Commitments and Contingencies (Power Purchase Agreements Narrative) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecorded Unconditional Purchase Obligation [Line Items]
Costs incurred for power purchase agreements	$ 3,600	$ 3,300	$ 3,200
Signed contracts, not meeting critical contract provisions
Unrecorded Unconditional Purchase Obligation [Line Items]
2018	29
2019	109
2020	231
2021	312
2022	301
Thereafter	3,800
Operating Leases Purchase Power Contracts
Unrecorded Unconditional Purchase Obligation [Line Items]
Net operating leases expense	2,300	1,900	1,700
Contingent operating lease expense	1,800	1,400	1,100
Contingent capital lease expense	$ 99	$ 109	$ 1