Northern States Power 10-K 23 Feb 23 2022 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 23, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		933,000
Entity Registrant Name	NORTHERN STATES POWER CO
Entity Central Index Key	0000072909
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Public Float			$ 0

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2022
Auditor [Line Items]
Auditor Name	DELOITTE & TOUCHE LLP
Auditor Location	Minneapolis, Minnesota
Auditor Firm ID	34

Accounting Pronouncements

Accounting Pronouncements	12 Months Ended
	Dec. 31, 2022
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Pronouncements	As of Dec. 31, 2022, there was no material impact from the recent adoption of new accounting pronouncements, nor expected material impact from recently issued accounting pronouncements yet to be adopted, on NSP-Wisconsin’s consolidated financial statements.

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues
Electric, non-affiliates	$ 800	$ 733	$ 687
Electric, affiliates	202	189	168
Natural gas	198	182	119
Other	1	1	0
Total operating revenues	1,201	1,105	974
Operating expenses
Electric fuel and purchased power, non-affiliates	17	20	13
Purchased power, affiliates	446	408	379
Cost of natural gas sold and transported	116	117	53
Operating and maintenance expenses	223	198	191
Conservation program expenses	13	13	13
Depreciation and amortization	158	147	156
Taxes (other than income taxes)	31	28	28
Total operating expenses	1,004	931	833
Operating income	197	174	141
Other Income and Expenses [Abstract]
Other expense, net	(2)	(1)	(8)
Allowance for funds used during construction — equity	7	5	5
Interest charges and financing costs
Interest charges — includes other financing costs of $1, $1 and $1, respectively	45	42	40
Allowance for funds used during construction — debt	(3)	(2)	(2)
Total interest charges and financing costs	42	40	38
Income before income taxes	160	138	100
Income tax expense (benefit)	35	30	(7)
Net income	$ 125	$ 108	$ 107

CONSOLIDATED STATEMENTS OF IN_2

CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Interest charges and financing costs
Other financing costs	$ 1	$ 1	$ 1

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net income	$ 125	$ 108	$ 107
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	159	148	158
Deferred income taxes	(2)	9	(36)
Allowance for equity funds used during construction	(7)	(5)	(5)
Provision for bad debts	4	4	7
Changes in operating assets and liabilities:
Accounts receivable	(13)	(5)	(12)
Accrued unbilled revenues	(5)	(16)	0
Inventories	(14)	(12)	(5)
Other current assets	(20)	(4)	(3)
Accounts payable	5	8	(3)
Net regulatory assets and liabilities	18	(41)	0
Other current liabilities	16	2	4
Pension and other employee benefit obligations	(4)	(9)	(7)
Other, net	(5)	(1)	(3)
Net cash provided by operating activities	257	186	202
Investing activities
Capital/construction expenditures	(353)	(264)	(238)
Investments In Utility Money Pool Arrangement	(100)	(71)	0
Repayments From Utility Money Pool Arrangement	100	71	0
Net cash used in investing activities	(353)	(264)	(238)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(35)	64	(46)
Proceeds from issuance of long-term debt	99	99	97
Repayments of long-term debt	0	(19)	0
Borrowings Under Utility Money Pool Arrangement	591	358	0
Repayments Under Utility Money Pool Arrangement	(591)	(358)	0
Capital contributions from parent	114	46	56
Dividends paid to parent	(91)	(103)	(70)
Net cash provided by financing activities	87	87	37
Net change in cash, cash equivalents and restricted cash	(9)	9	1
Cash, cash equivalents and restricted cash at beginning of period	11	2	1
Cash, cash equivalents and restricted cash at end of period	2	11	2
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(39)	(38)	(36)
Cash paid for income taxes, net	(32)	(22)	(26)
Other Noncash Investing and Financing Items [Abstract]
Supplemental disclosure of non-cash investing and financing transactions:	54	43	21
Inventory transfers to plant, property and equipment	1	1	5
Allowance for Funds Used During Construction, Investing Activities	$ 7	$ 5	$ 5

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 2	$ 11
Accounts receivable, net	84	71
Accrued unbilled revenues	74	69
Other receivables	19	3
Inventories	39	27
Regulatory assets	44	21
Prepaid taxes	27	25
Prepayments and other	11	7
Total current assets	300	234
Property, Plant and Equipment, Net	2,914	2,660
Other assets
Regulatory assets	193	225
Other	3	4
Total other assets	196	229
Total assets	3,410	3,123
Current liabilities
Short-term debt	47	83
Accounts payable	92	69
Accounts payable to affiliates	19	23
Dividends payable to parent	23	26
Regulatory liabilities	21	4
Taxes accrued	13	10
Accrued interest	12	10
Other	28	21
Total current liabilities	255	246
Deferred credits and other liabilities
Deferred income taxes	333	325
Deferred investment tax credits	5	5
Regulatory liabilities	383	372
Customer advances	23	23
Pension and employee benefit obligations	23	16
Other	43	46
Total deferred credits and other liabilities	810	787
Commitments and contingencies
Capitalization
Long-term debt	1,086	987
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at Dec. 31, 2022 and Dec. 31, 2021, respectively	93	93
Additional paid in capital	761	642
Retained earnings	405	368
Total common stockholder's equity	1,259	1,103
Total liabilities and equity	$ 3,410	$ 3,123

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
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

CONSOLIDATED STATEMENTS OF COMM

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings
Beginning Balance at Dec. 31, 2019	$ 967	$ 93	$ 537	$ 337
Balance (in shares) at Dec. 31, 2019		933,000
Increase (Decrease) in Stockholder's Equity
Net income	107			107
Dividends, Common Stock, Cash	(74)			(74)
Contribution of capital by parent	68		68
Ending Balance at Dec. 31, 2020	1,068	$ 93	605	370
Balance (in shares) at Dec. 31, 2020		933,000
Increase (Decrease) in Stockholder's Equity
Net income	108			108
Dividends, Common Stock, Cash	(110)			(110)
Contribution of capital by parent	37		37
Ending Balance at Dec. 31, 2021	$ 1,103	$ 93	642	368
Balance (in shares) at Dec. 31, 2021	933,000	933,000
Increase (Decrease) in Stockholder's Equity
Net income	$ 125			125
Dividends, Common Stock, Cash	(88)			(88)
Contribution of capital by parent	119		119
Ending Balance at Dec. 31, 2022	$ 1,259	$ 93	$ 761	$ 405
Balance (in shares) at Dec. 31, 2022	933,000	933,000

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	General — NSP-Wisconsin is engaged in the regulated generation, transmission, distribution and sale of electricity and the regulated purchase, transportation, distribution and sale of natural gas. NSP-Wisconsin’s consolidated financial statements include its wholly-owned subsidiaries and VIEs for which it is the primary beneficiary. In the consolidation process, all intercompany transactions and balances are eliminated. NSP-Wisconsin has investments in certain transmission facilities jointly owned with nonaffiliated utilities. NSP-Wisconsin’s proportionate share of jointly owned facilities is recorded as property, plant and equipment on the consolidated balance sheets and NSP-Wisconsin’s proportionate share of operating costs associated with these facilities is included in its consolidated statements of income. NSP-Wisconsin’s consolidated financial statements are presented in accordance with GAAP. All of NSP-Wisconsin’s underlying accounting records also conform to the FERC uniform system of accounts or to systems required by various state regulatory commissions. Certain amounts in the consolidated financial statements or notes have been reclassified for comparative purposes; however, such reclassifications did not affect net income, total assets, liabilities, equity or cash flows. NSP-Wisconsin has evaluated events occurring after Dec. 31, 2022 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. Use of Estimates — NSP-Wisconsin uses estimates based on the best information available in recording transactions and balances resulting from business operations. Estimates are used for items such as plant depreciable lives or potential disallowances, AROs, certain regulatory assets and liabilities, tax provisions, uncollectible amounts, environmental costs, unbilled revenues, jurisdictional fuel and energy cost allocations and actuarially determined benefit costs. Recorded estimates are revised when better information becomes available or actual amounts can be determined. Revisions can affect operating results. Regulatory Accounting — NSP-Wisconsin accounts for income and expense items in accordance with accounting guidance for regulated operations. Under this guidance: • Certain costs, which would otherwise be charged to expense or other comprehensive income, are deferred as regulatory assets based on the expected ability to recover the costs in future rates. • Certain credits, which would otherwise be reflected as income or other comprehensive income, are deferred as regulatory liabilities based on the expectation the amounts will be returned to customers in future rates or because the amounts were collected in rates prior to the costs being incurred. Estimates and assumptions for recovery of deferred costs and refund of deferred credits are based on specific ratemaking decisions, precedent or other information available. Regulatory assets and liabilities are amortized consistent with the treatment in the rate setting process. If changes in the regulatory environment occur, NSP-Wisconsin may no longer be eligible to apply this accounting treatment and may be required to eliminate regulatory assets and liabilities. Such changes could have a material effect on NSP-Wisconsin’s results of operations, financial condition and cash flows. See Note 4 for further information. Income Taxes — NSP-Wisconsin accounts for income taxes using the asset and liability method, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Income taxes are deferred for all temporary differences between pretax financial and taxable income and between the book and tax bases of assets and liabilities. NSP-Wisconsin uses rates that are scheduled to be in effect when the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the period that includes the enactment date. The effects of tax rate changes that are attributable to the utility subsidiaries are generally subject to a normalization method of accounting. Therefore, the revaluation of most of the utility subsidiaries’ net deferred taxes upon a tax rate reduction results in the establishment of a net regulatory liability, refundable to utility customers over the remaining life of the related assets. NSP-Wisconsin anticipates that a tax rate increase would predominantly result in the establishment of a regulatory asset, subject to an evaluation of whether future recovery is expected. Reversal of certain temporary differences are accounted for as current income tax expense due to the effects of past regulatory practices when deferred taxes were not required to be recorded due to the use of flow through accounting for ratemaking purposes. Tax credits are recorded when earned unless there is a requirement to defer the benefit and amortize over the book depreciable lives of the related property. The requirement to defer and amortize these credits specifically applies to certain federal ITCs, as determined by tax regulations and NSP-Wisconsin tax elections. For tax credits otherwise eligible to be recognized when earned, NSP-Wisconsin considers the impact of rate regulation to determine if these credits and related adjustments should be deferred as regulatory assets or liabilities. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized. Utility rate regulation has resulted in the recognition of regulatory assets and liabilities related to income taxes. NSP-Wisconsin measures and discloses uncertain tax positions that it has taken or expects to take in its income tax returns. A tax position is recognized in the consolidated financial statements when it is more likely than not that the position will be sustained upon examination based on the technical merits of the position. Recognition of changes in uncertain tax positions are reflected as a component of income tax expense. Interest and penalties related to income taxes are reported within other (expense) income or interest charges in the consolidated statements of income. Xcel Energy Inc. and its subsidiaries, including NSP-Wisconsin file consolidated federal income tax returns as well as consolidated or separate state income tax returns. Federal income taxes paid by Xcel Energy Inc. are allocated to its subsidiaries based on separate company computations. A similar allocation is made for state income taxes paid by Xcel Energy Inc. in connection with consolidated state filings. Xcel Energy Inc. also allocates its own income tax benefits to its direct subsidiaries. See Note 7 for further information. Property, Plant and Equipment and Depreciation in Regulated Operations — Property, plant and equipment is stated at original cost. The cost of plant includes direct labor and materials, contracted work, overhead costs and AFUDC. The cost of plant retired is charged to accumulated depreciation and amortization. Amounts recovered in rates for future removal costs are recorded as regulatory liabilities. Significant additions or improvements extending asset lives are capitalized, while repairs and maintenance costs are charged to expense as incurred. Maintenance and replacement of items determined to be less than a unit of property are charged to operating expenses as incurred. Property, plant and equipment is tested for impairment when it is determined that the carrying value of the assets may not be recoverable. A loss is recognized in the current period if it becomes probable that part of a cost of a plant under construction or recently completed plant will be disallowed for recovery from customers and a reasonable estimate of the disallowance can be made. For investments in property, plant and equipment that are abandoned and not expected to go into service, incurred costs and related deferred tax amounts are compared to the discounted estimated future rate recovery, and a loss is recognized, if necessary. Depreciation expense is recorded using the straight-line method over the plant’s commission approved useful life. Actuarial life studies are performed and submitted to the state and federal commissions for review. Upon acceptance by the various commissions, the resulting lives and net salvage rates are used to calculate depreciation. Plant removal costs are typically recognized at the amounts recovered in rates as authorized by the applicable regulator. Accumulated removal costs are reflected in the consolidated balance sheet as a regulatory liability. Depreciation expense, expressed as a percentage of average depreciable property, was approxim at ely 3.6% in 2022, 2021 and 2020. See Note 3 for further information. AROs — NSP-Wisconsin records AROs as a liability for the fair value of an ARO to be recognized in the period incurred (if it can be reasonably estimated), with the offsetting/associated costs capitalized as a long-lived asset. The liability is generally increased over time by applying the effective interest method of accretion and the capitalized costs are typically depreciated over the useful life of the long-lived asset. Changes resulting from revisions to timing or amounts of expected asset retirement cash flows are recognized as an increase or a decrease in the ARO. See Note 10 for further information. Benefit Plans and Other Postretirement Benefits — NSP-Wisconsin maintains pension and postretirement benefit plans for eligible employees. Recognizing the cost of providing benefits and measuring the projected benefit obligation of these plans requires management to make various assumptions and estimates. Certain unrecognized actuarial gains and losses and unrecognized prior service costs or credits are deferred as regulatory assets and liabilities, rather than recorded as other comprehensive income, based on regulatory recovery mechanisms. See Note 9 for further information. Environmental Costs — Environmental costs are recorded when it is probable NSP-Wisconsin is liable for remediation costs and the amount can be reasonably estimated. Costs are deferred as a regulatory asset if it is probable the costs will be recovered from customers in future rates. Otherwise, the costs are expensed. For certain environmental costs related to facilities currently in use, such as for emission-control equipment, the cost is capitalized and depreciated over the life of the plant. Estimated remediation costs are regularly adjusted as estimates are revised and remediation is performed. If other participating potentially responsible parties exist and acknowledge their potential involvement with a site, costs are estimated and recorded only for NSP-Wisconsin’s expected share of the cost. Future costs of restoring sites are treated as a capitalized cost of plant retirement. The depreciation expense levels recoverable in rates include a provision for removal expenses. Removal costs recovered in rates before the related costs are incurred are classified as a regulatory liability. See Note 10 for further information. Revenue from Contracts with Customers — Performance obligations related to the sale of energy are satisfied as energy is delivered to customers. NSP-Wisconsin recognizes revenue that corresponds to the price of the energy delivered to the customer. The measurement of energy sales to customers is generally based on the reading of their meters, which occurs systematically throughout the month. At the end of each month, amounts of energy delivered to customers since the date of the last meter reading are estimated, and the corresponding unbilled revenue is recognized. A separate financing component of collections from customers is not recognized as contract terms are short-term in nature. Revenues are net of any excise or sales taxes or fees. NSP-Wisconsin has various rate-adjustment mechanisms that provide for the recovery of natural gas, electric fuel and purchased energy costs. Cost-adjustment tariffs may increase or decrease the level of revenue collected from customers and are revised periodically for differences between the total amount collected under the clauses and the costs incurred. When applicable, fuel cost over-recoveries (the excess of fuel revenue billed to customers over fuel costs incurred) are deferred as regulatory liabilities and under-recoveries (the excess of fuel costs incurred over fuel revenues billed to customers) are deferred as regulatory assets. NSP-Wisconsin must submit a forward looking fuel cost plan annually for approval by the PSCW. The rules also allow for deferral of any under-recovery or over-recovery of fuel costs in excess of a 2% annual tolerance band, for future rate recovery or refund, subject to PSCW approval. Cash and Cash Equivalents — NSP-Wisconsin considers investments in instruments with a remaining maturity of three months or less at the time of purchase to be cash equivalents. Accounts Receivable and Allowance for Bad Debts — Accounts receivable are stated at the actual billed amount net of an allowance for bad debts. NSP-Wisconsin establishes an allowance for uncollectible receivables based on a policy that reflects its expected exposure to the credit risk of customers. As of Dec. 31, 2022 and 2021, the allowance for bad debts was $9 million and $8 million, respectively. Inventory — Inventory is recorded at the lower of average cost or net realizable value and consisted of the following: (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Inventories Materials and supplies $ 8 $ 8 Fuel 11 9 Natural gas 20 10 Total inventories $ 39 $ 27 Fair Value Measurements — NSP-Wisconsin presents cash equivalents, interest rate derivatives and commodity derivatives at estimated fair values in its consolidated financial statements. For interest rate derivatives, quoted prices based primarily on observable market interest rate curves are used to estimate fair value. For commodity derivatives, the most observable inputs available are generally used to determine the fair value of each contract. In the absence of a quoted price, quoted prices for similar contracts or internally prepared valuation models may be used to determine fair value. For the pension and postretirement plan assets and nuclear decommissioning fund, published trading data and pricing models, generally using the most observable inputs available, are utilized to determine fair value for each security. See Notes 8 and 9 for further information. Derivative Instruments — NSP-Wisconsin uses derivative instruments in connection with its commodity trading activities, and to manage risk associated with changes in interest rates, and utility commodity prices, including forward contracts, futures, swaps and options. Any derivative instruments not qualifying for the normal purchases and normal sales exception are recorded on the consolidated balance sheets at fair value as derivative instruments. Classification of changes in fair value for those derivative instruments is dependent on the designation of a qualifying hedging relationship. Changes in fair value of derivative instruments not designated in a qualifying hedging relationship are reflected in current earnings or as a regulatory asset or liability. Classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. Gains or losses on commodity trading transactions are recorded as a component of electric operating revenues. Normal Purchases and Normal Sales — NSP-Wisconsin enters into contracts for purchases and sales of commodities for use in its operations. At inception, contracts are evaluated to determine whether they contain a derivative, and if so, whether they may be exempted from derivative accounting if designated as normal purchases or normal sales. See Note 8 for further information. Other Utility Items AFUDC — AFUDC represents the cost of capital used to finance utility construction activity and is computed by applying a composite financing rate to qualified CWIP. The amount of AFUDC capitalized as a utility construction cost is credited to other nonoperating income (for equity capital) and interest charges (for debt capital). AFUDC amounts capitalized are included in NSP-Wisconsin’s rate base. Alternative Revenue — Certain rate rider mechanisms qualify as alternative revenue programs. These mechanisms arise from instances in which the regulator authorizes a future surcharge in response to past activities or completed events. When certain criteria are met, including expected collection within 24 months, revenue is recognized, which may include incentives and return on rate base items. The mechanisms are revised periodically for differences between total amount collected and the revenue earned, which may increase or decrease the level of revenue collected from customers. Alternative revenues arising from these programs are presented on a gross basis and disclosed separately from revenue from contracts with customers. See Note 6 for further information. Conservation Programs — NSP-Wisconsin participates in and funds conservation programs in its retail jurisdictions to assist customers in conserving energy and reducing peak demand on the electric and natural gas systems. NSP-Wisconsin recovers approved conservation program costs in base rate revenue. For operations in the state of Wisconsin, NSP-Wisconsin is required to contribute 1.2% of its three Emissions Allowances — Emissions allowances are recorded at cost, including broker commission fees. The inventory accounting model is utilized for all emissions allowances and any sales of these allowances are included in electric revenues. RECs — Cost of RECs that are utilized for compliance is recorded as electric fuel and purchased power expense. An inventory accounting model is used to account for RECs.

Property Plant and Equipment Pr

Property Plant and Equipment Property Plant and Equipment	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Major classes of property, plant and equipment (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Property, plant and equipment, net Electric plant $ 3,579 $ 3,348 Natural gas plant 465 423 Common and other property 260 233 CWIP 174 134 Total property, plant and equipment 4,478 4,138 Less accumulated depreciation (1,564) (1,478) Property, plant and equipment, net $ 2,914 $ 2,660 Joint Ownership of Transmission Facilities Jointly owned assets as of Dec. 31, 2022: (Millions of Dollars, Except Percent Owned) Plant in Service Accumulated Depreciation Percent Owned Electric transmission: La Crosse, WI to Madison, WI $ 177 $ 20 37 % CapX2020 166 34 80 Total (a) $ 343 $ 54 (a) Projects additionally include $1 million in CWIP. NSP-Wisconsin’s share of operating expenses and construction expenditures is included in the applicable utility accounts. Respective owners are responsible for providing their own financing.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	12 Months Ended
	Dec. 31, 2022
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory assets and liabilities are created for amounts that regulators may allow to be collected or may require to be paid back to customers in future electric and natural gas rates. NSP-Wisconsin would be required to recognize the write-off of regulatory assets and liabilities in net income or other comprehensive income if changes in the utility industry no longer allow for the application of regulatory accounting guidance under GAAP. Components of regulatory assets: (Millions of Dollars) See Note(s) Remaining Amortization Period Dec. 31, 2022 Dec. 31, 2021 (a) Regulatory Assets Current Noncurrent Current Noncurrent Environmental remediation costs 1, 10 Various $ 13 $ 63 $ 13 $ 79 Pension and retiree medical obligations 9 Various 2 61 4 55 State commission adjustments Plant lives 1 22 1 21 Recoverable deferred taxes on AFUDC Plant lives — 20 — 19 Net AROs (b) 1, 10 Various — 18 — 10 Deferred natural gas and electric energy/fuel costs 7 One 23 — 2 29 Other Various 5 9 1 12 Total regulatory assets $ 44 $ 193 $ 21 $ 225 (a) Prior period amounts have been restated to conform with current year presentation. (b) Includes amounts recorded for future recovery of AROs, less amounts recovered through NSP-Wisconsin’s share of nuclear decommissioning accruals and gains from decommissioning investments. Components of regulatory liabilities: (Millions of Dollars) See Note(s) Remaining Amortization Period Dec. 31, 2022 Dec. 31, 2021 Regulatory Liabilities Current Noncurrent Current Noncurrent Plant removal costs 1, 10 Various $ — $ 223 $ — $ 201 Deferred income tax adjustments and TCJA refunds (a) 7 Various — 144 — 152 United States Department of Energy Settlement Various 12 3 — 14 Deferred natural gas and electric energy/fuel costs Less than one 5 — 3 — Other Various 4 13 1 5 Total regulatory liabilities $ 21 $ 383 $ 4 $ 372 (a) Includes the revaluation of recoverable/regulated plant accumulated deferred income taxes and revaluation impact of non-plant accumulated deferred income taxes due to the TCJA. NSP-Wisconsin’s regulatory assets not earning a return include the unfunded portion of pension and retiree medical obligations and net AROs (i.e. deferrals for where cash has not been disbursed). At Dec. 31, 2022 and 2021, there were no regulatory assets of past expenditures that were not eligible to earn a return.

Debt

Debt	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Borrowings and Other Financing Instruments	5. 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: (Millions of Dollars, Except Interest Rates) Three Months Ended Dec. 31, 2022 Year Ended 2022 2021 Borrowing limit $ 150 $ 150 $ 150 Amount outstanding at period end — — — Average amount outstanding 1 25 16 Maximum amount outstanding 16 81 78 Weighted average interest rate, computed on a daily basis 4.07 % 1.10 % 0.05 % Weighted average interest rate at period end N/A N/A N/A Commercial Paper — Commercial paper outstanding: (Millions of Dollars, Except Interest Rates) Three Months Ended Dec. 31, 2022 Year Ended Dec. 31 2022 2021 2020 Borrowing limit $ 150 $ 150 $ 150 $ 150 Amount outstanding at period end 47 47 83 19 Average amount outstanding 9 18 3 30 Maximum amount outstanding 52 123 83 95 Weighted average interest rate, computed on a daily basis 4.39 1.03 0.18 1.59 Weighted average interest rate at end of period 4.55 4.55 0.21 0.17 Letters of Credit — NSP-Wisconsin may use letters of credit, typically with terms of one year, to provide financial guarantees for certain operating obligations. At Dec. 31, 2022 and 2021, there were no letters of credit outstanding. Credit Facility — In order to use commercial paper programs to fulfill short-term funding needs, NSP-Wisconsin must have revolving credit facilities in place at least equal to the amount of their respective commercial paper borrowing limits and cannot issue commercial paper exceeding available capacity under these credit facilities. The lines of credit provide short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings. Features of the credit facility: Debt-to-Total Capitalization Ratio (a) Amount Facility May Be Increased (millions of dollars) Additional Periods for Which a One-Year Extension May Be Requested (b) 2022 2021 47 % 49 % N/A 1 (a) The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%. (b) All extension requests are subject to majority bank group approval. The credit facility has a cross-default provision that NSP-Wisconsin would be in default on borrowings under the facility if NSP-Wisconsin or any of its subsidiaries, whose total assets exceed 15% of NSP-Wisconsin’s consolidated total assets, default on certain indebtedness in an aggregate principal amount exceeding $75 million. If NSP-Wisconsin does not comply with the covenant, an event of default may be declared, and if not remedied, any outstanding amounts due under the facility can be declared due by the lender . As of Dec. 31, 2022, NSP-Wisconsin was in compliance with all financial covenants. NSP-Wisconsin had the following committed credit facility available as of Dec. 31, 2022 (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 150 $ 47 $ 103 (a) This credit facility matures in September 2027. (b) Includes outstanding commercial paper. All credit facility bank 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 facility outstanding at Dec. 31, 2022 and 2021, respectively . Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary , had an immaterial note payable to Xcel Energy Inc. at Dec. 31, 2022 and 2021, respectively. Long-Term Borrowings and Other Financing Instruments Generally, the property of NSP-Wisconsin is subject to the lien of its first mortgage indenture for the benefit of bondholders. Debt premiums, discounts and expenses are amortized over the life of the related debt. The premiums, discounts and expenses for refinanced debt are deferred and amortized over the life of new issuance. Long-term debt obligations for NSP-Wisconsin as of Dec. 31 (in millions of dollars): Financing Instrument Interest Rate Maturity Date 2022 2021 First mortgage bonds 3.30 June 15, 2024 100 100 First mortgage bonds 3.30 June 15, 2024 100 100 First mortgage bonds 6.375 Sept. 1, 2038 200 200 First mortgage bonds 3.70 Oct. 1, 2042 100 100 First mortgage bonds 3.75 Dec. 1, 2047 100 100 First mortgage bonds 4.20 Sept. 1, 2048 200 200 First mortgage bonds 3.05 May 1, 2051 100 100 First mortgage bonds (a) 2.82 May 1, 2051 100 100 First mortgage bonds (b) 4.86 Sept. 15, 2052 100 — Other long-term debt — 1 Unamortized discount (3) (4) Unamortized debt issuance cost (11) (10) Total long-term debt $ 1,086 $ 987 (a) 2021 financing. (b) 2022 financing. Maturities of long-term debt: (Millions of Dollars) 2023 $ — 2024 200 2025 — 2026 — 2027 — Deferred Financing Costs — Deferred financing costs of approximately $11 million and $10 million, net of amortization, are presented as a deduction from the carrying amount of long-term debt at Dec. 31, 2022 and 2021, respectively. NSP-Wisconsin is amortizing these financing costs over the remaining maturity periods of the related debt. Dividend Restrictions — NSP-Wisconsin’s dividends are subject to the FERC’s jurisdiction, which prohibits the payment of dividends out of capital accounts. Dividends are solely to be paid from retained earnings. NSP-Wisconsin’s state regulatory commission additionally imposes dividend limitations, which are more restrictive than those imposed by the FERC. Requirements and actuals as of Dec. 31, 2022: Equity to Total Equity to Total Capitalization Ratio Actual Low High 2022 52.5 % N/A 52.8 % Unrestricted Retained Earnings Total Capitalization Limit on Total Capitalization (a) $ 11 million 2,280 million N/A	[1],[2]
[1]All extension requests are subject to majority bank group approval.[2]The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.

Revenues

Revenues	12 Months Ended
	Dec. 31, 2022
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: Year Ended Dec. 31, 2022 (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 293 $ 103 $ — $ 396 C&I 485 87 — 572 Other 7 — — 7 Total retail 785 190 — 975 Interchange 202 — — 202 Other 4 4 — 8 Total revenue from contracts with customers 991 194 — 1,185 Alternative revenue and other 11 4 1 16 Total revenues $ 1,002 $ 198 $ 1 $ 1,201 Year Ended Dec. 31, 2021 (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 272 $ 91 $ — $ 363 C&I 441 85 — 526 Other 8 — 1 9 Total retail 721 176 1 898 Interchange 189 — — 189 Other — 4 — 4 Total revenue from contracts with customers 910 180 1 1,091 Alternative revenue and other 12 2 — 14 Total revenues $ 922 $ 182 $ 1 $ 1,105 Year Ended Dec. 31, 2020 (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 258 $ 64 $ — $ 322 C&I 411 49 — 460 Other 6 — — 6 Total retail 675 113 — 788 Interchange 168 — — 168 Other — 4 — 4 Total revenue from contracts with customers 843 117 — 960 Alternative revenue and other 12 2 — 14 Total revenues $ 855 $ 119 $ — $ 974

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Total income tax expense from operations differs from the amount computed by applying the statutory federal income tax rate to income before income tax expense. Effective income tax rate for years ended Dec. 31: 2022 2021 (b) 2020 (b) Federal statutory rate 21.0 % 21.0 % 21.0 % State income tax on pretax income, net of federal tax effect 6.2 6.2 6.2 Increases (decreases) in tax from: Plant regulatory differences (a) (3.8) (4.1) (19.3) Other tax credits, net NOL & tax credit allowances (0.8) (1.0) (1.5) Amortization of excess nonplant deferred taxes — — (12.6) Other, net (0.7) (0.4) (0.8) Effective income tax rate 21.9 % 21.7 % (7.0) % (a) 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 taxes are offset by corresponding revenue reductions. (b) Prior period amounts have been restated to conform with current year presentation. Components of income tax expense for years ended Dec. 31: (Millions of Dollars) 2022 2021 2020 Current federal tax expense $ 28 $ 17 $ 25 Current state tax expense 9 4 6 Current change in unrecognized tax benefit — — (1) Deferred federal tax (benefit) expense (5) 3 (37) Deferred state tax expense 3 6 1 Deferred ITCs — — (1) Total income tax expense (benefit) $ 35 $ 30 $ (7) Components of deferred income tax expense as of Dec. 31: (Millions of Dollars) 2022 2021 2020 Deferred tax expense excluding items below $ 8 $ 18 $ 9 Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities (10) (10) (45) Other — 1 — Deferred tax (benefit) expense $ (2) $ 9 $ (36) Components of the net deferred tax liability as of Dec. 31: (Millions of Dollars) 2022 2021 Deferred tax liabilities: Difference between book and tax bases of property $ 343 $ 331 Regulatory assets 25 29 Pension expense 10 11 Deferred fuel costs 6 8 Other 8 7 Total deferred tax liabilities $ 392 $ 386 Deferred tax assets: Regulatory liabilities $ 36 $ 38 Tax credit carryforward 7 8 Environmental remediation 4 5 Other employee benefits 3 4 Rate refund 3 — Deferred ITCs 2 2 Other 4 4 Total deferred tax assets $ 59 $ 61 Net deferred tax liability $ 333 $ 325 Other Income Tax Matters — NOL amounts represent the tax loss that is carried forward and tax credits represent the deferred tax asset. NOL and tax credit carryforwards as of Dec. 31 were as follows: (Millions of Dollars) 2022 2021 Federal tax credit carryforwards $ 7 $ 8 State NOL carryforward 2 2 Federal carryforward periods expire between 2032 and 2042 and state carryforward periods expire between 2031 and 2036. Federal Tax Loss Carryback Claims — In 2020, Xcel Energy identified certain expenses related to tax years 2009 - 2011 that qualify for an extended carryback claim. NSP-Wisconsin is not expected to accrue any income tax expense related to this adjustment. Unrecognized Tax Benefits Federal Audit — NSP-Wisconsin 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 consolidated federal income tax returns expire as follows: Tax Year(s) Expiration 2014 - 2016 March 2024 2019 October 2023 Additionally, the statute of limitations related to certain federal tax credit carryforwards will remain open until those credits are utilized in subsequent returns. Further, the statute of limitations related to the additional 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-Wisconsin is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of Dec. 31, 2022, NSP-Wisconsin’s earliest open tax years that are subject to examination by state taxing authorities under applicable statutes of limitations are as follows: State Tax Year(s) Expiration Wisconsin 2016-2017 April 2023 Wisconsin 2018 October 2023 In 2021, Wisconsin began an audit of tax years 2016-2019. As of Dec. 31, 2022 no material adjustments have been proposed. Unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which deductibility is highly certain, but for which there is uncertainty about the timing. A change in the timing of deductibility would not affect the ETR but would accelerate the payment to the taxing authority. Unrecognized tax benefits — permanent vs. temporary: (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Unrecognized tax benefit — Permanent tax positions $ 2 $ 2 Unrecognized tax benefit — Temporary tax positions 1 1 Total unrecognized tax benefit $ 3 $ 3 Changes in unrecognized tax benefits: (Millions of Dollars) 2022 2021 2020 Balance at Jan. 1 $ 3 $ 2 $ 3 Additions for tax positions of prior years — 1 1 Reductions for tax positions of prior years — — (2) Balance at Dec. 31 $ 3 $ 3 $ 2 Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards: (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 NOL and tax credit carryforwards $ (2) $ (2) As the IRS progresses its review of the tax loss carryback claims and as state audits progress, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $2 million in the next 12 months.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
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 Dec. 31, 2022, 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: Pre-Tax Fair Value Gains (Losses) Recognized During the Period in: (Millions of Dollars) Regulatory (Assets) and Liabilities Year Ended Dec. 31, 2022 Other derivative instruments Natural gas commodity (1) Total $ (1) Year Ended Dec. 31, 2021 Other derivative instruments Natural gas commodity (1) Total $ (1) Year Ended Dec. 31, 2020 Other derivative instruments Natural gas commodity (1) Total $ (1) Pre-Tax (Gains) Losses Pre-Tax Gains (Losses) (Millions of Dollars) Regulatory Year Ended Dec. 31, 2022 Other derivative instruments Natural gas commodity — (2) (a) Total $ — $ (2) Year Ended Dec. 31, 2021 Other derivative instruments Natural gas commodity — (1) (a) Total $ — $ (1) Year Ended Dec. 31, 2020 Other derivative instruments Natural gas commodity 1 (a) (1) (a) Total $ 1 $ (1) (a) Recorded to cost of natural gas sold and transported. These losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate. NSP-Wisconsin had no derivative instruments designated as fair value hedges during the years ended Dec. 31, 2022, 2021 and 2020. Derivative assets and liabilities measured at fair value on a recurring basis were as follows: Dec. 31, 2022 Dec. 31, 2021 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 (b) Natural gas commodity $ — $ 2 $ — $ 2 $ — $ 2 $ — $ 1 $ — $ 1 $ — $ 1 Current derivative liabilities (c) Natural gas commodity $ — $ 1 $ — $ 1 $ — $ 1 $ — $ 1 $ — $ 1 $ — $ 1 (a) NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement. Counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements. (b) Included in prepayments and other current assets at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet. (c) Included in other current liabilities at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet. Fair Value of Long-Term Debt As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value: 2022 2021 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 1,086 $ 980 $ 987 $ 1,143 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 Dec. 31, 2022 and 2021, 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	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Benefit Plans and Other Postretirement Benefits	9. Benefit Plans and Other Postretirement Benefits Pension and Postretirement Health Care Benefits Xcel Energy, which includes NSP-Wisconsin, has several noncontributory, qualified, defined benefit pension plans that cover almost all employees. All newly hired or rehired employees participate under the Cash Balance formula, which is based on pay credits using a percentage of annual eligible pay and annual interest credits. The average annual interest crediting rates for these plans was 4.86, 1.96 and 1.78 percent in 2022, 2021, and 2020, respectively. Some employees may participate under legacy formulas such as the traditional final average pay or pension equity. Xcel Energy’s policy is to fully fund into an external trust the actuarially determined pension costs subject to the limitations of applicable employee benefit and tax laws. In addition to the qualified pension plans, Xcel Energy maintains a SERP and a nonqualified pension plan. The SERP is maintained for certain executives who participated in the plan in 2008, when the SERP was closed to new participants. The nonqualified pension plan provides benefits for compensation that is in excess of the limits applicable to the qualified pension plans, with distributions funded by Xcel Energy’s consolidated operating cash flows. Obligations of the SERP and nonqualified plan as of Dec. 31, 2022 and 2021 were $11 million and $43 million, respectively, of which the amounts attributable to NSP-Wisconsin were immaterial in both years. Xcel Energy recognized net benefit cost for the SERP and nonqualified plans of $17 million and $4 million in 2022 and 2021, respectively, of which amounts attributable to NSP-Wisconsin were immaterial. Investment-return assumption considers the expected long-term performance for each of the asset classes in its pension and postretirement health care portfolio. Xcel Energy considers the historical returns achieved by its asset portfolios over long time periods, as well as the long-term projected return levels from investment experts. Pension cost determination assumes a forecasted mix of investment types over the long-term. • Investment returns in 2022 were below the assumed level of 6.60%. • Investment returns in 2021 were above the assumed level of 6.60%. • Investment returns in 2020 were above the assumed level of 7.10%. • In 2023, NSP-Wisconsin’s expected investment-return assumption is 7.25%. Pension plan and postretirement benefit assets are invested in a portfolio according to Xcel Energy’s return, liquidity and diversification objectives to provide a source of funding for plan obligations and minimize contributions to the plan, within appropriate levels of risk. The principal mechanism for achieving these objectives is the asset allocation given the long-term risk, return, correlation and liquidity characteristics of each particular asset class. There were no significant concentrations of risk in any industry, index, or entity. Market volatility can impact even well-diversified portfolios and significantly affect the return levels achieved by the assets in any year. Xcel Energy’s ongoing investment strategy is based on plan-specific investment recommendations that seek to minimize potential investment and interest rate risk as a plan’s funded status increases over time. The investment recommendations consider many factors and generally result in a greater percentage of long-duration fixed income securities being allocated to specific plans having relatively higher funded status ratios and a greater percentage of growth assets being allocated to plans having relatively lower funded status ratios. Plan Assets For each of the fair value hierarchy levels, NSP-Wisconsin’s pension plan assets measured at fair value: Dec. 31, 2022 (a) Dec. 31, 2021 (a) (Millions of Dollars) Level 1 Level 2 Level 3 Measured at NAV Total Level 1 Level 2 Level 3 Measured at NAV Total Cash equivalents $ 4 $ — $ — $ — $ 4 $ 5 $ — $ — $ — $ 5 Commingled funds 35 — — 34 69 49 — — 44 93 Debt securities — 22 — — 22 — 36 — — 36 Equity securities 2 — — — 2 3 — — — 3 Total $ 41 $ 22 $ — $ 34 $ 97 $ 57 $ 36 $ — $ 44 $ 137 (a) See Note 8 for further information on fair value measurement inputs and methods. NSP-Wisconsin has immaterial postretirement benefit plan assets that were measured at fair value at Dec. 31, 2022 and 2021. No ass ets were transferred in or out of Level 3 for 2022 or 2021. Funded Status — Benefit obligations for both pension and postretirement plans decreased from Dec. 31, 2021 to Dec. 31, 2022, due primarily to benefit payments and increases in discount rates used in actuarial valuations. Comparisons of the actuarially computed benefit obligation, changes in plan assets and funded status of the pension and postretirement health care plans for NSP-Wisconsin are as follows: Pension Benefits Postretirement Benefits (Millions of Dollars) 2022 2021 2022 2021 Change in Benefit Obligation: Obligation at Jan. 1 $ 141 $ 154 $ 11 $ 13 Service cost 5 5 — — Interest cost 4 4 1 1 Actuarial gain (21) (4) (3) (1) Benefit payments (17) (18) (1) (2) Obligation at Dec. 31 $ 112 $ 141 $ 8 $ 11 Change in Fair Value of Plan Assets: Fair value of plan assets at Jan. 1 $ 137 $ 140 $ — $ — Actual return on plan assets (24) 10 — — Employer contributions 1 5 1 1 Benefit payments (17) (18) (1) (1) Fair value of plan assets at Dec. 31 $ 97 $ 137 $ — $ — Funded status of plans at Dec. 31 $ (15) $ (4) $ (8) $ (11) Amounts recognized in the Consolidated Balance Sheet at Dec. 31: Current liabilities $ — $ — $ — $ (1) Noncurrent liabilities (15) (4) (8) (10) Net amounts recognized $ (15) $ (4) $ (8) $ (11) Pension Benefits Postretirement Benefits Significant Assumptions Used to Measure Benefit Obligations: 2022 2021 2022 2021 Discount rate for year-end valuation 5.80 % 3.08 % 5.80 % 3.09 % Expected average long-term increase in compensation level 4.25 % 3.75 % N/A N/A Mortality table Pri-2012 Pri-2012 Pri-2012 Pri-2012 Health care costs trend rate — initial: Pre-65 N/A N/A 6.50 % 5.30 % Health care costs trend rate — initial: Post-65 N/A N/A 5.50 % 4.90 % Ultimate trend assumption — initial: Pre-65 N/A N/A 4.50 % 4.50 % Ultimate trend assumption — initial: Post-65 N/A N/A 4.50 % 4.50 % Years until ultimate trend is reached N/A N/A 7 4 Accumulated benefit obligation for the pension plan was $101 million and $129 million as of Dec. 31, 2022 and 2021, respectively. Net Periodic Benefit Cost (Credit) — Net periodic benefit cost (credit), other than the service cost component, is included in other expense in the consolidated statements of income. Components of net periodic benefit cost (credit) and amounts recognized in other comprehensive income and regulatory assets and liabilities: Pension Benefits Postretirement Benefits (Millions of Dollars) 2022 2021 2020 2022 2021 2020 Service cost $ 5 $ 5 $ 4 $ — $ — $ — Interest cost 4 4 5 1 1 1 Expected return on plan assets (8) (8) (8) — — — Amortization of net loss 3 5 5 — — — Settlement charge (a) 6 5 — — — — Net periodic pension cost $ 10 $ 11 $ 6 $ 1 $ 1 $ 1 Effects of regulation (2) (3) 7 — — Net benefit cost recognized for financial reporting $ 8 $ 8 $ 13 $ 1 $ 1 $ 1 Significant Assumptions Used to Measure Costs: Discount rate 3.08 % 2.71 % 3.49 % 3.09 % 2.65 % 3.47 % Expected average long-term increase in compensation level 3.75 3.75 3.75 — — — Expected average long-term rate of return on assets 6.60 6.60 7.10 4.10 4.10 4.50 (a) 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 annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020. Pension Benefits Postretirement Benefits (Millions of Dollars) 2022 2021 2022 2021 Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost: Net loss $ 45 $ 44 $ 4 $ 6 Prior service credit — — — — Total $ 45 $ 44 $ 4 $ 6 Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates: Current regulatory assets $ 1 $ 4 $ — $ — Noncurrent regulatory assets 44 40 4 6 Total $ 45 $ 44 $ 4 $ 6 Measurement date Dec. 31, 2022 Dec. 31, 2021 Dec. 31, 2022 Dec. 31, 2021 Cash Flows — Funding requirements can be impacted by changes to actuarial assumptions, actual asset levels and other calculations prescribed by the requirements of income tax and other pension-related regulations. Required contributions were made in 2020-2023 to meet minimum funding requirements. Total voluntary and required pension funding contributions across all four of Xcel Energy’s pension plans were as follows: • $50 million in January 2023, of which $4 million was attributable to NSP-Wisconsin. • $50 million in 2022, of which $1 million was attributable to NSP-Wisconsin. • $131 million in 2021, of which $5 million was attributable to NSP-Wisconsin. • $150 million in 2020, of which $7 million was attributable to NSP-Wisconsin. The postretirement health care plans have no funding requirements other than fulfilling benefit payment obligations when claims are presented and approved. Additional cash funding requirements are prescribed by certain state and federal rate regulatory authorities. Xcel Energy’s voluntary postretirement funding contributions were as follows: • $12 million expected in 2023, of which $1 million is attributable to NSP-Wisconsin. • $13 million during 2022, of which $1 million was attributable to NSP-Wisconsin. • $15 million during 2021, of which $2 million was attributable to NSP-Wisconsin. • $11 million during 2020, of which $1 million was attributable to NSP-Wisconsin. Target asset allocations: Pension Benefits Postretirement Benefits 2022 2021 2022 2021 Domestic and international equity securities 33 % 33 % 16 % 15 % Long-duration fixed income and interest rate swap securities 38 37 — — Short-to-intermediate fixed income securities 9 11 71 71 Alternative investments 18 17 12 8 Cash 2 2 1 6 Total 100 % 100 % 100 % 100 % The asset allocations above reflect target allocations approved in the calendar year to take effect in the subsequent year. Plan Amendments — In 2022 and 2020, there were no significant plan amendments made which affected the postretirement benefit obligation. In 2021, Xcel Energy amended the Xcel Energy Pension Plan and Xcel Energy Inc. Nonbargaining Pension Plan (South) to reduce supplemental benefits for non-bargaining participants as well as to allow the transfer of a portion of non-qualified pension obligations into the qualified plans. Projected Benefit Payments NSP-Wisconsin’s projected benefit payments: (Millions of Dollars) Projected Gross Projected Postretirement Health Care Benefit Payments (a) 2023 $ 11 $ 1 2024 10 1 2025 11 1 2026 10 1 2027 10 1 2028-2032 54 3 (a) Amount is reported net of expected Medicare Part D subsidies, which are immaterial. Defined Contribution Plans Xcel Energy, which includes NSP-Wisconsin, maintains 401(k) and other defined contribution plans that cover most employees. The expense to these plans for NSP-Wisconsin was approximately $2 million in 2022, 2021 and 2020. Multiemployer Plans NSP-Wisconsin contributes to several union multiemployer pension plans, none of which are individually significant. These plans provide pension benefits to certain union employees who may perform services for multiple employers and do not participate in the NSP-Wisconsin sponsored pension plans. Contributing to these types of plans creates risk that differs from providing benefits under NSP-Wisconsin sponsored plans, in that if another participating employer ceases to contribute to a multiemployer plan, additional unfunded obligations may need to be funded over time by remaining participating employers.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
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 on June 30, 2022 granting plaintiffs’ class certification. Defendants will work together to prepare and file a petition appealing the class certification ruling to the Seventh Circuit. Xcel Energy has concluded that a loss is remote for the remaining lawsuit 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 consolidated financial statements. Environmental New and changing federal and state environmental mandates can create financial liabilities for NSP-Wisconsin, which are normally recovered through the regulated rate process. Site Remediation Various federal and state environmental laws impose liability where hazardous substances or other regulated materials have been released to the environment. NSP-Wisconsin may sometimes pay all or a portion of the cost to remediate sites where past activities of NSP-Wisconsin’s predecessors or other parties have caused environmental contamination. Environmental contingencies could arise from various situations, including sites of former MGPs; and third-party sites, such as landfills, for which NSP-Wisconsin is alleged to have sent wastes to that site. Historical MGP, Landfill and Disposal Sites NSP-Wisconsin is currently investigating, remediating or performing post-closure actions at one historical MGP site 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 AROs — AROs have been recorded for NSP-Wisconsin’s assets. NSP-Wisconsin’s AROs were as follows: 2022 (Millions of Dollars) Jan. 1, 2022 Accretion Cash Flow Revisions (a) Dec. 31, 2022 Electric Steam, hydro and other production $ 9 $ 1 $ — $ 10 Distribution 5 — — 5 Natural gas Distribution 12 — 1 13 Total liability (b) $ 26 $ 1 $ 1 $ 28 (a) In 2022, AROs were revised for changes in timing and estimates of cash flows. (b) Included in other long-term liabilities balance in the consolidated balance sheet. 2021 (Millions of Dollars) Jan. 1, 2021 Accretion Cash Flow Revisions (a) Dec. 31, 2021 Electric Steam, hydro and other production 8 1 — 9 Distribution $ 5 $ — $ — $ 5 Natural gas Distribution 9 — 3 12 Total liability (b) $ 22 $ 1 $ 3 $ 26 (a) In 2021, AROs were revised for changes in timing and estimates of cash flows. Changes in gas distribution AROs were primarily related to changes in labor rates coupled with increased gas line mileage and number of services. (b) Included in other long-term liabilities balance in the consolidated balance sheet. Indeterminate AROs — Outside of the recorded asbestos AROs, other plants or buildings may contain asbestos due to the age of many of NSP-Wisconsin’s facilities, but no confirmation or measurement of the cost of removal could be determined as of Dec. 31, 2022. Therefore, an ARO has not been recorded for these facilities. Joint Operating System The electric production and transmission system of NSP-Wisconsin is managed as the NSP System. The electric production and transmission costs of the entire NSP System are shared by NSP-Minnesota and NSP-Wisconsin. A FERC approved agreement between the two companies, called the Interchange Agreement, provides for the sharing of all costs of generation and transmission facilities of the system, including capital costs. Such costs include current and potential obligations of NSP-Minnesota related to its nuclear generating facilities. NSP-Minnesota’s public liability for claims from any nuclear incident is limited to $13.7 billion under the Price-Anderson amendment to the Atomic Energy Act. NSP-Minnesota has secured $450 million of coverage for its public liability exposure with a pool of insurance companies. The remaining $13.2 billion of exposure is funded by the Secondary Financial Protection Program available from assessments by the federal government. NSP-Minnesota is subject to assessments of up to $138 million per reactor-incident for each of its three reactors, for public liability arising from a nuclear incident at any licensed nuclear facility in the United States. The maximum funding requirement is $20 million per reactor-incident during any one year. Maximum assessments are subject to inflation adjustments by the NRC. NSP-Minnesota purchases insurance for property damage and site decontamination cleanup costs from NEIL and EMANI. The coverage limits are $2.8 billion for each of NSP-Minnesota’s two nuclear plant sites. NEIL also provides business interruption insurance coverage up to $350 million, including the cost of replacement power during prolonged accidental outages of nuclear generating units. Premiums are expensed over the policy term. All companies insured with NEIL are subject to retroactive premium adjustments if losses exceed accumulated reserve funds. Capital has been accumulated in the reserve funds of NEIL and EMANI to the extent that NSP-Minnesota would have no exposure for retroactive premium assessments in case of a single incident under the business interruption and the property damage insurance coverage. NSP-Minnesota could be subject to annual maximum assessments of $12 million for business interruption insurance and $32 million for property damage insurance if losses exceed accumulated reserve funds. NSP-Wisconsin has entered into various long-term commitments for the purchase and delivery of a significant portion of its refuse-derived fuel/wood and natural gas requirements. These contracts expire between 2023 and 2032. NSP-Wisconsin is required to pay additional amounts depending on actual quantities shipped under these agreements. As NSP-Wisconsin does not have an automatic electric fuel adjustment clause for Wisconsin retail customers, NSP-Wisconsin utilizes deferred accounting treatment for future rate recovery or refund when fuel costs differ from the amount included in rates by more than 2% on an annual basis, as determined by the PSCW after an opportunity for a hearing and an earnings test based on NSP-Wisconsin’s authorized ROE. Estimated minimum purchases under these contracts as of Dec. 31, 2022: (Millions of Dollars) Refuse-derived fuel/wood Natural gas Natural gas 2023 $ 4 $ 17 $ 21 2024 1 — 20 2025 1 — 18 2026 1 — 17 2027 1 — 10 Thereafter 2 — 8 Total (a) $ 10 $ 17 $ 94 (a) Excludes additional amounts allocated to NSP-Minnesota through intercompany charges. Additional expenditures for fuel and natural gas storage and transportation will be required to meet expected future electric generation and natural gas needs.

Other Comprehensive Income

Other Comprehensive Income	12 Months Ended
	Dec. 31, 2022
Stockholders' Equity Note [Abstract]
Other Comprehensive Income	Changes in accumulated other comprehensive loss, net of tax, for the years ended Dec. 31: Gains and Losses on Cash Flow Hedges (Millions of Dollars) 2022 2021 Accumulated other comprehensive loss at Jan. 1 $ — $ — Losses reclassified from net accumulated other comprehensive loss: Interest rate derivatives (net of taxes of $—) (a) — — Net current period other comprehensive income (loss) — — Accumulated other comprehensive loss at Dec. 31 $ — $ — (a) Included in interest charges.

Segments and Related Informatio

Segments and Related Information	12 Months Ended
	Dec. 31, 2022
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, transmits and distributes electricity in Wisconsin and Michigan. • Regulated Natural Gas — The regulated natural gas utility segment transports, stores and distributes natural gas in portions of Wisconsin and Michigan. NSP-Wisconsin also presents All Other, which includes operating segments with revenues below the necessary quantitative thresholds. Those operating segments primarily include investments in rental housing projects that qualify for low-income housing tax credits. 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: (Millions of Dollars) 2022 2021 2020 Regulated Electric Operating revenues — external (a) $ 1,002 $ 922 $ 855 Intersegment revenue — — 1 Total revenues $ 1,002 $ 922 $ 856 Depreciation and amortization 131 120 108 Interest charges and financing costs 38 36 34 Income tax expense 29 27 12 Net income 105 98 98 Regulated Natural Gas Operating revenues — external $ 198 $ 182 $ 119 Intersegment revenue — 1 — Total revenues $ 198 $ 183 $ 119 Depreciation and amortization 27 27 48 Interest charges and financing costs 4 4 4 Income tax expense (benefit) 6 2 (20) Net income 17 7 7 All Other Total revenues $ 1 $ 1 $ — Income tax expense — 1 1 Net income 3 3 2 Consolidated Total Total revenues (a) $ 1,201 $ 1,106 $ 975 Reconciling eliminations — (1) (1) Total operating revenues $ 1,201 $ 1,105 $ 974 Depreciation and amortization 158 147 156 Interest charges and financing costs 42 40 38 Income tax expense (benefit) 35 30 (7) Net income 125 108 107 (a) Operating revenues include $202 million, $189 million and $168 million of affiliate electric revenue for the years ended Dec. 31, 2022, 2021 and 2020, respectively. See Note 12 for further information.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions Xcel Energy Services Inc. provides management, administrative and other services for the subsidiaries of Xcel Energy Inc., including NSP-Wisconsin. The services are provided and billed to each subsidiary in accordance with service agreements executed by each subsidiary. NSP-Wisconsin uses services provided by Xcel Energy Services Inc. whenever possible. Costs are charged directly to the subsidiary and are allocated if they cannot be directly assigned. Xcel Energy, Inc., NSP-Minnesota, NSP-Wisconsin, PSCo and SPS have established a utility money pool arrangement. The electric production and transmission costs of the entire NSP System are shared by NSP-Minnesota and NSP-Wisconsin. The Interchange Agreement provides for the sharing of all costs of generation and transmission facilities of the system, including capital costs. Significant affiliate transactions among the companies and related parties including billings under the Interchange Agreement for the years ended Dec. 31: (Millions of Dollars) 2022 2021 2020 Operating revenues: Electric $ 202 $ 189 $ 168 Operating expenses: Purchased power 445 408 379 Transmission expense 68 64 61 Natural gas purchased for resale — 1 1 Other operating expenses — paid to Xcel Energy Services Inc. 114 99 92 Interest expense 1 — — Accounts receivable and payable with affiliates at Dec. 31 were: 2022 2021 (Millions of Dollars) Accounts Receivable Accounts Payable Accounts Receivable Accounts Payable NSP-Minnesota $ — $ 4 $ — $ 13 PSCo 2 — 2 — Other subsidiaries of Xcel Energy Inc. 6 15 1 10 $ 8 $ 19 $ 3 $ 23

Schedule II, Valuation and Qual

Schedule II, Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2022
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II, Valuation and Qualifying Accounts	NSP-Wisconsin and Subsidiaries Valuation and Qualifying Accounts Years Ended Dec. 31 Allowance for bad debts (Millions of Dollars) 2022 2021 2020 Balance at Jan. 1 $ 8 $ 8 $ 6 Additions charged to costs and expenses 4 4 7 Additions charged to other accounts (a) 1 1 1 Deductions from reserves (b) (4) (5) (6) Balance at Dec. 31 $ 9 $ 8 $ 8 (a) Recovery of amounts previously written-off. (b) Deductions related primarily to bad debt write-offs.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Business and System of Accounts	General — NSP-Wisconsin is engaged in the regulated generation, transmission, distribution and sale of electricity and the regulated purchase, transportation, distribution and sale of natural gas.
Principles of Consolidation	NSP-Wisconsin’s consolidated financial statements include its wholly-owned subsidiaries and VIEs for which it is the primary beneficiary. In the consolidation process, all intercompany transactions and balances are eliminated. NSP-Wisconsin has investments in certain transmission facilities jointly owned with nonaffiliated utilities. NSP-Wisconsin’s proportionate share of jointly owned facilities is recorded as property, plant and equipment on the consolidated balance sheets and NSP-Wisconsin’s proportionate share of operating costs associated with these facilities is included in its consolidated statements of income.
Subsequent Events	NSP-Wisconsin has evaluated events occurring after Dec. 31, 2022 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation.
Use of Estimates	Use of Estimates — NSP-Wisconsin uses estimates based on the best information available in recording transactions and balances resulting from business operations. Estimates are used for items such as plant depreciable lives or potential disallowances, AROs, certain regulatory assets and liabilities, tax provisions, uncollectible amounts, environmental costs, unbilled revenues, jurisdictional fuel and energy cost allocations and actuarially determined benefit costs. Recorded estimates are revised when better information becomes available or actual amounts can be determined. Revisions can affect operating results.
Regulatory Accounting	Regulatory Accounting — NSP-Wisconsin accounts for income and expense items in accordance with accounting guidance for regulated operations. Under this guidance: • Certain costs, which would otherwise be charged to expense or other comprehensive income, are deferred as regulatory assets based on the expected ability to recover the costs in future rates. • Certain credits, which would otherwise be reflected as income or other comprehensive income, are deferred as regulatory liabilities based on the expectation the amounts will be returned to customers in future rates or because the amounts were collected in rates prior to the costs being incurred. Estimates and assumptions for recovery of deferred costs and refund of deferred credits are based on specific ratemaking decisions, precedent or other information available. Regulatory assets and liabilities are amortized consistent with the treatment in the rate setting process. If changes in the regulatory environment occur, NSP-Wisconsin may no longer be eligible to apply this accounting treatment and may be required to eliminate regulatory assets and liabilities. Such changes could have a material effect on NSP-Wisconsin’s results of operations, financial condition and cash flows. See Note 4 for further information.
Income Taxes	Income Taxes — NSP-Wisconsin accounts for income taxes using the asset and liability method, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Income taxes are deferred for all temporary differences between pretax financial and taxable income and between the book and tax bases of assets and liabilities. NSP-Wisconsin uses rates that are scheduled to be in effect when the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the period that includes the enactment date. The effects of tax rate changes that are attributable to the utility subsidiaries are generally subject to a normalization method of accounting. Therefore, the revaluation of most of the utility subsidiaries’ net deferred taxes upon a tax rate reduction results in the establishment of a net regulatory liability, refundable to utility customers over the remaining life of the related assets. NSP-Wisconsin anticipates that a tax rate increase would predominantly result in the establishment of a regulatory asset, subject to an evaluation of whether future recovery is expected. Reversal of certain temporary differences are accounted for as current income tax expense due to the effects of past regulatory practices when deferred taxes were not required to be recorded due to the use of flow through accounting for ratemaking purposes. Tax credits are recorded when earned unless there is a requirement to defer the benefit and amortize over the book depreciable lives of the related property. The requirement to defer and amortize these credits specifically applies to certain federal ITCs, as determined by tax regulations and NSP-Wisconsin tax elections. For tax credits otherwise eligible to be recognized when earned, NSP-Wisconsin considers the impact of rate regulation to determine if these credits and related adjustments should be deferred as regulatory assets or liabilities. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized. Utility rate regulation has resulted in the recognition of regulatory assets and liabilities related to income taxes. NSP-Wisconsin measures and discloses uncertain tax positions that it has taken or expects to take in its income tax returns. A tax position is recognized in the consolidated financial statements when it is more likely than not that the position will be sustained upon examination based on the technical merits of the position. Recognition of changes in uncertain tax positions are reflected as a component of income tax expense. Interest and penalties related to income taxes are reported within other (expense) income or interest charges in the consolidated statements of income. Xcel Energy Inc. and its subsidiaries, including NSP-Wisconsin file consolidated federal income tax returns as well as consolidated or separate state income tax returns. Federal income taxes paid by Xcel Energy Inc. are allocated to its subsidiaries based on separate company computations. A similar allocation is made for state income taxes paid by Xcel Energy Inc. in connection with consolidated state filings. Xcel Energy Inc. also allocates its own income tax benefits to its direct subsidiaries. See Note 7 for further information.
Property, Plant and Equipment and Depreciation	Property, Plant and Equipment and Depreciation in Regulated Operations — Property, plant and equipment is stated at original cost. The cost of plant includes direct labor and materials, contracted work, overhead costs and AFUDC. The cost of plant retired is charged to accumulated depreciation and amortization. Amounts recovered in rates for future removal costs are recorded as regulatory liabilities. Significant additions or improvements extending asset lives are capitalized, while repairs and maintenance costs are charged to expense as incurred. Maintenance and replacement of items determined to be less than a unit of property are charged to operating expenses as incurred. Property, plant and equipment is tested for impairment when it is determined that the carrying value of the assets may not be recoverable. A loss is recognized in the current period if it becomes probable that part of a cost of a plant under construction or recently completed plant will be disallowed for recovery from customers and a reasonable estimate of the disallowance can be made. For investments in property, plant and equipment that are abandoned and not expected to go into service, incurred costs and related deferred tax amounts are compared to the discounted estimated future rate recovery, and a loss is recognized, if necessary. Depreciation expense is recorded using the straight-line method over the plant’s commission approved useful life. Actuarial life studies are performed and submitted to the state and federal commissions for review. Upon acceptance by the various commissions, the resulting lives and net salvage rates are used to calculate depreciation. Plant removal costs are typically recognized at the amounts recovered in rates as authorized by the applicable regulator. Accumulated removal costs are reflected in the consolidated balance sheet as a regulatory liability. Depreciation expense, expressed as a percentage of average depreciable property, was approxim at ely 3.6% in 2022, 2021 and 2020.
Asset Retirement Obligations	AROs — NSP-Wisconsin records AROs as a liability for the fair value of an ARO to be recognized in the period incurred (if it can be reasonably estimated), with the offsetting/associated costs capitalized as a long-lived asset. The liability is generally increased over time by applying the effective interest method of accretion and the capitalized costs are typically depreciated over the useful life of the long-lived asset. Changes resulting from revisions to timing or amounts of expected asset retirement cash flows are recognized as an increase or a decrease in the ARO. See Note 10 for further information.
Benefit Plans and Other Postretirement Benefits	Benefit Plans and Other Postretirement Benefits — NSP-Wisconsin maintains pension and postretirement benefit plans for eligible employees. Recognizing the cost of providing benefits and measuring the projected benefit obligation of these plans requires management to make various assumptions and estimates. Certain unrecognized actuarial gains and losses and unrecognized prior service costs or credits are deferred as regulatory assets and liabilities, rather than recorded as other comprehensive income, based on regulatory recovery mechanisms. See Note 9 for further information.
Environmental Costs	Environmental Costs — Environmental costs are recorded when it is probable NSP-Wisconsin is liable for remediation costs and the amount can be reasonably estimated. Costs are deferred as a regulatory asset if it is probable the costs will be recovered from customers in future rates. Otherwise, the costs are expensed. For certain environmental costs related to facilities currently in use, such as for emission-control equipment, the cost is capitalized and depreciated over the life of the plant. Estimated remediation costs are regularly adjusted as estimates are revised and remediation is performed. If other participating potentially responsible parties exist and acknowledge their potential involvement with a site, costs are estimated and recorded only for NSP-Wisconsin’s expected share of the cost. Future costs of restoring sites are treated as a capitalized cost of plant retirement. The depreciation expense levels recoverable in rates include a provision for removal expenses. Removal costs recovered in rates before the related costs are incurred are classified as a regulatory liability. See Note 10 for further information.
Revenue From Contracts With Customers	Revenue from Contracts with Customers — Performance obligations related to the sale of energy are satisfied as energy is delivered to customers. NSP-Wisconsin recognizes revenue that corresponds to the price of the energy delivered to the customer. The measurement of energy sales to customers is generally based on the reading of their meters, which occurs systematically throughout the month. At the end of each month, amounts of energy delivered to customers since the date of the last meter reading are estimated, and the corresponding unbilled revenue is recognized. A separate financing component of collections from customers is not recognized as contract terms are short-term in nature. Revenues are net of any excise or sales taxes or fees. NSP-Wisconsin has various rate-adjustment mechanisms that provide for the recovery of natural gas, electric fuel and purchased energy costs. Cost-adjustment tariffs may increase or decrease the level of revenue collected from customers and are revised periodically for differences between the total amount collected under the clauses and the costs incurred. When applicable, fuel cost over-recoveries (the excess of fuel revenue billed to customers over fuel costs incurred) are deferred as regulatory liabilities and under-recoveries (the excess of fuel costs incurred over fuel revenues billed to customers) are deferred as regulatory assets. NSP-Wisconsin must submit a forward looking fuel cost plan annually for approval by the PSCW. The rules also allow for deferral of any under-recovery or over-recovery of fuel costs in excess of a 2% annual tolerance band, for future rate recovery or refund, subject to PSCW approval.
Cash and Cash Equivalents	Cash and Cash Equivalents — NSP-Wisconsin considers investments in instruments with a remaining maturity of three months or less at the time of purchase to be cash equivalents.
Accounts Receivable and Allowance for Bad Debts	Accounts Receivable and Allowance for Bad Debts — Accounts receivable are stated at the actual billed amount net of an allowance for bad debts. NSP-Wisconsin establishes an allowance for uncollectible receivables based on a policy that reflects its expected exposure to the credit risk of customers.
Inventory	Inventory — Inventory is recorded at the lower of average cost or net realizable value and consisted of the following: (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Inventories Materials and supplies $ 8 $ 8 Fuel 11 9 Natural gas 20 10 Total inventories $ 39 $ 27
Fair Value Measurements	Fair Value Measurements — NSP-Wisconsin presents cash equivalents, interest rate derivatives and commodity derivatives at estimated fair values in its consolidated financial statements. For interest rate derivatives, quoted prices based primarily on observable market interest rate curves are used to estimate fair value. For commodity derivatives, the most observable inputs available are generally used to determine the fair value of each contract. In the absence of a quoted price, quoted prices for similar contracts or internally prepared valuation models may be used to determine fair value. For the pension and postretirement plan assets and nuclear decommissioning fund, published trading data and pricing models, generally using the most observable inputs available, are utilized to determine fair value for each security. See Notes 8 and 9 for further information.
Derivative Instruments	Derivative Instruments — NSP-Wisconsin uses derivative instruments in connection with its commodity trading activities, and to manage risk associated with changes in interest rates, and utility commodity prices, including forward contracts, futures, swaps and options. Any derivative instruments not qualifying for the normal purchases and normal sales exception are recorded on the consolidated balance sheets at fair value as derivative instruments. Classification of changes in fair value for those derivative instruments is dependent on the designation of a qualifying hedging relationship. Changes in fair value of derivative instruments not designated in a qualifying hedging relationship are reflected in current earnings or as a regulatory asset or liability. Classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. Gains or losses on commodity trading transactions are recorded as a component of electric operating revenues. Normal Purchases and Normal Sales — NSP-Wisconsin enters into contracts for purchases and sales of commodities for use in its operations. At inception, contracts are evaluated to determine whether they contain a derivative, and if so, whether they may be exempted from derivative accounting if designated as normal purchases or normal sales. See Note 8 for further information.
AFUDC	AFUDC
Alternative revenue programs	Alternative Revenue — Certain rate rider mechanisms qualify as alternative revenue programs. These mechanisms arise from instances in which the regulator authorizes a future surcharge in response to past activities or completed events. When certain criteria are met, including expected collection within 24 months, revenue is recognized, which may include incentives and return on rate base items. The mechanisms are revised periodically for differences between total amount collected and the revenue earned, which may increase or decrease the level of revenue collected from customers. Alternative revenues arising from these programs are presented on a gross basis and disclosed separately from revenue from contracts with customers. See Note 6 for further information. Conservation Programs — NSP-Wisconsin participates in and funds conservation programs in its retail jurisdictions to assist customers in conserving energy and reducing peak demand on the electric and natural gas systems. NSP-Wisconsin recovers approved conservation program costs in base rate revenue. three
Emission Allowances	Emissions Allowances — Emissions allowances are recorded at cost, including broker commission fees. The inventory accounting model is utilized for all emissions allowances and any sales of these allowances are included in electric revenues.
Renewable Energy Credits	RECs — Cost of RECs that are utilized for compliance is recorded as electric fuel and purchased power expense. An inventory accounting model is used to account for RECs.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Inventory (Tables)	12 Months Ended
	Dec. 31, 2022
Balance Sheet Related Disclosure - Inventory [Abstract]
Public Utilities, Inventory	Inventory — Inventory is recorded at the lower of average cost or net realizable value and consisted of the following: (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Inventories Materials and supplies $ 8 $ 8 Fuel 11 9 Natural gas 20 10 Total inventories $ 39 $ 27

Property Plant and Equipment _2

Property Plant and Equipment Property Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Public Utility Property, Plant, and Equipment	Major classes of property, plant and equipment (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Property, plant and equipment, net Electric plant $ 3,579 $ 3,348 Natural gas plant 465 423 Common and other property 260 233 CWIP 174 134 Total property, plant and equipment 4,478 4,138 Less accumulated depreciation (1,564) (1,478) Property, plant and equipment, net $ 2,914 $ 2,660
Schedule of Jointly Owned Utility Plants	Jointly owned assets as of Dec. 31, 2022: (Millions of Dollars, Except Percent Owned) Plant in Service Accumulated Depreciation Percent Owned Electric transmission: La Crosse, WI to Madison, WI $ 177 $ 20 37 % CapX2020 166 34 80 Total (a) $ 343 $ 54 (a) Projects additionally include $1 million in CWIP.

Regulatory Assets and Liabili_2

Regulatory Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2022
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets	Components of regulatory assets: (Millions of Dollars) See Note(s) Remaining Amortization Period Dec. 31, 2022 Dec. 31, 2021 (a) Regulatory Assets Current Noncurrent Current Noncurrent Environmental remediation costs 1, 10 Various $ 13 $ 63 $ 13 $ 79 Pension and retiree medical obligations 9 Various 2 61 4 55 State commission adjustments Plant lives 1 22 1 21 Recoverable deferred taxes on AFUDC Plant lives — 20 — 19 Net AROs (b) 1, 10 Various — 18 — 10 Deferred natural gas and electric energy/fuel costs 7 One 23 — 2 29 Other Various 5 9 1 12 Total regulatory assets $ 44 $ 193 $ 21 $ 225 (a) Prior period amounts have been restated to conform with current year presentation. (b) Includes amounts recorded for future recovery of AROs, less amounts recovered through NSP-Wisconsin’s share of nuclear decommissioning accruals and gains from decommissioning investments.
Regulatory Liabilities	Components of regulatory liabilities: (Millions of Dollars) See Note(s) Remaining Amortization Period Dec. 31, 2022 Dec. 31, 2021 Regulatory Liabilities Current Noncurrent Current Noncurrent Plant removal costs 1, 10 Various $ — $ 223 $ — $ 201 Deferred income tax adjustments and TCJA refunds (a) 7 Various — 144 — 152 United States Department of Energy Settlement Various 12 3 — 14 Deferred natural gas and electric energy/fuel costs Less than one 5 — 3 — Other Various 4 13 1 5 Total regulatory liabilities $ 21 $ 383 $ 4 $ 372 (a) Includes the revaluation of recoverable/regulated plant accumulated deferred income taxes and revaluation impact of non-plant accumulated deferred income taxes due to the TCJA.	[1]
[1]Includes the revaluation of recoverable/regulated plant accumulated deferred income taxes and revaluation impact of non-plant accumulated deferred income taxes due to the TCJA.

Borrowings and Other Financing

Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Money Pool	Money pool borrowings: (Millions of Dollars, Except Interest Rates) Three Months Ended Dec. 31, 2022 Year Ended 2022 2021 Borrowing limit $ 150 $ 150 $ 150 Amount outstanding at period end — — — Average amount outstanding 1 25 16 Maximum amount outstanding 16 81 78 Weighted average interest rate, computed on a daily basis 4.07 % 1.10 % 0.05 % Weighted average interest rate at period end N/A N/A N/A
Commercial Paper	Commercial paper outstanding: (Millions of Dollars, Except Interest Rates) Three Months Ended Dec. 31, 2022 Year Ended Dec. 31 2022 2021 2020 Borrowing limit $ 150 $ 150 $ 150 $ 150 Amount outstanding at period end 47 47 83 19 Average amount outstanding 9 18 3 30 Maximum amount outstanding 52 123 83 95 Weighted average interest rate, computed on a daily basis 4.39 1.03 0.18 1.59 Weighted average interest rate at end of period 4.55 4.55 0.21 0.17
Schedule of Debt To Total Capitalization Ratio	Debt-to-Total Capitalization Ratio (a) Amount Facility May Be Increased (millions of dollars) Additional Periods for Which a One-Year Extension May Be Requested (b) 2022 2021 47 % 49 % N/A 1 (a) The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.
Credit Facilities	(in millions of dollars): Credit Facility (a) Drawn (b) Available $ 150 $ 47 $ 103 (a) This credit facility matures in September 2027. (b) Includes outstanding commercial paper.	[1],[2]
Schedule of Long-Term Debt	Long-term debt obligations for NSP-Wisconsin as of Dec. 31 (in millions of dollars): Financing Instrument Interest Rate Maturity Date 2022 2021 First mortgage bonds 3.30 June 15, 2024 100 100 First mortgage bonds 3.30 June 15, 2024 100 100 First mortgage bonds 6.375 Sept. 1, 2038 200 200 First mortgage bonds 3.70 Oct. 1, 2042 100 100 First mortgage bonds 3.75 Dec. 1, 2047 100 100 First mortgage bonds 4.20 Sept. 1, 2048 200 200 First mortgage bonds 3.05 May 1, 2051 100 100 First mortgage bonds (a) 2.82 May 1, 2051 100 100 First mortgage bonds (b) 4.86 Sept. 15, 2052 100 — Other long-term debt — 1 Unamortized discount (3) (4) Unamortized debt issuance cost (11) (10) Total long-term debt $ 1,086 $ 987 (a) 2021 financing. (b) 2022 financing.
Schedule of Maturities of Long-term Debt	Maturities of long-term debt: (Millions of Dollars) 2023 $ — 2024 200 2025 — 2026 — 2027 —
Dividend Payment Restrictions	Equity to Total Equity to Total Capitalization Ratio Actual Low High 2022 52.5 % N/A 52.8 % Unrestricted Retained Earnings Total Capitalization Limit on Total Capitalization (a) $ 11 million 2,280 million N/A
[1]Includes outstanding commercial paper[2]This credit facility matures in September 2027.

Revenues Revenues (Tables)

Revenues Revenues (Tables)	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	NSP-Wisconsin’s operating revenues consisted of the following: Year Ended Dec. 31, 2022 (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 293 $ 103 $ — $ 396 C&I 485 87 — 572 Other 7 — — 7 Total retail 785 190 — 975 Interchange 202 — — 202 Other 4 4 — 8 Total revenue from contracts with customers 991 194 — 1,185 Alternative revenue and other 11 4 1 16 Total revenues $ 1,002 $ 198 $ 1 $ 1,201 Year Ended Dec. 31, 2021 (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 272 $ 91 $ — $ 363 C&I 441 85 — 526 Other 8 — 1 9 Total retail 721 176 1 898 Interchange 189 — — 189 Other — 4 — 4 Total revenue from contracts with customers 910 180 1 1,091 Alternative revenue and other 12 2 — 14 Total revenues $ 922 $ 182 $ 1 $ 1,105 Year Ended Dec. 31, 2020 (Millions of Dollars) Electric Natural Gas All Other Total Major revenue types Revenue from contracts with customers: Residential $ 258 $ 64 $ — $ 322 C&I 411 49 — 460 Other 6 — — 6 Total retail 675 113 — 788 Interchange 168 — — 168 Other — 4 — 4 Total revenue from contracts with customers 843 117 — 960 Alternative revenue and other 12 2 — 14 Total revenues $ 855 $ 119 $ — $ 974

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	Effective income tax rate for years ended Dec. 31: 2022 2021 (b) 2020 (b) Federal statutory rate 21.0 % 21.0 % 21.0 % State income tax on pretax income, net of federal tax effect 6.2 6.2 6.2 Increases (decreases) in tax from: Plant regulatory differences (a) (3.8) (4.1) (19.3) Other tax credits, net NOL & tax credit allowances (0.8) (1.0) (1.5) Amortization of excess nonplant deferred taxes — — (12.6) Other, net (0.7) (0.4) (0.8) Effective income tax rate 21.9 % 21.7 % (7.0) % (a) 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 taxes are offset by corresponding revenue reductions.
Schedule of Components of Income Tax Expense (Benefit)	Components of income tax expense for years ended Dec. 31: (Millions of Dollars) 2022 2021 2020 Current federal tax expense $ 28 $ 17 $ 25 Current state tax expense 9 4 6 Current change in unrecognized tax benefit — — (1) Deferred federal tax (benefit) expense (5) 3 (37) Deferred state tax expense 3 6 1 Deferred ITCs — — (1) Total income tax expense (benefit) $ 35 $ 30 $ (7) Components of deferred income tax expense as of Dec. 31: (Millions of Dollars) 2022 2021 2020 Deferred tax expense excluding items below $ 8 $ 18 $ 9 Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities (10) (10) (45) Other — 1 — Deferred tax (benefit) expense $ (2) $ 9 $ (36)
Schedule of Deferred Tax Assets and Liabilities	Components of the net deferred tax liability as of Dec. 31: (Millions of Dollars) 2022 2021 Deferred tax liabilities: Difference between book and tax bases of property $ 343 $ 331 Regulatory assets 25 29 Pension expense 10 11 Deferred fuel costs 6 8 Other 8 7 Total deferred tax liabilities $ 392 $ 386 Deferred tax assets: Regulatory liabilities $ 36 $ 38 Tax credit carryforward 7 8 Environmental remediation 4 5 Other employee benefits 3 4 Rate refund 3 — Deferred ITCs 2 2 Other 4 4 Total deferred tax assets $ 59 $ 61 Net deferred tax liability $ 333 $ 325
NOL and Tax Credit Carryforwards	NOL amounts represent the tax loss that is carried forward and tax credits represent the deferred tax asset. NOL and tax credit carryforwards as of Dec. 31 were as follows: (Millions of Dollars) 2022 2021 Federal tax credit carryforwards $ 7 $ 8 State NOL carryforward 2 2
Summary of Statute of Limitations Applicable to Open Tax Years [Table Text Block]	NSP-Wisconsin 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 consolidated federal income tax returns expire as follows: Tax Year(s) Expiration 2014 - 2016 March 2024 2019 October 2023
Reconciliation of Unrecognized Tax Benefits	Unrecognized tax benefits — permanent vs. temporary: (Millions of Dollars) Dec. 31, 2022 Dec. 31, 2021 Unrecognized tax benefit — Permanent tax positions $ 2 $ 2 Unrecognized tax benefit — Temporary tax positions 1 1 Total unrecognized tax benefit $ 3 $ 3 Changes in unrecognized tax benefits: (Millions of Dollars) 2022 2021 2020 Balance at Jan. 1 $ 3 $ 2 $ 3 Additions for tax positions of prior years — 1 1 Reductions for tax positions of prior years — — (2) Balance at Dec. 31 $ 3 $ 3 $ 2
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) Dec. 31, 2022 Dec. 31, 2021 NOL and tax credit carryforwards $ (2) $ (2)

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level	Dec. 31, 2022 Dec. 31, 2021 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 (b) Natural gas commodity $ — $ 2 $ — $ 2 $ — $ 2 $ — $ 1 $ — $ 1 $ — $ 1 Current derivative liabilities (c) Natural gas commodity $ — $ 1 $ — $ 1 $ — $ 1 $ — $ 1 $ — $ 1 $ — $ 1 (a) NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement. Counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements. (b) Included in prepayments and other current assets at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet. (c) Included in other current liabilities at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet.
Carrying Amount and Fair Value of Long-term Debt	As of Dec. 31, other financial instruments for which the carrying amount did not equal fair value: 2022 2021 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 1,086 $ 980 $ 987 $ 1,143
Derivative Instruments, Gain (Loss)	Pre-Tax Fair Value Gains (Losses) Recognized During the Period in: (Millions of Dollars) Regulatory (Assets) and Liabilities Year Ended Dec. 31, 2022 Other derivative instruments Natural gas commodity (1) Total $ (1) Year Ended Dec. 31, 2021 Other derivative instruments Natural gas commodity (1) Total $ (1) Year Ended Dec. 31, 2020 Other derivative instruments Natural gas commodity (1) Total $ (1) Pre-Tax (Gains) Losses Pre-Tax Gains (Losses) (Millions of Dollars) Regulatory Year Ended Dec. 31, 2022 Other derivative instruments Natural gas commodity — (2) (a) Total $ — $ (2) Year Ended Dec. 31, 2021 Other derivative instruments Natural gas commodity — (1) (a) Total $ — $ (1) Year Ended Dec. 31, 2020 Other derivative instruments Natural gas commodity 1 (a) (1) (a) Total $ 1 $ (1) (a) Recorded to cost of natural gas sold and transported. These losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.

Benefit Plans and Other Postr_2

Benefit Plans and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2022
Benefit Plans and Other Postretirement Benefits [Abstract]
Funded Status of Plans	Pension Benefits Postretirement Benefits (Millions of Dollars) 2022 2021 2022 2021 Change in Benefit Obligation: Obligation at Jan. 1 $ 141 $ 154 $ 11 $ 13 Service cost 5 5 — — Interest cost 4 4 1 1 Actuarial gain (21) (4) (3) (1) Benefit payments (17) (18) (1) (2) Obligation at Dec. 31 $ 112 $ 141 $ 8 $ 11 Change in Fair Value of Plan Assets: Fair value of plan assets at Jan. 1 $ 137 $ 140 $ — $ — Actual return on plan assets (24) 10 — — Employer contributions 1 5 1 1 Benefit payments (17) (18) (1) (1) Fair value of plan assets at Dec. 31 $ 97 $ 137 $ — $ — Funded status of plans at Dec. 31 $ (15) $ (4) $ (8) $ (11) Amounts recognized in the Consolidated Balance Sheet at Dec. 31: Current liabilities $ — $ — $ — $ (1) Noncurrent liabilities (15) (4) (8) (10) Net amounts recognized $ (15) $ (4) $ (8) $ (11) Pension Benefits Postretirement Benefits Significant Assumptions Used to Measure Benefit Obligations: 2022 2021 2022 2021 Discount rate for year-end valuation 5.80 % 3.08 % 5.80 % 3.09 % Expected average long-term increase in compensation level 4.25 % 3.75 % N/A N/A Mortality table Pri-2012 Pri-2012 Pri-2012 Pri-2012 Health care costs trend rate — initial: Pre-65 N/A N/A 6.50 % 5.30 % Health care costs trend rate — initial: Post-65 N/A N/A 5.50 % 4.90 % Ultimate trend assumption — initial: Pre-65 N/A N/A 4.50 % 4.50 % Ultimate trend assumption — initial: Post-65 N/A N/A 4.50 % 4.50 % Years until ultimate trend is reached N/A N/A 7 4
Components of Net Periodic Benefit Costs	Pension Benefits Postretirement Benefits (Millions of Dollars) 2022 2021 2020 2022 2021 2020 Service cost $ 5 $ 5 $ 4 $ — $ — $ — Interest cost 4 4 5 1 1 1 Expected return on plan assets (8) (8) (8) — — — Amortization of net loss 3 5 5 — — — Settlement charge (a) 6 5 — — — — Net periodic pension cost $ 10 $ 11 $ 6 $ 1 $ 1 $ 1 Effects of regulation (2) (3) 7 — — Net benefit cost recognized for financial reporting $ 8 $ 8 $ 13 $ 1 $ 1 $ 1 Significant Assumptions Used to Measure Costs: Discount rate 3.08 % 2.71 % 3.49 % 3.09 % 2.65 % 3.47 % Expected average long-term increase in compensation level 3.75 3.75 3.75 — — — Expected average long-term rate of return on assets 6.60 6.60 7.10 4.10 4.10 4.50 (a) 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 annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020.
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost	Pension Benefits Postretirement Benefits (Millions of Dollars) 2022 2021 2022 2021 Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost: Net loss $ 45 $ 44 $ 4 $ 6 Prior service credit — — — — Total $ 45 $ 44 $ 4 $ 6 Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates: Current regulatory assets $ 1 $ 4 $ — $ — Noncurrent regulatory assets 44 40 4 6 Total $ 45 $ 44 $ 4 $ 6
Target Asset Allocations and Plan Assets Measured at Fair Value	For each of the fair value hierarchy levels, NSP-Wisconsin’s pension plan assets measured at fair value: Dec. 31, 2022 (a) Dec. 31, 2021 (a) (Millions of Dollars) Level 1 Level 2 Level 3 Measured at NAV Total Level 1 Level 2 Level 3 Measured at NAV Total Cash equivalents $ 4 $ — $ — $ — $ 4 $ 5 $ — $ — $ — $ 5 Commingled funds 35 — — 34 69 49 — — 44 93 Debt securities — 22 — — 22 — 36 — — 36 Equity securities 2 — — — 2 3 — — — 3 Total $ 41 $ 22 $ — $ 34 $ 97 $ 57 $ 36 $ — $ 44 $ 137 (a) See Note 8 for further information on fair value measurement inputs and methods. NSP-Wisconsin has immaterial postretirement benefit plan assets that were measured at fair value at Dec. 31, 2022 and 2021. No ass ets were transferred in or out of Level 3 for 2022 or 2021. Target asset allocations: Pension Benefits Postretirement Benefits 2022 2021 2022 2021 Domestic and international equity securities 33 % 33 % 16 % 15 % Long-duration fixed income and interest rate swap securities 38 37 — — Short-to-intermediate fixed income securities 9 11 71 71 Alternative investments 18 17 12 8 Cash 2 2 1 6 Total 100 % 100 % 100 % 100 % The asset allocations above reflect target allocations approved in the calendar year to take effect in the subsequent year.
Projected Benefit Payments for the Pension and Postretirement Benefit Plans	(Millions of Dollars) Projected Gross Projected Postretirement Health Care Benefit Payments (a) 2023 $ 11 $ 1 2024 10 1 2025 11 1 2026 10 1 2027 10 1 2028-2032 54 3 (a) Amount is reported net of expected Medicare Part D subsidies, which are immaterial.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Asset Retirement Obligations	NSP-Wisconsin’s AROs were as follows: 2022 (Millions of Dollars) Jan. 1, 2022 Accretion Cash Flow Revisions (a) Dec. 31, 2022 Electric Steam, hydro and other production $ 9 $ 1 $ — $ 10 Distribution 5 — — 5 Natural gas Distribution 12 — 1 13 Total liability (b) $ 26 $ 1 $ 1 $ 28 (a) In 2022, AROs were revised for changes in timing and estimates of cash flows. (b) Included in other long-term liabilities balance in the consolidated balance sheet. 2021 (Millions of Dollars) Jan. 1, 2021 Accretion Cash Flow Revisions (a) Dec. 31, 2021 Electric Steam, hydro and other production 8 1 — 9 Distribution $ 5 $ — $ — $ 5 Natural gas Distribution 9 — 3 12 Total liability (b) $ 22 $ 1 $ 3 $ 26 (a) In 2021, AROs were revised for changes in timing and estimates of cash flows. Changes in gas distribution AROs were primarily related to changes in labor rates coupled with increased gas line mileage and number of services. (b) Included in other long-term liabilities balance in the consolidated balance sheet.
Estimated Minimum Purchases Under Fuel Contracts	Estimated minimum purchases under these contracts as of Dec. 31, 2022: (Millions of Dollars) Refuse-derived fuel/wood Natural gas Natural gas 2023 $ 4 $ 17 $ 21 2024 1 — 20 2025 1 — 18 2026 1 — 17 2027 1 — 10 Thereafter 2 — 8 Total (a) $ 10 $ 17 $ 94 (a) Excludes additional amounts allocated to NSP-Minnesota through intercompany charges.
Low-income Housing Limited Partnerships	Low-Income Housing Limited Partnerships — NSP-Wisconsin has entered into limited partnerships with affordable rental housing activities that qualify for low-income housing tax credits. NSP-Wisconsin, as a primary beneficiary of these activities, consolidates these limited partnerships in its consolidated financial statements.
Estimated Minimum Purchases Under Fuel Contracts	(Millions of Dollars) Refuse-derived fuel/wood Natural gas Natural gas 2023 $ 4 $ 17 $ 21 2024 1 — 20 2025 1 — 18 2026 1 — 17 2027 1 — 10 Thereafter 2 — 8 Total (a) $ 10 $ 17 $ 94

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2022
Stockholders' Equity Note [Abstract]
Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax	Gains and Losses on Cash Flow Hedges (Millions of Dollars) 2022 2021 Accumulated other comprehensive loss at Jan. 1 $ — $ — Losses reclassified from net accumulated other comprehensive loss: Interest rate derivatives (net of taxes of $—) (a) — — Net current period other comprehensive income (loss) — — Accumulated other comprehensive loss at Dec. 31 $ — $ — (a) Included in interest charges.

Segments and Related Informat_2

Segments and Related Information (Tables)	12 Months Ended
	Dec. 31, 2022
Segment Reporting [Abstract]
Results from Operations by Reportable Segment	NSP-Wisconsin’s segment information: (Millions of Dollars) 2022 2021 2020 Regulated Electric Operating revenues — external (a) $ 1,002 $ 922 $ 855 Intersegment revenue — — 1 Total revenues $ 1,002 $ 922 $ 856 Depreciation and amortization 131 120 108 Interest charges and financing costs 38 36 34 Income tax expense 29 27 12 Net income 105 98 98 Regulated Natural Gas Operating revenues — external $ 198 $ 182 $ 119 Intersegment revenue — 1 — Total revenues $ 198 $ 183 $ 119 Depreciation and amortization 27 27 48 Interest charges and financing costs 4 4 4 Income tax expense (benefit) 6 2 (20) Net income 17 7 7 All Other Total revenues $ 1 $ 1 $ — Income tax expense — 1 1 Net income 3 3 2 Consolidated Total Total revenues (a) $ 1,201 $ 1,106 $ 975 Reconciling eliminations — (1) (1) Total operating revenues $ 1,201 $ 1,105 $ 974 Depreciation and amortization 158 147 156 Interest charges and financing costs 42 40 38 Income tax expense (benefit) 35 30 (7) Net income 125 108 107 (a) Operating revenues include $202 million, $189 million and $168 million of affiliate electric revenue for the years ended Dec. 31, 2022, 2021 and 2020, respectively. See Note 12 for further information.

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions	Significant affiliate transactions among the companies and related parties including billings under the Interchange Agreement for the years ended Dec. 31: (Millions of Dollars) 2022 2021 2020 Operating revenues: Electric $ 202 $ 189 $ 168 Operating expenses: Purchased power 445 408 379 Transmission expense 68 64 61 Natural gas purchased for resale — 1 1 Other operating expenses — paid to Xcel Energy Services Inc. 114 99 92 Interest expense 1 — — Accounts receivable and payable with affiliates at Dec. 31 were: 2022 2021 (Millions of Dollars) Accounts Receivable Accounts Payable Accounts Receivable Accounts Payable NSP-Minnesota $ — $ 4 $ — $ 13 PSCo 2 — 2 — Other subsidiaries of Xcel Energy Inc. 6 15 1 10 $ 8 $ 19 $ 3 $ 23

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense expressed as a percentage of average depreciable property	3.60%
Operating revenues
Minimum annual tolerance band percentage for future rate recovery or refund of fuel costs	2%
Cash and Cash Equivalents [Abstract]
Maximum number of months of remaining maturity at time of purchase to consider investments in certain instruments as cash equivalents	3 months
Accounts and Financing Receivable, after Allowance for Credit Loss, Current and Noncurrent [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 9	$ 8
Alternative Revenue Programs [Abstract]
Maximum number of months following end of annual period in which revenues are earned to be included in incentive programs	24 months
Percentage of Average Annual Operating Revenues	1.20%
Number of Years Annual Operating Revenues are Averaged	3 years
Public Utilities, Inventory [Line Items]
Inventories	$ 39	27
Accounts Receivable, Allowance for Credit Loss, Current	9	8
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventories	8	8
Fuel
Public Utilities, Inventory [Line Items]
Inventories	11	9
Natural gas
Public Utilities, Inventory [Line Items]
Inventories	$ 20	$ 10

Property Plant and Equipment _3

Property Plant and Equipment Property Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 4,478	$ 4,138
Accumulated Depreciation	1,564	1,478
Property, Plant and Equipment, Net	2,914	2,660
Electric plant
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	3,579	3,348
Natural gas plant
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	465	423
Common and other property
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	260	233
CWIP
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 174	$ 134

Property Plant and Equipment Jo

Property Plant and Equipment Joint Ownership (Details) $ in Millions	Dec. 31, 2022 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 343	[1]
Accumulated Depreciation	54	[1]
NSP Wisconsin [Member]
Jointly Owned Utility Plant Interests [Line Items]
CWIP	1
Jointly Owned Electricity Generation Plant [Member] | La Crosse, Wis. to Madison, Wis.
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	177
Accumulated Depreciation	$ 20
Percent Owned	37%
Jointly Owned Electricity Generation Plant [Member] | CapX2020 Transmission
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 166
Accumulated Depreciation	$ 34
Percent Owned	80%
[1]Projects additionally include $1 million in CWIP.

Regulatory Assets and Liabili_3

Regulatory Assets and Liabilities, Regulatory Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 44	$ 21
Regulatory Asset, Noncurrent		193	225
Environmental Remediation Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		13	13	[1]
Regulatory Asset, Noncurrent		63	79	[1]
Pension and Retiree Medical Obligations
Regulatory Assets [Line Items]
Regulatory Asset, Current		2	4	[1]
Regulatory Asset, Noncurrent		61	55	[1]
Deferred Fuel Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current		23	2	[1]
Regulatory Asset, Noncurrent		$ 0	29	[1]
Deferred Fuel Costs | Minimum
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
State Commission Adjustments
Regulatory Assets [Line Items]
Regulatory Asset, Current		$ 1	1	[1]
Regulatory Asset, Noncurrent		22	21	[1]
Recoverable Deferred Taxes on AFUDC Recorded in Plant
Regulatory Assets [Line Items]
Regulatory Asset, Current		0	0	[1]
Regulatory Asset, Noncurrent		20	19	[1]
Asset Retirement Obligation Costs
Regulatory Assets [Line Items]
Regulatory Asset, Current	[2]	0	0	[1]
Regulatory Asset, Noncurrent	[2]	18	10	[1]
Other
Regulatory Assets [Line Items]
Regulatory Asset, Current		5	1	[1]
Regulatory Asset, Noncurrent		$ 9	$ 12	[1]
[1]Prior period amounts have been restated to conform with current year presentation.[2]Includes amounts recorded for future recovery of AROs, less amounts recovered through NSP-Wisconsin’s share of nuclear decommissioning accruals and gains from decommissioning investments.

Regulatory Assets and Liabili_4

Regulatory Assets and Liabilities, Regulatory Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		$ 21	$ 4
Regulatory Liability, Noncurrent		$ 383	372
Minimum | Deferred Electric Production And Natural Gas Costs
Regulatory Liabilities [Line Items]
Regulatory Asset, Amortization Period		1 year
Plant Removal Costs
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		$ 0	0
Regulatory Liability, Noncurrent		223	201
Deferred Income Tax Adjustments and TCJA Refunds
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	[1]	0	0
Regulatory Liability, Noncurrent	[1]	144	152
United States Department of Energy Settlement
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		12	0
Regulatory Liability, Noncurrent		3	14
Deferred Electric Production And Natural Gas Costs
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		5	3
Regulatory Liability, Noncurrent		0	0
Other
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		4	1
Regulatory Liability, Noncurrent		$ 13	$ 5
[1]Includes the revaluation of recoverable/regulated plant accumulated deferred income taxes and revaluation impact of non-plant accumulated deferred income taxes due to the TCJA.

Commercial Paper (Details)

Commercial Paper (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Amount outstanding at period end	$ 47	$ 47	$ 83
money pool
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	150	150	150
Amount outstanding at period end	0	0	0
Average amount outstanding	1	25	16
Maximum amount outstanding	$ 16	$ 81	$ 78
Line of Credit Facility, Interest Rate During Period	4.07%	1.10%	0.05%
Commercial Paper [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 150	$ 150	$ 150	$ 150
Amount outstanding at period end	47	47	83	19
Average amount outstanding	9	18	3	30
Maximum amount outstanding	$ 52	$ 123	$ 83	$ 95
Line of Credit Facility, Interest Rate During Period	4.39%	1.03%	0.18%	1.59%
Weighted average interest rate at period end (percentage)	4.55%	4.55%	0.21%	0.17%

Letters of Credit (Details)

Letters of Credit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 47	$ 83
Long-term Debt
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	0	1
Letter of Credit
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 0	0
Letter of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Period	1 year
Credit Facilities
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 0	$ 0

Credit Facilities (Details)

Credit Facilities (Details) - Credit Facilities $ in Millions		12 Months Ended
		Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions		15%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions		$ 75
Long-term Line of Credit		$ 0	$ 0
NSP Wisconsin [Member]
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	[1]	47%	49%
Credit Facility	[2]	$ 150
Drawn	[3]	47
Available		$ 103
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	[4]	1
[1]The credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.[2]This credit facility matures in September 2027.[3]Includes outstanding commercial paper[4]All extension requests are subject to majority bank group approval.

Long-Term Borrowings and Other

Long-Term Borrowings and Other Financing Instruments (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Long-Term Borrowings and Other Financing Instruments
Unamortized discount		$ (3)	$ (4)
Unamortized debt expense		(11)	(10)
Long-term debt, noncurrent		1,086	987
2023		0
2024		200
2025		0
2026		0
2027		$ 0
Series Due June 15, 2024 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		3.30%
Debt Instrument, Face Amount		$ 100	100
Series Due June 15, 2024 2 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		3.30%
Debt Instrument, Face Amount		$ 100	100
Series Due Sept. 1, 2038 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		6.375%
Debt Instrument, Face Amount		$ 200	200
Series Due Oct. 1, 2042 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		3.70%
Debt Instrument, Face Amount		$ 100	100
Series Due December 1, 2047 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		3.75%
Debt Instrument, Face Amount		$ 100	100
Series Due December 1, 2048 [Member] | First Mortgage Bonds
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		4.20%
Debt Instrument, Face Amount		$ 200	200
Series Due May 1, 2051 [Member] | First Mortgage Bonds | NSP Wisconsin [Member]
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage		3.05%
Debt Instrument, Face Amount		$ 100	100
Series Due May 1, 2051 2 | First Mortgage Bonds | NSP Wisconsin [Member]
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	[1]	2.82%
Debt Instrument, Face Amount	[1]	$ 100	100
Series Due Sept. 15, 2052 | First Mortgage Bonds | NSP Wisconsin [Member]
Long-Term Borrowings and Other Financing Instruments
Debt Instrument, Interest Rate, Stated Percentage	[2]	4.86%
Debt Instrument, Face Amount	[2]	$ 100	$ 0
[1]2021 financing.[2]2022 financing.

Deferred Financing Costs (Detai

Deferred Financing Costs (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred Financing Costs [Abstract]
Deferred Finance Costs, Noncurrent, Net	$ 11	$ 10

Dividend and Other Capital-Rela

Dividend and Other Capital-Related Restrictions (Details) $ in Millions	Dec. 31, 2022 USD ($)
Dividend and Other Capital-Related Restrictions [Abstract]
Minimum calendar year average equity to total capitalization ratio authorized by state commission	52.50%
Equity to total capitalization ratio	52.80%
Unrestricted Retained Earnings Per State Regulatory Commissions Dividend Restrictions	$ 11
Total Capitalization	$ 2,280

Revenues (Details)

Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 1,185	$ 1,091	$ 960
Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	975	898	788
Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	396	363	322
Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	572	526	460
Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	9	6
Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	202	189	168
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8	4	4
Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	16	14	14
Regulated Electric | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	991	910	843
Regulated Electric | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	785	721	675
Regulated Electric | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	293	272	258
Regulated Electric | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	485	441	411
Regulated Electric | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	8	6
Regulated Electric | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	202	189	168
Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	0	0
Regulated Electric | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	11	12	12
Regulated Natural Gas | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	194	180	117
Regulated Natural Gas | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	190	176	113
Regulated Natural Gas | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	103	91	64
Regulated Natural Gas | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	87	85	49
Regulated Natural Gas | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Regulated Natural Gas | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0
Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	4	4
Regulated Natural Gas | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	4	2	2
All Other | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail | C&I
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Retail | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Interchange
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
All Other | Alternative and Other [Member]
Disaggregation of Revenue [Line Items]
Alternative revenue and other	1
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,201	1,105	974
Total revenues | Regulated Electric
Disaggregation of Revenue [Line Items]
Total revenues	1,002	922	855
Total revenues | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues	198	$ 182	$ 119
Total revenues | All Other
Disaggregation of Revenue [Line Items]
Total revenues	$ 1

State Audits (Details)

State Audits (Details)	12 Months Ended
	Dec. 31, 2022 USD ($)
WISCONSIN
Income Tax Examination [Line Items]
Potential Tax Adjustments	$ 0

Unrealized Tax Benefits (Detail

Unrealized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Examination [Line Items]
Unrecognized tax benefit — Permanent tax positions	$ 2	$ 2
Unrecognized tax benefit — Temporary tax positions	1	1
Total unrecognized tax benefit	3	3	$ 2	$ 3
Additions for tax positions of prior years	0	1	1
Reductions for tax positions of prior years	0	0	(2)
NOL and tax credit carryforwards	(2)	(2)
Decrease in Unrecognized Tax Benefits is Reasonably Possible	2
Unrecognized Tax Benefits, Income Tax Penalties Expense	$ 0	$ 0	$ 0

Other Income Tax Matters (Detai

Other Income Tax Matters (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2020
Income Tax Examination [Line Items]
Tax credit carryforward		$ 7	$ 8
State NOL carryforward		$ 2	$ 2
Federal statutory rate		21%	21%	[1]	21%	[1]
State income tax on pretax income, net of federal tax effect		6.20%	6.20%	[1]	6.20%	[1]
Plant regulatory differences (a)	[2]	(3.80%)	(4.10%)	[1]	(19.30%)	[1]
Other tax credits, net NOL & tax credit allowances		(0.80%)	(1.00%)	[1]	(1.50%)	[1]
Amortization of excess nonplant deferred taxes		0%	0%	[1]	(12.60%)	[1]
Other, net		(0.70%)	(0.40%)	[1]	(0.80%)	[1]
Effective income tax rate		21.90%	21.70%	[1]	(7.00%)	[1]
Total income tax expense (benefit)		$ 35	$ 30		$ (7)
Deferred tax expense excluding items below		8	18		9
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities		(10)	(10)		(45)
Other		0	1		0
Deferred tax (benefit) expense		(2)	(9)		(36)
Environmental remediation		4	5
income tax expense [Member]
Income Tax Examination [Line Items]
Current federal tax expense		28	17		25
Current state tax expense		9	4		6
Current change in unrecognized tax benefit		0	0		(1)
Deferred federal tax (benefit) expense		(5)	3		(37)
Deferred state tax expense		3	6		1
Deferred ITCs		0	0		(1)
Total income tax expense (benefit)		35	30		$ (7)
Net Deferred Tax Liablility [Member]
Income Tax Examination [Line Items]
Tax credit carryforward		7	8
Deferred ITCs		(2)	(2)
Other		4	4
Deferred tax (benefit) expense		(59)	(61)
Difference between book and tax bases of property		343	331
Regulatory assets		25	29
Pension expense		10	11
Deferred fuel costs		6	8
Other		8	7
Total deferred tax liabilities		392	386
Regulatory liabilities		36	38
Other employee benefits		3	4
Rate refund		3	0
Net deferred tax liability		$ 333	$ 325
[1]Prior period amounts have been restated to conform with 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 taxes are offset by corresponding revenue reductions.

Interest Rate Derivatives (Deta

Interest Rate Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Derivative Instruments
Interest Rate Derivatives [Abstract]
Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net	$ (1)	$ (1)	$ (1)
Natural Gas Commodity Contract | Other Derivative Instruments
Interest Rate Derivatives [Abstract]
Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net	(1)	$ (1)	$ (1)
Cash Flow Hedges
Interest Rate Derivatives [Abstract]
Derivative Instruments in Hedges, at Fair Value, Net	$ 0

Impact of Derivative Activities

Impact of Derivative Activities on Income (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net		$ (1)	$ (1)	$ (1)
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)		0	0	1
Derivative, Gain (Loss) on Derivative, Net		(2)	(1)	(1)
Natural Gas Commodity Contract
Derivative [Line Items]
Derivative Instruments Gain (Loss) Reclassified To Regulatory Assets And Liabilities Net		(1)	(1)	(1)
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)		0	0	(1)
Derivative, Gain (Loss) on Derivative, Net	[1]	$ (2)	$ (1)	$ (1)
[1]Recorded to cost of natural gas sold and transported. These losses are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.

Recurring Fair Value Measuremen

Recurring Fair Value Measurement (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Prepayments and other		$ 11	$ 7
Other Liabilities, Noncurrent		$ 43	$ 46
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Assets, Current	Assets, Current
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other Liabilities, Current	Other Liabilities, Current
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Natural Gas Commodity Contract
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	[1]	$ 2	$ 1
Netting	[1],[2]	0	0
Derivative Asset, Net	[1]	2	1
Derivative Liability, Fair Value, Gross Liability	[3]	1	1
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[2],[3]	0	0
Derivative Liability	[3]	1	1
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Natural Gas Commodity Contract | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	[1]	0	0
Derivative Liability, Fair Value, Gross Liability	[3]	0	0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Natural Gas Commodity Contract | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	[1]	2	1
Derivative Liability, Fair Value, Gross Liability	[3]	1	1
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Natural Gas Commodity Contract | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross	[1]	0	0
Derivative Liability, Fair Value, Gross Liability	[3]	$ 0	$ 0
[1]Included in prepayments and other current assets at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet.[2]NSP-Wisconsin nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement. Counterparty netting excludes settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.[3]Included in other current liabilities at Dec. 31, 2022 and Dec. 31, 2021 on the consolidated balance sheet.

Fair Value of Long-Term Debt (D

Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Long-term debt, Fair Value	$ 980	$ 1,143
Long-term Debt, Gross	$ 1,086	$ 987

Benefit Plans and Other Postr_3

Benefit Plans and Other Postretirement Benefits, Pension Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Operating and maintenance expenses		$ 223,000,000	$ 198,000,000	$ 191,000,000
Target Pension Asset Allocations [Abstract]
annual interest crediting rates [Domain]		4.86	1.96	1.78
annual interest crediting rates [Domain]		4.86	1.96	1.78
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Operating and maintenance expenses			1,000,000
Pension Benefits [Abstract]
Total benefit obligation		112,000,000	141,000,000	154,000,000
Net benefit cost recognized for financial reporting		$ 8,000,000	$ 8,000,000	$ 13,000,000
Expected average long-term rate of return on assets (as a percent)		6.60%	6.60%	7.10%
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		100%	100%
Pension Plan [Member] | Domestic and international equity securities
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		33%	33%
Pension Plan [Member] | Long-duration fixed income and interest rate swap securities
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		38%	37%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		9%	11%
Pension Plan [Member] | Alternative investments
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		18%	17%
Pension Plan [Member] | Cash
Target Pension Asset Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		2%	2%
Forecast [Member] | Pension Plan [Member]
Pension Benefits [Abstract]
Expected average long-term rate of return on assets for next fiscal year (as a percent)	7.25%
Parent Company [Member] | Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Pension Benefits [Abstract]
Total benefit obligation		$ 11,000,000	$ 43,000,000
Net benefit cost recognized for financial reporting		$ 17,000,000	$ 4,000,000

Benefit Plans and Other Postr_4

Benefit Plans and Other Postretirement Benefits, Fair Value of Pension Plan Assets (Details) - Pension Plan [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets		$ 97	[1]	$ 137	$ 140
Plan assets at net asset value	[1]	34		44
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	[2]	(6)		(5)	0
NSP Wisconsin [Member]
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]			137
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		(6)		(5)	$ 0
Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	41		57
Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	22		36
Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Cash equivalents
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	4		5
Plan assets at net asset value	[1]	0		0
Cash equivalents | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	4		5
Cash equivalents | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Cash equivalents | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Commingled funds
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	69		93
Plan assets at net asset value	[1]	34		44
Commingled funds | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	35		49
Commingled funds | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Commingled funds | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Debt Securities [Member]
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	22		36
Plan assets at net asset value	[1]	0		0
Debt Securities [Member] | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Debt Securities [Member] | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	22		36
Debt Securities [Member] | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Domestic and international equity securities
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	2		3
Plan assets at net asset value	[1]	0		0
Domestic and international equity securities | Level 1
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	2		3
Domestic and international equity securities | Level 2
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	0		0
Domestic and international equity securities | Level 3
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	[1]	$ 0		$ 0
[1]See Note 8 for further information on fair value measurement inputs and methods.[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 annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020.

Benefit Plans and Other Postr_5

Benefit Plans and Other Postretirement Benefits, Pension Plan Benefit Obligations, Cash Flows and Benefit Costs (Details)		1 Months Ended		12 Months Ended
		Jan. 31, 2023 USD ($)		Dec. 31, 2022 USD ($) Plan		Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Settlement Charge Recognized in Operating and Maintenance Expenses				$ 223,000,000		$ 198,000,000	$ 191,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Liability, Defined Benefit Plan, Noncurrent				(23,000,000)		(16,000,000)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation at Dec. 31				101,000,000		129,000,000
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		$ 112,000,000		141,000,000		154,000,000
Service cost				5,000,000		5,000,000	4,000,000
Interest cost				4,000,000		4,000,000	5,000,000
Actuarial loss				(21,000,000)		(4,000,000)
Benefit payments				(17,000,000)		(18,000,000)
Obligation at Dec. 31				112,000,000		141,000,000	154,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		97,000,000	[1]	137,000,000		140,000,000
Actual return (loss) on plan assets				(24,000,000)		10,000,000
Employer contributions				1,000,000		5,000,000
Benefit payments				(17,000,000)		(18,000,000)
Fair value of plan assets at Dec. 31				97,000,000	[1]	137,000,000	140,000,000
Funded Status of Plans at Dec. 31 [Abstract]
Funded status				(15,000,000)		(4,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss				45,000,000		44,000,000
Prior service (credit) cost				0		0
Total				45,000,000		44,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets				1,000,000		4,000,000
Noncurrent regulatory assets				44,000,000		40,000,000
Total				$ 45,000,000		$ 44,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)				5.80%		3.08%
Expected average long-term increase in compensation level (as a percent)				4.25%		3.75%
Cash Flows [Abstract]
Payment for Pension Benefits		50,000,000
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				$ 5,000,000		$ 5,000,000	4,000,000
Interest cost				4,000,000		4,000,000	5,000,000
Expected return on plan assets				(8,000,000)		(8,000,000)	(8,000,000)
Amortization of net loss				3,000,000		5,000,000	5,000,000
Settlement charge	[2]			6,000,000		5,000,000	0
Net periodic benefit cost				10,000,000		11,000,000	6,000,000
Net benefit cost recognized for financial reporting				$ 8,000,000		8,000,000	$ 13,000,000
Settlement Charge Recognized in Operating and Maintenance Expenses						$ 1,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)				3.08%		2.71%	3.49%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase				3.75%		3.75%	3.75%
Liability, Defined Benefit Plan, Current				$ 0		$ 0
Liability, Defined Benefit Plan, Noncurrent				(15,000,000)		(4,000,000)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position				(15,000,000)		(4,000,000)
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation				$ (2,000,000)		$ 3,000,000	$ (7,000,000)
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets				6.60%		6.60%	7.10%
Pension Plan [Member] | NSP Wisconsin [Member]
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	[1]			$ 137,000,000
Fair value of plan assets at Dec. 31	[1]					$ 137,000,000
Cash Flows [Abstract]
Payment for Pension Benefits		4,000,000		1,000,000		5,000,000	$ 7,000,000
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Settlement charge				6,000,000		5,000,000	0
Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		8,000,000		11,000,000		13,000,000
Service cost				0		0	0
Interest cost				1,000,000		1,000,000	1,000,000
Actuarial loss				(3,000,000)		(1,000,000)
Benefit payments				(1,000,000)		(2,000,000)
Obligation at Dec. 31				8,000,000		11,000,000	13,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		$ 0		0		0
Actual return (loss) on plan assets				0		0
Employer contributions				1,000,000		1,000,000
Benefit payments				(1,000,000)		(1,000,000)
Fair value of plan assets at Dec. 31				0		0	0
Funded Status of Plans at Dec. 31 [Abstract]
Funded status				(8,000,000)		(11,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss				4,000,000		6,000,000
Prior service (credit) cost				0		0
Total				4,000,000		6,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets				0		0
Noncurrent regulatory assets				4,000,000		6,000,000
Total				$ 4,000,000		$ 6,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)				5.80%		3.09%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				$ 0		$ 0	0
Interest cost				1,000,000		1,000,000	1,000,000
Expected return on plan assets				0		0	0
Amortization of net loss				0		0	0
Settlement charge	[2]			0		0	0
Net periodic benefit cost				1,000,000		1,000,000	1,000,000
Net benefit cost recognized for financial reporting				$ 1,000,000		$ 1,000,000	$ 1,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)				3.09%		2.65%	3.47%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase				0%		0%	0%
Liability, Defined Benefit Plan, Current				$ 0		$ 1,000,000
Liability, Defined Benefit Plan, Noncurrent				(8,000,000)		(10,000,000)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position				$ (8,000,000)		$ (11,000,000)
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65				6.50%		5.30%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65				5.50%		4.90%
Ultimate health care trend assumption rate (as a percent)				4.50%		4.50%
Period until ultimate trend rate is reached (in years)				$ 7		$ 4
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation				$ 0			$ 0
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets				4.10%		4.10%	4.50%
Parent Company [Member] | Pension Plan [Member]
Cash Flows [Abstract]
Number of pension plans to which contributions were made | Plan				4
[1]See Note 8 for further information on fair value measurement inputs and methods.[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 annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020.

Benefit Plans and Other Postr_6

Benefit Plans and Other Postretirement Benefits, Defined Contribution Plans (Details) - USD ($)		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Administrative Expense		$ 2,000,000	$ 2,000,000	$ 2,000,000
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for year-end valuation (as a percent)		5.80%	3.09%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65		6.50%	5.30%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65		5.50%	4.90%
Ultimate health care trend assumption rate (as a percent)		4.50%	4.50%
Period until ultimate trend rate is reached (in years)		$ 7	$ 4
Net benefit cost recognized for financial reporting		1,000,000	1,000,000	1,000,000
Settlement charge	[1]	$ 0	$ 0	0
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for year-end valuation (as a percent)		5.80%	3.08%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase		4.25%	3.75%
Net benefit cost recognized for financial reporting		$ 8,000,000	$ 8,000,000	13,000,000
Settlement charge	[1]	6,000,000	5,000,000	0
Pension Plan [Member] | NSP Wisconsin [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		6,000,000	5,000,000	$ 0
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan | Parent Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Net benefit cost recognized for financial reporting		$ 17,000,000	$ 4,000,000
[1]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 annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020.

Benefit Plans and Other Postr_7

Benefit Plans and Other Postretirement Benefits, Postretirement Health Care Benefits (Details) - Other Postretirement Benefits Plan [Member]	Dec. 31, 2022	Dec. 31, 2021
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100%	100%
Domestic and international equity securities
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	16%	15%
Short-to-intermediate fixed income securities
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	71%	71%
Alternative investments
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	12%	8%
Cash
Postretirement Health Care Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	1%	6%

Benefit Plans and Other Postr_8

Benefit Plans and Other Postretirement Benefits, Fair Value of Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100%	100%
Plan Assets Measured at Fair Value for Each of the Fair Value Hierarchy Levels [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	$ 0	$ 0	$ 0
Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	1%	6%
Domestic and international equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	16%	15%
Long-duration fixed income and interest rate swap securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Short-to-intermediate fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	71%	71%
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	12%	8%

Benefit Plans and Other Postr_9

Benefit Plans and Other Postretirement Benefits, Postretirement Benefit Plan Benefit Obligations, Cash Flows and Benefit Costs (Details) - USD ($)		1 Months Ended		12 Months Ended
		Jan. 31, 2023		Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Funded Status of Plans at Dec. 31 [Abstract]
Noncurrent liabilities				$ (23,000,000)		$ (16,000,000)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits		$ 50,000,000
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		112,000,000		141,000,000		154,000,000
Service cost				5,000,000		5,000,000	$ 4,000,000
Interest cost				4,000,000		4,000,000	5,000,000
Actuarial loss				(21,000,000)		(4,000,000)
Benefit payments				(17,000,000)		(18,000,000)
Obligation at Dec. 31				112,000,000		141,000,000	154,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		97,000,000	[1]	137,000,000		140,000,000
Actual return (loss) on plan assets				(24,000,000)		10,000,000
Employer contributions				1,000,000		5,000,000
Benefit payments				(17,000,000)		(18,000,000)
Fair value of plan assets at Dec. 31				97,000,000	[1]	137,000,000	140,000,000
Funded Status of Plans at Dec. 31 [Abstract]
Funded status				(15,000,000)		(4,000,000)
Current liabilities				0		0
Noncurrent liabilities				(15,000,000)		(4,000,000)
Net postretirement amounts recognized on consolidated balance sheets				(15,000,000)		(4,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss				45,000,000		44,000,000
Prior service (credit) cost				0		0
Total				45,000,000		44,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets				1,000,000		4,000,000
Noncurrent regulatory assets				44,000,000		40,000,000
Total				$ 45,000,000		$ 44,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)				5.80%		3.08%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase				4.25%		3.75%
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				$ 5,000,000		$ 5,000,000	4,000,000
Interest cost				4,000,000		4,000,000	5,000,000
Expected return on plan assets				(8,000,000)		(8,000,000)	(8,000,000)
Amortization of net loss				3,000,000		5,000,000	5,000,000
Settlement charge	[2]			6,000,000		5,000,000	0
Net periodic benefit cost				$ 10,000,000		$ 11,000,000	$ 6,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)				3.08%		2.71%	3.49%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase				3.75%		3.75%	3.75%
Expected average long-term rate of return on assets (as a percent)				6.60%		6.60%	7.10%
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation				$ 2,000,000		$ (3,000,000)	$ 7,000,000
Net benefit cost recognized for financial reporting				8,000,000		8,000,000	13,000,000
Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		8,000,000		11,000,000		13,000,000
Service cost				0		0	0
Interest cost				1,000,000		1,000,000	1,000,000
Actuarial loss				(3,000,000)		(1,000,000)
Benefit payments				(1,000,000)		(2,000,000)
Obligation at Dec. 31				8,000,000		11,000,000	13,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1		$ 0		0		0
Actual return (loss) on plan assets				0		0
Employer contributions				1,000,000		1,000,000
Benefit payments				(1,000,000)		(1,000,000)
Fair value of plan assets at Dec. 31				0		0	0
Funded Status of Plans at Dec. 31 [Abstract]
Funded status				(8,000,000)		(11,000,000)
Current liabilities				0		(1,000,000)
Noncurrent liabilities				(8,000,000)		(10,000,000)
Net postretirement amounts recognized on consolidated balance sheets				(8,000,000)		(11,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss				4,000,000		6,000,000
Prior service (credit) cost				0		0
Total				4,000,000		6,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Current regulatory assets				0		0
Noncurrent regulatory assets				4,000,000		6,000,000
Total				$ 4,000,000		$ 6,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Discount rate for year-end valuation (as a percent)				5.80%		3.09%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65				6.50%		5.30%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65				5.50%		4.90%
Ultimate health care trend assumption rate (as a percent)				4.50%		4.50%
Period until ultimate trend rate is reached (in years)				$ 7		$ 4
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost				0		0	0
Interest cost				1,000,000		1,000,000	1,000,000
Expected return on plan assets				0		0	0
Amortization of net loss				0		0	0
Settlement charge	[2]			0		0	0
Net periodic benefit cost				$ 1,000,000		$ 1,000,000	$ 1,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)				3.09%		2.65%	3.47%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase				0%		0%	0%
Expected average long-term rate of return on assets (as a percent)				4.10%		4.10%	4.50%
Defined Benefit Plan Credits (Costs) Not Recognized Due To Effects of Regulation				$ 0			$ 0
Net benefit cost recognized for financial reporting				$ 1,000,000		$ 1,000,000	$ 1,000,000
[1]See Note 8 for further information on fair value measurement inputs and methods.[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 annual net periodic pension cost. In 2022 and 2021, as a result of lump-sum distributions during the plan years, NSP-Wisconsin recorded a total pension settlement charge of $6 million and $5 million, respectively, a total of $1 million of that amount was recorded in the income statement in both years. There were no settlement charges recorded to the qualified pension plans in 2020.

Benefit Plans and Other Post_10

Benefit Plans and Other Postretirement Benefits, Projected Benefit Payments (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Defined Contribution Plan, Administrative Expense			$ 2	$ 2	$ 2
Pension Plan [Member]
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2021			11
2022			10
2023			11
2024			10
2025			10
2026-2030			54
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits	$ 50
Pension Plan [Member] | NSP Wisconsin [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits	$ 4		1	5	7
Pension Plan [Member] | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits			50	131	150
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2021			1
2022			1
2023			1
2024			1
2025			1
2026-2030			3
Defined Benefit Plan, Overfunded Plan [Member] | NSP Wisconsin [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits		$ 1	1	2	1
Defined Benefit Plan, Overfunded Plan [Member] | Xcel Energy [Member]
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
Payment for Pension Benefits		$ 12	$ 13	$ 15	$ 11

Commitments and Contingencies M

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

Commitments and Contingencies_2

Commitments and Contingencies MGP Sites (Details)	Dec. 31, 2022
Other MGP, Landfill, or Disposal Sites [Domain]
Loss Contingencies [Line Items]
Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation	1

Commitments and Contingencies E

Commitments and Contingencies Environmental Requirements - Water and Waste (Details) $ in Millions	Dec. 31, 2022 USD ($)
Capital Addition Purchase Commitments [Member] | Federal Clean Water Act Section 316 (b) [Member]
Loss Contingencies [Line Items]
Liability for estimated cost to comply with regulation	$ 5

Commitments and Contingencies,

Commitments and Contingencies, Asset Retirement Obligations (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	[2]	$ 26	[1]	$ 22
Accretion	[3]	1
Cash Flow Revisions		1	[3],[4]	3	[2],[5]
Ending balance		28	[3]	26	[1],[2]
Steam, hydro and other production
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		9		8
Accretion		1		1
Cash Flow Revisions		0	[4]	0	[5]
Ending balance		10		9
Electric Plant Electric Distribution
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		5		5
Accretion		0		0
Cash Flow Revisions		0	[4]	0	[5]
Ending balance		5		5
Natural Gas Plant Gas Distribution
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance		12		9
Accretion		0
Cash Flow Revisions		1	[4]	3	[5]
Ending balance		$ 13		$ 12
[1]Included in other long-term liabilities balance in the consolidated balance sheet.[2]Included in other long-term liabilities balance in the consolidated balance sheet.[3]Included in other long-term liabilities balance in the consolidated balance sheet.[4]In 2022, AROs were revised for changes in timing and estimates of cash flows.[5]In 2021, AROs were revised for changes in timing and estimates of cash flows. Changes in gas distribution AROs were primarily related to changes in labor rates coupled with increased gas line mileage and number of services.

Indeterminate AROs (Details)

Indeterminate AROs (Details) $ in Millions	Dec. 31, 2022 USD ($)
Asset Retirement Obligations [Line Items]
Indeterminate Costs Incurred, Asset Retirement Obligation Due to Asbestos	$ 0

Commitments and Contingencies_3

Commitments and Contingencies, Joint Operating System (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Reactor Plant Counterparty
Joint Operating System [Abstract]
Number of companies covered by FERC approved Interchange Agreement | Counterparty	2
NSP-Minnesota | Nuclear Insurance
Joint Operating System [Abstract]
Nuclear insurance coverage secured for the Company's public liability exposure	$ 450
Nuclear insurance coverage exposure funded by the Secondary Financial Protection Program	13,200
Maximum assessments per reactor per accident	$ 138
Number of owned and licensed reactors | Reactor	3
Maximum funding requirement per reactor for any one year	$ 20
Number of nuclear plant sites operated by NSP-Minnesota | Plant	2
Maximum assessments for business interruption insurance each calendar year	$ 12
Maximum assessment for property damage insurance NSP-Minnesota is subject to each calendar year	32
NSP-Minnesota | Maximum | Nuclear Insurance
Joint Operating System [Abstract]
Maximum possible loss contingency	13,700
Insurance coverage limits for NSP-Minnesota's nuclear plant sites	2,800
Business Interruption Insurance Coverage Provided by NEIL	$ 350

Commitments and Contingencies_4

Commitments and Contingencies, Fuel Contracts (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Minimum annual tolerance band percentage for future rate recovery or refund of fuel costs	2%
Coal
Fuel Contracts [Abstract]
2023	$ 4
2024	1
2025	1
2026	1
2027	1
Thereafter	2
Total	10	[1]
Natural Gas Supply
Fuel Contracts [Abstract]
2023	17
2024	0
2025	0
2026	0
2027	0
Thereafter	0
Total	17	[1]
Natural Gas Storage and Transportation
Fuel Contracts [Abstract]
2023	21
2024	20
2025	18
2026	17
2027	10
Thereafter	8
Total	$ 94	[1]
[1]Excludes additional amounts allocated to NSP-Minnesota through intercompany charges.

Commitments and Contingencies_5

Commitments and Contingencies, Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Amount Reflected in Consolidated Balance Sheets [Abstract]
Variable interest entity, consolidated, carrying amount, assets	$ 1	$ 1
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	1	1
Other Commitments [Line Items]
Variable interest entity, consolidated, carrying amount, assets	1	1
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 1	$ 1

Other Comprehensive Income (Det

Other Comprehensive Income (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	$ 1,103
Accumulated other comprehensive loss at end of period	1,259
Gains and Losses on Cash Flow Hedges | Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of losses, Derivatives	$ 0	[1]
[1]Included in interest charges.

Other Comprehensive Income Othe

Other Comprehensive Income Other Comprehensive Income Phantom (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total income tax expense (benefit)	$ 35	$ 30	$ (7)

Segments and Related Informat_3

Segments and Related Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Unregulated Operating Revenue		$ 1	$ 1	$ 0
Regulated and Unregulated Operating Revenue		1,201	1,105	974
Depreciation and amortization		158	147	156
Interest charges and financing costs		42	40	38
Total income tax expense (benefit)		35	30	(7)
Net income		125	108	107
Electric, affiliates		202	189	168
Natural gas		198	182	119
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		1,002	922	856
Depreciation and amortization		131	120	108
Interest charges and financing costs		38	36	34
Total income tax expense (benefit)		29	27	12
Net income		105	98	98
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		198	183	119
Depreciation and amortization		27	27	48
Interest charges and financing costs		4	4	4
Total income tax expense (benefit)		6	2	(20)
Net income		17	7	7
All Other
Segment Reporting Information [Line Items]
Total income tax expense (benefit)		0	1	1
Net income		3	3	2
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	1,201	1,106	975
Total revenues | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric	[1]	1,002	922	855
Total revenues | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas		198	182	119
Total revenues | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue		1	1	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue		0	(1)	(1)
Intersegment Eliminations | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric		0	0	1
Intersegment Eliminations | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas		$ 0	$ 1	$ 0
[1]Operating revenues include $202 million, $189 million and $168 million of affiliate electric revenue for the years ended Dec. 31, 2022, 2021 and 2020, respectively. See Note 12 for further information.

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating expenses
Interest Expense, Related Party	$ 1	$ 0	$ 0
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	8	3
Accounts payable	19	23
NSP-Minnesota
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	0	0
Accounts payable	4	13
PSCo
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	2	2
Accounts payable	0	0
Other subsidiaries of Xcel Energy Inc.
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	6	1
Accounts payable	15	10
Purchased Power
Operating expenses
Costs and Expenses, Related Party	445	408	379
Transmission Expense
Operating expenses
Costs and Expenses, Related Party	68	64	61
Natural Gas Purchase for Resale
Operating expenses
Costs and Expenses, Related Party	0	1	1
Other Expense
Operating expenses
Costs and Expenses, Related Party	114	99	92
Electricity, US Regulated
Operating revenues
Revenue from Related Parties	$ 202	$ 189	$ 168

Schedule II, Valuation and Qu_2

Schedule II, Valuation and Qualifying Accounts (Details) - Allowance for Bad Debts - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Jan. 1		$ 8	$ 8	$ 6
Charged to costs and expenses		4	4	7
Charged to other accounts	[1]	1	1	1
Deductions from reserves	[2]	(4)	(5)	(6)
Balance at Dec. 31		$ 9	$ 8	$ 8
[1]Recovery of amounts previously written-off.[2]Deductions related primarily to bad debt write-offs.