Southwestern Public Service 10-Q 1 Aug 24 2024 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2024	Aug. 01, 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	Q2
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 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		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating revenues
Operating revenues	$ 458	$ 496	$ 886	$ 1,004
Operating expenses
Electric fuel and purchased power	103	211	263	456
Operating and maintenance expenses	83	69	155	149
Demand side management expenses	5	4	11	10
Depreciation and amortization	136	92	235	183
Taxes (other than income taxes)	29	24	50	49
Total operating expenses	356	400	714	847
Operating income	102	96	172	157
Other expense, net	4	1	5	1
Allowance for funds used during construction — equity	4	2	6	3
Interest charges and financing costs
Interest charges and other financing costs	41	37	78	71
Allowance for funds used during construction — debt	(2)	(2)	(4)	(3)
Total interest charges and financing costs	39	35	74	68
Income before income taxes	71	64	109	93
Income tax benefit	(18)	(17)	(37)	(42)
Net income	$ 89	$ 81	$ 146	$ 135

STATEMENTS OF CASH FLOWS (UNAUD

STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Operating activities
Net income	$ 146	$ 135
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	237	184
Deferred income taxes	94	(77)
Allowance for equity funds used during construction	(6)	(3)
Provision for bad debts	3	6
Changes in operating assets and liabilities:
Accounts receivable	66	3
Accrued unbilled revenues	19	12
Inventories	(27)	(23)
Prepayments and other	(4)	7
Accounts payable	20	(21)
Net regulatory assets and liabilities	36	194
Other current liabilities	(25)	(10)
Pension and other employee benefit obligations	(2)	0
Other, net	(13)	(4)
Net cash provided by operating activities	506	379
Investing activities
Utility capital/construction expenditures	(428)	(351)
Net cash used in investing activities	(428)	(351)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(75)	34
Proceeds from issuance of long-term debt, net	588	0
Borrowings under utility money pool arrangement	437	174
Repayments under utility money pool arrangement	(464)	(74)
Capital contributions from parent	272	0
Repayments of Long-Term Debt	(350)	0
Dividends paid to parent	(148)	(163)
Net cash provided by (used in) financing activities	260	(29)
Net change in cash, cash equivalents and restricted cash	338	(1)
Cash, cash equivalents and restricted cash at beginning of period	3	2
Cash, cash equivalents and restricted cash at end of period	341	1
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(68)	(65)
Cash received (paid) for income taxes, net; includes proceeds from tax credit transfers	117	(35)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	57	41
Inventory transfers to property, plant and equipment	26	17
Allowance for equity funds used during construction	6	3
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 341	$ 1

BALANCE SHEETS (UNAUDITED)

BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 341	$ 3
Accrued unbilled revenues	159	139
Inventories	70	69
Regulatory assets	51	30
Derivative instruments	148	42
Prepaid taxes	2	2
Prepayments and other	262	32
Total current assets	1,202	565
Property, plant and equipment, net	8,783	8,536
Other assets
Regulatory assets	349	349
Operating lease right-of-use assets	387	403
Other	43	28
Total other assets	779	780
Total assets	10,764	9,881
Current liabilities
Long-Term Debt and Lease Obligation, Current	0	350
Short-term debt	0	75
Borrowings under utility money pool arrangement	0	27
Regulatory liabilities	289	116
Taxes accrued	50	77
Accrued interest	35	33
Dividends payable to parent	46	59
Derivative instruments	0	2
Operating lease liabilities	33	32
Other	266	42
Total current liabilities	929	1,008
Deferred credits and other liabilities
Deferred income taxes	726	622
Regulatory liabilities	767	761
Asset retirement obligations	160	153
Pension and employee benefit obligations	9	12
Operating lease liabilities	354	371
Other	9	7
Total deferred credits and other liabilities	2,025	1,926
Capitalization
Long-term debt	3,550	2,961
Common stock — 200 shares authorized of $1.00 par value; 100 shares outstanding at June 30, 2024 and Dec. 31, 2023, respectively	$ 0	$ 0
Common Stock, Shares Authorized	200	200
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares, Outstanding	100	100
Additional paid in capital	$ 3,633	$ 3,370
Retained earnings	628	617
Accumulated other comprehensive loss	(1)	(1)
Total common stockholder's equity	4,260	3,986
Total liabilities and equity	10,764	9,881
Related Party
Current assets
Accounts receivable, net	157	222
Current liabilities
Accounts payable	191	188
Affiliated Entity
Current assets
Accounts receivable, net	12	26
Current liabilities
Accounts payable	$ 19	$ 7

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	135			135
Dividends declared to parent	(168)			(168)
Ending balance (in shares) at Jun. 30, 2023		100
Ending balance at Jun. 30, 2023	3,825	$ 0	3,319	507	(1)
Increase (Decrease) in Stockholders' Equity
Contributions of capital by parent	8		8
Beginning balance (in shares) at Mar. 31, 2023		100
Beginning balance at Mar. 31, 2023	3,838	$ 0	3,311	528	(1)
Increase (Decrease) in Stockholders' Equity
Net income	81			81
Dividends declared to parent	(102)			(102)
Ending balance (in shares) at Jun. 30, 2023		100
Ending balance at Jun. 30, 2023	3,825	$ 0	3,319	507	(1)
Increase (Decrease) in Stockholders' Equity
Contributions of capital by parent	$ 8		8
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	146			146
Dividends declared to parent	$ (135)			(135)
Ending balance (in shares) at Jun. 30, 2024	100	100
Ending balance at Jun. 30, 2024	$ 4,260	$ 0	3,633	628	(1)
Increase (Decrease) in Stockholders' Equity
Contributions of capital by parent	263		263
Beginning balance (in shares) at Mar. 31, 2024		100
Beginning balance at Mar. 31, 2024	3,954	$ 0	3,370	585	(1)
Increase (Decrease) in Stockholders' Equity
Net income	89			89
Dividends declared to parent	$ (46)			(46)
Ending balance (in shares) at Jun. 30, 2024	100	100
Ending balance at Jun. 30, 2024	$ 4,260	$ 0	3,633	$ 628	$ (1)
Increase (Decrease) in Stockholders' Equity
Contributions of capital by parent	$ 263		$ 263

Management's Opinion

Management's Opinion	6 Months Ended
	Jun. 30, 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 June 30, 2024 and Dec. 31, 2023; the results of SPS’ operations, including the components of net income and changes in stockholder’s equity for the three and six months ended June 30, 2024 and 2023; and SPS’ cash flows for the six months ended June 30, 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 June 30, 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	6 Months Ended
	Jun. 30, 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	6 Months Ended
	Jun. 30, 2024
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Pronouncements	Recently Issued Segment Reporting — In November 2023, the FASB issued ASU 2023-07 – Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures , which extends the existing requirements for annual disclosures to quarterly periods, and requires that both annual and quarterly disclosures present segment expenses using line items consistent with information regularly provided to the chief operating decision maker. The ASU is effective for annual periods beginning after Dec. 15, 2023 and quarterly periods beginning after Dec. 15, 2024, and SPS does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements. Income Taxes — In December 2023, the FASB issued ASU 2023-09 – Income Taxes (Topic 740) – Improvements to Income Tax Disclosures , with new disclosure requirements including presentation of prescribed line items in the effective tax rate reconciliation and disclosures regarding state and local tax payments. The ASU is effective for annual periods beginning after Dec. 15, 2024, and SPS does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements. Climate-Related Disclosures — In March 2024, the SEC issued Final Rule 33-11275 – The Enhancement and Standardization of Climate-Related Disclosures for Investors. This rule requires registrants to provide standardized disclosures in Form 10-K related to climate-related risks, Scope 1 and 2 greenhouse gas emissions, as well as to include in a footnote to the consolidated financial statements the financial impact of severe weather events and other natural conditions. The rule requires implementation in phases between 2025 and 2033. In April 2024, the SEC announced that it would voluntarily stay its final climate disclosure rules pending judicial review. SPS does not expect implementation of the new guidance to have a material impact on the consolidated financial statements.

Selected Balance Sheet Data

Selected Balance Sheet Data	6 Months Ended
	Jun. 30, 2024
Balance Sheet Related Disclosures [Abstract]
Selected Balance Sheet Data	3. Selected Balance Sheet Data (Millions of Dollars) June 30, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 169 $ 237 Less allowance for bad debts (12) (15) Accounts receivable, net $ 157 $ 222 (Millions of Dollars) June 30, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 59 $ 56 Fuel 11 13 Total inventories $ 70 $ 69 (Millions of Dollars) June 30, 2024 Dec. 31, 2023 Property, plant and equipment, net Electric plant $ 11,005 $ 10,752 Plant to be retired (a) 190 248 CWIP 420 226 Total property, plant and equipment 11,615 11,226 Less accumulated depreciation (2,832) (2,690) Property, plant and equipment, net $ 8,783 $ 8,536 (a) Amounts include Tolk and coal generation assets at Harrington pending facility gas conversion. Amounts are reported net of accumulated depreciation.

Borrowings and Other Financing

Borrowings and Other Financing Instruments	6 Months Ended
	Jun. 30, 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 June 30, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 100 $ 100 Amount outstanding at period end — 27 Average amount outstanding 48 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 N/A 5.34 Commercial Paper — Commercial paper outstanding: (Amounts in Millions, Except Interest Rates) Three Months Ended June 30, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 500 $ 500 Amount outstanding at period end — 75 Average amount outstanding 51 50 Maximum amount outstanding 160 119 Weighted average interest rate, computed on a daily basis 5.59 % 5.12 % Weighted average interest rate at period end N/A 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 June 30, 2024 and Dec. 31, 2023, there w e re no letters of credit outstanding under the credit facility. Amounts approximate their fair value and are subject to fees. Revolving Credit Facility — In order to issue its commercial paper, 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 June 30, 2024, SPS had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 500 $ — $ 500 (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 had no direct advances on the credit facility outstanding as of June 30, 2024 and Dec. 31, 2023. Long-Term Borrowings

Revenues

Revenues	6 Months Ended
	Jun. 30, 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 June 30 (Millions of Dollars) 2024 2023 Major revenue types Revenue from contracts with customers: Residential $ 83 $ 91 Commercial and Industrial 219 257 Other 13 14 Total retail 315 362 Wholesale 30 51 Transmission 70 72 Other 1 2 Total revenue from contracts with customers 416 487 Alternative revenue and other 42 9 Total revenues $ 458 $ 496 Six Months Ended June 30 (Millions of Dollars) 2024 2023 Major revenue types Revenue from contracts with customers: Residential $ 169 $ 192 Commercial and Industrial (a) 436 524 Other 22 26 Total retail 627 742 Wholesale 66 96 Transmission 141 146 Other 1 2 Total revenue from contracts with customers 835 986 Alternative revenue and other 51 18 Total revenues $ 886 $ 1,004 (a) For the six months ended June 30, 2024, revenues from one C&I customer represented approximately 10.2% of total revenues.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	6. Income Taxes Reconciliation between the statutory rate and ETR: Six Months Ended June 30 2024 2023 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 2.5 2.2 (Decreases) increases: Wind PTCs (a) (53.2) (65.2) Plant regulatory differences (b) (4.6) (3.5) Amortization of excess nonplant deferred taxes 0.3 0.3 Other, net 0.1 — Effective income tax rate (33.9) % (45.2) % (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	6 Months Ended
	Jun. 30, 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 June 30, 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 June 30, 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 June 30, 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 June 30, 2024, SPS had no commodity contracts designated as cash flow hedges. Gross notional amounts of FTRs: Amounts in Millions (a) June 30, 2024 Dec. 31, 2023 Megawatt hours of electricity 16 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 June 30, 2024, two of the ten most significant counterparties for these activities, comprising $6 million, or 20%, of this credit exposure, had investment grade credit ratings from S&P Global Ratings, Moody’s Investor Services or Fitch Ratings. Five of the ten most significant counterparties, comprising $22 million, or 78%, of this credit exposure, were not rated by external ratings agencies, but based on SPS’ internal analysis, had credit quality consistent with investment grade. Three 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 Gains (Losses) Recognized During the Period in: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended June 30, 2024 Other derivative instruments Electric commodity $ 41 Total $ 41 Six Months Ended June 30, 2024 Other derivative instruments Electric commodity $ 40 Total $ 40 Three Months Ended June 30, 2023 Other derivative instruments Electric commodity $ (8) Total $ (8) Six Months Ended June 30, 2023 Other derivative instruments Electric commodity $ (83) Total $ (83) Pre-Tax Losses Reclassified into Income During the Period from: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended June 30, 2024 Other derivative instruments Electric commodity $ (16) (a) Total $ (16) Six Months Ended June 30, 2024 Other derivative instruments Electric commodity $ (8) (a) Total $ (8) Three Months Ended June 30, 2023 Other derivative instruments Electric commodity $ 4 (a) Total $ 4 Six Months Ended June 30, 2023 Other derivative instruments Electric commodity $ 72 (a) Total $ 72 (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 six months ended June 30, 2024 and 2023. Derivative assets and liabilities measured at fair value on a recurring basis were as follows: June 30, 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 $ — $ — $ 146 $ 146 $ — $ 146 $ — $ — $ 39 $ 39 $ — $ 39 Total current derivative assets $ — $ — $ 146 $ 146 $ — 146 $ — $ — $ 39 $ 39 $ — 39 PPAs (b) 2 3 Current derivative instruments $ 148 $ 42 Current derivative liabilities PPAs (b) — 2 Current derivative instruments $ — $ 2 (a) SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At June 30, 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 June 30 (Millions of Dollars) 2024 2023 Balance at April 1 $ 52 $ 23 Purchases (a) 102 68 Settlements (a) (83) (32) Net transactions recorded during the period: Net gains recognized as regulatory assets and liabilities (a) 75 24 Balance at June 30 $ 146 $ 83 Six Months Ended June 30 (Millions of Dollars) 2024 2023 Balance at Jan. 1 $ 39 $ 119 Purchases (a) 105 74 Settlements (a) (119) (48) Net transactions recorded during the period: Net gains (losses) recognized as regulatory assets and liabilities (a) 121 (62) Balance at June 30 $ 146 $ 83 (a) Relates primarily to FTR instruments administered by SPP. Fair Value of Long-Term Debt As of June 30, 2024, other financial instruments for which the carrying amount did not equal fair value: June 30, 2024 Dec. 31, 2023 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 3,550 $ 2,919 $ 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 June 30, 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	6 Months Ended
	Jun. 30, 2024
Retirement Benefits [Abstract]
Benefit Plans and Other Postretirement Benefits	Components of Net Periodic Benefit Cost Three Months Ended June 30 2024 2023 2024 2023 (Millions of Dollars) Pension Benefits Postretirement Health Service cost $ 2 $ 2 $ — $ — Interest cost (a) 6 6 1 — Expected return on plan assets (a) (8) (8) (1) — Net periodic benefit (credit) cost — — — — Effects of regulation (2) 1 — — Net benefit (credit) cost recognized for financial reporting $ (2) $ 1 $ — $ — Six Months Ended June 30 2024 2023 2024 2023 (Millions of Dollars) Pension Benefits Postretirement Health Service cost $ 4 $ 3 $ — $ — Interest cost (a) 11 12 1 1 Expected return on plan assets (a) (16) (16) (1) (1) Amortization of net loss (a) 1 1 — — Net periodic benefit cost — — — — Effects of regulation (1) 2 — — Net benefit (credit) cost recognized for financial reporting $ (1) $ 2 $ — $ — (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	6 Months Ended
	Jun. 30, 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 On February 26, 2024, multiple wildfires began in the Texas Panhandle, including the Smokehouse Creek Fire and the 687 Reamer Fire, which 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. According to the Texas A&M Forest Service’s Incident Viewer and news reports, the Smokehouse Creek Fire Complex burned approximately 1,055,000 acres. SPS is aware of approximately 21 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’s 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 141 claims for losses related to the Smokehouse Creek Fire Complex through its claims process and has reached final settlements on 43 of those claims. In July 2024, SPS reached a settlement of a complaint related to one of the two fatalities believed to be associated with the Smokehouse Creek Fire Complex. 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 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 has accrued a $215 million estimated loss for the matter (before available insurance), presented in other current liabilities as of June 30, 2024. 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 remains 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. SPS has recorded an insurance receivable for $215 million, presented within prepayments and other current assets as of June 30, 2024. 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 obligations 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 three historical MGP, landfill or other disposal sites across its service territories, in addition to sites that are being addressed under current coal ash regulations (see below). SPS has recognized its best estimate of costs/liabilities for resolution of these issues; however, the final outcomes 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. Water and Waste Coal Ash Regulation — SPS is subject to the CCR Rule, which imposes requirements for handling, storage, treatment and disposal of coal ash and other solid waste. In May 2024, final amendments to the CCR Rule were published. These include legacy CCR surface impoundments at inactive facilities and previously exempt areas where CCR was placed directly on land at CCR-regulated facilities, including areas of beneficial use. As a specific requirement of the CCR Rule, utilities must complete facility evaluations and groundwater sampling around their subject landfills, surface impoundments and certain other areas where coal ash was placed on land, as well as perform corrective actions where offsite groundwater has been impacted. If certain impacts to groundwater are detected, utilities may be required to perform additional groundwater investigations and/or perform corrective actions, typically beginning with an Assessment of Corrective Measures. SPS expects to incur $4 million for investigations through 2028 to perform required reporting and assess whether corrective actions are necessary. Asset retirement obligations have been recorded for each of these activities, and amounts are expected to be recoverable through regulatory mechanisms. SPS continues to evaluate the 2024 updates to the CCR rule, the interpretations of those updates and how they will apply to specific sites. Assessment of the recent updates to the CCR Rule and corresponding site investigation activities may result in updates to estimated costs as well as identification of additional required corrective actions. 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. The regulation may become applicable in the future, depending on the outcome of the litigation. 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. In June 2024, the U.S. Supreme Court issued an order granting a stay of the final rule. SPS continues to evaluate impacts to its generation units. 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 June 30 (Millions of Dollars) 2024 2023 Operating leases PPA capacity payments $ 13 $ 14 Other operating leases (a) 1 1 Total operating lease expense (b) $ 14 $ 15 (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. Six Months Ended June 30 (Millions of Dollars) 2024 2023 Operating leases PPA capacity payments $ 26 $ 27 Other operating leases (a) 2 2 Total operating lease expense (b) $ 28 $ 29 (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 June 30, 2024: (Millions of Dollars) PPA Operating Leases Other Operating Leases Total Operating Leases Total minimum obligation $ 428 $ 48 $ 476 Interest component of obligation (77) (12) (89) Present value of minimum obligation $ 351 $ 36 387 Less current portion (33) Noncurrent operating lease liabilities $ 354 Variable Interest Entities Under certain PPAs, SPS purchases power from IPPs for which SPS is required to reimburse fuel costs, or to participate in tolling arrangements under which SPS procures the natural gas required to produce the energy that it purchases. SPS has determined that certain IPPs are VIEs. SPS is not subject to risk of loss from the operations of these entities, and no significant financial support is required other than contractual payments for energy and capacity. In addition, certain solar PPAs provide an option to purchase emission allowances or sharing provisions related to production credits generated by the solar facility under contract. These specific PPAs create a variable interest in the IPP. SPS evaluated each of these VIEs for possible consolidation, including review of qualitative factors such as the length and terms of the contract, control over O&M, control over dispatch of electricity, historical and estimated future fuel and electricity prices, and financing activities. SPS concluded that these entities are not required to be consolidated in its financial statements because it does not have the power to direct the activities that most significantly impact the entities’ economic performance. SPS had approximately 1,197 MW of capacity under long-term PPAs at both June 30, 2024 and Dec. 31, 2023 with entities that have been determined to be VIEs. These agreements have expiration dates through 2041.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net income	$ 89	$ 81	$ 146	$ 135

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 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)	6 Months Ended
	Jun. 30, 2024
Balance Sheet Related Disclosures [Abstract]
Accounts Receivable, Net	(Millions of Dollars) June 30, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 169 $ 237 Less allowance for bad debts (12) (15) Accounts receivable, net $ 157 $ 222
Inventories	(Millions of Dollars) June 30, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 59 $ 56 Fuel 11 13 Total inventories $ 70 $ 69
Property, Plant and Equipment, Net	3. Selected Balance Sheet Data (Millions of Dollars) June 30, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 169 $ 237 Less allowance for bad debts (12) (15) Accounts receivable, net $ 157 $ 222 (Millions of Dollars) June 30, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 59 $ 56 Fuel 11 13 Total inventories $ 70 $ 69 (Millions of Dollars) June 30, 2024 Dec. 31, 2023 Property, plant and equipment, net Electric plant $ 11,005 $ 10,752 Plant to be retired (a) 190 248 CWIP 420 226 Total property, plant and equipment 11,615 11,226 Less accumulated depreciation (2,832) (2,690) Property, plant and equipment, net $ 8,783 $ 8,536 (a) Amounts include Tolk and coal generation assets at Harrington pending facility gas conversion. Amounts are reported net of accumulated depreciation.

Borrowings and Other Financin_2

Borrowings and Other Financing Instruments (Tables)	6 Months Ended
	Jun. 30, 2024
Borrowings and Other Financing Instruments [Abstract]
Credit Facilities	As of June 30, 2024, SPS had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 500 $ — $ 500 (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 June 30, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 100 $ 100 Amount outstanding at period end — 27 Average amount outstanding 48 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 N/A 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 June 30, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 500 $ 500 Amount outstanding at period end — 75 Average amount outstanding 51 50 Maximum amount outstanding 160 119 Weighted average interest rate, computed on a daily basis 5.59 % 5.12 % Weighted average interest rate at period end N/A 5.56

Revenues (Tables)

Revenues (Tables)	6 Months Ended
	Jun. 30, 2024
Revenue from Contract with Customer [Abstract]
Disaggregation of 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 June 30 (Millions of Dollars) 2024 2023 Major revenue types Revenue from contracts with customers: Residential $ 83 $ 91 Commercial and Industrial 219 257 Other 13 14 Total retail 315 362 Wholesale 30 51 Transmission 70 72 Other 1 2 Total revenue from contracts with customers 416 487 Alternative revenue and other 42 9 Total revenues $ 458 $ 496 Six Months Ended June 30 (Millions of Dollars) 2024 2023 Major revenue types Revenue from contracts with customers: Residential $ 169 $ 192 Commercial and Industrial (a) 436 524 Other 22 26 Total retail 627 742 Wholesale 66 96 Transmission 141 146 Other 1 2 Total revenue from contracts with customers 835 986 Alternative revenue and other 51 18 Total revenues $ 886 $ 1,004 (a) For the six months ended June 30, 2024, revenues from one C&I customer represented approximately 10.2% of total revenues.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Reconciliation between the statutory rate and ETR: Six Months Ended June 30 2024 2023 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 2.5 2.2 (Decreases) increases: Wind PTCs (a) (53.2) (65.2) Plant regulatory differences (b) (4.6) (3.5) Amortization of excess nonplant deferred taxes 0.3 0.3 Other, net 0.1 — Effective income tax rate (33.9) % (45.2) % (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)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Gross Notional Amounts of Commodity FTRs	Amounts in Millions (a) June 30, 2024 Dec. 31, 2023 Megawatt hours of electricity 16 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	June 30, 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 $ — $ — $ 146 $ 146 $ — $ 146 $ — $ — $ 39 $ 39 $ — $ 39 Total current derivative assets $ — $ — $ 146 $ 146 $ — 146 $ — $ — $ 39 $ 39 $ — 39 PPAs (b) 2 3 Current derivative instruments $ 148 $ 42 Current derivative liabilities PPAs (b) — 2 Current derivative instruments $ — $ 2 (a) SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At June 30, 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 June 30 (Millions of Dollars) 2024 2023 Balance at April 1 $ 52 $ 23 Purchases (a) 102 68 Settlements (a) (83) (32) Net transactions recorded during the period: Net gains recognized as regulatory assets and liabilities (a) 75 24 Balance at June 30 $ 146 $ 83 Six Months Ended June 30 (Millions of Dollars) 2024 2023 Balance at Jan. 1 $ 39 $ 119 Purchases (a) 105 74 Settlements (a) (119) (48) Net transactions recorded during the period: Net gains (losses) recognized as regulatory assets and liabilities (a) 121 (62) Balance at June 30 $ 146 $ 83 (a) Relates primarily to FTR instruments administered by SPP.
Carrying Amount and Fair Value of Long-term Debt	June 30, 2024 Dec. 31, 2023 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 3,550 $ 2,919 $ 3,311 $ 2,818
Derivative Instruments, Gain (Loss)	Pre-Tax Fair Value Gains (Losses) Recognized During the Period in: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended June 30, 2024 Other derivative instruments Electric commodity $ 41 Total $ 41 Six Months Ended June 30, 2024 Other derivative instruments Electric commodity $ 40 Total $ 40 Three Months Ended June 30, 2023 Other derivative instruments Electric commodity $ (8) Total $ (8) Six Months Ended June 30, 2023 Other derivative instruments Electric commodity $ (83) Total $ (83) Pre-Tax Losses Reclassified into Income During the Period from: (Millions of Dollars) Regulatory Assets and Liabilities Three Months Ended June 30, 2024 Other derivative instruments Electric commodity $ (16) (a) Total $ (16) Six Months Ended June 30, 2024 Other derivative instruments Electric commodity $ (8) (a) Total $ (8) Three Months Ended June 30, 2023 Other derivative instruments Electric commodity $ 4 (a) Total $ 4 Six Months Ended June 30, 2023 Other derivative instruments Electric commodity $ 72 (a) Total $ 72 (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)	6 Months Ended
	Jun. 30, 2024
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost (Credit)	Components of Net Periodic Benefit Cost Three Months Ended June 30 2024 2023 2024 2023 (Millions of Dollars) Pension Benefits Postretirement Health Service cost $ 2 $ 2 $ — $ — Interest cost (a) 6 6 1 — Expected return on plan assets (a) (8) (8) (1) — Net periodic benefit (credit) cost — — — — Effects of regulation (2) 1 — — Net benefit (credit) cost recognized for financial reporting $ (2) $ 1 $ — $ — Six Months Ended June 30 2024 2023 2024 2023 (Millions of Dollars) Pension Benefits Postretirement Health Service cost $ 4 $ 3 $ — $ — Interest cost (a) 11 12 1 1 Expected return on plan assets (a) (16) (16) (1) (1) Amortization of net loss (a) 1 1 — — Net periodic benefit cost — — — — Effects of regulation (1) 2 — — Net benefit (credit) cost recognized for financial reporting $ (1) $ 2 $ — $ — (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	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Lease, Cost	Components of lease expense: Three Months Ended June 30 (Millions of Dollars) 2024 2023 Operating leases PPA capacity payments $ 13 $ 14 Other operating leases (a) 1 1 Total operating lease expense (b) $ 14 $ 15 (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. Six Months Ended June 30 (Millions of Dollars) 2024 2023 Operating leases PPA capacity payments $ 26 $ 27 Other operating leases (a) 2 2 Total operating lease expense (b) $ 28 $ 29 (a) Includes immaterial short-term lease expense for 2024 and 2023. (b)
Lessee, Operating Lease, Liability, Maturity		Commitments under operating leases as of June 30, 2024: (Millions of Dollars) PPA Operating Leases Other Operating Leases Total Operating Leases Total minimum obligation $ 428 $ 48 $ 476 Interest component of obligation (77) (12) (89) Present value of minimum obligation $ 351 $ 36 387 Less current portion (33) Noncurrent operating lease liabilities $ 354

Selected Balance Sheet Data Acc

Selected Balance Sheet Data Accounts Receivable, Net (Details) - Related Party - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Related Party Transaction [Line Items]
Accounts receivable	$ 169	$ 237
Accounts Receivable, Allowance for Credit Loss, Current	12	15
Accounts receivable, net	$ 157	$ 222

Selected Balance Sheet Data Sel

Selected Balance Sheet Data Selected Balance Sheet Data Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Inventories	$ 70	$ 69
Inventory, Net	70	69
Materials and supplies
Inventories	59	56
Fuel
Inventories	$ 11	$ 13

Selected Balance Sheet Data Bal

Selected Balance Sheet Data Balance Sheet Related Disclosures, Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions		Jun. 30, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 11,615	$ 11,226
Accumulated depreciation		(2,832)	(2,690)
Property, plant and equipment, net		8,783	8,536
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		11,005	10,752
Plant to be Retired
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	[1]	190	248
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 420	$ 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
	Jun. 30, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Short-term debt	$ 0	$ 75
Money Pool
Short-term Debt [Line Items]
Borrowing limit	100	100
Short-term debt	0	27
Average amount outstanding	48	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		5.34%
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	$ 500	$ 500
Short-term debt	0	75
Average amount outstanding	51	50
Maximum amount outstanding	$ 160	$ 119
Weighted average interest rate, computed on a daily basis	5.59%	5.12%
Weighted average interest rate at period end		5.56%

Borrowings and Other Financin_4

Borrowings and Other Financing Instruments - Commercial Paper (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Short-term debt	$ 0	$ 75
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	500	500
Short-term debt	0	75
Average amount outstanding	51	50
Maximum amount outstanding	$ 160	$ 119
Weighted average interest rate, computed on a daily basis	5.59%	5.12%
Weighted average interest rate at period end		5.56%

Borrowings and Other Financin_5

Borrowings and Other Financing Instruments - Letters of Credit (Details) - USD ($)	6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Short-term debt	$ 0	$ 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	$ 0

Borrowings and Other Financin_6

Borrowings and Other Financing Instruments - Credit Facility (Details)		6 Months Ended
		Jun. 30, 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]	0
Available		500,000,000
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 - Long-Term Borrowings (Details) - Series Due June 1, 2054 - Bonds [Member] $ in Millions	Jun. 30, 2024 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6%
Debt Instrument, Face Amount	$ 600

Borrowings and Other Financin_8

Borrowings and Other Financing Instruments - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
Short-term debt	$ 0	$ 75

Revenues (Details)

Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024		Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 416	$ 487	$ 835		$ 986
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	458	496	886		1,004
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	315	362	627		742
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	83	91	169		192
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	219	257	436	[1]	524
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13	14	22		26
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30	51	66		96
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	70	72	141		146
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	42	9	51		18
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1	$ 2	$ 1		$ 2
[1] For the six months ended June 30, 2024, revenues from one C&I customer represented approximately 10.2% of total revenues.

Income Taxes (Details)

Income Taxes (Details)		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Federal statutory rate, percent		21%	21%
State tax (net of federal tax effect), percent		2.50%	2.20%
Wind PTCs, percent	[1]	(53.20%)	(65.20%)
Plant regulatory differences, percent	[2]	(4.60%)	(3.50%)
Other tax credits, percent		0.30%	0.30%
Other (net), percent		0.10%	0%
Effective income tax rate, percent		(33.90%)	(45.20%)
[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. 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		3 Months Ended		6 Months Ended
		Jun. 30, 2024 USD ($) MWh	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) MWh	Jun. 30, 2023 USD ($)	Dec. 31, 2023 MWh
Other Derivative Instruments
Derivative [Line Items]
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)		$ (16)	$ 4	$ (8)	$ 72
Electric Commodity [Member]
Derivative [Line Items]
Mwh of electricity | MWh	[1]	16		16		8
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges		$ 0		$ 0
Electric Commodity | Other Derivative Instruments
Derivative [Line Items]
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)	[2]	$ (16)	$ 4	$ (8)	$ 72
[1] Not reflective of net positions in the underlying commodities. 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_4

Fair Value of Financial Assets and Liabilities - Consideration of Credit Risk Concentrations (Details) - Credit Concentration Risk $ in Millions	Jun. 30, 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	2
Credit exposure | $	$ 6
Credit exposure, percentage	20%
Internal investment grade
Derivative [Line Items]
Significant counterparties	5
Credit exposure | $	$ 22
Credit exposure, percentage	78%
External Credit Rating, Non Investment Grade [Member]
Derivative [Line Items]
Significant counterparties	3
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		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 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	$ 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		0
Other Derivative Instruments
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
FTR settlement gains		(16)	4	(8)	72
Pre-Tax fair value gains (losses) recognized during the period in		41	(8)	40	(83)
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]	(16)	4	(8)	72
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		$ 41	$ (8)	$ 40	$ (83)
[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		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Derivatives, Fair Value
Return Cash Collateral		$ 0		$ 0		$ 0
Changes in Level 3 Commodity Derivatives
Derivative instruments designated as fair value hedges		0	$ 0	0	$ 0
Derivative Asset, Current		148		148		42
Derivative Liability, Noncurrent		0		0		2
Commodity Contract [Member]
Changes in Level 3 Commodity Derivatives
Balance at beginning of period		52	23	39	119
Purchases	[1]	102	68	105	74
Settlements	[1]	(83)	(32)	(119)	(48)
Net gains recognized as regulatory assets and liabilities	[1]	75	24	121	(62)
Balance at end of period		146	$ 83	146	$ 83
Fair Value Measured on a Recurring Basis
Derivatives, Fair Value
Derivative asset, gross		146		146		39
Asset, netting	[2]	0		0		0
Changes in Level 3 Commodity Derivatives
Derivative Asset, Current		146		146		39
Fair Value Measured on a Recurring Basis | Level 1
Derivatives, Fair Value
Derivative asset, gross		0		0		0
Fair Value Measured on a Recurring Basis | Level 2
Derivatives, Fair Value
Derivative asset, gross		0		0		0
Fair Value Measured on a Recurring Basis | Level 3
Derivatives, Fair Value
Derivative asset, gross		146		146		39
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		146		146		39
Asset, netting	[2]	0		0		0
Changes in Level 3 Commodity Derivatives
Derivative Asset, Current		146		146		39
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value
Derivative asset, gross		146		146		39
Fair Value, Measurements, Nonrecurring | PPAs
Changes in Level 3 Commodity Derivatives
Derivative Asset, Current	[3]	2		2		3
Derivative Liability, Noncurrent	[3]	$ 0		$ 0		$ 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 June 30, 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	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Amount	$ 3,550	$ 3,311
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 2,919	$ 2,818

Benefit Plans and Other Postr_3

Benefit Plans and Other Postretirement Benefits (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		6 Months Ended
		Jan. 31, 2024	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pension Plan [Member]
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			$ 2	$ 2	$ 4	$ 3
Interest cost (a)	[1]		6	6	11	12
Expected return on plan assets (a)	[1]		(8)	(8)	(16)	(16)
Amortization of net loss (gain) (a)	[1]				1	1
Net periodic benefit cost (credit)			0	0	0	0
Contributions to pension plans		$ 3
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation			(2)	1	(1)	2
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)			(2)	1	(1)	2
Pension Plan [Member] | Xcel Energy Inc.
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to pension plans		$ 100
Other Postretirement Benefits Plan [Member]
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			0	0	0	0
Interest cost (a)	[1]		1	0	1	1
Expected return on plan assets (a)	[1]		(1)	0	(1)	(1)
Amortization of net loss (gain) (a)	[1]				0	0
Net periodic benefit cost (credit)			0	0	0	0
Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation			0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)			$ 0	$ 0	$ 0	$ 0
[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	Jun. 30, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
SPP OATT Upgrade Costs	$ 13

Commitments and Contingencies_2

Commitments and Contingencies - Environmental (Details) $ in Millions	Jun. 30, 2024 USD ($)
Public Utilities, General Disclosures [Line Items]
Legacy CCR Investigation and Remediation Costs	$ 4
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	3

Leases (Details)

Leases (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2024		Jun. 30, 2023		Jun. 30, 2024		Jun. 30, 2023	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		$ 14	[1]	$ 15	[1]	$ 28	[1]	$ 29
Lessee, Operating Lease, Liability, to be Paid		476				476
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(89)				(89)
Operating Lease, Liability		387				387
Operating Lease, Liability, Current		(33)				(33)			$ (32)
Operating lease liabilities		354				354			$ 371
PPAs
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		13		14		26		27
Lessee, Operating Lease, Liability, to be Paid		428				428
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(77)				(77)
Operating Lease, Liability		351				351
Property, Plant and Equipment, Other Types
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[2]	1		$ 1		2		$ 2
Lessee, Operating Lease, Liability, to be Paid		48				48
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(12)				(12)
Operating Lease, Liability		$ 36				$ 36
[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	Jun. 30, 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	Jun. 30, 2024 USD ($) complaint Claims Period
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	21
Number of claims related to the Smokehouse Creek Complex | Claims	141
Number of claims settled related to the Smokehouse Creek Complex | Period	43