Southwestern Public Service 10-Q 25 Apr 24 2024 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2024	Apr. 25, 2024
Cover [Abstract]
Entity Registrant Name	SOUTHWESTERN PUBLIC SERVICE CO
Entity Central Index Key	0000092521
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity Tax Identification Number	75-0575400
Entity Incorporation, State or Country Code	NM
Entity Address, Address Line One	790 South Buchanan Street
Entity Address, City or Town	Amarillo
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	79101
City Area Code	(303)
Local Phone Number	571-7511
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		100
Entity File Number	001-03789

STATEMENTS OF INCOME (UNAUDITED

STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating revenues
Operating revenues	$ 428	$ 508
Operating expenses
Electric fuel and purchased power	160	245
Operating and maintenance expenses	72	80
Demand side management expenses	6	6
Depreciation and amortization	99	91
Taxes (other than income taxes)	21	25
Total operating expenses	358	447
Operating income	70	61
Other expense, net	1	0
Allowance for funds used during construction — equity	2	1
Interest charges and financing costs
Interest charges and other financing costs	37	34
Allowance for funds used during construction — debt	(2)	(1)
Total interest charges and financing costs	35	33
Income before income taxes	38	29
Income tax benefit	(19)	(25)
Net income	$ 57	$ 54

STATEMENTS OF CASH FLOWS (UNAUD

STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net income	$ 57	$ 54
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	100	92
Deferred income taxes	14	(40)
Allowance for equity funds used during construction	(2)	(1)
Provision for bad debts	2	2
Changes in operating assets and liabilities:
Accounts receivable	79	23
Accrued unbilled revenues	(2)	3
Inventories	(13)	(14)
Prepayments and other	(7)	4
Accounts payable	3	(30)
Net regulatory assets and liabilities	15	108
Other current liabilities	(25)	(3)
Pension and other employee benefit obligations	(2)	(1)
Other, net	(15)	(3)
Net cash provided by operating activities	208	188
Investing activities
Utility capital/construction expenditures	(206)	(170)
Net cash used in investing activities	(206)	(170)
Financing activities
Proceeds from short-term borrowings, net	70	44
Borrowings under utility money pool arrangement	246	5
Repayments under utility money pool arrangement	(173)	0
Capital contributions from parent	12	0
Dividends paid to parent	(101)	(66)
Net cash used in financing activities	54	(17)
Net change in cash, cash equivalents and restricted cash	56	1
Cash, cash equivalents and restricted cash at beginning of period	3	2
Cash, cash equivalents and restricted cash at end of period	59	3
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(25)	(22)
Cash received (paid) for income taxes, net; includes proceeds from tax credit transfers	15	(11)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	55	46
Inventory transfers to property, plant and equipment	10	9
Allowance for equity funds used during construction	2	1
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 59	$ 3

BALANCE SHEETS (UNAUDITED)

BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 59	$ 3
Accrued unbilled revenues	137	139
Inventories	72	69
Regulatory assets	40	30
Derivative instruments	47	42
Prepaid taxes	4	2
Prepayments and other	258	32
Total current assets	773	565
Property, plant and equipment, net	8,658	8,536
Other assets
Regulatory assets	343	349
Derivative instruments	7	0
Operating lease right-of-use assets	395	403
Other	36	28
Total other assets	781	780
Total assets	10,212	9,881
Current liabilities
Long-Term Debt and Lease Obligation, Current	350	350
Short-term debt	145	75
Borrowings under utility money pool arrangement	100	27
Regulatory liabilities	134	116
Taxes accrued	38	77
Accrued interest	42	33
Dividends payable to parent	47	59
Derivative instruments	1	2
Operating lease liabilities	33	32
Other	267	42
Total current liabilities	1,351	1,008
Deferred credits and other liabilities
Deferred income taxes	642	622
Regulatory liabilities	769	761
Asset retirement obligations	155	153
Pension and employee benefit obligations	9	12
Operating lease liabilities	362	371
Other	8	7
Total deferred credits and other liabilities	1,945	1,926
Capitalization
Long-term debt	2,962	2,961
Common stock — 200 shares authorized of $1.00 par value; 100 shares outstanding at March 31, 2024 and Dec. 31, 2023, respectively	0	0
Additional paid in capital	3,370	3,370
Retained earnings	585	617
Accumulated other comprehensive loss	(1)	(1)
Total common stockholder's equity	3,954	3,986
Total liabilities and equity	10,212	9,881
Related Party
Current assets
Accounts receivable, net	142	222
Current liabilities
Accounts payable	179	188
Affiliated Entity
Current assets
Accounts receivable, net	14	26
Current liabilities
Accounts payable	$ 15	$ 7

BALANCE SHEETS (UNAUDITED) (Par

BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common Stock, Shares Authorized	200	200
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares, Outstanding	100	100

CONSOLIDATED STATEMENTS OF COMM

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Common Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2022		100
Beginning balance at Dec. 31, 2022	$ 3,850	$ 0	$ 3,311	$ 540	$ (1)
Increase (Decrease) in Stockholders' Equity
Net income	54			54
Dividends declared to parent	(66)			(66)
Ending balance (in shares) at Mar. 31, 2023		100
Ending balance at Mar. 31, 2023	$ 3,838	$ 0	3,311	528	(1)
Beginning balance (in shares) at Dec. 31, 2023	100	100
Beginning balance at Dec. 31, 2023	$ 3,986	$ 0	3,370	617	(1)
Increase (Decrease) in Stockholders' Equity
Net income	57			57
Dividends declared to parent	$ (89)			(89)
Ending balance (in shares) at Mar. 31, 2024	100	100
Ending balance at Mar. 31, 2024	$ 3,954	$ 0	$ 3,370	$ 585	$ (1)

Management's Opinion

Management's Opinion	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Management's Opinion	In the opinion of management, the accompanying unaudited financial statements contain all adjustments necessary to present fairly, in accordance with GAAP, the financial position of SPS as of March 31, 2024 and Dec. 31, 2023; the results of SPS’ operations, including the components of net income, cash flows and changes to stockholders’ equity for the three months ended March 31, 2024 and 2023. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2024 up to the date of issuance of these financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2023 balance sheet information has been derived from the audited 2023 financial statements included in the SPS Annual Report on Form 10-K for the year ended Dec. 31, 2023. Notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the financial statements and notes thereto included in the SPS Annual Report on Form 10-K for the year ended Dec. 31, 2023, filed with the SEC on Feb. 21, 2024. Due to the seasonality of SPS’ electric sales, interim results are not necessarily an appropriate base from which to project annual results.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	The significant accounting policies set forth in Note 1 to the financial statements in the SPS Annual Report on Form 10-K for the year ended Dec. 31, 2023 appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

Accounting Pronouncements

Accounting Pronouncements	3 Months Ended
	Mar. 31, 2024
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Pronouncements

Selected Balance Sheet Data

Selected Balance Sheet Data	3 Months Ended
	Mar. 31, 2024
Balance Sheet Related Disclosures [Abstract]
Selected Balance Sheet Data	3. Selected Balance Sheet Data (Millions of Dollars) March 31, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 156 $ 237 Less allowance for bad debts (14) (15) Accounts receivable, net $ 142 $ 222 (Millions of Dollars) March 31, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 59 $ 56 Fuel 13 13 Total inventories $ 72 $ 69 (Millions of Dollars) March 31, 2024 Dec. 31, 2023 Property, plant and equipment, net Electric plant $ 10,825 $ 10,752 Plant to be retired (a) 242 248 CWIP 352 226 Total property, plant and equipment 11,419 11,226 Less accumulated depreciation (2,761) (2,690) Property, plant and equipment, net $ 8,658 $ 8,536 (a)

Borrowings and Other Financing

Borrowings and Other Financing Instruments	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Borrowings and Other Financing Instruments	Short-Term Borrowings SPS 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 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 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. Money pool borrowings: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 100 $ 100 Amount outstanding at period end 100 27 Average amount outstanding 41 46 Maximum amount outstanding 100 100 Weighted average interest rate, computed on a daily basis 5.33 % 5.04 % Weighted average interest rate at period end 5.33 5.34 Commercial Paper — Commercial paper outstanding: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 500 $ 500 Amount outstanding at period end 145 75 Average amount outstanding 75 50 Maximum amount outstanding 156 119 Weighted average interest rate, computed on a daily basis 5.52 % 5.12 % Weighted average interest rate at period end 5.52 5.56 Letters of Credit — SPS uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At both March 31, 2024 and Dec. 31, 2023, there w ere no l etters of credit outstanding under the credit facility. Amounts approximate their fair value and are subject to fees. Revolving Credit Facility — In order to issue its commercial paper, SPS must have a revolving credit facility equal to or greater than the commercial paper borrowing limit and cannot issue commercial paper exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings. SPS has the right to request an extension of the revolving credit facility termination date for two additional one-year periods. All extension requests are subject to majority bank group approval. As of March 31, 2024, SPS had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 500 $ 145 $ 355 (a) Expires in September 2027. (b) Includes outstanding letters of credit. All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. SPS ha d no d irect advances on the credit facility outstanding as of March 31, 2024 and Dec. 31, 2023.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenue	Revenue is classified by the type of goods/services rendered and market/customer type. SPS’ operating revenues consisted of the following: Three Months Ended March 31 (Millions of Dollars) 2024 2023 Major revenue types Revenue from contracts with customers: Residential $ 86 $ 101 Commercial and Industrial (a) 217 267 Other 9 12 Total retail 312 380 Wholesale 36 45 Transmission 71 74 Total revenue from contracts with customers 419 499 Alternative revenue and other 9 9 Total revenues $ 428 $ 508 (a) In 2024, revenues from one C&I customer represented approximately 10.7% of total revenues.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	6. Income Taxes Reconciliation between the statutory rate and ETR: Three Months Ended March 31 2024 2023 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 2.5 2.3 (Decreases) increases: Wind PTCs (a) (69.7) (105.5) Plant regulatory differences (b) (4.5) (3.7) Amortization of excess nonplant deferred taxes 0.3 0.3 Other (net) 0.4 (0.6) Effective income tax rate (50.0) % (86.2) % (a) Wind PTCs net of estimated transfer discounts. Gross wind PTCs are credited to customers (reduction to revenue) and do not materially impact net income. (b)

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	3 Months Ended
	Mar. 31, 2024
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: Interest rate derivatives — Fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts. 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. Electric commodity derivatives held by SPS include transmission congestion instruments, generally referred to as FTRs. FTRs purchased from an RTO are financial instruments that entitle or obligate the holder to monthly revenues or charges based on transmission congestion across a given transmission path. The values of these instruments are derived from, and designed to offset, the costs of transmission congestion. In addition to overall transmission load, congestion is also influenced by the operating schedules of power plants and the consumption of electricity pertinent to a given transmission path. Unplanned plant outages, scheduled plant maintenance, changes in the relative costs of fuels used in generation, weather and overall changes in demand for electricity can each impact the operating schedules of the power plants on the transmission grid and the value of these instruments. FTRs are recognized at fair value and adjusted each period prior to settlement. Given the limited observability of certain variables underlying the reported auction values of FTRs, these fair value measurements have been assigned a Level 3 classification. Net congestion costs, including the impact of FTR settlements, are shared through fuel and purchased energy cost recovery mechanisms. As such, the fair value of the unsettled instruments (i.e., derivative asset or liability) is offset/deferred as a regulatory asset or liability. Derivative Activities and Fair Value Measurements SPS enters into derivative instruments, including forward contracts, for trading purposes and to manage risk in connection with changes in interest rates and utility commodity prices. Interest Rate Derivatives — SPS enters into contracts that effectively fix the interest rate on a specified principal amount of a hypothetical future debt issuance. These financial swaps net settle based on changes in a specified benchmark interest rate, acting as a hedge of changes in market interest rates that will impact specified anticipated debt issuances. These derivative instruments are designated as cash flow hedges for accounting purposes, with changes in fair value prior to occurrence of the hedged transactions recorded as other comprehensive income. As of March 31, 2024, accumulated other comprehensive loss related to interest rate derivatives included immaterial net losses expected to be reclassified into earnings during the next 12 months as the hedged transactions impact earnings. As of March 31, 2024, SPS had no unsettled interest rate derivatives. Wholesale and Commodity Trading — SPS conducts various wholesale and commodity trading activities, including the purchase and sale of electric capacity, energy and energy-related instruments, including derivatives. SPS is allowed to conduct these activities within guidelines and limitations as approved by its risk management committee, comprised of management personnel not directly involved in the activities governed by this policy. Results of derivative instrument transactions entered into for trading purposes are presented in the statements of income as electric revenues, net of any sharing with customers. These activities are not intended to mitigate commodity price risk associated with regulated electric operations. Sharing of these margins is determined through state regulatory proceedings as well as the operation of the FERC-approved joint operating agreement. Commodity Derivatives — SPS enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric utility operations. This could include the purchase or sale of energy or energy-related products and FTRs. The most significant derivative positions outstanding at March 31, 2024 for this purpose relate to FTR instruments administered by SPP. These instruments are intended to offset the impacts of transmission system congestion. When SPS enters into derivative instruments that mitigate commodity price risk on behalf of electric customers, the instruments are not typically designated as qualifying hedging transactions. The classification of unrealized losses or gains on these instruments as a regulatory asset or liability, if applicable, is based on approved regulatory recovery mechanisms. As of March 31, 2024, SPS had no commodity contracts designated as cash flow hedges. Gross notional amounts of FTRs: Amounts in Millions (a) March 31, 2024 Dec. 31, 2023 Megawatt hours of electricity 10 8 (a) Not reflective of net positions in the underlying commodities. Consideration of Credit Risk and Concentrations — SPS 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 balance sheets. SPS’ most significant concentrations of credit risk with particular entities or industries are contracts with counterparties to its wholesale, trading and non-trading commodity activities. As of March 31, 2024, three of the ten most significant counterparties for these activities, comprising $4 million, or 15%, of this credit exposure, had investment grade credit ratings from S&P Global Ratings, Moody’s Investor Services or Fitch Ratings. Six of the ten most significant counterparties, comprising $22 million, or 85%, of this credit exposure, were not rated by external ratings agencies, but based on SPS’ internal analysis, had credit quality consistent with investment grade. One of these counterparties, comprising an immaterial amount or less than 1% of this credit exposure, had credit quality less than investment grade, based on internal analysis. Seven of these counterparties are municipal or cooperative electric entities, RTOs or other utilities. Recurring Derivative Fair Value Measurements Impact of derivative activity: Pre-Tax Fair Value Losses Recognized During the Period in: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended March 31, 2024 Other derivative instruments Electric commodity $ (1) Total $ (1) Three Months Ended March 31, 2023 Other derivative instruments Electric commodity $ (75) Total $ (75) Pre-Tax Losses Reclassified into Income During the Period from: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended March 31, 2024 Other derivative instruments Electric commodity $ 8 (a) Total $ 8 Three Months Ended March 31, 2023 Other derivative instruments Electric commodity $ 68 (a) Total $ 68 (a) Recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate. FTR settlements are shared with customers and do not have a material impact on net income. Presented amounts reflect changes in fair value between auction and settlement dates, but exclude the original auction fair value. SPS had no derivative instruments designated as fair value hedges during the three months ended March 31, 2024 and 2023. Derivative assets and liabilities measured at fair value on a recurring basis were as follows: March 31, 2024 Dec. 31, 2023 Fair Value Fair Value Total Netting (a) Total Fair Value Fair Value Total Netting (a) Total (Millions of Dollars) Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Current derivative assets Other derivative instruments: Electric commodity $ — $ — $ 45 $ 45 $ — $ 45 $ — $ — $ 39 $ 39 $ — $ 39 Total current derivative assets $ — $ — $ 45 $ 45 $ — 45 $ — $ — $ 39 $ 39 $ — 39 PPAs (b) 2 3 Current derivative instruments $ 47 $ 42 Noncurrent derivative assets Other derivative instruments: Electric commodity $ — $ — $ 7 $ — $ — $ 7 $ — $ — $ — $ — $ — $ — Total noncurrent derivative assets $ — $ — $ 7 $ — $ — $ 7 $ — $ — $ — $ — $ — $ — Current derivative liabilities PPAs (b) 1 2 Current derivative instruments $ 1 $ 2 (a) SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At March 31, 2024 and Dec. 31, 2023, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. (b) SPS currently applies the normal purchase exception to qualifying PPAs. Balance relates to specific contracts that were previously recognized at fair value prior to applying the normal purchase exception, and are being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities. Changes in Level 3 commodity derivatives: Three Months Ended March 31 (Millions of Dollars) 2024 2023 Balance at Jan. 1 $ 39 $ 119 Purchases (a) 3 6 Settlements (a) (36) (16) Net transactions recorded during the period: Net gains (losses) recognized as regulatory assets and liabilities (a) 46 (86) Balance at March 31 $ 52 $ 23 (a) Relates primarily to FTR instruments administered by SPP. Fair Value of Long-Term Debt As of March 31, 2024, other financial instruments for which the carrying amount did not equal fair value: March 31, 2024 Dec. 31, 2023 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 3,312 $ 2,696 $ 3,311 $ 2,818 Fair value of SPS’ long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of March 31, 2024 and Dec. 31, 2023, 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	3 Months Ended
	Mar. 31, 2024
Retirement Benefits [Abstract]
Benefit Plans and Other Postretirement Benefits	Components of Net Periodic Benefit Cost Three Months Ended March 31 2024 2023 (Millions of Dollars) Pension Benefits Service cost $ 2 $ 2 Interest cost (a) 5 6 Expected return on plan assets (a) (8) (8) Amortization of net loss (a) 1 — Net periodic benefit (credit) cost $ — $ — Effects of regulation 1 1 Net benefit cost recognized for financial reporting $ 1 $ 1 (a) The components of net periodic cost other than the service cost component are included in the line item “Other expense, net” in the statements of income or capitalized on the balance sheets as a regulatory asset.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Legal SPS 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 SPS’ financial statements. Legal fees are generally expensed as incurred. 2024 Smokehouse Creek Fire Complex Beginning on February 26, 2024, multiple wildfires began in the Texas Panhandle, including the Smokehouse Creek Fire and the 687 Reamer Fire, which news reports indicate burned into the perimeter of the Smokehouse Creek Fire (together, referred to herein as the “Smokehouse Creek Fire Complex”). The Texas A&M Forest Service issued incident reports that determined that the Smokehouse Creek Fire and the 687 Reamer Fire were caused by power lines owned by SPS after wooden poles near each fire origin failed. SPS is continuing to conduct investigations into other potential ignitions associated with the Smokehouse Creek Fire Complex. According to the Texas A&M Forest Service’s Incident Viewer and news reports, as of March 19, 2024, the Smokehouse Creek Fire Complex burned approximately 1,055,000 acres. On March 12, 2024, the Speaker of the Texas House of Representatives created the Investigative Committee on the Panhandle Wildfires (the “Investigative Committee”). The Investigative Committee held public hearings in Pampa, Texas, between April 2 and April 4, 2024, and stated that it plans to issue a report by early May 2024. SPS is aware of approximately 15 complaints, most of which have also named Xcel Energy Services Inc. as an additional defendant, relating to the Smokehouse Creek Fire Complex, including one putative class action on behalf of persons or entities who owned rangelands or pastures that were damaged by the fire. The complaints generally allege that SPS’ equipment ignited the Smokehouse Creek Fire Complex and seek compensation for losses resulting from the fire, asserting various causes of action under Texas law. In addition to seeking compensatory damages, certain of the complaints also seek exemplary damages. SPS has also received approximately 46 claims for losses related to the Smokehouse Creek Fire Complex through its claims process. Texas law does not apply strict liability in determining an electric utility company’s liability for fire-related damages. For negligence claims under Texas law, a public utility has a duty to exercise ordinary and reasonable care. Potential liabilities related to the Smokehouse Creek Fire Complex depend on various factors, including the cause of the equipment failure and the extent and magnitude of potential damages, including damages to residential and commercial structures, personal property, vegetation, livestock and livestock feed (including replacement feed), personal injuries and any other damages, penalties, fines or restitution that may be imposed by courts or other governmental entities if SPS is found to have been negligent. Based on the current state of the law and the facts and circumstances available to Xcel Energy as of the date of this filing, Xcel Energy believes it is probable that it will incur a loss in connection with the Smokehouse Creek Fire Complex and accordingly recorded a pre-tax charge in the amount of $215 million, presented in other current liabilities as of March 31, 2024 (before available insurance). The aggregate liability of $215 million for claims in connection with the Smokehouse Creek Fire Complex (before available insurance) corresponds to the lower end of the range of Xcel Energy’s reasonably estimable range of losses, and is subject to change based on additional information. This $215 million estimate does not include, among other things, amounts for (i) potential penalties or fines that may be imposed by governmental entities on Xcel Energy, (ii) exemplary or punitive damages, (iii) compensation claims by federal, state, county and local government entities or agencies, (iv) compensation claims for damage to trees, railroad lines, or oil and gas equipment, or (v) other amounts that are not reasonably estimable. Xcel Energy is unable to reasonably estimate any additional loss or the upper end of the range because there are a number of unknown facts and legal considerations that may impact the amount of any potential liability. In the event that SPS or Xcel Energy Services Inc. was found liable related to the litigation related to the Smokehouse Creek Fire Complex and was required to pay damages, such amounts could exceed our insurance coverage of approximately $500 million for the annual policy period and could have a material adverse effect on our financial condition, results of operations or cash flows. The process for estimating losses associated with potential claims related to the Smokehouse Creek Fire Complex requires management to exercise significant judgment based on a number of assumptions and subjective factors, including the factors identified above and estimates based on currently available information and prior experience with wildfires. As more information becomes available, management estimates and assumptions regarding the potential financial impact of the Smokehouse Creek Fire Complex may change. SPS records insurance recoveries when it is deemed probable that recovery will occur, and SPS can reasonably estimate the amount or range. As of March 31, 2024, SPS has recorded an insurance receivable for $215 million within prepayments and other current assets. While SPS plans to seek recovery of all insured losses, it is unable to predict the ultimate amount and timing of such insurance recoveries. Rate Matters and Other SPS is involved in various regulatory proceedings arising in the ordinary course of business. Until resolution, typically in the form of a rate order, uncertainties may exist regarding the ultimate rate treatment for certain activities and transactions. Amounts have been recognized for probable and reasonably estimable losses that may result. Unless otherwise disclosed, any reasonably possible range of loss in excess of any recognized amount is not expected to have a material effect on the financial statements. SPP OATT Upgrade Costs — Costs of transmission upgrades may be recovered from other SPP customers whose transmission service depends on capacity enabled by the upgrade under the SPP OATT. SPP had not been charging its customers for these upgrades, even though the SPP OATT had allowed SPP to do so since 2008. In 2016, the FERC granted SPP’s request to recover these previously unbilled charges and SPP subsequently billed SPS approximately $13 million. In 2018, SPS’ appeal to the D.C. Circuit over the FERC rulings granting SPP the right to recover previously unbilled charges was remanded to the FERC. In 2019, the FERC reversed its 2016 decision and ordered SPP to refund charges retroactively collected from its transmission customers, including SPS, related to periods before September 2015. In 2020, SPP and Oklahoma Gas & Electric separately filed petitions for review of the FERC’s orders at the D.C. Circuit. In 2021, the D.C. Circuit issued a decision denying these appeals and upholding the FERC’s orders. Refunds received by SPS are expected to be given back to SPS customers through future rates. Environmental New and changing federal and state environmental mandates can create financial liabilities for SPS, 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. SPS may sometimes pay all or a portion of the cost to remediate sites where past activities of their 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 SPS is alleged to have sent wastes to that site. MGP, Landfill and Disposal Sites SPS is investigating, remediating or performing post-closure actions at two historical MGP, landfill or other disposal sites across its service territories, excluding sites that are being addressed under current coal ash regulations (see below). SPS 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 regulatory recovery, insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of costs incurred. Environmental Requirements — Air Clean Air Act NOx Allowance Allocations — In June 2023, the EPA published final regulations for ozone under the "Good Neighbor" provisions of the Clean Air Act. The final rule applies to generation facilities in Texas, as well as other states outside of our service territory. The rule establishes an allowance trading program for NOx that will impact SPS’ fossil fuel-fired electric generating facilities. Subject facilities will have to secure additional allowances, install NOx controls and/or develop a strategy of operations that utilizes the existing allowance allocations. Guidelines are also established for allowance banking and emission limit backstops. While the financial impacts of the final rule are uncertain and dependent on market forces and anticipated generation, SPS anticipates the annual costs could be significant, but would be recoverable through regulatory mechanisms. SPS has joined other companies in litigation challenging the EPA’s disapproval of Texas’ state implementation plan. Currently, the regulation is under a judicial stay for Texas and not applicable in that jurisdiction until litigation concludes. In February 2024, the EPA proposed to partially disapprove New Mexico’s state implementation plan and bring New Mexico into the federal Good Neighbor Plan. Xcel Energy continues to evaluate impacts to generation units at SPS. Leases SPS evaluates contracts that may contain leases, including PPAs and arrangements for the use of office space and other facilities, vehicles and equipment. A contract contains a lease if it conveys the exclusive right to control the use of a specific asset. Components of lease expense: Three Months Ended March 31 (Millions of Dollars) 2024 2023 Operating leases PPA capacity payments $ 13 $ 13 Other operating leases (a) 1 1 Total operating lease expense (b) $ 14 $ 14 (a) Includes immaterial short-term lease expense for 2024 and 2023. (b) PPA capacity payments are included in electric fuel and purchased power on the statements of income. Expense for other operating leases is included in operating and maintenance expense and electric fuel and purchased power. Commitments under operating leases as of March 31, 2024: (Millions of Dollars) PPA Operating Leases Other Operating Leases Total Operating Leases Total minimum obligation $ 439 $ 49 $ 488 Interest component of obligation (81) (12) (93) Present value of minimum obligation $ 358 $ 37 395 Less current portion (33) Noncurrent operating lease liabilities $ 362 Variable Interest Entities

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net income	$ 57	$ 54

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Selected Balance Sheet Data (Ta

Selected Balance Sheet Data (Tables)	3 Months Ended
	Mar. 31, 2024
Balance Sheet Related Disclosures [Abstract]
Accounts Receivable, Net	(Millions of Dollars) March 31, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 156 $ 237 Less allowance for bad debts (14) (15) Accounts receivable, net $ 142 $ 222
Inventories	(Millions of Dollars) March 31, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 59 $ 56 Fuel 13 13 Total inventories $ 72 $ 69
Property, Plant and Equipment, Net	3. Selected Balance Sheet Data (Millions of Dollars) March 31, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 156 $ 237 Less allowance for bad debts (14) (15) Accounts receivable, net $ 142 $ 222 (Millions of Dollars) March 31, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 59 $ 56 Fuel 13 13 Total inventories $ 72 $ 69 (Millions of Dollars) March 31, 2024 Dec. 31, 2023 Property, plant and equipment, net Electric plant $ 10,825 $ 10,752 Plant to be retired (a) 242 248 CWIP 352 226 Total property, plant and equipment 11,419 11,226 Less accumulated depreciation (2,761) (2,690) Property, plant and equipment, net $ 8,658 $ 8,536 (a)

Borrowings and Other Financin_2

Borrowings and Other Financing Instruments (Tables)	3 Months Ended
	Mar. 31, 2024
Borrowings and Other Financing Instruments [Abstract]
Credit Facilities	As of March 31, 2024, SPS had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 500 $ 145 $ 355 (a) Expires in September 2027. (b) Includes outstanding letters of credit.
Money Pool
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Money pool borrowings: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 100 $ 100 Amount outstanding at period end 100 27 Average amount outstanding 41 46 Maximum amount outstanding 100 100 Weighted average interest rate, computed on a daily basis 5.33 % 5.04 % Weighted average interest rate at period end 5.33 5.34
Commercial Paper
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Commercial paper outstanding: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 500 $ 500 Amount outstanding at period end 145 75 Average amount outstanding 75 50 Maximum amount outstanding 156 119 Weighted average interest rate, computed on a daily basis 5.52 % 5.12 % Weighted average interest rate at period end 5.52 5.56

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	SPS’ operating revenues consisted of the following: Three Months Ended March 31 (Millions of Dollars) 2024 2023 Major revenue types Revenue from contracts with customers: Residential $ 86 $ 101 Commercial and Industrial (a) 217 267 Other 9 12 Total retail 312 380 Wholesale 36 45 Transmission 71 74 Total revenue from contracts with customers 419 499 Alternative revenue and other 9 9 Total revenues $ 428 $ 508 (a) In 2024, revenues from one C&I customer represented approximately 10.7% of total revenues.

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Reconciliation between the statutory rate and ETR: Three Months Ended March 31 2024 2023 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 2.5 2.3 (Decreases) increases: Wind PTCs (a) (69.7) (105.5) Plant regulatory differences (b) (4.5) (3.7) Amortization of excess nonplant deferred taxes 0.3 0.3 Other (net) 0.4 (0.6) Effective income tax rate (50.0) % (86.2) % (a) Wind PTCs net of estimated transfer discounts. Gross wind PTCs are credited to customers (reduction to revenue) and do not materially impact net income. (b)

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Gross Notional Amounts of Commodity FTRs	Amounts in Millions (a) March 31, 2024 Dec. 31, 2023 Megawatt hours of electricity 10 8 (a) Not reflective of net positions in the underlying commodities.
Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level	March 31, 2024 Dec. 31, 2023 Fair Value Fair Value Total Netting (a) Total Fair Value Fair Value Total Netting (a) Total (Millions of Dollars) Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Current derivative assets Other derivative instruments: Electric commodity $ — $ — $ 45 $ 45 $ — $ 45 $ — $ — $ 39 $ 39 $ — $ 39 Total current derivative assets $ — $ — $ 45 $ 45 $ — 45 $ — $ — $ 39 $ 39 $ — 39 PPAs (b) 2 3 Current derivative instruments $ 47 $ 42 Noncurrent derivative assets Other derivative instruments: Electric commodity $ — $ — $ 7 $ — $ — $ 7 $ — $ — $ — $ — $ — $ — Total noncurrent derivative assets $ — $ — $ 7 $ — $ — $ 7 $ — $ — $ — $ — $ — $ — Current derivative liabilities PPAs (b) 1 2 Current derivative instruments $ 1 $ 2 (a) SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At March 31, 2024 and Dec. 31, 2023, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. (b) SPS currently applies the normal purchase exception to qualifying PPAs. Balance relates to specific contracts that were previously recognized at fair value prior to applying the normal purchase exception, and are being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.
Changes in Level 3 Commodity Derivatives	Three Months Ended March 31 (Millions of Dollars) 2024 2023 Balance at Jan. 1 $ 39 $ 119 Purchases (a) 3 6 Settlements (a) (36) (16) Net transactions recorded during the period: Net gains (losses) recognized as regulatory assets and liabilities (a) 46 (86) Balance at March 31 $ 52 $ 23 (a) Relates primarily to FTR instruments administered by SPP.
Carrying Amount and Fair Value of Long-term Debt	March 31, 2024 Dec. 31, 2023 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 3,312 $ 2,696 $ 3,311 $ 2,818
Derivative Instruments, Gain (Loss)	Pre-Tax Fair Value Losses Recognized During the Period in: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended March 31, 2024 Other derivative instruments Electric commodity $ (1) Total $ (1) Three Months Ended March 31, 2023 Other derivative instruments Electric commodity $ (75) Total $ (75) Pre-Tax Losses Reclassified into Income During the Period from: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended March 31, 2024 Other derivative instruments Electric commodity $ 8 (a) Total $ 8 Three Months Ended March 31, 2023 Other derivative instruments Electric commodity $ 68 (a) Total $ 68 (a) Recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate. FTR settlements are shared with customers and do not have a material impact on net income. Presented amounts reflect changes in fair value between auction and settlement dates, but exclude the original auction fair value.

Benefit Plans and Other Postr_2

Benefit Plans and Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2024
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost (Credit)	Components of Net Periodic Benefit Cost Three Months Ended March 31 2024 2023 (Millions of Dollars) Pension Benefits Service cost $ 2 $ 2 Interest cost (a) 5 6 Expected return on plan assets (a) (8) (8) Amortization of net loss (a) 1 — Net periodic benefit (credit) cost $ — $ — Effects of regulation 1 1 Net benefit cost recognized for financial reporting $ 1 $ 1 (a) The components of net periodic cost other than the service cost component are included in the line item “Other expense, net” in the statements of income or capitalized on the balance sheets as a regulatory asset.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Lease, Cost	Three Months Ended March 31 (Millions of Dollars) 2024 2023 Operating leases PPA capacity payments $ 13 $ 13 Other operating leases (a) 1 1 Total operating lease expense (b) $ 14 $ 14 (a) Includes immaterial short-term lease expense for 2024 and 2023. (b)
Lessee, Operating Lease, Liability, Maturity	Commitments under operating leases as of March 31, 2024: (Millions of Dollars) PPA Operating Leases Other Operating Leases Total Operating Leases Total minimum obligation $ 439 $ 49 $ 488 Interest component of obligation (81) (12) (93) Present value of minimum obligation $ 358 $ 37 395 Less current portion (33) Noncurrent operating lease liabilities $ 362

Selected Balance Sheet Data Acc

Selected Balance Sheet Data Accounts Receivable, Net (Details) - Related Party - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Accounts receivable	$ 156	$ 237
Accounts Receivable, Allowance for Credit Loss, Current	14	15
Accounts receivable, net	$ 142	$ 222

Selected Balance Sheet Data Sel

Selected Balance Sheet Data Selected Balance Sheet Data Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Inventories	$ 72	$ 69
Inventory, Net	72	69
Materials and supplies
Inventories	59	56
Fuel
Inventories	$ 13	$ 13

Selected Balance Sheet Data Bal

Selected Balance Sheet Data Balance Sheet Related Disclosures, Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions		Mar. 31, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 11,419	$ 11,226
Accumulated depreciation		(2,761)	(2,690)
Property, plant and equipment, net		8,658	8,536
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		10,825	10,752
Plant to be Retired
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	[1]	242	248
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 352	$ 226
[1] Amounts include Tolk and coal generation assets at Harrington pending facility gas conversion. Amounts are reported net of accumulated depreciation.

Borrowings and Other Financin_3

Borrowings and Other Financing Instruments - Money Pool (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Short-term debt	$ 145	$ 75
Money Pool
Short-term Debt [Line Items]
Borrowing limit	100	100
Short-term debt	100	27
Average amount outstanding	41	46
Maximum amount outstanding	$ 100	$ 100
Weighted average interest rate, computed on a daily basis	5.33%	5.04%
Weighted average interest rate at period end	5.33%	5.34%
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	$ 500	$ 500
Short-term debt	145	75
Average amount outstanding	75	50
Maximum amount outstanding	$ 156	$ 119
Weighted average interest rate, computed on a daily basis	5.52%	5.12%
Weighted average interest rate at period end	5.52%	5.56%

Borrowings and Other Financin_4

Borrowings and Other Financing Instruments - Commercial Paper (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Short-term debt	$ 145	$ 75
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	500	500
Short-term debt	145	75
Average amount outstanding	75	50
Maximum amount outstanding	$ 156	$ 119
Weighted average interest rate, computed on a daily basis	5.52%	5.12%
Weighted average interest rate at period end	5.52%	5.56%

Borrowings and Other Financin_5

Borrowings and Other Financing Instruments - Letters of Credit (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Short-term debt	$ 145,000,000	$ 75,000,000
Letter of Credit
Line of Credit Facility [Line Items]
Debt Instrument, Term	1 year
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Direct advances on the credit facility outstanding	$ 0	0
Letter of Credit
Line of Credit Facility [Line Items]
Direct advances on the credit facility outstanding		$ 0

Borrowings and Other Financin_6

Borrowings and Other Financing Instruments - Credit Facility (Details)		3 Months Ended
		Mar. 31, 2024 USD ($) Plan	Dec. 31, 2023 USD ($)
Line of Credit Facility [Line Items]
Number of extension you can request | Plan		2
Credit Facility
Line of Credit Facility [Line Items]
Credit Facility	[1]	$ 500,000,000
Outstanding	[2]	145,000,000
Available		355,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
[1]Expires in September 2027[2] Includes outstanding letters of credit.

Borrowings and Other Financin_7

Borrowings and Other Financing Instruments - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
Short-term debt	$ 145	$ 75

Revenues (Details)

Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024		Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 419		$ 499
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	428		508
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	312		380
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	86		101
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	217	[1]	267
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9		12
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	36		45
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	71		74
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 9		$ 9
[1] In 2024, revenues from one C&I customer represented approximately 10.7% of total revenues.

Income Taxes (Details)

Income Taxes (Details)		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Federal statutory rate, percent		21%	21%
State tax (net of federal tax effect), percent		2.50%	2.30%
Wind PTCs, percent	[1]	(69.70%)	(105.50%)
Plant regulatory differences, percent	[2]	(4.50%)	(3.70%)
Other tax credits, percent		0.30%	0.30%
Other (net), percent		0.40%	(0.60%)
Effective income tax rate, percent		(50.00%)	(86.20%)
[1] Wind PTCs net of estimated transfer discounts. Gross wind PTCs are credited to customers (reduction to revenue) and do not materially impact net income. Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) MWh in Millions, $ in Millions		Mar. 31, 2024 USD ($) MWh	Dec. 31, 2023 MWh
Electric Commodity [Member]
Derivative [Line Items]
Mwh of electricity | MWh	[1]	10	8
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges | $		$ 0
[1] Not reflective of net positions in the underlying commodities.

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Consideration of Credit Risk Concentrations (Details) - Credit Concentration Risk $ in Millions	Mar. 31, 2024 USD ($) Counterparty
Derivative [Line Items]
Significant counterparties	10
Municipal or cooperative electric entities or other utilities
Derivative [Line Items]
Significant counterparties	7
External credit rating, investment grade
Derivative [Line Items]
Significant counterparties	3
Credit exposure | $	$ 4
Credit exposure, percentage	15%
Internal investment grade
Derivative [Line Items]
Significant counterparties	6
Credit exposure | $	$ 22
Credit exposure, percentage	85%
External Credit Rating, Non Investment Grade [Member]
Derivative [Line Items]
Significant counterparties	1
Credit exposure, percentage	1%

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Impact of Derivative Activities on Income and Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Derivative instruments designated as fair value hedges		$ 0	$ 0
Interest Rate Swap [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Derivative Liability, Notional Amount		0
Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
FTR settlement gains		8	68
Pre-Tax fair value gains (losses) recognized during the period in		(1)	(75)
Other Derivative Instruments | Electric Commodity
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
FTR settlement gains	[1]	8	68
Other Derivative Instruments | Commodity Contract [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Pre-Tax fair value gains (losses) recognized during the period in		$ (1)	$ (75)
[1] Recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate. FTR settlements are shared with customers and do not have a material impact on net income. Presented amounts reflect changes in fair value between auction and settlement dates, but exclude the original auction fair value.

Fair Value of Financial Asset_6

Fair Value of Financial Assets and Liabilities - Recurring Fair Value Measurements (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Derivatives, Fair Value
Return Cash Collateral		$ 0		$ 0
Changes in Level 3 Commodity Derivatives
Derivative instruments designated as fair value hedges		0	$ 0
Derivative Asset, Current		$ 47		$ 42
Derivative Asset, Current, Statement of Financial Position [Extensible Enumeration]		Assets, Current		Assets, Current
Derivative Liability, Noncurrent		$ 1		$ 2
External credit rating, investment grade | Credit Concentration Risk
Changes in Level 3 Commodity Derivatives
Credit exposure, percentage		15%
Commodity Contract [Member]
Changes in Level 3 Commodity Derivatives
Balance at beginning of period		$ 39	119
Purchases	[1]	3	6
Settlements	[1]	(36)	(16)
Net gains recognized as regulatory assets and liabilities	[1]	46	(86)
Balance at end of period		52	$ 23
Fair Value Measured on a Recurring Basis
Derivatives, Fair Value
Derivative asset, gross		45		39
Asset, netting	[2]	0		0
Changes in Level 3 Commodity Derivatives
Derivative Asset, Current		45		39
Derivative Asset, Noncurrent		7		0
Fair Value Measured on a Recurring Basis | Level 1
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Level 2
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Level 3
Derivatives, Fair Value
Derivative asset, gross		45		39
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		45		39
Asset, netting	[2]	0		0
Changes in Level 3 Commodity Derivatives
Derivative Asset, Current		45		39
Derivative Asset, Noncurrent		7		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		45		39
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets
Derivatives, Fair Value
Derivative asset, gross		0		0
Asset, netting		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 1
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 2
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 3
Derivatives, Fair Value
Derivative asset, gross		7		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0
Asset, netting		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		7		0
Fair Value, Measurements, Nonrecurring | PPAs
Changes in Level 3 Commodity Derivatives
Derivative Asset, Current	[3]	2		3
Derivative Liability, Noncurrent	[3]	$ 1		$ 2
[1] Relates primarily to FTR instruments administered by SPP. SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At March 31, 2024 and Dec. 31, 2023, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. SPS currently applies the normal purchase exception to qualifying PPAs. Balance relates to specific contracts that were previously recognized at fair value prior to applying the normal purchase exception, and are being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.

Fair Value of Financial Asset_7

Fair Value of Financial Assets and Liabilities - Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Amount	$ 3,312	$ 3,311
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 2,696	$ 2,818

Benefit Plans and Other Postr_3

Benefit Plans and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2024	Mar. 31, 2024	Mar. 31, 2023
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 2	$ 2
Interest cost (a)	[1]		5	6
Expected return on plan assets (a)	[1]		(8)	(8)
Amortization of net loss (gain) (a)	[1]		1	0
Net periodic benefit cost (credit)			0	0
Contributions to pension plans		$ 3
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation			1	1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)			$ 1	$ 1
Xcel Energy Inc.
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to pension plans		$ 100
[1] The components of net periodic cost other than the service cost component are included in the line item “Other expense, net” in the statements of income or capitalized on the balance sheets as a regulatory asset.

Commitments and Contingencies -

Commitments and Contingencies - SPP OATT Upgrade Costs (Details) $ in Millions	Mar. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
SPP OATT Upgrade Costs	$ 13

Commitments and Contingencies_2

Commitments and Contingencies - Environmental (Details)	Mar. 31, 2024
Other MGP, Landfill, or Disposal Sites
Public Utilities, General Disclosures [Line Items]
Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation	2

Leases (Details)

Leases (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[1]	$ 14	$ 14
Lessee, Operating Lease, Liability, to be Paid		488
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(93)
Operating Lease, Liability		395
Operating Lease, Liability, Current		(33)		$ (32)
Operating lease liabilities		362		$ 371
PPAs
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		13	13
Lessee, Operating Lease, Liability, to be Paid		439
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(81)
Operating Lease, Liability		358
Property, Plant and Equipment, Other Types
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[2]	1	$ 1
Lessee, Operating Lease, Liability, to be Paid		49
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(12)
Operating Lease, Liability		$ 37
[1] PPA capacity payments are included in electric fuel and purchased power on the statements of income. Expense for other operating leases is included in operating and maintenance expense and electric fuel and purchased power. Includes immaterial short-term lease expense for 2024 and 2023.

Commitments and Contingencies_3

Commitments and Contingencies - Variable Interest Entities (Details) - MW	Mar. 31, 2024	Dec. 31, 2023
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Purchased Power Agreements [Abstract]
Generating capacity (in MW)	1,197	1,197

Commitment and Contingencies -

Commitment and Contingencies - Smokehouse Creek Complex (Details) $ in Millions	Mar. 31, 2024 USD ($) complaint Claims
Statement of Financial Position [Abstract]
Smokehouse probably loss	$ 215
Amount of insurance coverage	500
Smokehouse Creek Insurance Receivable	$ 215
Number of complaints related to the Smokehouse Creek Complex | complaint	15
Number of claims related to the Smokehouse Creek Complex | Claims	46