v3.26.1
Fair Value of Financial Assets and Liabilities - Fair Value Reconciliation of Level 3 Assets and Liabilities Measured on a Recurring Basis (Details) - Level 3 - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning Balance $ 668 $ 502
Contracts acquired at acquisition date 1,290  
Total realized / unrealized gains (losses)    
Included in net income (loss) 850 (130)
Included in Payables related to Regulatory Agreement Units 5  
Change in collateral (102) 67
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]    
Purchases 20 15
Sales (5) (3)
Settlements   (2)
Transfers into Level 3 14 0
Transfers out of Level 3 159 36
Amortization of acquired contracts (191)  
Ending Balance 2,708 485
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities 570 (95)
NDT Fund Investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning Balance 527 502
Contracts acquired at acquisition date 0  
Total realized / unrealized gains (losses)    
Included in net income (loss) 2 1
Included in Payables related to Regulatory Agreement Units 5  
Change in collateral 0 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]    
Purchases 0 0
Sales 0 0
Settlements   (2)
Transfers into Level 3 0 1
Transfers out of Level 3 0 0
Amortization of acquired contracts 0  
Ending Balance 534 502
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities 2 1
Derivatives    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning Balance 140 (1)
Contracts acquired at acquisition date 1,290  
Total realized / unrealized gains (losses)    
Included in net income (loss) 848 (131)
Included in Payables related to Regulatory Agreement Units 0  
Change in collateral (102) 67
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]    
Purchases 20 15
Sales (5) (3)
Settlements   0
Transfers into Level 3 14 (1)
Transfers out of Level 3 159 36
Amortization of acquired contracts (191)  
Ending Balance 2,173 (18)
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities 568 (96)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]    
Realized gains (losses) 89 (35)
Rabbi trust investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning Balance 1 1
Contracts acquired at acquisition date 0  
Total realized / unrealized gains (losses)    
Included in net income (loss) 0 0
Included in Payables related to Regulatory Agreement Units 0  
Change in collateral 0 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]    
Purchases 0 0
Sales 0 0
Settlements   0
Transfers into Level 3 0 0
Transfers out of Level 3 0 0
Amortization of acquired contracts 0  
Ending Balance 1 1
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities $ 0 $ 0