Compensation and Benefit Plans (Textual) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended						1 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 Restricted Stock Units (RSUs)	Dec. 31, 2012 Employee Stock Option	Dec. 31, 2011 Employee Stock Option	Dec. 31, 2010 Employee Stock Option	Dec. 31, 2012 Performance Shares	Aug. 31, 2012 Employee Severance Southern California Edison	Aug. 31, 2012 San Onofre (nuclear) Employee Severance Southern California Edison
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized by new plan or amendments	49.5
Number of shares available for grant	26
Number of years for accrual of dividend equivalents from grant of option	5 years
Period of historical volatility used to compute expected volatility			83 months	84 months	87 months	36 months
Performance shares market condition based on performance measuring period						3 years
Award expiration period			10 years
Award vesting period		3 years 2 days	4 years
Cash severance costs							$ 76	$ 36