Asset Retirement Obligations - NPC - Change in Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 1,428	$ 1,328
Change in estimated costs	63	54
Additions	39	56
Retirements	(38)	(64)
Accretion	58	54
Ending Balance	1,550	1,428
Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	34
Ending Balance	63	34
Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	1,394
Ending Balance	1,487	1,394
NPC
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	62	59
Change in estimated costs	(3)	6
Additions	3	3
Retirements	(8)	(9)
Accretion	3	3
Ending Balance	57	62
NPC | Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	9
Ending Balance	5	9
NPC | Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	53
Ending Balance	$ 52	$ 53