Income Taxes (Components of Net Accumulated Deferred Income Tax Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013
Deferred tax assets:
Property and software related	$ 549	$ 675
Nuclear decommissioning trust assets in excess of nuclear ARO liability	348	360
Loss and credit carryforwards	1,418	1,388	$ 2,200
Regulatory balancing accounts	15	21
Pension and PBOPs	300	337
Other	419	499
Sub-total	3,049	3,280
Less valuation allowance	24	32
Total	3,025	3,248
Deferred tax liabilities:
Property-related	10,330	9,606
Capitalized software costs	237	207
Regulatory balancing accounts	134	202
Nuclear decommissioning trust assets	348	360
PBOPs	13	71
Other	202	189
Total	11,264	10,635
Accumulated deferred income tax liability, net	8,239	7,387
SCE
Deferred tax assets:
Property and software related	548	675
Nuclear decommissioning trust assets in excess of nuclear ARO liability	348	360
Loss and credit carryforwards	0	0
Regulatory balancing accounts	15	21
Pension and PBOPs	93	154
Other	408	411
Sub-total	1,412	1,621
Less valuation allowance	0	0
Total	1,412	1,621
Deferred tax liabilities:
Property-related	10,330	9,600
Capitalized software costs	237	207
Regulatory balancing accounts	134	202
Nuclear decommissioning trust assets	348	360
PBOPs	13	71
Other	148	161
Total	11,210	10,601
Accumulated deferred income tax liability, net	$ 9,798	$ 8,980