v3.26.3
Fair Value of Financial Assets and Liabilities (Tables)
 9 Months Ended
Sep. 30, 2026
Fair Value Disclosures [Abstract]  
Gross Notional Amounts of Commodity FTRs
Amounts in Millions (a)
Sept. 30, 2026Dec. 31, 2025
MWh of electricity10 7 
(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
Sept. 30, 2026Dec. 31, 2025
Fair ValueFair Value Total
Netting (a)
TotalFair ValueFair Value Total
Netting (a)
Total
(Millions of Dollars)Level 1Level 2Level 3Level 1Level 2Level 3
Current derivative assets
Other derivative instruments:
Electric commodity$— $— $64 $64 $— $64 $— $— $79 $79 $— $79 
Total current derivative assets$— $— $64 $64 $— $64 $— $— $79 $79 $— $79 
(a)SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At Sept. 30, 2026 and Dec. 31, 2025, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. Counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.
Changes in Level 3 Commodity Derivatives
Three Months Ended Sept. 30
(Millions of Dollars)20262025
Balance at July 1$87 $184 
Settlements (a)
(9)(39)
Net transactions recorded during the period:
Net losses recognized as regulatory assets and liabilities (a)
(14)(5)
Balance at Sept. 30$64 $140 
Nine Months Ended Sept. 30
(Millions of Dollars)20262025
Balance at Jan. 1$79 $67 
Purchases (a)
151 199 
Settlements (a)
(69)(161)
Net transactions recorded during the period:
Net (losses) gains recognized as regulatory assets and liabilities (a)
(97)35 
Balance at Sept. 30$64 $140 
(a)Relates primarily to FTR instruments administered by SPP.
Carrying Amount and Fair Value of Long-term Debt
Sept. 30, 2026Dec. 31, 2025
(Millions of Dollars)Carrying AmountFair ValueCarrying AmountFair Value
Long-term debt, including current portion$5,077 $4,252 $4,046 $3,529 
Long-term debt - related parties158 107 — — 
Derivative Instruments, Gain (Loss)
Pre-Tax Fair Value (Losses) Gains Recognized During the Period in:
(Millions of Dollars)Regulatory Assets and Liabilities
Three Months Ended Sept. 30, 2026
Other derivative instruments:
Electric commodity$(11)
Total$(11)
Three Months Ended Sept. 30, 2025
Other derivative instruments:
Electric commodity$2 
Total$2 
Nine Months Ended Sept. 30, 2026
Other derivative instruments:
Electric commodity$(82)
Total$(82)
Nine Months Ended Sept. 30, 2025
Other derivative instruments:
Electric commodity$21 
Total$21 
Pre-Tax Losses (Gains) Reclassified into Income During the Period from:
(Millions of Dollars)Regulatory Assets and Liabilities
Three Months Ended Sept. 30, 2026
Other derivative instruments:
Electric commodity$18 
(a)
Total$18 
Three Months Ended Sept. 30, 2025
Other derivative instruments:
Electric commodity$2 
(a)
Total$2 
Nine Months Ended Sept. 30, 2026
Electric commodity$39 
(a)
Total$39 
Nine Months Ended Sept. 30, 2025
Other derivative instruments:
Electric commodity$(27)
(a)
Total$(27)
(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.