Capital Accounts, Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance			$ 365	$ 286
Other comprehensive income (loss) for period, before reclassifications			(48)	(60)
Reclassification of losses (gains) to net income during period			(49)	(49)
Total other comprehensive income (loss) for period	$ 27	$ (63)	(97)	(109)
Accumulated Other Comprehensive Income (Loss), Ending balance	268	177	268	177
Interest expense	302	309	616	628
Revenue	(10,651)	(16,060)	(23,095)	(29,068)
Operating costs and expenses	9,137	14,341	19,894	25,738
Total	(1,283)	(1,440)	(2,705)	(2,771)
Cash Flow Hedges [Member] | Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance			192	147
Other comprehensive income (loss) for period, before reclassifications			(5)	0
Reclassification of losses (gains) to net income during period			(1)	14
Total other comprehensive income (loss) for period			(6)	14
Accumulated Other Comprehensive Income (Loss), Ending balance	186	161	186	161
Cash Flow Hedges [Member] | Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Beginning Balance			171	137
Other comprehensive income (loss) for period, before reclassifications			(43)	(60)
Reclassification of losses (gains) to net income during period			(48)	(63)
Total other comprehensive income (loss) for period			(91)	(123)
Accumulated Other Comprehensive Income (Loss), Ending balance	80	14	80	14
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	2
Reclassification of Losses (Gains) out of Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total	(19)	(102)	(49)	(49)
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	(3)	6	(1)	14
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	(27)	(86)	(51)	(47)
Operating costs and expenses	$ 11	$ (22)	$ 3	$ (16)