Capital Accounts, Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	$ 307	$ 365
Other comprehensive income (loss) for period, before reclassifications	113	57
Reclassification of losses (gains) to net income during period	(184)	(115)
Total other comprehensive income (loss) for period	(71)	(58)	$ 79
Accumulated Other Comprehensive Income (Loss), Ending balance	236	307	365
Interest expense	1,352	1,269	1,244
Revenue	(56,219)	(49,715)	(58,186)
Operating costs and expenses	49,045	43,017	51,502
Total	(5,970)	(5,657)	(5,615)
Cash Flow Hedges [Member] | Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	154	171
Other comprehensive income (loss) for period, before reclassifications	115	93
Reclassification of losses (gains) to net income during period	(178)	(110)
Total other comprehensive income (loss) for period	(63)	(17)
Accumulated Other Comprehensive Income (Loss), Ending balance	91	154	171
Cash Flow Hedges [Member] | Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	151	192
Other comprehensive income (loss) for period, before reclassifications	(2)	(36)
Reclassification of losses (gains) to net income during period	(6)	(5)
Total other comprehensive income (loss) for period	(8)	(41)
Accumulated Other Comprehensive Income (Loss), Ending balance	143	151	192
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	2	2
Other comprehensive income (loss) for period, before reclassifications	0	0
Reclassification of losses (gains) to net income during period	0	0
Total other comprehensive income (loss) for period	0	0
Accumulated Other Comprehensive Income (Loss), Ending balance	2	2	$ 2
Reclassification of Losses (Gains) out of Accumulated Other Comprehensive Income (Loss) [Member] | Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total	(184)	(115)
Reclassification of Losses (Gains) out of Accumulated Other Comprehensive Income (Loss) [Member] | Cash Flow Hedges [Member] | Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Revenue	(249)	(106)
Operating costs and expenses	71	(4)
Reclassification of Losses (Gains) out of Accumulated Other Comprehensive Income (Loss) [Member] | Cash Flow Hedges [Member] | Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Interest expense	$ (6)	$ (5)