Compensation and Benefit Plans (Plan Assets and Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in projected benefit obligation
Service cost	$ 169
Amounts recognized in the consolidated balance sheets consist of:
Long-term liabilities	(943)	$ (1,354)
SCE
Change in projected benefit obligation
Service cost	164
Amounts recognized in the consolidated balance sheets consist of:
Long-term liabilities	(483)	(896)
Pension Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	4,284	4,374
Service cost	137	139
Interest cost	164	171
Actuarial gain	(46)	(125)
Benefits paid	(360)	(275)
Projected benefit obligation at end of year	4,179	4,284	$ 4,374
Change in plan assets
Fair value of plan assets at beginning of year	3,388	3,298
Actual return on plan assets	483	262
Employer contributions	105	103
Benefits paid	(360)	(275)
Fair value of plan assets at end of year	3,616	3,388	3,298
Funded status at end of year	(563)	(896)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	7	2
Current liabilities	(17)	(50)
Long-term liabilities	(553)	(848)
Total liabilities	(563)	(896)
Amounts recognized in accumulated other comprehensive loss consist of:
Prior service cost	(1)	(1)
Net loss	(77)	(93)
Total amounts recognized in accumulated other comprehensive loss	(76)	(92)
Amounts recognized as a regulatory (liability) asset	271	574
Total not yet recognized as (income) expense	347	666
Accumulated benefit obligation at end of year	4,022	4,138
Pension plans with an accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	4,179	4,284
Accumulated benefit obligation	4,022	4,138
Fair value of plan assets	$ 3,616	$ 3,388
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.46%	3.94%
Rate of compensation increase	4.10%	4.00%
Pension Plans | Edison International
Assumed health care cost trend rates:
Long-term payable	$ 114	$ 124
Pension Plans | SCE
Change in projected benefit obligation
Projected benefit obligation at beginning of year	3,791	3,878
Service cost	129	132
Interest cost	144	150
Actuarial gain	(74)	(140)
Benefits paid	(288)	(229)
Projected benefit obligation at end of year	3,702	3,791	3,878
Change in plan assets
Fair value of plan assets at beginning of year	3,172	3,080
Actual return on plan assets	442	239
Employer contributions	64	82
Benefits paid	(288)	(229)
Fair value of plan assets at end of year	3,390	3,172	3,080
Funded status at end of year	(312)	(619)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	0	0
Current liabilities	(4)	(4)
Long-term liabilities	(308)	(615)
Total liabilities	(312)	(619)
Amounts recognized in accumulated other comprehensive loss consist of:
Prior service cost	0	0
Net loss	(21)	(24)
Total amounts recognized in accumulated other comprehensive loss	(21)	(24)
Amounts recognized as a regulatory (liability) asset	271	574
Total not yet recognized as (income) expense	292	598
Accumulated benefit obligation at end of year	3,585	3,683
Pension plans with an accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	3,702	3,791
Accumulated benefit obligation	3,585	3,683
Fair value of plan assets	$ 3,390	$ 3,172
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.46%	3.94%
Rate of compensation increase	4.10%	4.00%
Assumed health care cost trend rates:
Net loss reclassified from other comprehensive loss	$ 19	$ 20
Postretirement Benefits Other Than Pensions
Change in projected benefit obligation
Projected benefit obligation at beginning of year	2,276	2,350
Service cost	31	35	46
Interest cost	86	97	102
Special termination benefits	1	2
Plan Amendments	0	(6)
Actuarial gain	24	(110)
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Projected benefit obligation at end of year	2,337	2,276	2,350
Change in plan assets
Fair value of plan assets at beginning of year	2,102	2,036
Actual return on plan assets	297	137
Employer contributions	12	21
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Fair value of plan assets at end of year	2,330	2,102	2,036
Funded status at end of year	(7)	(174)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	6	0
Current liabilities	(13)	(14)
Long-term liabilities	0	(160)
Total liabilities	(7)	(174)
Amounts recognized in accumulated other comprehensive loss consist of:
Total amounts recognized in accumulated other comprehensive loss	(4)	(4)
Amounts recognized as a regulatory (liability) asset	(26)	136
Total not yet recognized as (income) expense	$ (22)	$ 140
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.70%	4.29%
Assumed health care cost trend rates:
Rate assumed for following year	6.75%	7.00%
Ultimate rate	5.00%	5.00%
Postretirement Benefits Other Than Pensions | SCE
Change in projected benefit obligation
Projected benefit obligation at beginning of year	$ 2,266	$ 2,341
Service cost	31	34	46
Interest cost	85	97	102
Special termination benefits	1	2
Plan Amendments	0	(6)
Actuarial gain	23	(110)
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Projected benefit obligation at end of year	2,325	2,266	2,341
Change in plan assets
Fair value of plan assets at beginning of year	2,102	2,036
Actual return on plan assets	297	137
Employer contributions	12	21
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Fair value of plan assets at end of year	2,330	2,102	$ 2,036
Funded status at end of year	5	(164)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	17	0
Current liabilities	(12)	(13)
Long-term liabilities	0	(151)
Total liabilities	5	(164)
Amounts recognized in accumulated other comprehensive loss consist of:
Total amounts recognized in accumulated other comprehensive loss	0	0
Amounts recognized as a regulatory (liability) asset	(26)	136
Total not yet recognized as (income) expense	$ (26)	$ 136
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.70%	4.29%
Assumed health care cost trend rates:
Rate assumed for following year	6.75%	7.00%
Ultimate rate	5.00%	5.00%