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.