Compensation and Benefit Plans (Details) (USD $) In Millions, unless otherwise specified		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
Mar. 01, 2012	Jun. 30, 2012 Pension Plans	Jun. 30, 2011 Pension Plans	Jun. 30, 2012 Pension Plans	Jun. 30, 2011 Pension Plans	Jun. 30, 2012 Postretirement Benefits Other Than Pensions	Jun. 30, 2011 Postretirement Benefits Other Than Pensions	Jun. 30, 2012 Postretirement Benefits Other Than Pensions	Jun. 30, 2011 Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Employer contributions				$ 13				$ 2
Additional plan year contributions		9		9		1		1
Expense components are:
Service cost		4	5	9	9	1	1	2	2
Interest cost		4	3	7	7	1	1	3	3
Expected return on plan assets		(4)	(3)	(7)	(6)
Net amortization		2	1	3	2	1	0	1	0
Total expense		6	6	12	12	3	2	6	5
After tax value of post retirement benefits to be assumed by Edison International	$ 25

Liability related to after tax value of post retirement benefits to be assumed by parent company.

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The amount of gains or losses recognized in net periodic benefit cost.

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The increase in the fair value of plan assets from contributions made by the employer.

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The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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