Northern States Power 10-Q 27 Oct 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 27, 2023
Cover [Abstract]
Entity Registrant Name	NORTHERN STATES POWER CO /WI/
Entity Central Index Key	0000072909
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-03140
Entity Incorporation, State or Country Code	WI
Entity Tax Identification Number	39-0508315
Entity Address, Address Line One	1414 West Hamilton Avenue
Entity Address, City or Town	Eau Claire
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	54701
City Area Code	(715)
Local Phone Number	737-2625
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		933,000

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2023		Sep. 30, 2022		Sep. 30, 2023	Sep. 30, 2022
Operating revenues
Electric, non-affiliates	$ 213		$ 223		$ 602	$ 617
Electric, affiliates	50		51		151	150
Natural gas	15		20		116	133
Total operating revenues	279	[1]	294	[1]	870	900
Operating expenses
Electric fuel and purchased power, non-affiliates	3		5		10	13
Purchased power, affiliates	109		115		305	343
Cost of natural sold and transported	6		10		61	75
Operating and maintenance expenses	58		53		173	160
Conservation program expenses	3		4		10	10
Depreciation and amortization	43		39		126	117
Taxes (other than income taxes)	8		8		25	23
Total operating expenses	230		234		710	741
Operating income	49		60		160	159
Other income (expense), net	1		(1)		2	(2)
Allowance for funds used during construction — equity	3		2		7	5
Interest charges and financing costs
Interest charges and other financing costs	14		11		40	33
Allowance for funds used during construction — debt	(1)		(1)		(3)	(2)
Total interest charges and financing costs	13		10		37	31
Income before income taxes	40		51		132	131
Income tax expense	9		11		30	29
Net income	$ 31		$ 40		$ 102	$ 102
[1]Total revenues include $50 million and $51 million of affiliate electric revenue for the three months ended Sept. 30, 2023 and 2022, respectively.

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities
Net income	$ 102	$ 102
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	128	118
Deferred income taxes	(17)	0
Allowance for equity funds used during construction	7	5
Provision for bad debts	3	2
Changes in operating assets and liabilities:
Accounts receivable	1	(1)
Accrued unbilled revenues	23	19
Inventories	4	(21)
Other current assets	28	(2)
Accounts payable	12	2
Net regulatory assets and liabilities	61	5
Other current liabilities	3	6
Pension and other employee benefit obligations	(2)	(3)
Other, net	4	(3)
Net cash provided by operating activities	343	219
Investing activities
Capital/construction expenditures	(343)	(244)
Investments in utility money pool arrangement	(88)	(36)
Repayments from utility money pool arrangement	88	0
Net cash used in investing activities	(343)	(280)
Financing activities
Repayments of short-term borrowings, net	(47)	(83)
Borrowings under utility money pool arrangement	73	575
Repayments under utility money pool arrangement	(73)	(575)
Proceeds from long-term debt	124	99
Capital contributions from parent	57	111
Dividends paid to parent	(72)	(67)
Net cash provided by financing activities	62	60
Net change in cash, cash equivalents and restricted cash	62	(1)
Cash, cash equivalents and restricted cash at beginning of period	2	11
Cash, cash equivalents and restricted cash at end of period	64	10
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(34)	(30)
Cash paid for income taxes, net	(30)	(26)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	31	30
Inventory transfers to property, plant and equipment	5	2
Allowance for equity funds used during construction	$ 7	$ 5

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 64	$ 2
Accounts receivable, net	74	84
Accrued unbilled revenues	51	74
Other receivables	0	19
Inventories	29	39
Regulatory assets	28	44
Prepaid taxes	22	27
Prepayments and other	6	11
Total current assets	274	300
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, net	3,155	2,914
Other assets
Regulatory assets	181	193
Other	3	3
Total other assets	184	196
Total assets	3,613	3,410
Current liabilities
Current portion of long-term debt	200	0
Short-term debt	0	47
Dividends payable to parent	24	23
Regulatory liabilities	47	21
Taxes accrued	20	13
Accrued interest	13	12
Other	20	28
Total current liabilities	420	255
Deferred credits and other liabilities
Deferred income taxes	324	333
Deferred investment tax credits	5	5
Regulatory liabilities	417	383
Customer advances	25	23
Pension and employee benefit obligations	22	23
Other	42	43
Total deferred credits and other liabilities	835	810
Commitments and contingencies
Capitalization
Long-term debt	1,011	1,086
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at Sept. 30, 2023 and Dec. 31, 2022, respectively	$ 93	$ 93
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares outstanding (in shares)	933,000	933,000
Additional paid in capital	$ 820	$ 761
Retained earnings	434	405
Total common stockholder's equity	1,347	1,259
Total liabilities and equity	3,613	3,410
Related Party
Current liabilities
Accounts payable	70	92
Affiliated Entity
Current liabilities
Accounts payable	$ 26	$ 19

CONSOLIDATED STATEMENTS OF COMM

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings
Balance (in shares) at Dec. 31, 2021		933,000
Beginning Balance at Dec. 31, 2021	$ 1,103	$ 93	$ 642	$ 368
Increase (Decrease) in Stockholder's Equity
Net income	102
Common dividends declared to parent	(64)			(64)
Contribution of capital by parent	110		110
Balance (in shares) at Sep. 30, 2022		933,000
Ending Balance at Sep. 30, 2022	1,251	$ 93	752	406
Balance (in shares) at Jun. 30, 2022		933,000
Beginning Balance at Jun. 30, 2022	1,184	$ 93	702	389
Increase (Decrease) in Stockholder's Equity
Net income	40			40
Common dividends declared to parent	(23)			(23)
Contribution of capital by parent	50		50
Balance (in shares) at Sep. 30, 2022		933,000
Ending Balance at Sep. 30, 2022	$ 1,251	$ 93	752	406
Balance (in shares) at Dec. 31, 2022	933,000	933,000
Beginning Balance at Dec. 31, 2022	$ 1,259	$ 93	761	405
Increase (Decrease) in Stockholder's Equity
Net income	102
Common dividends declared to parent	(73)			(73)
Contribution of capital by parent	$ 59		59
Balance (in shares) at Sep. 30, 2023	933,000	933,000
Ending Balance at Sep. 30, 2023	$ 1,347	$ 93	820	434
Balance (in shares) at Jun. 30, 2023		933,000
Beginning Balance at Jun. 30, 2023	1,326	$ 93	806	427
Increase (Decrease) in Stockholder's Equity
Net income	31			31
Common dividends declared to parent	(24)			(24)
Contribution of capital by parent	$ 14		14
Balance (in shares) at Sep. 30, 2023	933,000	933,000
Ending Balance at Sep. 30, 2023	$ 1,347	$ 93	$ 820	$ 434

Management's Opinion

Management's Opinion	9 Months Ended
	Sep. 30, 2023
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-Wisconsin and its subsidiaries as of Sept. 30, 2023 and Dec. 31, 2022; the results of NSP-Wisconsin's operations, including the components of net income, changes in stockholder's equity and comprehensive income for the three and nine months ended Sept. 30, 2023 and 2022; and NSP-Wisconsin's cash flows for the nine months ended Sept. 30, 2023 and 2022. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after Sept. 30, 2023 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, 2022 balance sheet information has been derived from the audited 2022 consolidated financial statements included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2022. 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-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2022, filed with the SEC on Feb. 23, 2023. Due to the seasonality of NSP-Wisconsin’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
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-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2022 appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

Accounting Pronouncements

Accounting Pronouncements	9 Months Ended
	Sep. 30, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Pronouncements	As of Sept. 30, 2023

Selected Balance Sheet Data

Selected Balance Sheet Data	9 Months Ended
	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Selected Balance Sheet Data	(Millions of dollars) Sept. 30, 2023 Dec. 31, 2022 Accounts receivable, net Accounts receivable $ 82 $ 93 Less allowance for bad debts (8) (9) Accounts receivable, net $ 74 $ 84 (Millions of dollars) Sept. 30, 2023 Dec. 31, 2022 Inventories Materials and supplies $ 11 $ 8 Fuel 10 11 Natural gas 8 20 Total inventories $ 29 $ 39 (Millions of dollars) Sept. 30, 2023 Dec. 31, 2022 Property, plant and equipment, net Electric plant $ 3,767 $ 3,579 Natural gas plant 496 465 Common and other property 290 260 Construction work in progress 237 174 Total property, plant and equipment 4,790 4,478 Less accumulated depreciation (1,635) (1,564) Property, plant and equipment, net $ 3,155 $ 2,914

Borrowings and Other Financing

Borrowings and Other Financing Instruments	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Borrowings and Other Financing Instruments	Short-Term Borrowings NSP-Wisconsin 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: (Amounts in Millions, Except Interest Rates) Three Months Ended Sept. 30, 2023 Year Ended Dec. 31, 2022 Borrowing limit $ 150 $ 150 Amount outstanding at period end — — Average amount outstanding — 25 Maximum amount outstanding — 81 Weighted average interest rate, computed on a daily basis N/A 1.10 % Weighted average interest rate at period end N/A N/A Commercial Paper — Commercial paper outstanding: (Amounts in Millions, Except Interest Rates) Three Months Ended Sept. 30, 2023 Year Ended Dec. 31, 2022 Borrowing limit $ 150 $ 150 Amount outstanding at period end — 47 Average amount outstanding — 18 Maximum amount outstanding — 123 Weighted average interest rate, computed on a daily basis N/A 1.03 % Weighted average interest rate at period end N/A 4.55 Letters of Credit — NSP-Wisconsin uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At both Sept. 30, 2023 and Dec. 31, 2022, there we re no l etters of credit outstanding under the credit facility. Revolving Credit Facility — In order to issue its commercial paper, NSP-Wisconsin must have a revolving credit facility equal to or greater than the commercial paper borrowing limit and cannot issue commercial paper exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings. NSP-Wisconsin has the right to request an extension of the revolving credit facility termination date for an additional one-year period. All extension requests are subject to majority bank group approval. As of Sept. 30, 2023, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Outstanding (b) Available $ 150 $ — $ 150 (a) Expires in September 2027. (b) Includes outstanding commercial paper. All credit facility ban k borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the credit facility outstanding at Sept. 30, 2023 and Dec. 31, 2022. Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, had an immaterial note payable to Xcel Energy Inc. as of Sept. 30, 2023 and Dec. 31, 2022, respectively. Long-Term Borrowings and Other Financing Instruments During the nine months ended Sept. 30, 2023, NSP-Wisconsin issued $125 million of 5.30% private placement first mortgage bonds due June 15, 2053.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenues	Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Wisconsin’s operating revenues consisted of the following: Three Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 79 $ 8 $ — $ 87 C&I 136 5 — 141 Other 2 — 1 3 Total retail 217 13 1 231 Interchange and other 43 1 — 44 Total revenue from contracts with customers 260 14 1 275 Alternative revenue and other 3 1 — 4 Total revenues $ 263 $ 15 $ 1 $ 279 Three Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 78 $ 9 $ — $ 87 C&I 139 9 — 148 Other 2 — — 2 Total retail 219 18 — 237 Interchange and other 52 1 — 53 Total revenue from contracts with customers 271 19 — 290 Alternative revenue and other 3 1 — 4 Total revenues $ 274 $ 20 $ — $ 294 Nine Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 229 $ 62 $ — $ 291 C&I 378 48 — 426 Other 6 — 1 7 Total retail 613 110 1 724 Interchange and other 131 2 — 133 Total revenue from contracts with customers 744 112 1 857 Alternative revenue and other 9 4 — 13 Total revenues $ 753 $ 116 $ 1 $ 870 Nine Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 226 $ 69 $ — $ 295 C&I 374 58 — 432 Other 6 — — 6 Total retail 606 127 — 733 Interchange and other 153 3 — 156 Total revenue from contracts with customers 759 130 — 889 Alternative revenue and other 8 3 — 11 Total revenues $ 767 $ 133 $ — $ 900

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	6. Income Taxes Reconciliation between the statutory rate and effective tax rate: Nine Months Ended Sept. 30 2023 2022 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 6.2 6.2 Decreases: Plant regulatory differences (a) (3.4) (3.7) Other (net) (1.1) (1.4) Effective income tax rate 22.7 % 22.1 %

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	7. Fair Value of Financial Assets and Liabilities Fair Value Measurements Accounting guidance for fair value measurements and disclosures provides a hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value. • Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are actively traded instruments with observable actual trading prices. • Level 2 — Pricing inputs are other than actual trading 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 include those valued with models requiring significant judgment or estimation. Specific valuation methods include: Commodity Derivatives — 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 contracts relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges, the significance of the use of less observable inputs on a valuation is evaluated, and may result in Level 3 classification. Derivative Activities and Fair Value Measurements NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, to manage risk in connection with changes in utility commodity prices. Commodity Derivatives — NSP-Wisconsin enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale. As of Sept. 30, 2023, NSP-Wisconsin had no commodity contracts designated as cash flow hedges. Consideration of Credit Risk and Concentrations — NSP-Wisconsin 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. Recurring Derivative Fair Value Measurements Impact of derivative activity: Changes in the fair value of natural gas commodity derivatives resulted in immaterial net losses and gains for the three and nine months ended Sept. 30, 2023 and 2022, which were recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. During the three and nine months ended Sept. 30, 2023 and 2022, there were immaterial natural gas commodity derivatives settlement losses and gains. During the three and nine months ended Sept. 30, 2023 and 2022, immaterial pre-tax losses were recognized during the period in income related to option premium amortization. NSP-Wisconsin had immaterial outstanding derivative assets or liabilities measured at fair value as of Sept. 30, 2023 and Dec. 31, 2022. Fair Value of Long-Term Debt As of Sept. 30, 2023, other financial instruments for which the carrying amount did not equal fair value: Sept. 30, 2023 Dec. 31, 2022 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 1,211 $ 1,062 $ 1,086 $ 980 Fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of Sept. 30, 2023 and Dec. 31, 2022, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

Benefit Plans and Other Postret

Benefit Plans and Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2023
Retirement Benefits [Abstract]
Benefit Plans and Other Postretirement Benefits	Components of Net Periodic Benefit Cost Three Months Ended Sept. 30 2023 2022 (Millions of Dollars) Pension Benefits Service cost $ 1 $ 2 Interest cost (a) 2 1 Expected return on plan assets (a) (2) (2) Amortization of net loss (a) — 1 Settlement charge (b) — 4 Net periodic benefit cost $ 1 $ 6 Effects of regulation — (2) Net benefit cost recognized for financial reporting $ 1 $ 4 Nine Months Ended Sept. 30 2023 2022 (Millions of Dollars) Pension Benefits Service cost $ 3 $ 4 Interest cost (a) 5 3 Expected return on plan assets (a) (6) (6) Amortization of net loss (a) 1 3 Settlement charge (b) — 4 Net periodic benefit cost $ 3 $ 8 Effects of regulation — (2) Net benefit cost recognized for financial reporting $ 3 $ 6 (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. (b) A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the net periodic pension cost. In the third quarter of 2022 as a result of lump-sum distributions during the 2022 plan year, NSP-Wisconsin recorded a pension settlement charge of $4 million, the majority of which was not recognized in earnings due to the effects of regulation.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Legal NSP-Wisconsin 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, 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-Wisconsin’s consolidated financial statements. Legal fees are generally expensed as incurred. Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003. Multiple lawsuits involving multiple plaintiffs seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada. One case remains active which includes a multi-district litigation matter consisting of a Wisconsin purported class (Arandell Corp.). The Court issued a ruling in June 2022 granting plaintiffs’ class certification. In April 2023, the Seventh Circuit Court of Appeals heard the defendants’ appeal challenging whether the district court properly assessed class certification. A decision relating to class certification is expected later this year. Xcel Energy considers the reasonably possible loss associated with this litigation to be immaterial. Rate Matters NSP-Wisconsin is involved in various regulatory proceedings arising in the ordinary course of business. Until resolution, typically in the form of a rate order, uncertainties may exist regarding the ultimate rate treatment for certain activities and transactions. Amounts have been recognized for probable and reasonably estimable losses that may result. Unless otherwise disclosed, any reasonably possible range of loss in excess of any recognized amount is not expected to have a material effect on the financial statements. 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%. The FERC subsequently issued various related orders (including Opinion Nos. 569, 569A and 569B) related to ROE methodology/calculations and timing. NSP-Minnesota has processed refunds to customers for applicable complaint periods based on the ROE in the most recent applicable opinions on behalf of the NSP System. The MISO TOs and various other parties have filed petitions for review of the FERC’s most recent applicable opinions at the D.C. Circuit. In August 2022, the D.C. Circuit ruled that FERC had not adequately supported its conclusions, vacated FERC’s related orders, and remanded the issue back to FERC for further proceedings, which remain pending. Additional exposure, if any, related to this matter is expected to be immaterial. Environmental MGP, Landfill and Disposal Sites NSP-Wisconsin is investigating, remediating or performing post-closure actions at one MGP, landfill or other disposal sites across its service territories. NSP-Wisconsin has recognized its best estimate of costs/liabilities from final resolution of these issues, however, the outcome and timing are 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 Federal Clean Water Act Section 316(b) — The Federal Clean Water Act requires the EPA to regulate cooling water intake structures to assure they reflect the best technology available for minimizing impingement and entrainment of aquatic species. NSP-Wisconsin estimates capital expenditures of approximately $5 million may be required to comply with the requirements. NSP-Wisconsin believes two plants could be required to make improvements to reduce impingement and entrainment. NSP-Wisconsin anticipates these costs will be recoverable through regulatory mechanisms. Environmental Requirements — Air Clean Air Act NOx Allowance Allocations — In June 2023, after disapproving state implementation plans, the EPA published final regulations under the "Good Neighbor" provisions of the Clean Air Act. The final rule applies to generation facilities in Wisconsin, as well as other states outside of our service territory. The rule establishes an allowance trading program for NOx that will impact NSP-Wisconsin’s fossil fuel-fired electric generating facilities. Applicable facilities will have to secure additional allowances, install NOx controls and/or develop a strategy of operations that utilizes the existing allowance allocations. Guidelines are also established for allowance banking and emission limit backstops. While the financial impacts of the final rule are uncertain and dependent on market forces and anticipated generation, NSP-Wisconsin anticipates the costs would be recoverable through regulatory mechanisms.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Segment Information	NSP-Wisconsin 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-Wisconsin has the following reportable segments: • Regulated Electric — The regulated electric utility segment generates electricity, which is transmitted and distributed in Wisconsin and Michigan. • Regulated Natural Gas — The regulated natural gas utility segment purchases, transports, stores and distributes natural gas in portions of Wisconsin and Michigan. Asset and capital expenditure information is not provided for NSP-Wisconsin's reportable segments. As an integrated electric and natural gas utility, NSP-Wisconsin 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-Wisconsin's segment information: Three Months Ended Sept. 30 (Millions of Dollars) 2023 2022 Regulated Electric Total revenues (a) $ 263 $ 274 Net income 32 42 Regulated Natural Gas Total revenues $ 15 $ 20 Net loss (3) (3) All Other Total revenues $ 1 $ — Net income $ 2 $ 1 Consolidated Total Total operating revenues (a) $ 279 $ 294 Net income 31 40 (a) Total revenues include $50 million and $51 million of affiliate electric revenue for the three months ended Sept. 30, 2023 and 2022, respectively. Nine Months Ended Sept. 30 (Millions of Dollars) 2023 2022 Regulated Electric Total revenues (a) $ 753 $ 767 Net income 95 89 Regulated Natural Gas Operating revenues $ 116 $ 133 Intersegment revenue 1 — Total revenues $ 117 $ 133 Net income 5 11 All Other Total revenues $ 1 $ — Net income $ 2 $ 2 Consolidated Total Operating revenues (a) $ 871 $ 900 Reconciling eliminations (1) — Total operating revenues $ 870 $ 900 Net income 102 102

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income	$ 31	$ 40	$ 102	$ 102

Insider Trading Arrangements

Insider Trading Arrangements	9 Months Ended
	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Selected Balance Sheet Data (Ta

Selected Balance Sheet Data (Tables)	9 Months Ended
	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Accounts Receivable, Net	(Millions of dollars) Sept. 30, 2023 Dec. 31, 2022 Accounts receivable, net Accounts receivable $ 82 $ 93 Less allowance for bad debts (8) (9) Accounts receivable, net $ 74 $ 84
Inventories	(Millions of dollars) Sept. 30, 2023 Dec. 31, 2022 Inventories Materials and supplies $ 11 $ 8 Fuel 10 11 Natural gas 8 20 Total inventories $ 29 $ 39
Property, Plant and Equipment, Net	(Millions of dollars) Sept. 30, 2023 Dec. 31, 2022 Property, plant and equipment, net Electric plant $ 3,767 $ 3,579 Natural gas plant 496 465 Common and other property 290 260 Construction work in progress 237 174 Total property, plant and equipment 4,790 4,478 Less accumulated depreciation (1,635) (1,564) Property, plant and equipment, net $ 3,155 $ 2,914

Borrowings and Other Financin_2

Borrowings and Other Financing Instruments (Tables)	9 Months Ended
	Sep. 30, 2023
Borrowings and Other Financing Instruments [Abstract]
Credit Facilities	As of Sept. 30, 2023, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Outstanding (b) Available $ 150 $ — $ 150 (a) Expires in September 2027. (b) Includes outstanding commercial paper.
Money Pool
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Money pool borrowings: (Amounts in Millions, Except Interest Rates) Three Months Ended Sept. 30, 2023 Year Ended Dec. 31, 2022 Borrowing limit $ 150 $ 150 Amount outstanding at period end — — Average amount outstanding — 25 Maximum amount outstanding — 81 Weighted average interest rate, computed on a daily basis N/A 1.10 % 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: (Amounts in Millions, Except Interest Rates) Three Months Ended Sept. 30, 2023 Year Ended Dec. 31, 2022 Borrowing limit $ 150 $ 150 Amount outstanding at period end — 47 Average amount outstanding — 18 Maximum amount outstanding — 123 Weighted average interest rate, computed on a daily basis N/A 1.03 % Weighted average interest rate at period end N/A 4.55

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	NSP-Wisconsin’s operating revenues consisted of the following: Three Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 79 $ 8 $ — $ 87 C&I 136 5 — 141 Other 2 — 1 3 Total retail 217 13 1 231 Interchange and other 43 1 — 44 Total revenue from contracts with customers 260 14 1 275 Alternative revenue and other 3 1 — 4 Total revenues $ 263 $ 15 $ 1 $ 279 Three Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 78 $ 9 $ — $ 87 C&I 139 9 — 148 Other 2 — — 2 Total retail 219 18 — 237 Interchange and other 52 1 — 53 Total revenue from contracts with customers 271 19 — 290 Alternative revenue and other 3 1 — 4 Total revenues $ 274 $ 20 $ — $ 294 Nine Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 229 $ 62 $ — $ 291 C&I 378 48 — 426 Other 6 — 1 7 Total retail 613 110 1 724 Interchange and other 131 2 — 133 Total revenue from contracts with customers 744 112 1 857 Alternative revenue and other 9 4 — 13 Total revenues $ 753 $ 116 $ 1 $ 870 Nine Months Ended (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 226 $ 69 $ — $ 295 C&I 374 58 — 432 Other 6 — — 6 Total retail 606 127 — 733 Interchange and other 153 3 — 156 Total revenue from contracts with customers 759 130 — 889 Alternative revenue and other 8 3 — 11 Total revenues $ 767 $ 133 $ — $ 900

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Reconciliation between the statutory rate and effective tax rate: Nine Months Ended Sept. 30 2023 2022 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 6.2 6.2 Decreases: Plant regulatory differences (a) (3.4) (3.7) Other (net) (1.1) (1.4) Effective income tax rate 22.7 % 22.1 %

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level	Recurring Derivative Fair Value Measurements Impact of derivative activity: Changes in the fair value of natural gas commodity derivatives resulted in immaterial net losses and gains for the three and nine months ended Sept. 30, 2023 and 2022, which were recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. During the three and nine months ended Sept. 30, 2023 and 2022, there were immaterial natural gas commodity derivatives settlement losses and gains. During the three and nine months ended Sept. 30, 2023 and 2022, immaterial pre-tax losses were recognized during the period in income related to option premium amortization. NSP-Wisconsin had immaterial outstanding derivative assets or liabilities measured at fair value as of Sept. 30, 2023 and Dec. 31, 2022.
Carrying Amount and Fair Value of Long-term Debt	Sept. 30, 2023 Dec. 31, 2022 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 1,211 $ 1,062 $ 1,086 $ 980

Benefit Plans and Other Postr_2

Benefit Plans and Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2023
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost Three Months Ended Sept. 30 2023 2022 (Millions of Dollars) Pension Benefits Service cost $ 1 $ 2 Interest cost (a) 2 1 Expected return on plan assets (a) (2) (2) Amortization of net loss (a) — 1 Settlement charge (b) — 4 Net periodic benefit cost $ 1 $ 6 Effects of regulation — (2) Net benefit cost recognized for financial reporting $ 1 $ 4 Nine Months Ended Sept. 30 2023 2022 (Millions of Dollars) Pension Benefits Service cost $ 3 $ 4 Interest cost (a) 5 3 Expected return on plan assets (a) (6) (6) Amortization of net loss (a) 1 3 Settlement charge (b) — 4 Net periodic benefit cost $ 3 $ 8 Effects of regulation — (2) Net benefit cost recognized for financial reporting $ 3 $ 6 (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. (b) A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the net periodic pension cost. In the third quarter of 2022 as a result of lump-sum distributions during the 2022 plan year, NSP-Wisconsin recorded a pension settlement charge of $4 million, the majority of which was not recognized in earnings due to the effects of regulation. In January 2023, contributions totaling $50 million were made across Xcel Energy’s pension plans, of which $4 million was attributable to NSP-Wisconsin. Xcel Energy does not expect additional pension contributions during 2023.

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	NSP-Wisconsin's segment information: Three Months Ended Sept. 30 (Millions of Dollars) 2023 2022 Regulated Electric Total revenues (a) $ 263 $ 274 Net income 32 42 Regulated Natural Gas Total revenues $ 15 $ 20 Net loss (3) (3) All Other Total revenues $ 1 $ — Net income $ 2 $ 1 Consolidated Total Total operating revenues (a) $ 279 $ 294 Net income 31 40 (a) Total revenues include $50 million and $51 million of affiliate electric revenue for the three months ended Sept. 30, 2023 and 2022, respectively. Nine Months Ended Sept. 30 (Millions of Dollars) 2023 2022 Regulated Electric Total revenues (a) $ 753 $ 767 Net income 95 89 Regulated Natural Gas Operating revenues $ 116 $ 133 Intersegment revenue 1 — Total revenues $ 117 $ 133 Net income 5 11 All Other Total revenues $ 1 $ — Net income $ 2 $ 2 Consolidated Total Operating revenues (a) $ 871 $ 900 Reconciling eliminations (1) — Total operating revenues $ 870 $ 900 Net income 102 102 (a) Total revenues include $151 million and $150 million of affiliate electric revenue for the nine months ended Sept. 30, 2023 and 2022, respectively.

Selected Balance Sheet Data - A

Selected Balance Sheet Data - Accounts Receivable (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Accounts Receivable, Net
Accounts receivable	$ 82	$ 93
Less allowance for bad debts	(8)	(9)
Accounts receivable, net	$ 74	$ 84

Selected Balance Sheet Data - I

Selected Balance Sheet Data - Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Inventory [Line Items]
Total Inventories	$ 29	$ 39
Materials and supplies
Inventory [Line Items]
Inventories	11	8
Fuel
Inventory [Line Items]
Inventories	10	11
Natural gas
Inventory [Line Items]
Inventories	$ 8	$ 20

Selected Balance Sheet Data - P

Selected Balance Sheet Data - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 4,790	$ 4,478
Less accumulated depreciation	(1,635)	(1,564)
Property, plant and equipment, net	3,155	2,914
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,767	3,579
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	496	465
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	290	260
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 237	$ 174

Borrowings and Other Financin_3

Borrowings and Other Financing Instruments, Commercial Paper (Details) - USD ($)		3 Months Ended	12 Months Ended
		Sep. 30, 2023	Dec. 31, 2022
Short-term Debt [Line Items]
Amount outstanding at period end		$ 0	$ 47,000,000
Credit Facility
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	[1]	150,000,000
Long-term Line of Credit		0	0
Commercial Paper
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		150,000,000	150,000,000
Amount outstanding at period end		0	47,000,000
Average amount outstanding		0	18,000,000
Maximum amount outstanding		0	$ 123,000,000
Weighted average interest rate, computed on a daily basis			1.03%
Weighted average interest rate at period end			4.55%
Money Pool
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		150,000,000	$ 150,000,000
Amount outstanding at period end		0	0
Average amount outstanding		0	25,000,000
Maximum amount outstanding		$ 0	$ 81,000,000
Weighted average interest rate, computed on a daily basis			1.10%
[1]Expires in September 2027.

Borrowings and Other Financin_4

Borrowings and Other Financing Instruments, Letters of Credit (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Period	1 year
Amount outstanding at period end	$ 0	$ 47,000,000
Credit Facility
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 0	$ 0

Borrowings and Other Financin_5

Borrowings and Other Financing Instruments, Credit Facility (Details) - USD ($)		Sep. 30, 2023	Dec. 31, 2022
Payable to Affiliates
Line of Credit Facility [Line Items]
Notes Payable, Current		$ 0	$ 0
Credit Facility
Line of Credit Facility [Line Items]
Credit Facility	[1]	150,000,000
Outstanding	[2]	0
Available		150,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
[1]Expires in September 2027.[2]Includes outstanding commercial paper.

Borrowings and Other Financin_6

Borrowings and Other Financing Instruments (Details) - Series Due June 15, 2053 - Bonds [Member] $ in Millions	Sep. 30, 2023 USD ($)
Short-term Debt [Line Items]
Debt Instrument, Face Amount	$ 125
Debt Instrument, Interest Rate, Stated Percentage	5.30%

Revenues (Details)

Revenues (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 279	$ 294	$ 870	$ 900
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	263	274	753	767
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	15	20	116	133
All Other | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1	0	1	0
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	231	237	724	733
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	87	87	291	295
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	141	148	426	432
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3	2	7	6
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	217	219	613	606
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	79	78	229	226
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	136	139	378	374
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2	6	6
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13	18	110	127
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8	9	62	69
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5	9	48	58
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Retail | All Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1	0	1	0
Retail | All Other | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail | All Other | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Retail | All Other | Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1	0	1	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	44	53	133	156
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	43	52	131	153
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1	2	3
Interchange | All Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	275	290	857	889
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	260	271	744	759
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14	19	112	130
Total revenue from contracts with customers | All Other
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1	0	1	0
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	4	4	13	11
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	3	3	9	8
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	1	1	4	3
Alternative revenue and other | All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 0	$ 0	$ 0	$ 0

Income Taxes (Details)

Income Taxes (Details)		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21%	21%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		6.20%	6.20%
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	[1]	(3.40%)	(3.70%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		(1.10%)	(1.40%)
Effective Income Tax Rate Reconciliation, Percent		22.70%	22.10%
[1]Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) $ in Millions	Sep. 30, 2023 USD ($)
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges	$ 0

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Recurring Fair Value Measurements (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Prepayments and other	$ 6	$ 11

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Amount	$ 1,211	$ 1,086
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 1,062	$ 980

Benefit Plans and Other Postr_3

Benefit Plans and Other Postretirement Benefits (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended			9 Months Ended
		Jan. 31, 2023	Sep. 30, 2023	Sep. 30, 2022		Sep. 30, 2023	Sep. 30, 2022
Components of Net Periodic Benefit Cost [Abstract]
Operating and maintenance expenses			$ 58	$ 53		$ 173	$ 160
Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost			1	2		3	4
Interest cost (a)	[1]		2	1		5	3
Expected return on plan assets (a)	[1]		(2)	(2)		(6)	(6)
Amortization of net loss (a)	[1]		0	1		1	3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			0	4	[2]	0	4	[2]
Net periodic benefit cost			1	6		3	8
Effects of regulation			0	(2)		0	(2)
Net benefit cost recognized for financial reporting			$ 1	$ 4		$ 3	$ 6
Contributions to pension plans		$ 4
Pension Plan [Member] | Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 50
[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.[2]A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the net periodic pension cost. In the third quarter of 2022 as a result of lump-sum distributions during the 2022 plan year, NSP-Wisconsin recorded a pension settlement charge of $4 million, the majority of which was not recognized in earnings due to the effects of regulation.

Commitments and Contingencies G

Commitments and Contingencies Gas Trading Litigation (Details)	Sep. 30, 2023
Gas Trading Litigation
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	1

MISO ROE Complaints (Details)

MISO ROE Complaints (Details) - Federal Energy Regulatory Commission (FERC) - FERC Proceeding, MISO ROE Complaint - NSP Minnesota and NSP Wisconsin [Member] [Member]	1 Months Ended
	Feb. 28, 2015	Nov. 30, 2013
Rate Matters [Abstract]
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%

Commitments and Contingencies (

Commitments and Contingencies (Details) - Enviromental Requirements $ in Millions	Sep. 30, 2023 USD ($)
Loss Contingencies [Line Items]
Liability for estimated cost to comply with regulation	$ 5
Gain Contingencies [Line Items]
Liability for estimated cost to comply with regulation	$ 5
Plants required for improvements	2
Public Utilities, General Disclosures [Line Items]
Plants required for improvements	2
Other MGP, Landfill, or Disposal Sites [Domain]
Loss Contingencies [Line Items]
Number of identified MGP sites under current investigation and/or remediation	1
Gain Contingencies [Line Items]
Number of identified MGP sites under current investigation and/or remediation	1

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2023		Sep. 30, 2022		Sep. 30, 2023		Sep. 30, 2022
Segment Reporting Information [Line Items]
Net income		$ 31		$ 40		$ 102		$ 102
Other		1		0		1		0
Regulated and Unregulated Operating Revenue		279	[1]	294	[1]	870		900
Affiliate Revenue		50		51
Natural gas		15		20		116		133
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[2]					871		900
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue						(1)		0
Regulated Electric
Segment Reporting Information [Line Items]
Net income		32		42		95		89
Regulated Electric | Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric		263	[1]	274	[1]	753	[2]	767	[2]
Regulated Natural Gas
Segment Reporting Information [Line Items]
Net income		(3)		(3)		5		11
Revenues Including Intersegment Revenues		15		20		117		133
Regulated Natural Gas | Total revenues
Segment Reporting Information [Line Items]
Natural gas						116		133
Regulated Natural Gas | Intersegment Eliminations
Segment Reporting Information [Line Items]
Natural gas						1		0
All Other
Segment Reporting Information [Line Items]
Net income		2		1		2		2
All Other | Total revenues
Segment Reporting Information [Line Items]
Other		$ 1		$ 0		$ 1		$ 0
[1]Total revenues include $50 million and $51 million of affiliate electric revenue for the three months ended Sept. 30, 2023 and 2022, respectively.[2]Total revenues include $151 million and $150 million of affiliate electric revenue for the nine months ended Sept. 30, 2023 and 2022, respectively.