Asset Retirement Obligations - PAC - Change in Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 1,328	$ 1,340
Change in estimated costs	54	2
Additions	56	32
Retirements	(64)	(122)
Accretion	54	47
Ending Balance	1,428	1,328
Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	76
Ending Balance	34	76
Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	1,252
Ending Balance	1,394	1,252
PAC
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	331	304
Change in estimated costs	(4)	20
Additions	27	3
Retirements	(9)	(6)
Accretion	11	10
Ending Balance	356	331
PAC | Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	11
Ending Balance	9	11
PAC | Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	320
Ending Balance	$ 347	$ 320