Derivative Financial Instruments - Summary of Economic Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 568	$ 268	$ (222)
Not Designated as Hedging Instrument, Economic Hedge [Member] | Commodity Contract [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	571	280	(204)
Not Designated as Hedging Instrument, Economic Hedge [Member] | Commodity Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(635)	112	0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Commodity Contract [Member] | Purchased Power And Fuel [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	$ 1,206	$ 168	$ (204)