Asset Retirement Obligations - Change in Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 1,340	$ 1,341
Change in estimated costs	2	81
Acquisitions	29	0
Additions	32	15
Retirements	(122)	(144)
Accretion	47	47
Ending Balance	1,328	1,340
Other current liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	130
Ending Balance	76	130
Other long-term liabilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	1,210
Ending Balance	1,252	1,210
Fossil-fueled generating facilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	466
Ending Balance	396	466
MEC
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	787	818
Change in estimated costs	(27)	35
Additions	2	6
Retirements	(85)	(103)
Accretion	30	31
Ending Balance	707	787
MEC | Fossil-fueled generating facilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	161
Ending Balance	$ 76	$ 161