Income Taxes (Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Income from continuing operations before income taxes	$ 949	$ 1,590	$ 1,568
Provision for income tax at federal statutory rate of 35%	$ 332	$ 556	$ 549
Federal statutory rate	35.00%	35.00%	35.00%
Increase in income tax from:
Regulatory asset write-off	$ 0	$ 0	$ 382
State tax, net of federal benefit	2	29	5
Property-related	(439)	(362)	(341)
Change related to uncertain tax positions	(18)	(4)	(67)
Revised San Onofre Settlement Agreement	25	0	0
Share-based compensation	(55)	(28)	0
Effective Income Tax Rate Reconciliation,Tax Cuts and Jobs Act of 2017, Amount	466	0	0
Other	(32)	(14)	(42)
Total continuing operations	$ 281	$ 177	$ 486
Effective tax rate	29.60%	11.10%	31.00%
State
Increase in income tax from:
Share-based compensation	$ (11)	$ (4)
SCE
Income Tax Disclosure [Line Items]
Income from continuing operations before income taxes	1,106	1,755	$ 1,618
Provision for income tax at federal statutory rate of 35%	387	614	566
Increase in income tax from:
Regulatory asset write-off	0	0	382
State tax, net of federal benefit	8	43	34
Property-related	(439)	(362)	(341)
Change related to uncertain tax positions	(13)	(8)	(94)
Revised San Onofre Settlement Agreement	25	0	0
Share-based compensation	(11)	(13)	0
Effective Income Tax Rate Reconciliation,Tax Cuts and Jobs Act of 2017, Amount	33	0	0
Other	(20)	(18)	(40)
Total continuing operations	$ (30)	$ 256	$ 507
Effective tax rate	(2.70%)	14.60%	31.30%
SCE | State
Increase in income tax from:
Share-based compensation	$ (2)	$ (1)
SCE | Tax accounting method changes | IRS Examination
Increase in income tax from:
Federal tax liability	80
Tax benefits related to tax accounting method changes, pre-tax	$ 135