Regulatory Matters - MEC - Regulatory Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets	$ 3,743	$ 3,419
Regulatory assets not earning a return on investment	$ 2,300	1,800
Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory asset, amortization period	15 years
Employee benefit plans
Regulatory Assets [Line Items]
Regulatory asset, amortization period	14 years
MEC
Regulatory Assets [Line Items]
Regulatory assets	$ 550	473
Regulatory assets not earning a return on investment	$ 548	470
MEC | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory asset, amortization period	9 years
Regulatory assets	$ 469	393
MEC | Employee benefit plans
Regulatory Assets [Line Items]
Regulatory asset, amortization period	15 years
Regulatory assets	$ 47	42
MEC | Other
Regulatory Assets [Line Items]
Regulatory assets	$ 34	$ 38