Commitments and Contingencies (MHI Claims) (Details) - USD ($)	1 Months Ended
	Mar. 31, 2017	Apr. 30, 2016	Oct. 31, 2013	Jun. 30, 2010
Southern California Edison
Schedule Of Commitments And Contingencies [Line Items]
Damages sought				$ 112,000,000
Initial recovery rewarded		$ 124,000,000
San Onofre | Southern California Edison | Mitsubishi Heavy Industries Ltd
Schedule Of Commitments And Contingencies [Line Items]
Initial recovery rewarded	$ 52,000,000
Net recovery	$ 47,000,000
San Onofre | Southern California Edison | Mitsubishi Heavy Industries Ltd | Minimum
Schedule Of Commitments And Contingencies [Line Items]
Damages sought			$ 4,000,000,000
San Onofre | Mitsubishi Heavy Industries Ltd
Schedule Of Commitments And Contingencies [Line Items]
Asserted counterclaim			$ 41,000,000