Consolidated Statement of Changes in Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			$ 1,664		$ 2,821
Net income (loss)	(104)	(32)	(186)		(52)
Other comprehensive loss	(37)	(21)	(21)		(24)
Payments to Edison Interntional for stock purchases related to stock-based compensation			(12)		(3)
Excess tax benefits related to stock option exercises					1
Other stock transactions, net			3		2
Contributions from noncontrolling interests			242	[1]
Distributions to noncontrolling interests			(7)
Transfers of assets to Capistrano Wind Partners			(21)	[2]
Purchase of noncontrolling interest					(5)	[3]
Balance	1,662	2,740	1,662		2,740
Pinnacle Wind Force
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Ownership interest (as a percentage)		100.00%
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			64		64
Net income (loss)			0		0
Other comprehensive loss			0		0
Payments to Edison Interntional for stock purchases related to stock-based compensation			0		0
Excess tax benefits related to stock option exercises					0
Other stock transactions, net			0		0
Contributions from noncontrolling interests			0	[1]
Distributions to noncontrolling interests			0
Transfers of assets to Capistrano Wind Partners			0	[2]
Purchase of noncontrolling interest					0	[3]
Balance	64	64	64		64
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			1,327		1,336
Net income (loss)			0		0
Other comprehensive loss			0		0
Payments to Edison Interntional for stock purchases related to stock-based compensation			0		0
Excess tax benefits related to stock option exercises					1
Other stock transactions, net			3		2
Contributions from noncontrolling interests			0	[1]
Distributions to noncontrolling interests			0
Transfers of assets to Capistrano Wind Partners			(21)	[2]
Purchase of noncontrolling interest					(4)	[3]
Balance	1,309	1,335	1,309		1,335
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			365		1,448
Net income (loss)			(193)		(52)
Other comprehensive loss			0		0
Payments to Edison Interntional for stock purchases related to stock-based compensation			(12)		(3)
Excess tax benefits related to stock option exercises					0
Other stock transactions, net			0		0
Contributions from noncontrolling interests			0	[1]
Distributions to noncontrolling interests			0
Transfers of assets to Capistrano Wind Partners			0	[2]
Purchase of noncontrolling interest					0	[3]
Balance	160	1,393	160		1,393
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			(94)		(31)
Net income (loss)			0		0
Other comprehensive loss			(21)		(24)
Payments to Edison Interntional for stock purchases related to stock-based compensation			0		0
Excess tax benefits related to stock option exercises					0
Other stock transactions, net			0		0
Contributions from noncontrolling interests			0	[1]
Distributions to noncontrolling interests			0
Transfers of assets to Capistrano Wind Partners			0	[2]
Purchase of noncontrolling interest					0	[3]
Balance	(115)	(55)	(115)		(55)
Non-controlling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			2		4
Net income (loss)			7		0
Other comprehensive loss			0		0
Payments to Edison Interntional for stock purchases related to stock-based compensation			0		0
Excess tax benefits related to stock option exercises					0
Other stock transactions, net			0		0
Contributions from noncontrolling interests			242	[1]
Distributions to noncontrolling interests			(7)
Transfers of assets to Capistrano Wind Partners			0	[2]
Purchase of noncontrolling interest					(1)	[3]
Balance	$ 244	$ 3	$ 244		$ 3

[1] Funds contribution by third-party investors related to the Capistrano Wind equity capital raise are reported in noncontrolling interest. For further information, see Note 3—Variable Interest Entities—Projects or Entities that are Consolidated—Capistrano Wind Equity Capital.

[2] Additional paid in capital was reduced by $21 million during the six months ended June 30, 2012 due to a new tax basis in the assets transferred to Capistrano Wind Partners. The tax basis allocation to the transferred assets was updated during the three months ended June 30, 2012. For further information, see Note 3—Variable Interest Entities—Projects or Entities that are Consolidated—Capistrano Wind Equity Capital.

[3] During the second quarter of 2011, EME purchased a noncontrolling interest in Pinnacle Wind Force, LLC, which is now 100% owned by EME.