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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, 2025	Mar. 31, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 502	$ 1,299
Total realized / unrealized gains (losses)
Included in net income (loss)	(130)	(306)
Included in Payable related to Regulatory Agreement Units		3
Change in collateral	67	33
Purchases, sales, issuances and settlements
Purchases	15	37
Sales	(3)	(44)
Settlements	(2)	(7)
Transfers into Level 3	0	9
Transfers out of Level 3	36	(45)
Ending Balance	485	979
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities	(95)	29
NDT Fund Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	502	429
Total realized / unrealized gains (losses)
Included in net income (loss)	1	0
Included in Payable related to Regulatory Agreement Units		3
Change in collateral	0	0
Purchases, sales, issuances and settlements
Purchases	0	33
Sales	0	0
Settlements	(2)	(5)
Transfers into Level 3	1	0
Transfers out of Level 3	0	0
Ending Balance	502	460
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities	1	0
Mark-to-Market Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(1)	869
Total realized / unrealized gains (losses)
Included in net income (loss)	(131)	(306)
Included in Payable related to Regulatory Agreement Units		0
Change in collateral	67	33
Purchases, sales, issuances and settlements
Purchases	15	4
Sales	(3)	(44)
Settlements	0	(2)
Transfers into Level 3	(1)	9
Transfers out of Level 3	36	(45)
Ending Balance	(18)	518
The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities	(96)	29
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Realized gains (losses)	(35)	(337)
Rabbi trust investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1	1
Total realized / unrealized gains (losses)
Included in net income (loss)	0	0
Included in Payable related to Regulatory Agreement Units		0
Change in collateral	0	0
Purchases, sales, issuances and settlements
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	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

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