Pension Plans and Postretirement Other Than Pensions (Details) (USD $) In Millions, unless otherwise specified		3 Months Ended		6 Months Ended		1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Pension Plans	Jun. 30, 2011 Pension Plans	Jun. 30, 2012 Pension Plans	Jun. 30, 2011 Pension Plans	Jul. 31, 2012 Pension Plans Subsequent Event	Jun. 30, 2012 Pension Plans Estimated Contribution	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				$ 55		$ 58				$ 10
Additional plan year contributions		172		172			263	52		52
Collections from customer rates, benchmark for employer contributions		55		55
Requested recovery of plan contributions		168		168
Expense components are:
Service cost		37	38	74	76			12	10	24	20
Interest cost		45	47	90	94			28	31	56	62
Expected return on plan assets		(55)	(56)	(110)	(112)			(27)	(27)	(54)	(54)
Amortization of prior service cost (credit)		1	2	2	4			(9)	(9)	(18)	(18)
Amortization of net loss		15	4	30	8			11	9	22	18
Total expense		43	35	86	70			15	14	30	28
Regulatory adjustment (deferred)		27	(6)	54	(12)
Total expense recognized		70	29	140	58
After tax liability related to postretirment benefits to be assumed by Edison International	$ 113