Compensation and Benefit Plans (Expense Components) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 45.0			$ 135.0
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	36.0		$ 39.0	108.0	$ 117.0
Interest cost	41.0		44.0	123.0	132.0
Expected return on plan assets	(53.0)		(56.0)	(159.0)	(168.0)
Settlement costs	0.0		0.0	8.0	0.0
Amortization of prior service cost	0.0		1.0	2.0	3.0
Amortization of net loss	4.0		9.0	14.0	27.0
Expense under accounting standards	28.0		37.0	96.0	111.0
Regulatory adjustment	(3.0)		(9.0)	(9.0)	(27.0)
Total expense recognized	25.0		28.0	87.0	84.0
Settlement loss		$ 7.7
Settlement loss, net of tax		$ 4.6
Net loss reclassified	3.0		3.0	8.0	9.0
PBOP Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.0		10.0	27.0	30.0
Interest cost	24.0		26.0	72.0	78.0
Expected return on plan assets	(27.0)		(28.0)	(81.0)	(84.0)
Amortization of prior service cost	0.0		(1.0)	(2.0)	(3.0)
Expense under accounting standards	6.0		7.0	16.0	21.0
Southern California Edison
Defined Benefit Plan Disclosure [Line Items]
Service cost	44.0			132.0
Southern California Edison \| Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	35.0		38.0	105.0	114.0
Interest cost	37.0		41.0	111.0	123.0
Expected return on plan assets	(50.0)		(53.0)	(150.0)	(159.0)
Amortization of prior service cost	0.0		1.0	2.0	3.0
Amortization of net loss	4.0		8.0	12.0	24.0
Expense under accounting standards	26.0		35.0	80.0	105.0
Regulatory adjustment	(3.0)		(9.0)	(9.0)	(27.0)
Total expense recognized	23.0		26.0	71.0	78.0
Net loss reclassified	1.0		2.0	4.0	5.0
Southern California Edison \| PBOP Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.0		10.0	27.0	30.0
Interest cost	24.0		26.0	72.0	78.0
Expected return on plan assets	(27.0)		(28.0)	(81.0)	(84.0)
Amortization of prior service cost	0.0		(1.0)	(2.0)	(3.0)
Expense under accounting standards	$ 6.0		$ 7.0	$ 16.0	$ 21.0

The period expense recognized in the consolidated statements of income.

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Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments, Net Of Tax

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The difference between the period's pension costs calculated for GAAP and ratemaking purposes, which is deferred as a regulatory adjustment.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan.

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Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of net periodic benefit cost (credit) for defined benefit plan.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from settlement and curtailment.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount, before tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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