Summary of Significant Accounting Policies Revision to Consolidated Statement of Cash Flow (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allowance for equity during construction		$ 96
Total cash provided by operating activities	964	565
Purchases of nuclear decommissioning trust investments	(2,889)	(1,603)
Total cash used by investing activities	(1,294)	(1,042)
As Reported
Allowance for equity during construction		29
Total cash provided by operating activities		498
Purchases of nuclear decommissioning trust investments		(1,536)
Total cash used by investing activities		(975)
Adjustment
Allowance for equity during construction		67
Total cash provided by operating activities		67
Purchases of nuclear decommissioning trust investments		(67)
Total cash used by investing activities		(67)
Southern California Edison
Allowance for equity during construction		96
Total cash provided by operating activities	966	588
Purchases of nuclear decommissioning trust investments	(2,889)	(1,603)
Total cash used by investing activities	(1,288)	(1,041)
Southern California Edison | As Reported
Allowance for equity during construction		29
Total cash provided by operating activities		521
Purchases of nuclear decommissioning trust investments		(1,536)
Total cash used by investing activities		(974)
Southern California Edison | Adjustment
Allowance for equity during construction		67
Total cash provided by operating activities		67
Purchases of nuclear decommissioning trust investments		(67)
Total cash used by investing activities		$ (67)