Summary of Significant Accounting Policies (Prepaid Insurance) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Redeemable Noncontrolling Interest [Line Items]
Wildfire Insurance Fund contributions current			$ 323	$ 0
Wildfire Insurance Fund contributions			2,457	0	$ 0
Insurance fund liability included in other long-term liabilities			$ 785
Amortization period			10 years
SCE
Redeemable Noncontrolling Interest [Line Items]
Wildfire Insurance Fund contributions long term			$ 2,800
Wildfire Insurance Fund contributions current			323	0
Wildfire Insurance Fund contributions	$ 2,400	$ 2,400	$ 2,457	$ 0	$ 0
Measurement Input
Redeemable Noncontrolling Interest [Line Items]
Historical term used in estimate			5 years