Other Financial Statements Items - Schedule of Other Income and (Expense) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gain on sale of assets		$ 148	$ 10	$ 0
Allowance for funds used during construction		46	30	36
Carrying costs on regulatory assets		21	21	11
Non-service component of net periodic benefit cost		(79)	(128)	(120)
Other		(17)	1	11
Total Other Income (Expense)		119	(66)	$ (62)
Poseidon Project
Schedule of Investments [Line Items]
Gain (loss) on sale	$ 134	$ 134
Ownership percentage sold	50.00%	50.00%
Coyote Ridge Wind LLC
Schedule of Investments [Line Items]
Gain (loss) on sale		$ 4	$ 10