020, the MPUC opened a docket and invited utilities in the state to submit potential projects that would create jobs and help jump start the economy to offset the impacts of COVID-19.

In January 2021, the MPUC approved the repowering of 651 MW of owned wind projects and 20 MW of wind projects under PPAs. These projects are estimated to save customers approximately $160 million over the next 25 years.

NSP-Minnesota’s remaining proposal (revised in April 2021) included the following:

•Acquire 120 MW repowered wind farm and buy-out of the remaining PPA from ALLETE for $210 million. An MPUC decision was requested by July 29, 2021.

•Add solar facilities of 460 MW with an incremental investment of $575 million.

•Provide $150 million of incremental electric vehicle rebates.

The MPUC is expected to address the solar facility, ALLETE repower acquisition and the electric vehicle proposal in the second half of 2021.

Minnesota State ROFR Statute Complaint — In September 2017, LSP Transmission filed a complaint in the Minnesota District Court against the Minnesota Attorney General, MPUC and DOC. The complaint was in response to MISO assigning a transmission project to NSP-Minnesota and ITC Midwest, LLC as the incumbent utilities, consistent with a Minnesota state ROFR statute.

The complaint challenged the constitutionality of the statute and is seeking declaratory judgment that the statute violates the Commerce Clause of the U.S. Constitution and should not be enforced. In June 2018, the Minnesota District Court granted Minnesota state agencies and NSP-Minnesota’s motions to dismiss with prejudice. In February 2020, the Eighth Circuit Court of Appeals upheld the Minnesota District Court decision to dismiss. In June 2020, the Eighth Circuit denied LSP Transmission’s petition for rehearing. On March 1, 2021, the Supreme Court denied review and the appeals process has ended.

Nuclear Power Operations

NSP-Minnesota owns two nuclear generating plants: the Monticello plant and the Prairie Island plant. See Note 12 to the consolidated financial statements of NSP-Minnesota’s Annual Report on Form 10-K for the year ended Dec. 31, 2020, for further information. The circumstances set forth in Nuclear Power Operations included in Item 7 of NSP-Minnesota’s Annual Report on Form 10-K for the year ended Dec. 31, 2020, appropriately represent, in all material respects, the current status of nuclear power operations, and are incorporated by reference.

Environmental

Environmental Regulation

In July 2019, the EPA adopted the Affordable Clean Energy rule, which requires states to develop plans by 2022 for greenhouse gas reductions from coal-fired power plants. In January 2021, the U.S. Court of Appeals for the D.C. Circuit issued a decision vacating and remanding the Affordable Clean Energy rule. That decision, if not successfully appealed or reconsidered, would allow the EPA to proceed with alternate regulation of coal-fired power plants. If the new rules require additional investment, NSP-Minnesota believes, based on prior state commission practices, that the cost of these initiatives or replacement generation would be recoverable through rates.

ITEM 4 — CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

NSP-Minnesota 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 March 31, 2021, based on an evaluation carried out under the supervision and with the participation of NSP-Minnesota’s management, including the CEO and CFO, of the effectiveness of its disclosure controls and procedures, the CEO and CFO have concluded that NSP-Minnesota’s disclosure controls and procedures were effective.

Internal Control Over Financial Reporting

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

Part II — OTHER INFORMATION

ITEM 1 — LEGAL PROCEEDINGS

NSP-Minnesota 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 NSP-Minnesota’s consolidated 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

NSP-Minnesota’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, 2020, which is incorporated herein by reference. There have been no material changes from the risk factors previously disclosed in the Form 10-K.

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ITEM 6 — EXHIBITS

* Indicates incorporation by reference

Exhibit Number	Description	Report or Registration Statement	Exhibit Reference
3.01*	Articles of Incorporation and Amendments of Northern Power Corp. (renamed NSP-Minnesota on Aug. 21, 2000)	NSP-Minnesota Form 10-12G dated Oct. 5, 2000	3.01
3.02*	Amended and Restated Bylaws of NSP-Minnesota, dated Jan. 25, 2019	NSP-Minnesota Form 10-K for the year ended Dec. 31, 2018	3.02
4.01	Supplemental Trust Indenture dated as of March 1, 2021 between Northern States Power Company and The Bank of New York Mellon Trust Company, N.A., as successor Trustee, creating $425,000,000 aggregate principal amount of 2.25% First Mortgage Bonds, Series due April 1, 2031 and $425,000,000 aggregate principal amount of 3.20% First Mortgage Bonds, Series due April 1, 2052.	NSP-Minnesota 8-K dated March 30, 2021	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	Certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS	Inline 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	Inline XBRL Schema
101.CAL	Inline XBRL Calculation
101.DEF	Inline XBRL Definition
101.LAB	Inline XBRL Label
101.PRE	Inline XBRL Presentation
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

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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.

		Northern States Power Company (a Minnesota corporation)
April 29, 2021	By:	/s/ JEFFREY S. SAVAGE
		Jeffrey S. Savage
		Senior Vice President, Controller
		(Principal Accounting Officer)
		/s/ BRIAN J. VAN ABEL
		Brian J. Van Abel
		Executive Vice President, Chief Financial Officer and Director
		(Principal Financial Officer)

23

EX-31.01

Exhibit 31.01

CERTIFICATION

I, Ben Fowke, certify that:

1.I have reviewed this report on Form 10-Q of Northern States Power Company (a Minnesota corporation);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: April 29, 2021

/s/ BEN FOWKE

Ben Fowke

Chairman, Chief Executive Officer and Director

(Principal Executive Officer)

1

EX-31.02

Exhibit 31.02

CERTIFICATION

I, Brian J. Van Abel, certify that:

1.I have reviewed this report on Form 10-Q of Northern States Power Company (a Minnesota corporation);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: April 29, 2021

/s/ BRIAN J. VAN ABEL

Brian J. Van Abel

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 Northern States Power Company, a Minnesota corporation (NSP-Minnesota) on Form 10-Q for the quarter ended March 31, 2021, as filed with the SEC on the date hereof (Form 10-Q), each of the undersigned officers of NSP-Minnesota 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 NSP-Minnesota as of the dates and for the periods expressed in the Form 10-Q.

Date: April 29, 2021

/s/ BEN FOWKE

Ben Fowke

Chairman, Chief Executive Officer and Director

(Principal Executive Officer)

/s/ BRIAN J. VAN ABEL

Brian J. Van Abel

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 NSP-Minnesota and will be retained by NSP-Minnesota and furnished to the SEC or its staff upon request.

1

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Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 29, 2021
Cover [Abstract]
Entity Registrant Name	NORTHERN STATES POWER CO
Entity Central Index Key	0001123852
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-31387
Entity Incorporation, State or Country Code	MN
Entity Tax Identification Number	41-1967505
Entity Address, Address Line One	414 Nicollet Mall
Entity Address, City or Town	Minneapolis
Entity Address, State or Province	MN
Entity Address, Postal Zip Code	55401
City Area Code	612
Local Phone Number	330-5500
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		1,000,000

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CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating revenues
Electric, non-affiliates	$ 1,024	$ 925
Electric, affiliates	115	110
Natural gas	204	206
Other	9	9
Total operating revenues	1,352	1,250
Operating expenses
Electric fuel and purchased power	433	364
Cost of natural gas sold and transported	125	125
Cost of sales — other	5	6
Operating and maintenance expenses	298	296
Conservation program expenses	34	31
Depreciation and amortization	221	202
Taxes (other than income taxes)	69	69
Total operating expenses	1,185	1,093
Operating income	167	157
Other income (expense), net	2	(5)
Allowance for funds used during construction — equity	7	7
Interest charges and financing costs
Interest charges — includes other financing costs of $2 and $2, respectively	63	61
Allowance for funds used during construction — debt	(3)	(3)
Total interest charges and financing costs	60	58
Income before income taxes	116	101
Income tax benefit	(12)	(6)
Net income	$ 128	$ 107

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CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Other financing costs	$ 2	$ 2

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Comprehensive income:
Net income	$ 128	$ 107
Derivative instruments:
Reclassification of losses to net income, net of tax of $— and $—, respectively	1	0
Total other comprehensive income	1	0
Total comprehensive income	$ 129	$ 107

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Reclassification of losses on derivatives to net income, tax	$ 0	$ 0

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CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net income	$ 128	$ 107
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	223	204
Nuclear fuel amortization	30	33
Deferred income taxes	(8)	(15)
Allowance for equity funds used during construction	(7)	(7)
Provision for bad debts	6	5
Net realized and unrealized hedging and derivatives transactions	(6)	9
Changes in operating assets and liabilities:
Accounts receivable	(12)	3
Accrued unbilled revenues	43	52
Inventories	38	20
Accounts payable	(38)	(43)
Net regulatory assets and liabilities	(268)	33
Other current liabilities	26	(4)
Pension and other employee benefit obligations	(36)	(48)
Other, net	(2)	(8)
Net cash provided by operating activities	117	341
Investing activities
Capital/construction expenditures	(474)	(274)
Purchase of investment securities	(199)	(835)
Proceeds from the sale of investment securities	194	830
Investments in utility money pool arrangement	0	(305)
Repayments from utility money pool arrangement	0	257
Other, net	(2)	1
Net cash used in investing activities	(481)	(326)
Financing activities
Repayments of short-term borrowings, net	(179)	(30)
Borrowings under utility money pool arrangement	434	118
Repayments under utility money pool arrangement	(434)	(118)
Proceeds from issuance of long-term debt	836	0
Capital contributions from parent	424	114
Dividends paid to parent	(106)	(94)
Other, net	0	(4)
Net cash provided by (used in) financing activities	975	(14)
Net change in cash, cash equivalents and restricted cash	611	1
Cash, cash equivalents and restricted cash at beginning of period	46	126
Cash, cash equivalents and restricted cash at end of period	657	127
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(72)	(75)
Cash received (paid) for income taxes, net	1	(6)
Other Noncash Investing and Financing Items [Abstract]
Accrued property, plant and equipment additions	222	67
Inventory transfers to property, plant and equipment	5	4
Allowance for equity funds used during construction	$ 7	$ 7

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CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash, cash equivalents and restricted cash at beginning of period	$ 657	$ 46
Accounts receivable, net	385	392
Accounts receivable from affiliates	20	32
Accrued unbilled revenues	205	248
Inventories	253	295
Regulatory assets	554	411
Derivative instruments	8	17
Prepayments and other	47	50
Total current assets	2,129	1,491
Property, plant and equipment, net	15,679	15,308
Other assets
Nuclear decommissioning fund and other investments	2,881	2,830
Regulatory assets	1,047	924
Derivative instruments	26	5
Operating lease right-of-use assets	469	488
Other	19	14
Total other assets	4,442	4,261
Total assets	22,250	21,060
Current liabilities
Short-term debt	0	179
Accounts payable	461	438
Accounts payable to affiliates	43	66
Regulatory liabilities	115	123
Taxes accrued	314	263
Accrued interest	58	72
Dividends payable to parent	108	106
Derivative instruments	15	22
Operating Lease, Liability, Current	91	85
Other	177	154
Total current liabilities	1,382	1,508
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net	1,854	1,840
Deferred investment tax credits	18	18
Regulatory liabilities	1,899	1,896
Asset retirement obligations	2,440	2,350
Derivative instruments	84	71
Pension and employee benefit obligations	155	192
Operating lease liabilities	416	443
Other	71	69
Total deferred credits and other liabilities	6,937	6,879
Capitalization
Long-term debt	6,741	5,904
Common stock — 5,000,000 shares authorized of $0.01 par value; 1,000,000 shares outstanding at March 31, 2021 and Dec. 31, 2020, respectively	$ 0	$ 0
Common Stock, Shares Authorized	5,000,000	5,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares, Outstanding	1,000,000	1,000,000
Additional paid in capital	$ 4,985	$ 4,585
Retained earnings	2,226	2,206
Accumulated other comprehensive loss	(21)	(22)
Total common stockholder's equity	7,190	6,769
Total liabilities and equity	$ 22,250	$ 21,060

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CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Common Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2019		1,000,000
Beginning balance at Dec. 31, 2019	$ 6,082	$ 0	$ 4,068	$ 2,036	$ (22)
Increase (Decrease) in Stockholders' Equity
Net income	107			107
Other comprehensive income	0
Dividends declared on common stock	(100)			(100)
Contribution of capital by parent	80		80
Balance (in shares) at Mar. 31, 2020		1,000,000
Ending balance at Mar. 31, 2020	$ 6,169	$ 0	4,148	2,043	(22)
Balance (in shares) at Dec. 31, 2020	1,000,000	1,000,000
Beginning balance at Dec. 31, 2020	$ 6,769	$ 0	4,585	2,206	(22)
Increase (Decrease) in Stockholders' Equity
Net income	128			128
Other comprehensive income	1				1
Dividends declared on common stock	(108)			(108)
Contribution of capital by parent	$ 400		400
Balance (in shares) at Mar. 31, 2021	1,000,000	1,000,000
Ending balance at Mar. 31, 2021	$ 7,190	$ 0	$ 4,985	$ 2,226	$ (21)

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Management's Opinion

3 Months Ended

Mar. 31, 2021

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 GAAP, the financial position of NSP-Minnesota and its subsidiaries as of March 31, 2021 and Dec. 31, 2020; the results of operations, including the components of net income, comprehensive income, cash flows and changes in stockholder’s equity for the three months ended March 31, 2021 and 2020.

All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2021 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, 2020 balance sheet information has been derived from the audited 2020 consolidated financial statements included in the NSP-Minnesota Annual Report on Form 10-K for the year ended Dec. 31, 2020.

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 NSP-Minnesota Annual Report on Form 10-K for the year ended Dec. 31, 2020, filed with the SEC on Feb. 17, 2021. Due to the seasonality of NSP-Minnesota’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

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Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	The significant accounting policies set forth in Note 1 to the consolidated financial statements in the NSP-Minnesota Annual Report on Form 10-K for the year ended Dec. 31, 2020, appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

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Accounting Pronouncements

3 Months Ended

Mar. 31, 2021

Accounting Standards Update and Change in Accounting Principle [Abstract]

Accounting Pronouncements

Recently Adopted

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.

NSP-Minnesota implemented the guidance using a modified-retrospective approach, recognizing a cumulative effect charge of $1 million (after tax) to retained earnings on Jan. 1, 2020. Other than first-time recognition of an allowance for bad debts on accrued unbilled revenues, the Jan. 1, 2020 adoption of ASC Topic 326 did not have a significant impact on NSP-Minnesota’s consolidated financial statements.

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Selected Balance Sheet Data

3 Months Ended

Mar. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Selected Balance Sheet Data

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Accounts receivable, net
Accounts receivable	$	422	$	425
Less allowance for bad debts	(37)		(33)
Accounts receivable, net	$	385	$	392

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Inventories
Materials and supplies	$	181	$	178
Fuel	66		90
Natural gas	6		27
Total inventories	$	253	$	295

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Property, plant and equipment, net
Electric plant	$	19,647	$	18,948
Natural gas plant	1,720		1,707
Common and other property	969		955
Plant to be retired (a)	127		136
Construction work in progress	965		1,150
Total property, plant and equipment	23,428		22,896
Less accumulated depreciation	(8,106)		(7,898)
Nuclear fuel	3,047		2,970
Less accumulated amortization	(2,690)		(2,660)
Property, plant and equipment, net	$	15,679	$	15,308

(a)Includes regulator-approved retirements of Sherco Units 1 and 2.

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Borrowings and Other Financing Instruments

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Borrowings and Other Financing Instruments

Short-Term Borrowings

NSP-Minnesota 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 NSP-Minnesota were as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2021			Year Ended Dec. 31, 2020
Borrowing limit	$	250		$	250
Amount outstanding at period end	—			—
Average amount outstanding	24			3
Maximum amount outstanding	236			116
Weighted average interest rate, computed on a daily basis	0.07		%	1.53		%
Weighted average interest rate at period end	N/A			N/A

Commercial Paper — Commercial paper outstanding for NSP-Minnesota was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2021			Year Ended Dec. 31, 2020
Borrowing limit	$	500		$	500
Amount outstanding at period end	—			179
Average amount outstanding	104			10
Maximum amount outstanding	317			179
Weighted average interest rate, computed on a daily basis	0.18		%	1.25		%
Weighted average interest rate at period end	N/A			0.18

Letters of Credit — NSP-Minnesota uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At March 31, 2021 and Dec. 31, 2020, there were $10 million of letters of credit outstanding under the credit facility. Amounts approximate their fair value and are subject to fees.

Revolving Credit Facility — In order to issue its commercial paper, NSP-Minnesota 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 exceeding available capacity under this credit facility. The line of credit provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

NSP-Minnesota 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 March 31, 2021, NSP-Minnesota had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Drawn (b)		Available
$	500	$	10	$	490

(a)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. NSP-Minnesota had no direct advances on the credit facility outstanding at March 31, 2021 and Dec. 31, 2020.

Bilateral Credit Agreement — In April 2021, the uncommitted bilateral credit agreement was renewed for an additional one-year term. The credit agreement is limited in use to support letters of credit.

As of March 31, 2021, NSP-Minnesota’s outstanding letters of credit under the Bilateral Credit Agreement were as follows:

(Millions of Dollars)	Limit		Amount Outstanding		Available
NSP-Minnesota	$	75	$	49	$	26

Long-Term Borrowings

During the three months ended March 31, 2021, NSP-Minnesota issued $425 million of 2.25% first mortgage bonds due April 1, 2031 and $425 million of 3.20% first mortgage bonds due April 1, 2052.

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Revenues

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Minnesota’s operating revenues consisted of the following:

	Three Months Ended March 31, 2021
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	326	$	114	$	7	$	447
C&I	416		79		—		495
Other	8		—		2		10
Total retail	750		193		9		952
Wholesale	98		—		—		98
Transmission	57		—		—		57
Interchange	115		—		—		115
Other	2		—		—		2
Total revenue from contracts with customers	1,022		193		9		1,224
Alternative revenue and other	117		11		—		128
Total revenues	$	1,139	$	204	$	9	$	1,352

	Three Months Ended March 31, 2020
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	300	$	114	$	7	$	421
C&I	445		82		—		527
Other	7		—		2		9
Total retail	752		196		9		957
Wholesale	45		—		—		45
Transmission	56		—		—		56
Interchange	110		—		—		110
Other	2		1		—		3
Total revenue from contracts with customers	965		197		9		1,171
Alternative revenue and other	70		9		—		79
Total revenues	$	1,035	$	206	$	9	$	1,250

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Income Taxes

3 Months Ended

Mar. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

6.    Income Taxes

Note 7 to the consolidated financial statements included in NSP-Minnesota’s Annual Report on Form 10-K for the year ended Dec. 31, 2020 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:

	Three Months Ended March 31
	2021		2020 (a)
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	7.0		7.1
Increases (decreases) in tax from:
Wind PTCs	(30.4)		(24.8)
Plant regulatory differences (b)	(7.8)		(8.3)
Other tax credits, net NOL & tax credit allowances	(1.3)		(1.5)
Other (net)	1.2		0.6
Effective income tax rate	(10.3)	%	(5.9)	%

(a)     Prior periods have been restated to conform to current year presentation.

(b) Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reduction.

Federal Audits — NSP-Minnesota 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 Years	Expiration
2014 - 2016	January 2022
2017	September 2021

Additionally, the statute of limitations related to a federal tax loss carryback claim filed in 2020 has been extended. 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.

State Audits — NSP-Minnesota is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of March 31, 2021, NSP-Minnesota’s earliest open tax year subject to examination by state taxing authorities under applicable statutes of limitations is 2013. In July 2020, Minnesota began a review of tax years 2015-2018. In February 2021, Minnesota concluded its review and commenced an audit of the same tax years. As of March 31, 2021, no material adjustments have been proposed.

Unrecognized Benefits — The 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)	March 31, 2021		Dec. 31, 2020
Unrecognized tax benefit — Permanent tax positions	$	21	$	21
Unrecognized tax benefit — Temporary tax positions	3		3
Total unrecognized tax benefit	$	24	$	24

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

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
NOL and tax credit carryforwards	$	(11)	$	(11)

As IRS audits resume and the state audit progresses, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $15 million in the next 12 months.

Payable for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards.

Interest payable related to unrecognized tax benefits:

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Payable for interest related to unrecognized tax benefits at beginning of period	$	(2)	$	(2)
Interest expense related to unrecognized tax benefits	—		—
Payable for interest related to unrecognized tax benefits at end of period	$	(2)	$	(2)

No amounts were accrued for penalties related to unrecognized tax benefits as of March 31, 2021 or Dec. 31, 2020.

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Fair Value of Financial Assets and Liabilities

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

Fair Value Measurements

Accounting guidance for fair value measurements and disclosures provides a single definition of fair value and requires disclosures about assets and liabilities measured at fair value. A hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value is established by this guidance.

•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 NAV.

Investments in equity securities and other funds — Equity securities are valued using quoted prices in active markets. The fair values for commingled funds are measured using NAVs. The investments in commingled funds may be redeemed for NAV with proper notice. Private equity commingled fund investments require approval of the fund for any unscheduled redemption, and such redemptions may be approved or denied by the fund at its sole discretion.

Unscheduled distributions from real estate commingled funds’ investments may be redeemed with proper notice, however, may be delayed or discounted as a result of fund illiquidity.

Investments in debt securities — Fair values for debt securities are determined by a third-party pricing service using recent trades and observable spreads from benchmark interest rates for similar securities.

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 utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations and are generally assigned a Level 2 classification. When contractual settlements relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable forecasts of forward prices and volatilities on a valuation is evaluated, and may result in Level 3 classification.

Electric commodity derivatives held by NSP-Minnesota include transmission congestion instruments, generally referred to as FTRs. FTRs purchased from a RTO are financial instruments that entitle or obligate the holder to monthly revenues or charges based on transmission congestion across a given transmission path. The value of an FTR is derived from, and designed to offset, the cost of transmission congestion. In addition to overall transmission load, congestion is also influenced by the operating schedules of power plants and the consumption of electricity pertinent to a given transmission path. Unplanned plant outages, scheduled plant maintenance, changes in the relative costs of fuels used in generation, weather and overall changes in demand for electricity can each impact the operating schedules of the power plants on the transmission grid and the value of an FTR.

If forecasted costs of electric transmission congestion increase or decrease for a given FTR path, the value of that particular FTR instrument will likewise increase or decrease. Given the limited observability of certain inputs to the value of FTRs between auction processes, including expected plant operating schedules and retail and wholesale demand, fair value measurements for FTRs have been assigned a Level 3.

Non-trading monthly FTR settlements are included in fuel and purchased energy cost recovery mechanisms, and therefore changes in the fair value of the yet to be settled portions of most FTRs are deferred as a regulatory asset or liability. Given this regulatory treatment and the limited magnitude of NSP-Minnesota’s FTRs relative to its electric utility operations, the numerous unobservable quantitative inputs pertinent to the value of FTRs are immaterial to the consolidated financial statements of NSP-Minnesota.

Non-Derivative Fair Value Measurements

The Nuclear Regulatory Commission requires NSP-Minnesota to maintain a portfolio of investments to fund the costs of decommissioning its nuclear generating plants. Assets of the nuclear decommissioning fund are legally restricted for the purpose of decommissioning these facilities. The fund contains cash equivalents, debt securities, equity securities and other investments. NSP-Minnesota uses the MPUC approved asset allocation for the escrow and investment targets by asset class for both the escrow and qualified trust.

NSP-Minnesota recognizes the costs of funding the decommissioning over the lives of the nuclear plants, assuming rate recovery of all costs. Realized and unrealized gains on fund investments over the life of the fund are deferred as an offset of NSP-Minnesota’s regulatory asset for nuclear decommissioning costs. Consequently, any realized and unrealized gains and losses on securities in the nuclear decommissioning fund are deferred as a component of the regulatory asset.

Unrealized gains for the nuclear decommissioning fund were $1 billion and $981 million as of March 31, 2021 and Dec. 31, 2020, respectively, and unrealized losses were $8 million and $5 million as of March 31, 2021 and Dec. 31, 2020, respectively.

Non-derivative instruments with recurring fair value measurements in the nuclear decommissioning fund:

	March 31, 2021
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	32	$	32	$	—	$	—	$	—	$	32
Commingled funds	795		—		—		—		1,052		1,052
Debt securities	562		—		573		13		—		586
Equity securities	444		1,153		2		—		—		1,155
Total	$	1,833	$	1,185	$	575	$	13	$	1,052	$	2,825

(a)Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $56 million of rabbi trust assets and miscellaneous investments.

	Dec. 31, 2020
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	40	$	40	$	—	$	—	$	—	$	40
Commingled funds	787		—		—		—		1,041		1,041
Debt securities	528		—		572		13		—		585
Equity securities	446		1,109		2		—		—		1,111
Total	$	1,801	$	1,149	$	574	$	13	$	1,041	$	2,777

(a)Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $53 million of rabbi trust assets and miscellaneous investments.

For the three months ended March 31, 2021 and 2020, there were immaterial Level 3 nuclear decommissioning fund investments or transfer of amounts between levels.

Contractual maturity dates of debt securities in the nuclear decommissioning fund as of March 31, 2021:

	Final Contractual Maturity
(Millions of Dollars)	Due in 1 year or Less		Due in 1 to 5 Years		Due in 5 to 10 Years		Due after 10 Years		Total
Debt securities	$	3	$	133	$	202	$	248	$	586

Rabbi Trusts

NSP-Minnesota has established a rabbi trust to provide partial funding for future deferred compensation plan distributions.

Cost and fair value of assets held in rabbi trusts:

	March 31, 2021
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	6	$	6	$	—	$	—	$	6
Mutual funds	10		12		—		—		12
Total	$	16	$	18	$	—	$	—	$	18

	Dec. 31, 2020
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	1	$	1	$	—	$	—	$	1
Mutual funds	14		16		—		—		16
Total	$	15	$	17	$	—	$	—	$	17

(a)    Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets.

Derivative Instruments Fair Value Measurements

NSP-Minnesota 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 — NSP-Minnesota 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, with changes in fair value prior to settlement recorded as other comprehensive income.

At March 31, 2021, accumulated other comprehensive loss related to settled interest rate derivatives included $1 million of net losses expected to be reclassified into earnings during the next 12 months as the hedged interest rate transactions impact earnings. As of March 31, 2021, NSP-Minnesota had no unsettled interest rate derivatives.

Wholesale and Commodity Trading Risk — NSP-Minnesota 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. NSP-Minnesota 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. Sharing of any margins is determined through state regulatory proceedings as well as the operation of the FERC approved joint operating agreement.

Commodity Derivatives — NSP-Minnesota 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, FTRs, vehicle fuel, and weather derivatives.

At March 31, 2021, NSP-Minnesota had no commodity contracts designated as cash flow hedges. NSP-Minnesota 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. The classification as a regulatory asset or liability, if applicable, is based on approved regulatory recovery mechanisms.

NSP-Minnesota 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, options and FTRs:

(Amounts in Millions) (a)(b)	March 31, 2021	Dec. 31, 2020
Megawatt hours of electricity	49	65
Million British thermal units of natural gas	77	83

(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 — NSP-Minnesota continuously monitors the creditworthiness of 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. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets.

NSP-Minnesota’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.

As of March 31, 2021, six of NSP-Minnesota’s ten most significant counterparties for these activities, comprising $26 million, or 52%, of this credit exposure, had investment grade credit ratings from S&P Global Ratings, Moody’s Investor Services or Fitch Ratings. Three of the ten most significant counterparties, comprising $10 million, or 20%, of this credit exposure, were not rated by these external agencies, but based on NSP-Minnesota’s internal analysis, had credit quality consistent with investment grade. One of these significant counterparties, comprising $8 million or 16% of this credit exposure, had credit quality less than investment grade, based on internal analysis. Eight of these significant counterparties are municipal or cooperative electric entities, RTOs or other utilities.

The impact of derivative activity:

	Pre-Tax Fair Value Gains (Losses) Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss		Regulatory (Assets) and Liabilities
Three Months Ended March 31, 2021
Other derivative instruments
Natural gas commodity	$	—	$	1
Total	$	—	$	1

As of March 31, 2020, NSP-Minnesota had no activity for electric and natural gas commodity derivatives that were recognized in regulatory (assets) and liabilities.

	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 March 31, 2021
Other derivative instruments
Commodity trading	$	—	$	—		$	31	(a)
Electric commodity	—		(1)		(b)	—
Natural gas commodity	—		1		(c)	(3)		(c)
Total	$	—	$	—		$	28

	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 March 31, 2020
Other derivative instruments
Commodity trading	$	—	$	—		$	4	(a)
Electric commodity	—		(1)		(b)	—
Natural gas commodity	—		1		(c)	(2)		(c)
Total	$	—	$	—		$	2

(a)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.

(b)Amounts are recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

(c)Amounts are recorded to cost of natural gas sold and transported. These derivative settlement gains and losses are shared with natural gas customers through purchased natural gas cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

NSP-Minnesota had no derivative instruments designated as fair value hedges during the three months ended March 31, 2021 and 2020.

Credit Related Contingent Features — Contract provisions for derivative instruments that NSP-Minnesota 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 NSP-Minnesota’s credit ratings are downgraded below its investment grade credit rating by any of the major credit rating agencies. As of both March 31, 2021 and Dec. 31, 2020, there were $4 million derivative liabilities with such underlying contract provisions. Certain contracts also contain cross default provisions that may require the posting of collateral or settlement of the contracts if there was a failure under the other financing arrangements related to payment terms or other covenants. As of March 31, 2021 and Dec. 31, 2020, there were approximately $29 million and $14 million, respectively, of derivative liabilities with such underlying contract provisions.

Certain derivative instruments are also subject to contract provisions that contain adequate assurance clauses. Provisions allow counterparties to seek performance assurance, including cash collateral, in the event that NSP-Minnesota’s ability to fulfill its contractual obligations is reasonably expected to be impaired. NSP-Minnesota had no collateral posted related to adequate assurance clauses in derivative contracts as of March 31, 2021 and Dec. 31, 2020.

Recurring Fair Value Measurements — NSP-Minnesota’s derivative assets and liabilities measured at fair value on a recurring basis:

	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative assets
Other derivative instruments:
Commodity trading	$	1	$	23	$	—	$	24	$	(21)	$	3	$	1	$	26	$	—	$	27	$	(25)	$	2
Electric commodity	—		—		6		6		(1)		5		—		—		13		13		(1)		12
Natural gas commodity	—		—		—		—		—		—		—		3		—		3		—		3
Total current derivative assets	$	1	$	23	$	6	$	30	$	(22)	$	8	$	1	$	29	$	13	$	43	$	(26)	$	17
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	5	$	33	$	28	$	66	$	(40)	$	26	$	7	$	39	$	—	$	46	$	(41)	$	5
Total noncurrent derivative assets	$	5	$	33	$	28	$	66	$	(40)	$	26	$	7	$	39	$	—	$	46	$	(41)	$	5

	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative liabilities
Other derivative instruments:
Commodity trading	$	4	$	22	$	5	$	31	$	(29)	$	2	$	3	$	18	$	10	$	31	$	(25)	$	6
Electric commodity	—		—		—		—		—		—		—		—		1		1		(1)		—
Natural gas commodity	—		—		—		—		—		—		—		2		—		2		—		2
Total current derivative liabilities	$	4	$	22	$	5	$	31	$	(29)	2		$	3	$	20	$	11	$	34	$	(26)	8
PPAs (b)											13												14
Current derivative instruments											$	15											$	22
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	2	$	50	$	17	$	69	$	(30)	$	39	$	2	$	35	$	13	$	50	$	(27)	$	23
Total noncurrent derivative liabilities	$	2	$	50	$	17	$	69	$	(30)	39		$	2	$	35	$	13	$	50	$	(27)	23
PPAs (b)											45												48
Noncurrent derivative instruments											$	84											$	71

(a)NSP-Minnesota nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at March 31, 2021 and Dec. 31, 2020. At both March 31, 2021 and Dec. 31, 2020, derivative assets and liabilities include $15 million of obligations to return cash collateral. At March 31, 2021 and Dec. 31, 2020 derivative assets and liabilities include rights to reclaim cash collateral of $11 million and $1 million, respectively. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)During 2006, Xcel Energy 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.

Changes in Level 3 commodity derivatives for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Balance at Jan. 1	$	(11)	$	5
Settlements	(7)		(12)
Net transactions recorded during the period:
Gains recognized in earnings (a)	30		6
Net gains recognized as regulatory assets and liabilities	—		3
Balance at March 31	$	12	$	2

(a)Level 3 gains recognized in earnings are subject to offsetting losses of derivative instruments categorized as levels 1 and 2 in the income statement.

NSP-Minnesota recognizes transfers between levels as of the beginning of each period. There were no transfers of amounts between levels for derivative instruments for the three months ended March 31, 2021 and 2020.

Fair Value of Long-Term Debt

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

	March 31, 2021				Dec. 31, 2020
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	6,741	$	7,491	$	5,904	$	7,391

Fair value of NSP-Minnesota’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 March 31, 2021 and Dec. 31, 2020 and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

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Benefit Plans and Other Postretirement Benefits

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Benefit Plans and Other Postretirement Benefits

Components of Net Periodic Benefit Cost

	Three Months Ended March 31
	2021		2020		2021		2020
(Millions of Dollars)	Pension Benefits				Postretirement Health Care Benefits
Service cost	$	7	$	7	$	—	$	—
Interest cost (a)	6		8		1		1
Expected return on plan assets (a)	(13)		(14)		—		—
Amortization of prior service credit (a)	—		—		(1)		(1)
Amortization of net loss (a)	9		8		—		—
Net periodic benefit cost	9		9		—		—
Effects of regulation	(1)		(1)		—		—
Net benefit cost recognized for financial reporting	$	8	$	8	$	—	$	—

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

In January 2021, contributions of $125 million were made across four of Xcel Energy’s pension plans, of which $33 was attributable to NSP-Minnesota. Xcel Energy does not expect additional pension contributions during 2021.

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2021

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Legal

NSP-Minnesota 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, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Minnesota’s consolidated financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred.

Rate Matters and Other

Sherco — In 2018, NSP-Minnesota and SMMPA (Co-owner of Sherco Unit 3) reached a settlement with GE related to a 2011 incident, which damaged the turbine at Sherco Unit 3 and resulted in an extended outage for repair. NSP-Minnesota notified the MPUC of its proposal to refund settlement proceeds to customers through the FCA.

In March 2019, the MPUC approved NSP-Minnesota’s refund proposal. Additionally, the MPUC decided to withhold any decision as to NSP-Minnesota’s prudence in connection with the incident at Sherco Unit 3 until after conclusion of an appeal pending between GE and NSP-Minnesota’s insurers. In February 2020, the Minnesota Court of Appeals affirmed the district court’s judgment in favor of GE. In March 2020, NSP-Minnesota’s insurers filed a petition seeking additional review by the Minnesota Supreme Court.

In April 2020, the Minnesota Supreme Court denied the insurers’ petition for further review, ending the litigation. In accordance with a prior MPUC order, NSP-Minnesota made a compliance filing in August 2020 detailing all costs that resulted from the outage and all insurance recoveries received by NSP-Minnesota in connection with the outage.

In January 2021, the Minnesota Office of the Attorney General and DOC filed comments recommending that NSP-Minnesota refund approximately $17 million of replacement power costs previously recovered through the FCA. On Jan. 27, 2021, NSP-Minnesota filed its response, asserting that it acted prudently in connection with the Sherco Unit 3 outage, the MPUC has previously disallowed $22 million of related costs and no additional refund or disallowance is appropriate. A final decision by the MPUC is pending. A loss related to this matter is deemed remote.

Westmoreland Arbitration — In November 2014, insurers for Westmoreland Coal Company filed an arbitration demand against NSP-Minnesota, SMMPA and Western Fuels Association, seeking recovery of alleged business losses due to a turbine failure at Sherco Unit 3. The Westmoreland insurers claim NSP-Minnesota’s invocation of the force majeure clause to stop the supply of coal was improper because the incident was allegedly caused by NSP-Minnesota’s failure to conform to industry maintenance standards. Westmoreland’s insurers quantified their losses as approximately $36 million.

Arbitration was delayed pending resolution of a separate lawsuit brought by NSP-Minnesota, SMMPA, and their insurers against various GE entities based on the inspection and maintenance advice GE provided for Sherco Unit 3. In July 2020, following the conclusion of the appeal that fully resolved the GE litigation, Westmoreland’s insurers served notice, which triggered the arbitration to resume.

NSP-Minnesota denies the claims asserted by the Westmoreland insurers and believes it properly stopped the supply of coal based upon the force majeure provision. It is uncertain when a final resolution will occur, but it is unlikely an arbitration hearing will take place before the fourth quarter 2021. At this stage of the proceeding, a reasonable estimate of damages or range of damages cannot be determined.

MISO ROE Complaints — In November 2013 and February 2015, customer groups filed two ROE complaints against MISO TOs, which includes NSP-Minnesota and NSP-Wisconsin. The first complaint requested a reduction in base ROE transmission formula rates from 12.38% to 9.15% for the time period of Nov. 12, 2013 to Feb. 11, 2015, and removal of ROE adders (including those for RTO membership). The second complaint requested, for a subsequent time period, a base ROE reduction from 12.38% to 8.67%.

In September 2016, the FERC issued an order (Opinion No. 551) granting a 10.32% base ROE effective for the first complaint period of Nov. 12, 2013 to Feb. 11, 2015 and subsequent to the date of the order. The D.C Circuit subsequently vacated and remanded Opinion No. 551.

In November 2019, the FERC issued an order (Opinion No. 569), which set the MISO base ROE at 9.88%, effective Sept. 28, 2016 and for the first complaint period. The FERC also dismissed the second complaint. In December 2019, MISO TOs filed a request for rehearing regarding the new ROE methodology announced in Opinion No. 569. Customers also filed requests for rehearing claiming, among other points, that the FERC erred by dismissing the second complaint without refunds.

In May 2020, the FERC issued an order (Opinion No. 569-A) which granted rehearing in part to Opinion 569 and further refined the FERC’s ROE methodology, most significantly to incorporate the risk premium model (in addition to the discounted cash flow and capital asset pricing models), resulting in a new base ROE of 10.02%, effective Sept. 28, 2016 and for the first complaint period. The FERC also affirmed its decision in Opinion No. 569 to dismiss the second complaint.

In November 2020, the FERC issued an order (Opinion No. 569-B) in response to rehearing requests. The FERC corrected certain inputs to its ROE calculation model, did not change the ROE effective Sept. 28, 2016, and for the first MISO complaint period and upheld its decision to deny refunds for the second complaint period. NSP-Minnesota has recognized a liability for its best estimate of final refunds to customers. Each 10 basis point reduction in ROE for the first complaint period, second complaint period, and subsequent period relative to amounts accrued would reduce Xcel Energy’s net income by $1 million, $1 million, and $2 million, respectively.

The MISO TOs and various parties have filed petitions for review of Opinion Nos. 569, 569-A and 569-B at the D.C. Circuit with initial briefs filed in March 2021.

FERC NOPR on ROE Incentive Adders — In April 2021, the FERC issued a NOPR proposing to limit collection of ROE incentive adders for RTO membership to the first three years after an entity begins participation in an RTO. If adopted as a final rule, following a comment period expected to be complete by the end of 2021 or 2022, NSP-Minnesota, NSP-Wisconsin and SPS would prospectively discontinue charging their current 0.5% ROE incentive adders. Amounts related to a discontinuance of the adder would ultimately be offset by an increase in retail rates.

Environmental

MGP, Landfill and Disposal Sites

NSP-Minnesota is currently investigating, remediating or performing post-closure actions at seven MGP, landfill or other disposal sites across its service territories.

NSP-Minnesota 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 costs incurred.

Environmental Requirements — Water and Waste

Coal Ash Regulation — NSP-Minnesota’s operations are subject to federal and state regulations 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. Currently, NSP-Minnesota has three regulated ash units in operation.

NSP-Minnesota is conducting groundwater sampling and monitoring and implementing assessment of corrective measures at certain CCR landfills and surface impoundments. No results above the groundwater protection standards in the rule were identified. Until NSP-Minnesota completes its assessment, it is uncertain what impact, if any, there will be on the operations, financial condition or cash flows.

In August 2020, the EPA published its final rule to implement a cease receipt and initiate a closure date of April 2021 for all CCR impoundments affected by the August 2018 D.C. Circuit ruling. The D.C. Circuit concluded that the EPA cannot allow utilities to continue to use unlined impoundments (including clay lined impoundments) for the storage or disposal of coal ash. This final rule required Xcel Energy to expedite closure plans for one impoundment.

In October 2020, NSP-Minnesota completed construction and placed in service a new impoundment to replace the clay lined impoundment at a cost of $9 million. With the new ash pond in service, NSP-Minnesota has initiated closure activities for the existing ash pond at an estimated cost of $4 million. NSP-Minnesota has five years to complete closure activities.

Closure costs for existing impoundments are included in the calculation of the asset retirement obligation.

Leases

NSP-Minnesota evaluates contracts that may contain leases, including PPAs and arrangements for the use of office space and other facilities, vehicles and equipment. A contract contains a lease if it conveys the exclusive right to control the use of a specific asset.

Components of lease expense:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Operating leases
PPA capacity payments	$	19	$	21
Other operating leases (a)	2		2
Total operating lease expense (b)	$	21	$	23

(a)Includes immaterial short-term lease expense for 2021 and 2020, respectively.

(a)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.

Commitments under operating leases as of March 31, 2021:

(Millions of Dollars)	PPA Operating Leases		Other Operating Leases		Total Operating Leases
Total minimum obligation	$	485	$	79	$	564
Interest component of obligation	(43)		(14)		(57)
Present value of minimum obligation	$	442	$	65	507
Less current portion					(91)
Noncurrent operating lease liabilities					$	416

VIEs

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

NSP-Minnesota had approximately 1,347 MW of capacity under long-term PPAs at both March 31, 2021 and Dec. 31, 2020 with entities that have been determined to be VIEs. NSP-Minnesota concluded that these entities are not required to be consolidated in its consolidated financial statements because it does not have the power to direct the activities that most significantly impact the entities’ economic performance. The PPAs have expiration dates through 2039.

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Other Comprehensive Income (Loss)

3 Months Ended

Mar. 31, 2021

Stockholders' Equity Note [Abstract]

Other Comprehensive Income (Loss)

10. Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive income (loss), net of tax, for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31, 2021						Three Months Ended March 31, 2020
(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	$	(19)	$	(3)	$	(22)	$	(19)	$	(3)	$	(22)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives, net of tax of $— and $—, respectively (a)	1		—		1		—		—		—
Accumulated other comprehensive loss at March 31	$	(18)	$	(3)	$	(21)	$	(19)	$	(3)	$	(22)

(a)Included in interest charges.

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Segment Information

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Segment Information

NSP-Minnesota 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.

NSP-Minnesota has the following reportable segments:

•Regulated Electric — The regulated electric utility segment generates electricity which is transmitted and distributed in Minnesota, North Dakota and South Dakota. In addition, this segment includes sales for resale and provides wholesale transmission service to various entities in the United States. The regulated electric utility segment also includes NSP-Minnesota’s wholesale commodity and trading operations.

•Regulated Natural Gas — The regulated natural gas utility segment transports, stores and distributes natural gas in portions of Minnesota and North Dakota.

NSP-Minnesota also presents All Other, which includes operating segments with revenues below the necessary quantitative thresholds. Those operating segments primarily include appliance repair services, non-utility real estate activities and revenues associated with processing solid waste into refuse-derived fuel.

Asset and capital expenditure information is not provided for NSP-Minnesota’s reportable segments. As an integrated electric and natural gas utility, NSP-Minnesota 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.

NSP-Minnesota’s segment information:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Regulated Electric
Total revenues (a)	$	1,139	$	1,035
Net income	107		86
Regulated Natural Gas
Total revenues (b)	$	204	$	206
Net income	20		23
All Other
Total revenues	$	9	$	9
Net income (loss)	1		(2)
Consolidated Total
Total revenues (a)(b)	$	1,352	$	1,250
Net income	128		107

(a)    Total revenues include $115 million and $110 million of affiliate electric revenue for the three months ended March 31, 2021 and 2020.

(b)    Total revenues include an immaterial amount of affiliate gas revenue for the three months ended March 31, 2021 and 2020.

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Selected Balance Sheet Data (Tables)

3 Months Ended

Mar. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Accounts Receivable, Net

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Accounts receivable, net
Accounts receivable	$	422	$	425
Less allowance for bad debts	(37)		(33)
Accounts receivable, net	$	385	$	392

Inventories

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Inventories
Materials and supplies	$	181	$	178
Fuel	66		90
Natural gas	6		27
Total inventories	$	253	$	295

Property, plant and equipment, net

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Property, plant and equipment, net
Electric plant	$	19,647	$	18,948
Natural gas plant	1,720		1,707
Common and other property	969		955
Plant to be retired (a)	127		136
Construction work in progress	965		1,150
Total property, plant and equipment	23,428		22,896
Less accumulated depreciation	(8,106)		(7,898)
Nuclear fuel	3,047		2,970
Less accumulated amortization	(2,690)		(2,660)
Property, plant and equipment, net	$	15,679	$	15,308

(a)Includes regulator-approved retirements of Sherco Units 1 and 2.

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Borrowings and Other Financing Instruments (Tables)

3 Months Ended

Mar. 31, 2021

Borrowings and Other Financing Instruments [Abstract]

Credit Facilities

At March 31, 2021, NSP-Minnesota had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Drawn (b)		Available
$	500	$	10	$	490

(a)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 NSP-Minnesota were as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2021			Year Ended Dec. 31, 2020
Borrowing limit	$	250		$	250
Amount outstanding at period end	—			—
Average amount outstanding	24			3
Maximum amount outstanding	236			116
Weighted average interest rate, computed on a daily basis	0.07		%	1.53		%
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 NSP-Minnesota was as follows:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2021			Year Ended Dec. 31, 2020
Borrowing limit	$	500		$	500
Amount outstanding at period end	—			179
Average amount outstanding	104			10
Maximum amount outstanding	317			179
Weighted average interest rate, computed on a daily basis	0.18		%	1.25		%
Weighted average interest rate at period end	N/A			0.18

Bilateral Credit Agreement | Letter of Credit

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

As of March 31, 2021, NSP-Minnesota’s outstanding letters of credit under the Bilateral Credit Agreement were as follows:

(Millions of Dollars)	Limit		Amount Outstanding		Available
NSP-Minnesota	$	75	$	49	$	26

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Revenues (Tables)

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

NSP-Minnesota’s operating revenues consisted of the following:

	Three Months Ended March 31, 2021
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	326	$	114	$	7	$	447
C&I	416		79		—		495
Other	8		—		2		10
Total retail	750		193		9		952
Wholesale	98		—		—		98
Transmission	57		—		—		57
Interchange	115		—		—		115
Other	2		—		—		2
Total revenue from contracts with customers	1,022		193		9		1,224
Alternative revenue and other	117		11		—		128
Total revenues	$	1,139	$	204	$	9	$	1,352

	Three Months Ended March 31, 2020
(Millions of Dollars)	Electric		Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	300	$	114	$	7	$	421
C&I	445		82		—		527
Other	7		—		2		9
Total retail	752		196		9		957
Wholesale	45		—		—		45
Transmission	56		—		—		56
Interchange	110		—		—		110
Other	2		1		—		3
Total revenue from contracts with customers	965		197		9		1,171
Alternative revenue and other	70		9		—		79
Total revenues	$	1,035	$	206	$	9	$	1,250

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Income Taxes (Tables)

3 Months Ended

Mar. 31, 2021

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:

	Three Months Ended March 31
	2021		2020 (a)
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	7.0		7.1
Increases (decreases) in tax from:
Wind PTCs	(30.4)		(24.8)
Plant regulatory differences (b)	(7.8)		(8.3)
Other tax credits, net NOL & tax credit allowances	(1.3)		(1.5)
Other (net)	1.2		0.6
Effective income tax rate	(10.3)	%	(5.9)	%

(a)     Prior periods have been restated to conform to current year presentation.

(b) Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reduction.

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

Federal Audits — NSP-Minnesota 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 Years	Expiration
2014 - 2016	January 2022
2017	September 2021

Reconciliation of Unrecognized Tax Benefits

Unrecognized tax benefits — permanent vs. temporary:

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Unrecognized tax benefit — Permanent tax positions	$	21	$	21
Unrecognized tax benefit — Temporary tax positions	3		3
Total unrecognized tax benefit	$	24	$	24

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)	March 31, 2021		Dec. 31, 2020
NOL and tax credit carryforwards	$	(11)	$	(11)

Interest Payable related to Unrecognized Tax Benefits [Table Text Block]

Interest payable related to unrecognized tax benefits:

(Millions of Dollars)	March 31, 2021		Dec. 31, 2020
Payable for interest related to unrecognized tax benefits at beginning of period	$	(2)	$	(2)
Interest expense related to unrecognized tax benefits	—		—
Payable for interest related to unrecognized tax benefits at end of period	$	(2)	$	(2)

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Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Cost and Fair Value of Nuclear Decommissioning Fund Investments

Non-derivative instruments with recurring fair value measurements in the nuclear decommissioning fund:

	March 31, 2021
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	32	$	32	$	—	$	—	$	—	$	32
Commingled funds	795		—		—		—		1,052		1,052
Debt securities	562		—		573		13		—		586
Equity securities	444		1,153		2		—		—		1,155
Total	$	1,833	$	1,185	$	575	$	13	$	1,052	$	2,825

(a)Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $56 million of rabbi trust assets and miscellaneous investments.

	Dec. 31, 2020
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		NAV		Total
Nuclear decommissioning fund (a)
Cash equivalents	$	40	$	40	$	—	$	—	$	—	$	40
Commingled funds	787		—		—		—		1,041		1,041
Debt securities	528		—		572		13		—		585
Equity securities	446		1,109		2		—		—		1,111
Total	$	1,801	$	1,149	$	574	$	13	$	1,041	$	2,777

(a)Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $53 million of rabbi trust assets and miscellaneous investments.

Final Contractual Maturity Dates of Debt Securities in the Nuclear Decommissioning Fund by Asset Class

Contractual maturity dates of debt securities in the nuclear decommissioning fund as of March 31, 2021:

	Final Contractual Maturity
(Millions of Dollars)	Due in 1 year or Less		Due in 1 to 5 Years		Due in 5 to 10 Years		Due after 10 Years		Total
Debt securities	$	3	$	133	$	202	$	248	$	586

Rabbi Trust Securities Amortized Cost and Fair Value Measured on Recurrring Basis [Table Text Block]

Cost and fair value of assets held in rabbi trusts:

	March 31, 2021
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	6	$	6	$	—	$	—	$	6
Mutual funds	10		12		—		—		12
Total	$	16	$	18	$	—	$	—	$	18

	Dec. 31, 2020
			Fair Value
(Millions of Dollars)	Cost		Level 1		Level 2		Level 3		Total
Rabbi Trusts (a)
Cash equivalents	$	1	$	1	$	—	$	—	$	1
Mutual funds	14		16		—		—		16
Total	$	15	$	17	$	—	$	—	$	17

(a)    Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets.

Gross Notional Amounts of Commodity Forwards, Options, and FTRs

Gross notional amounts of commodity forwards, options and FTRs:

(Amounts in Millions) (a)(b)	March 31, 2021	Dec. 31, 2020
Megawatt hours of electricity	49	65
Million British thermal units of natural gas	77	83

(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

The impact of derivative activity:

	Pre-Tax Fair Value Gains (Losses) Recognized During the Period in:
(Millions of Dollars)	Accumulated Other Comprehensive Loss		Regulatory (Assets) and Liabilities
Three Months Ended March 31, 2021
Other derivative instruments
Natural gas commodity	$	—	$	1
Total	$	—	$	1

As of March 31, 2020, NSP-Minnesota had no activity for electric and natural gas commodity derivatives that were recognized in regulatory (assets) and liabilities.

	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 March 31, 2021
Other derivative instruments
Commodity trading	$	—	$	—		$	31	(a)
Electric commodity	—		(1)		(b)	—
Natural gas commodity	—		1		(c)	(3)		(c)
Total	$	—	$	—		$	28

	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 March 31, 2020
Other derivative instruments
Commodity trading	$	—	$	—		$	4	(a)
Electric commodity	—		(1)		(b)	—
Natural gas commodity	—		1		(c)	(2)		(c)
Total	$	—	$	—		$	2

(a)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.

(b)Amounts are recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

(c)Amounts are recorded to cost of natural gas sold and transported. These derivative settlement gains and losses are shared with natural gas customers through purchased natural gas cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

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

Recurring Fair Value Measurements — NSP-Minnesota’s derivative assets and liabilities measured at fair value on a recurring basis:

	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative assets
Other derivative instruments:
Commodity trading	$	1	$	23	$	—	$	24	$	(21)	$	3	$	1	$	26	$	—	$	27	$	(25)	$	2
Electric commodity	—		—		6		6		(1)		5		—		—		13		13		(1)		12
Natural gas commodity	—		—		—		—		—		—		—		3		—		3		—		3
Total current derivative assets	$	1	$	23	$	6	$	30	$	(22)	$	8	$	1	$	29	$	13	$	43	$	(26)	$	17
Noncurrent derivative assets
Other derivative instruments:
Commodity trading	$	5	$	33	$	28	$	66	$	(40)	$	26	$	7	$	39	$	—	$	46	$	(41)	$	5
Total noncurrent derivative assets	$	5	$	33	$	28	$	66	$	(40)	$	26	$	7	$	39	$	—	$	46	$	(41)	$	5

	March 31, 2021												Dec. 31, 2020
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative liabilities
Other derivative instruments:
Commodity trading	$	4	$	22	$	5	$	31	$	(29)	$	2	$	3	$	18	$	10	$	31	$	(25)	$	6
Electric commodity	—		—		—		—		—		—		—		—		1		1		(1)		—
Natural gas commodity	—		—		—		—		—		—		—		2		—		2		—		2
Total current derivative liabilities	$	4	$	22	$	5	$	31	$	(29)	2		$	3	$	20	$	11	$	34	$	(26)	8
PPAs (b)											13												14
Current derivative instruments											$	15											$	22
Noncurrent derivative liabilities
Other derivative instruments:
Commodity trading	$	2	$	50	$	17	$	69	$	(30)	$	39	$	2	$	35	$	13	$	50	$	(27)	$	23
Total noncurrent derivative liabilities	$	2	$	50	$	17	$	69	$	(30)	39		$	2	$	35	$	13	$	50	$	(27)	23
PPAs (b)											45												48
Noncurrent derivative instruments											$	84											$	71

(a)NSP-Minnesota nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at March 31, 2021 and Dec. 31, 2020. At both March 31, 2021 and Dec. 31, 2020, derivative assets and liabilities include $15 million of obligations to return cash collateral. At March 31, 2021 and Dec. 31, 2020 derivative assets and liabilities include rights to reclaim cash collateral of $11 million and $1 million, respectively. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

(b)During 2006, Xcel Energy 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.

Changes in Level 3 Commodity Derivatives

Changes in Level 3 commodity derivatives for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Balance at Jan. 1	$	(11)	$	5
Settlements	(7)		(12)
Net transactions recorded during the period:
Gains recognized in earnings (a)	30		6
Net gains recognized as regulatory assets and liabilities	—		3
Balance at March 31	$	12	$	2

(a)Level 3 gains recognized in earnings are subject to offsetting losses of derivative instruments categorized as levels 1 and 2 in the income statement.

Carrying Amount and Fair Value of Long-term Debt

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

	March 31, 2021				Dec. 31, 2020
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	6,741	$	7,491	$	5,904	$	7,391

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Benefit Plans and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Credit)

Components of Net Periodic Benefit Cost

	Three Months Ended March 31
	2021		2020		2021		2020
(Millions of Dollars)	Pension Benefits				Postretirement Health Care Benefits
Service cost	$	7	$	7	$	—	$	—
Interest cost (a)	6		8		1		1
Expected return on plan assets (a)	(13)		(14)		—		—
Amortization of prior service credit (a)	—		—		(1)		(1)
Amortization of net loss (a)	9		8		—		—
Net periodic benefit cost	9		9		—		—
Effects of regulation	(1)		(1)		—		—
Net benefit cost recognized for financial reporting	$	8	$	8	$	—	$	—

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

^[1]

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

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Commitment and Contingencies (Tables)

3 Months Ended

Mar. 31, 2021

Commitments and Contingencies Disclosure [Abstract]

Lease, Cost

Components of lease expense:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Operating leases
PPA capacity payments	$	19	$	21
Other operating leases (a)	2		2
Total operating lease expense (b)	$	21	$	23

(a)Includes immaterial short-term lease expense for 2021 and 2020, respectively.

(a)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.

Lessee, Operating Lease, Liability, Maturity

Commitments under operating leases as of March 31, 2021:

(Millions of Dollars)	PPA Operating Leases		Other Operating Leases		Total Operating Leases
Total minimum obligation	$	485	$	79	$	564
Interest component of obligation	(43)		(14)		(57)
Present value of minimum obligation	$	442	$	65	507
Less current portion					(91)
Noncurrent operating lease liabilities					$	416

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Other Comprehensive Income (Loss) (Tables)

3 Months Ended

Mar. 31, 2021

Stockholders' Equity Note [Abstract]

Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax

Changes in accumulated other comprehensive income (loss), net of tax, for the three months ended March 31, 2021 and 2020:

	Three Months Ended March 31, 2021						Three Months Ended March 31, 2020
(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	$	(19)	$	(3)	$	(22)	$	(19)	$	(3)	$	(22)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives, net of tax of $— and $—, respectively (a)	1		—		1		—		—		—
Accumulated other comprehensive loss at March 31	$	(18)	$	(3)	$	(21)	$	(19)	$	(3)	$	(22)

(a)Included in interest charges.

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Segment Information (Tables)

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Results from Operations by Reportable Segment

NSP-Minnesota’s segment information:

	Three Months Ended March 31
(Millions of Dollars)	2021		2020
Regulated Electric
Total revenues (a)	$	1,139	$	1,035
Net income	107		86
Regulated Natural Gas
Total revenues (b)	$	204	$	206
Net income	20		23
All Other
Total revenues	$	9	$	9
Net income (loss)	1		(2)
Consolidated Total
Total revenues (a)(b)	$	1,352	$	1,250
Net income	128		107

(a)    Total revenues include $115 million and $110 million of affiliate electric revenue for the three months ended March 31, 2021 and 2020.

(b)    Total revenues include an immaterial amount of affiliate gas revenue for the three months ended March 31, 2021 and 2020

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Accounting Pronouncements (Details) $ in Millions	Jan. 01, 2020 USD ($)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Credit Losses, Topic 326 (ASC Topic 326)	$ 1

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Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accounts Receivable	$ 422	$ 425
Less allowance for bad debts	(37)	(33)
Accounts receivable, net	$ 385	$ 392

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Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Public Utilities, Inventory [Line Items]
Inventories	$ 253	$ 295
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventories	181	178
Fuel
Public Utilities, Inventory [Line Items]
Inventories	66	90
Natural Gas
Public Utilities, Inventory [Line Items]
Inventories	$ 6	$ 27

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Property, Plant and Equipment (Details) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 23,428	$ 22,896
Accumulated depreciation and amortization		(8,106)	(7,898)
Property, plant and equipment, net		15,679	15,308
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		19,647	18,948
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		1,720	1,707
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		969	955
Plant to be Retired (a)
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	[1]	127	136
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		965	1,150
Nuclear fuel
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		3,047	2,970
Accumulated depreciation and amortization		$ (2,690)	$ (2,660)

[1] Includes regulator-approved retirements of Sherco Units 1 and 2.

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Money Pool (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Amount outstanding at period end	$ 0	$ 179
Money Pool
Short-term Debt [Line Items]
Borrowing limit	250	250
Amount outstanding at period end	0	0
Average amount outstanding	24	3
Maximum amount outstanding	$ 236	$ 116
Weighted average interest rate, computed on a daily basis	0.07%	1.53%

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Borrowings and Other Financing Instruments Commercial Paper (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Amount outstanding at period end	$ 0	$ 179
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	500	500
Amount outstanding at period end	0	179
Average amount outstanding	104	10
Maximum amount outstanding	$ 317	$ 179
Weighted average interest rate, computed on a daily basis	0.18%	1.25%
Weighted average interest rate at period end		0.18%

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Letters of Credit (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 0	$ 179
Letter of Credit
Line of Credit Facility [Line Items]
Direct advances on the credit facility outstanding	$ 10	$ 10

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Credit Facility (Details) $ in Millions		3 Months Ended
		Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Amount outstanding at period end		$ 0	$ 179
Credit Facility
Line of Credit Facility [Line Items]
Borrowing limit	[1]	500
Amount outstanding at period end	[2]	$ 10
Number of extension you can request		2
Available		$ 490
Direct advances on the credit facility outstanding		$ 0	$ 0

[1] Expires in June 2024.

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

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Bilateral Credit Agreement (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Amount outstanding at period end	$ 0	$ 179
Letter of Credit | Bilateral Credit Agreement
Short-term Debt [Line Items]
Borrowing Limit	75
Amount outstanding at period end	49
Available	$ 26
Letter of Credit | Bilateral Credit Agreement | NSP Minnesota [Member]
Short-term Debt [Line Items]
Debt Instrument, Term	1 year

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Borrowings and Other Financing Instruments (Details) - Bonds [Member] - NSP Minnesota [Member]	Mar. 30, 2021 USD ($)
Series Due April 1, 2031
Debt Disclosure [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	2.25%
Debt Instrument, Face Amount	$ 425,000,000
Short-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.25%
Debt Instrument, Face Amount	$ 425,000,000
Series Due April 1, 2052
Debt Disclosure [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	3.20%
Debt Instrument, Face Amount	$ 425,000,000
Short-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.20%
Debt Instrument, Face Amount	$ 425,000,000

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Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,352	$ 1,250
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,139	1,035
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	204	206
All Other | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	9	9
Retail
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	952	957
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	447	421
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	495	527
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	10	9
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	750	752
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	326	300
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	416	445
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	8	7
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	193	196
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	114	114
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	79	82
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Retail | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9	9
Retail | All Other | Residential
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7	7
Retail | All Other | C&I
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Retail | All Other | Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2	2
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	98	45
Wholesale | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	98	45
Wholesale | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Wholesale | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	57	56
Transmission | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	57	56
Transmission | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Transmission | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	115	110
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	115	110
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Interchange | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2	3
Other | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2	2
Other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	1
Other | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,224	1,171
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,022	965
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	193	197
Total revenue from contracts with customers | All Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9	9
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	128	79
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	117	70
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	11	9
Alternative revenue and other | All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 0	$ 0

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Income Taxes (Details)		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	[1]
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		7.00%	7.10%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent		(30.40%)	(24.80%)
Plant regulatory differences	[2]	(7.80%)	(8.30%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(1.30%)	(1.50%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		1.20%	0.60%
Effective Income Tax Rate Reconciliation, Percent, Total		(10.30%)	(5.90%)

[1]     Prior periods have been restated to conform to current year presentation.

[2] Regulatory differences for income tax primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reduction.

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Income Taxes Federal Audits (Details) $ in Millions	Mar. 31, 2021 USD ($)
Income Tax Disclosure [Abstract]
State income tax adjustment	$ 0

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Income Taxes Unrecognized Benefits (Details) - USD ($)	3 Months Ended	9 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	$ (2,000,000)		$ (2,000,000)	$ (2,000,000)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	21,000,000		21,000,000
Unrecognized Tax Benefits That Would Not Impact Effective Tax Rate	3,000,000		3,000,000
Unrecognized Tax Benefits	24,000,000		24,000,000
Tax Benefits Associated With Nol And Tax Credit Carryforwards	11,000,000		11,000,000
Decrease in Unrecognized Tax Benefits is Reasonably Possible	15,000,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	0		$ 0
Unrecognized Tax Benefits, Interest on Income Taxes Expense	$ 0	$ 0

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Fair Value of Financial Assets and Liabilities - Non-Derivative Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021		Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain on Securities	$ 1,000		$ 981
Unrealized Loss on Securities	8		5
Nuclear Decommissioning Fund [Abstract]
Miscellaneous investments	56		53
Final Contractual Maturity [Abstract]
Due in 1 Year or Less	3
Due in 1 to 5 Years	133
Due in 5 to 10 Years	202
Due after 10 Years	248
Total	586
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Cost
Nuclear Decommissioning Fund [Abstract]
Total	1,833	[1]	1,801	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Cost | Cash equivalents
Nuclear Decommissioning Fund [Abstract]
Cash equivalents	32	[1]	40	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Cost | Commingled Funds [Member]
Nuclear Decommissioning Fund [Abstract]
Commingled funds	795	[1]	787	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Cost | Debt Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Debt securities	562	[1]	528	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Cost | Equity Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Equity securities	444	[1]	446	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value
Nuclear Decommissioning Fund [Abstract]
NAV	1,052	[1]	1,041	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Cash equivalents
Nuclear Decommissioning Fund [Abstract]
Cash equivalents	32	[1]	40	[2]
NAV	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Commingled Funds [Member]
Nuclear Decommissioning Fund [Abstract]
Commingled funds	1,052	[1]	1,041	[2]
NAV	1,052	[1]	1,041	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Debt Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Debt securities	586	[1]	585	[2]
NAV	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Equity Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Equity securities	1,155	[1]	1,111	[2]
NAV	0	[1]	0	[2]
Total	2,825	[1]	2,777	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 1
Nuclear Decommissioning Fund [Abstract]
Total	1,185	[1]	1,149	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Cash equivalents
Nuclear Decommissioning Fund [Abstract]
Cash equivalents	32	[1]	40	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Commingled Funds [Member]
Nuclear Decommissioning Fund [Abstract]
Commingled funds	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Debt Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Debt securities	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 1 | Equity Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Equity securities	1,153	[1]	1,109	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 2
Nuclear Decommissioning Fund [Abstract]
Total	575	[1]	574	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Cash equivalents
Nuclear Decommissioning Fund [Abstract]
Cash equivalents	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Commingled Funds [Member]
Nuclear Decommissioning Fund [Abstract]
Commingled funds	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Debt Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Debt securities	573	[1]	572	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 2 | Equity Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Equity securities	2	[1]	2	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 3
Nuclear Decommissioning Fund [Abstract]
Total	13	[1]	13	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Cash equivalents
Nuclear Decommissioning Fund [Abstract]
Cash equivalents	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Commingled Funds [Member]
Nuclear Decommissioning Fund [Abstract]
Commingled funds	0	[1]	0	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Debt Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Debt securities	13	[1]	13	[2]
Nuclear Decommissioning Fund | Fair Value Measured on a Recurring Basis | Fair Value | Level 3 | Equity Securities [Member]
Nuclear Decommissioning Fund [Abstract]
Equity securities	$ 0	[1]	$ 0	[2]

[1] Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $56 million of rabbi trust assets and miscellaneous investments.

[2] Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets, which also includes $53 million of rabbi trust assets and miscellaneous investments.

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Fair Value of Financial Assets and Liabilities - Rabbi Trust (Details) - Rabbi Trust [Member] - Fair Value Measured on a Recurring Basis - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Cost
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	[1]	$ 16	$ 15
Cost | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	6	1
Cost | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mutual funds	[1]	10	14
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	[1]	18	17
Fair Value | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	6	1
Fair Value | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mutual funds	[1]	12	16
Fair Value | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	[1]	18	17
Fair Value | Level 1 | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	6	1
Fair Value | Level 1 | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mutual funds	[1]	12	16
Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	[1]	0	0
Fair Value | Level 2 | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	0	0
Fair Value | Level 2 | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mutual funds	[1]	0	0
Fair Value | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	[1]	0	0
Fair Value | Level 3 | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	[1]	0	0
Fair Value | Level 3 | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mutual funds	[1]	$ 0	$ 0

[1] Reported in nuclear decommissioning fund and other investments on the consolidated balance sheets.

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Fair Value of Financial Assets and Liabilities - Interest Rate Derivative (Details) - Interest Rate Derivatives $ in Millions	Mar. 31, 2021 USD ($)
Interest Rate Derivatives [Abstract]
Amount or interest rate derivatives expected to be reclassified	$ (1)
Derivative Liability, Notional Amount	$ 0

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Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) MWh in Millions, MMBTU in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2021 USD ($) MMBTU MWh	Mar. 31, 2020 USD ($)	Dec. 31, 2020 MMBTU MWh
Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		$ 0
Cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges		$ 0
Electric commodity
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative, Nonmonetary Notional amount | MWh	[1],[2]	49		65
Natural gas commodity
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Derivative, Nonmonetary Notional amount | MMBTU	[1],[2]	77		83
Natural Gas Commodity | Other Derivative Instruments
Gross Notional Amounts of Commodity Forwards, Options and FTRs [Abstract]
Pre-tax fair value gains (losses) recognized during the period in accumulated other comprehensive loss		$ 0	$ 0

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

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

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Fair Value of Financial Assets and Liabilities - Consideration of Credit Risk and Concentrations (Details) $ in Millions		3 Months Ended
		Mar. 31, 2021 USD ($) Counterparty	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Fair Value Hedges, Net		$ 0	$ 0
Derivative instruments in a gross liability position		4		$ 4
Other Derivative Instruments
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
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		1
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)		0	0
Pre-tax gains (losses) recognized during the period in income		28	2
Commodity Trading Contract | Other Derivative Instruments
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
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)		0	0
Pre-tax gains (losses) recognized during the period in income	[1]	31	4
Natural Gas Commodity | Other Derivative Instruments
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
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		1
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)	[2]	1	1
Pre-tax gains (losses) recognized during the period in income	[2]	(3)	(2)
Electric Commodity | Other Derivative Instruments
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
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	[3]	1	(1)
Pre-tax gains (losses) recognized during the period in income		$ 0	$ 0
Credit Concentration Risk
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure | Counterparty		10
Credit Concentration Risk | 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		8
Credit Concentration Risk | 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
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 26
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		52.00%
Credit Concentration Risk | 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
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 10
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		20.00%
Credit Concentration Risk | 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
Wholesale, trading and non trading commodity credit exposure for the most significant counterparties		$ 8
Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties		16.00%

[1] 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.

[2] Amounts are recorded to cost of natural gas sold and transported. These derivative settlement gains and losses are shared with natural gas customers through purchased natural gas cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

[3] Amounts are recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate.

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Fair Value of Financial Assets and Liabilities - Credit Related Contingent Features (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Derivative instruments in a gross liability position	$ 4	$ 4
Collateral posted related to adequate assurance clauses in derivative contracts	0	0
Derivative, Gross Liability with Cross Default Position, Aggregate Fair Value	$ 29	$ 14

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Fair Value of Financial Assets and Liabilities - Recurring Fair Value Measurements (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Obligation to return cash		$ 15		$ 15
Right to reclaim cash		11		1
Commodity Trading
Changes in Level 3 Commodity Derivatives [Roll Forward]
Balance at beginning of period		(11)	$ 5
Settlements		(7)	(12)
Gains (losses) recognized in earnings	[1]	30	6
Net gains (losses) recognized as regulatory assets and liabilities		0	3
Balance at end of period		12	2
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		15		22
Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		84		71
Fair Value Measured on a Recurring Basis | Level 3
Changes in Level 3 Commodity Derivatives [Roll Forward]
Transfers level 3, net		0	$ 0
Fair Value Measured on a Recurring Basis | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross		30		43
Netting, asset	[2]	(22)		(26)
Derivative asset		8		17
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative asset, gross		1		1
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative asset, gross		23		29
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative asset, gross		6		13
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		24		27
Netting, asset	[2]	(21)		(25)
Derivative asset		3		2
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		6		13
Netting, asset	[2]	(1)		(1)
Derivative asset		5		12
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		3
Netting, asset	[2]	0		0
Derivative asset		0		3
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		1		1
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 1 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		23		26
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 2 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		3
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		6		13
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 3 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative asset, gross		66		46
Netting, asset	[2]	(40)		(41)
Derivative asset		26		5
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative asset, gross		5		7
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative asset, gross		33		39
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative asset, gross		28		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		66		46
Netting, asset	[2]	(40)		(41)
Derivative asset		26		5
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		5		7
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		33		39
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative asset, gross		28		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross		31		34
Netting, liability	[2]	(29)		(26)
Derivative liability		2		8
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 1
Derivatives, Fair Value [Line Items]
Derivative liability, gross		4		3
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 2
Derivatives, Fair Value [Line Items]
Derivative liability, gross		22		20
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 3
Derivatives, Fair Value [Line Items]
Derivative liability, gross		5		11
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		31		31
Netting, liability	[2]	(29)		(25)
Derivative liability		2		6
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		1
Netting, liability	[2]	0		(1)
Derivative liability		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		2
Netting, liability	[2]	0		0
Derivative liability		0		2
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		4		3
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 1 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		22		18
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 2 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		2
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		5		10
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		1
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 3 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative liability, gross		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, gross		69		50
Netting, liability	[2]	(30)		(27)
Derivative liability		39		23
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 1
Derivatives, Fair Value [Line Items]
Derivative liability, gross		2		2
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 2
Derivatives, Fair Value [Line Items]
Derivative liability, gross		50		35
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 3
Derivatives, Fair Value [Line Items]
Derivative liability, gross		17		13
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		69		50
Netting, liability	[2]	(30)		(27)
Derivative liability		39		23
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		2		2
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		50		35
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative liability, gross		17		13
Fair Value, Measurements, Nonrecurring | Other Current Liabilities | PPAs
Derivatives, Fair Value [Line Items]
Derivative liability	[3]	13		14
Fair Value, Measurements, Nonrecurring | Other Noncurrent Liabilities | PPAs
Derivatives, Fair Value [Line Items]
Derivative liability	[3]	$ 45		$ 48

[1] Level 3 gains recognized in earnings are subject to offsetting losses of derivative instruments categorized as levels 1 and 2 in the income statement.

[2] NSP-Minnesota nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at March 31, 2021 and Dec. 31, 2020. At both March 31, 2021 and Dec. 31, 2020, derivative assets and liabilities include $15 million of obligations to return cash collateral. At March 31, 2021 and Dec. 31, 2020 derivative assets and liabilities include rights to reclaim cash collateral of $11 million and $1 million, respectively. The counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[3] During 2006, Xcel Energy 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.

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Fair Value of Financial Assets and Liabilities - Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, carrying amount	$ 6,741	$ 5,904
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 7,491	$ 7,391

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Benefit Plans and Other Postretirement Benefits (Details) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2021 USD ($) Plan	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service Cost			$ 7.0	$ 7.0
Interest cost (a)	[1]		6.0	8.0
Expected return on plan assets (a)	[1]		(13.0)	(14.0)
Amortization of prior service credit (a)	[1]		0.0	0.0
Amortization of net loss (a)	[1]		9.0	8.0
Net periodic benefit cost			9.0	9.0
Effects of regulation			(1.0)	(1.0)
Net benefit cost recognized for financial reporting			8.0	8.0
Total contributions to the pension plans during the period		$ 33.0
Pension Plan [Member] | Xcel Energy Inc.
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to the pension plans during the period		$ 125.0
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 [Abstract]
Service Cost			0.0	0.0
Interest cost (a)	[1]		1.0	1.0
Expected return on plan assets (a)	[1]		0.0	0.0
Amortization of prior service credit (a)	[1]		(1.0)	(1.0)
Amortization of net loss (a)	[1]		0.0	0.0
Net periodic benefit cost			0.0	0.0
Effects of regulation			0.0	0.0
Net benefit cost recognized for financial reporting			$ 0.0	$ 0.0

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

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Commitments and Contingencies - Sherco (Details) - USD ($) $ in Millions	1 Months Ended
	Jan. 31, 2021	Jan. 27, 2021
Rate Matters [Abstract]
Customer refund of previously recovered purchased power costs	$ 17
Amount MPUC previously disallowed related to Sherco outage		$ 22

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Commitments and Contingencies - Westmoreland Arbitration (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Gain (Loss) Related to Litigation Settlement	$ 36

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Commitments and Contingencies - MISO ROE Complaints (Details) - Federal Energy Regulatory Commission (FERC) - FERC Proceeding, MISO ROE Complaint - NSP Minnesota and NSP Wisconsin [Member] [Member]	1 Months Ended		3 Months Ended	7 Months Ended	10 Months Ended	11 Months Ended	17 Months Ended
	Feb. 28, 2015	Nov. 30, 2013	Dec. 31, 2016	Dec. 31, 2020	Mar. 31, 2021	Mar. 31, 2021	Mar. 31, 2021
Public Utilities, General Disclosures [Line Items]
Public Utilities, Base Return On Equity Charged To Customers Through Transmission Formula Rates	12.38%	12.38%
Public Utilities, ROE Applicable To Transmission Formula Rates In The MISO Region, Recommended By Third Parties	8.67%	9.15%
Public Utilities, ROE Applicable To Transmission Formula Rates In The MISO Region, Approved			10.32%
Public Utilities, ROE developed with new approach							9.88%
Public Utilities, ROE New Base, Complaint Number 1						10.02%
Basis Point Reduction					1000.00%
Basis Point Reduction - First Complaint				100000000.00%
Basis Point Reduction - Second Complaint				100000000.00%
Basis Point Reduction - Third Complaint				200000000.00%

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Commitments and Contingencies - FERC NOPR on ROE Incentive Adders (Details)	Mar. 31, 2021
Federal Energy Regulatory Commission (FERC) | NSP Minnesota, NSP Wisconsin and SPS
Public Utilities, General Disclosures [Line Items]
ROE incentive adders related to FERC NOPR	50.00%

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Commitments and Contingencies - Environmental, MGP, Landfill or Disposal Sites (Details)	Mar. 31, 2021
Other MGP, Landfill, or Disposal Sites
Site Contingency [Line Items]
Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation	7

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Commitments and Contingencies - Environmental Requirements - Water and Waste (Details) - Federal Coal Ash Regulation $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Site Contingency [Line Items]
Number of sites where regulated ash units will still be in operation at a specified date	3
Number of sites where statistically significant increases over established groundwater standards exist	0
Number of impoundments where closure plans will be expedited	1
Cost of construction of a new impoundment	$ 9
Estimated cost of closure of an impoundment	$ 4
Time period of existing ash pond closure completion in accordance with the CCR rule	5 years

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Commitments and Contingencies - Leases (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[1]	$ 21	$ 23
Lessee, Operating Lease, Liability, to be Paid		564
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(57)
Operating Lease, Liability		507
Operating Lease, Liability, Current		(91)		$ (85)
Operating lease liabilities		416		$ 443
Purchased Power Agreements
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		19	21
Lessee, Operating Lease, Liability, to be Paid		485
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(43)
Operating Lease, Liability		442
Property, Plant and Equipment, Other Types
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[2]	2	$ 2
Lessee, Operating Lease, Liability, to be Paid		79
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(14)
Operating Lease, Liability		$ 65

[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] Includes immaterial short-term lease expense for 2021 and 2020, respectively.

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Commitments and Contingencies - Variable Interest Entities (Details) - MW	Mar. 31, 2021	Dec. 31, 2020
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Variable Interest Entity [Line Items]
Generating capacity under long term purchased power agreements	1,347	1,347

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Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021		Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income at beginning of period		$ 6,769
Accumulated other comprehensive (loss) income at end of period		7,190
Income Tax Expense (Benefit)		(12)		$ (6)
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income at beginning of period		(19)		(19)
Accumulated other comprehensive (loss) income at end of period		(18)		(19)
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]
Income Tax Expense (Benefit)		0	[1]	0
Gains and Losses on Cash Flow Hedges | Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	1		0
Defined Benefit Pension and Postretirement Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income at beginning of period		(3)		(3)
Accumulated other comprehensive (loss) income at end of period		(3)		(3)
Defined Benefit Pension and Postretirement Items | Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	0		0
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income at beginning of period		(22)		(22)
Accumulated other comprehensive (loss) income at end of period		(21)		(22)
Total | Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	$ 1		$ 0

[1] Included in interest charges.

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Segment Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net income		$ 128	$ 107
Natural gas		204	206
Other		9	9
Regulated and Unregulated Operating Revenue		1,352	1,250
Affiliate Revenue		115	110
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1],[2]	1,352	1,250
Regulated Electric
Segment Reporting Information [Line Items]
Net income		107	86
Regulated Electric | Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	[1]	1,139	1,035
Regulated Natural Gas
Segment Reporting Information [Line Items]
Net income		20	23
Regulated Natural Gas | Total revenues
Segment Reporting Information [Line Items]
Natural gas	[2]	204	206
All Other
Segment Reporting Information [Line Items]
Net income		1	(2)
All Other | Total revenues
Segment Reporting Information [Line Items]
Other		$ 9	$ 9

[1] Total revenues include $115 million and $110 million of affiliate electric revenue for the three months ended March 31, 2021 and 2020.

[2] Total revenues include an immaterial amount of affiliate gas revenue for the three months ended March 31, 2021 and 2020.