Derivative Instruments (Balance Sheet Disclosures) (Details) - Southern California Edison Company - Commodity derivative contracts - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Other current liabilities
Net Liability
Collateral received	$ 1	$ 2
Electric Utility
Derivative Assets
Gross amounts recognized	61	75
Gross amounts offset in the consolidated balance sheets	(2)	(1)
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	59	74
Derivative Liabilities
Gross amounts recognized	1,060	1,158
Gross amounts offset in the consolidated balance sheets	(2)	(1)
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	1,058	1,157
Net Liability
Gross amounts recognized	999	1,083
Gross amounts offset in the consolidated balance sheets	0	0
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	999	1,083
Electric Utility | Derivative Assets, Short-Term
Derivative Assets
Gross amounts recognized	60	74
Gross amounts offset in the consolidated balance sheets	(2)	(1)
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	58	73
Electric Utility | Derivative Assets, Long-Term
Derivative Assets
Gross amounts recognized	1	1
Gross amounts offset in the consolidated balance sheets	0	0
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	1	1
Electric Utility | Derivative Liability, Short-Term
Derivative Liabilities
Gross amounts recognized	192	217
Gross amounts offset in the consolidated balance sheets	(2)	(1)
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	190	216
Electric Utility | Derivative Liability, Long-Term
Derivative Liabilities
Gross amounts recognized	868	941
Gross amounts offset in the consolidated balance sheets	0	0
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	$ 868	$ 941