Supplemental Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash payments for interest and taxes:
Interest, net of amounts capitalized	$ 548	$ 504	$ 512
Tax payments, net of refunds	1	18	1
Details of debt exchange:
Pollution-control bonds redeemed (2.875%)	0	0	(203)
Pollution-control bonds issued (1.875%)	$ 0	$ 0	$ 203
2.875% Pollution-Control Bonds
Details of debt exchange:
Interest rate on converted debt	2.875%	2.875%	2.875%
1.875% Pollution-Control Bonds Due in 2029
Details of debt exchange:
Interest rate on converted debt	1.875%	1.875%	1.875%
Common Stock
Non-cash financing and investing activities:
Dividends declared but not paid	$ 197	$ 177	$ 156
Preference stock
Non-cash financing and investing activities:
Dividends declared but not paid	12	12	14
SCE
Cash payments for interest and taxes:
Interest, net of amounts capitalized	509	475	478
Tax payments, net of refunds	2	78	144
Details of debt exchange:
Pollution-control bonds redeemed (2.875%)	0	0	(203)
Pollution-control bonds issued (1.875%)	0	0	203
Accrued capital expenditures	$ 652	$ 540	543
Reduction in lease obligation			$ 147
SCE | 2.875% Pollution-Control Bonds
Details of debt exchange:
Interest rate on converted debt	2.875%	2.875%	2.875%
SCE | 1.875% Pollution-Control Bonds Due in 2029
Details of debt exchange:
Interest rate on converted debt	1.875%	1.875%	1.875%
SCE | Common Stock
Non-cash financing and investing activities:
Dividends declared but not paid	$ 212	$ 0	$ 0
SCE | Preference stock
Non-cash financing and investing activities:
Dividends declared but not paid	$ 12	$ 12	$ 14