Accumulated Other Comprehensive Income (Loss), Net of Tax - Schedule of Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 16,370	$ 15,718	$ 16,114	$ 15,477	$ 15,477
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	3	1	5	3
Other Comprehensive Income (Loss), net of tax	13	(4)	10	6
Ending Balance	16,671	15,824	16,671	15,824	16,114
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	16	21	36	3	3
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	8	2	(12)	22	42
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	(1)	(3)	(1)	(5)	(9)
Other Comprehensive Income (Loss), net of tax	7	(1)	(13)	17
Ending Balance	23	20	23	20	36
Pension and OPEB Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(75)	(100)	(76)	(102)	(102)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	2	2	3	4
Other Comprehensive Income (Loss), net of tax	2	2	3	4
Ending Balance	(73)	(98)	(73)	(98)	(76)
Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(77)	(90)	(93)	(80)	(80)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	2	(7)	17	(19)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	2	2	3	4
Other Comprehensive Income (Loss), net of tax	4	(5)	20	(15)
Ending Balance	(73)	(95)	(73)	(95)	(93)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(136)	(169)	(133)	(179)	(179)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	10	(5)	5	3
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	3	1	5	3
Other Comprehensive Income (Loss), net of tax	13	(4)	10	6
Ending Balance	$ (123)	$ (173)	$ (123)	$ (173)	$ (133)