Asset Retirement Obligations - MEC - 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
Additions	32	15
Asset Retirement Obligation, Liabilities Settled	(122)	(144)
Accretion	47	47
Ending Balance	1,328	1,340
Total ARO liability	1,328	1,340
MEC
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	787	818
Change in estimated costs	(27)	35
Additions	2	6
Asset Retirement Obligation, Liabilities Settled	(85)	(103)
Accretion	30	31
Ending Balance	707	787
Current liabilities	24	73
Other long-term liabilities	683	714
Total ARO liability	707	787
Fossil-fueled generating facilities
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	466
Ending Balance	396	466
Total ARO liability	396	466
Fossil-fueled generating facilities | MEC
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	161
Ending Balance	76	161
Total ARO liability	$ 76	$ 161