Income Taxes (Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosures [Line Items]
Income from continuing operations before income taxes	$ 211	$ 352
Provision for income tax at federal statutory rate of 21% and 35%, respectively 1	44	124
Increase in income tax from:
State tax, net of federal benefit	(5)	10
Property-related	(69)	(113)
Change related to uncertain tax positions	0	(12)
Shared-based compensation	0	(43)
Other	(1)	(6)
Total income tax (benefit) expense from continuing operations	$ (31)	$ (40)
Effective tax rate	(14.70%)	(11.40%)
State
Increase in income tax from:
Shared-based compensation		$ 6
Southern California Edison
Income Tax Disclosures [Line Items]
Income from continuing operations before income taxes	$ 310	392
Provision for income tax at federal statutory rate of 21% and 35%, respectively 1	65	137
Increase in income tax from:
State tax, net of federal benefit	1	13
Property-related	(69)	(113)
Change related to uncertain tax positions	(1)	(11)
Shared-based compensation	0	(8)
Other	(2)	(6)
Total income tax (benefit) expense from continuing operations	$ (6)	$ 12
Effective tax rate	(1.90%)	3.10%
Southern California Edison | State
Increase in income tax from:
Shared-based compensation		$ 1