Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ (9,355)	$ (9,000)
Total utility property, plant and equipment	38,708	36,806
SCE
Property, Plant and Equipment [Line Items]
Distribution	23,633	22,332
Transmission	13,127	12,549
Generation	3,468	3,376
General plant and other	4,534	4,633
Accumulated depreciation	(9,355)	(9,000)
Total utility property, plant and equipment, Gross	35,407	33,890
Construction work in progress	3,175	2,790
Nuclear fuel, at amortized cost	126	126
Total utility property, plant and equipment	$ 38,708	$ 36,806