Derivative Instruments (Balance Sheet Disclosures) (Details) - SCE - Commodity derivative contracts - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Electric Utility
Derivative Assets
Gross amounts recognized	$ 75	$ 165
Gross amounts offset in consolidated balance sheets	(1)	(2)
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	74	163
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1,158	1,335
Gross amounts offset in consolidated balance sheets	(1)	(2)
Cash collateral posted	0	(15)
Net amounts presented in the consolidated balance sheets	1,157	1,318
Net Liability
Gross amounts recognized	1,083	1,170
Gross amounts offset in consolidated balance sheets	0	0
Cash collateral posted	0	(15)
Net amounts presented in the consolidated balance sheets	1,083	1,155
Derivative Assets, Short-Term | Electric Utility
Derivative Assets
Gross amounts recognized	74	81
Gross amounts offset in consolidated balance sheets	(1)	(2)
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	73	79
Derivative Assets, Long-Term | Electric Utility
Derivative Assets
Gross amounts recognized	1	84
Gross amounts offset in consolidated balance sheets	0	0
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	1	84
Derivative Liability, Short-Term | Electric Utility
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	217	235
Gross amounts offset in consolidated balance sheets	(1)	(2)
Cash collateral posted	0	(15)
Net amounts presented in the consolidated balance sheets	216	218
Derivative Liability, Long-Term | Electric Utility
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	941	1,100
Gross amounts offset in consolidated balance sheets	0	0
Cash collateral posted	0	0
Net amounts presented in the consolidated balance sheets	941	1,100
Other Current Liabilities
Net Liability
Cash collateral	$ 2
Other Current Assets
Net Liability
Cash collateral		$ 31