Income Taxes (Textual) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Accumulated deferred income net income tax liabilities		$ 4,500
Re-measurement of federal net operating loss carryforwards		466
Unrecognized tax benefits that would impact the effective tax rate		308	$ 197	$ 347
Tax Years 2007 To 2012
Income Tax Disclosure [Line Items]
Expected refund		7
Tax Years 1994 to 2006
Income Tax Disclosure [Line Items]
Expected refund			103
California Franchise Tax Board | Tax Years 1994 to 2006
Income Tax Disclosure [Line Items]
Expected refund			65
Capistrano Wind | Affiliated Entity | Tax Allocation Agreement
Income Tax Disclosure [Line Items]
Due to affiliate under tax allocation agreements		199	212
SCE
Income Tax Disclosure [Line Items]
Accumulated deferred income net income tax liabilities		5,000
Changes to earnings charge		33
Unrecognized tax benefits that would impact the effective tax rate		$ 167	95	$ 243
SCE | Tax Years 1994 to 2006
Income Tax Disclosure [Line Items]
Expected refund			70
EME | Tax Years 1994 to 2006
Income Tax Disclosure [Line Items]
Expected refund			$ 34
Forecast | SCE
Income Tax Disclosure [Line Items]
Changes to earnings charge	$ (70)