Summary of Significant Accounting Policies (SCE Dividend) (Details) - SCE - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Feb. 28, 2019	Jul. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Minimum percentage of weighted-average common equity component authorization, set by CPUC (as a percent)			48.00%
Weighted-average common equity component authorization, set by CPUC remaining over number of months (in months)			37 months
After-tax charge excused from capital structure		$ 448		$ 448
Weighted-average common equity component of total capitalization percent			49.70%
Capacity to pay additional dividends			$ 459
Restriction on net assets			$ 13,300
Waiver threshold percent			47.00%
Subsequent event
Significant Accounting Policies [Line Items]
Weighted-average common equity component of total capitalization percent	47.00%
Dividends	$ 200