CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Statement of Income and Comprehensive Income [Abstract]
Net Loss	$ (82)	$ (20)
Pension and postretirement benefits other than pensions
Net gain (loss) adjustment, net of tax	1	0
Amortization of net loss and prior service adjustment included in expense, net of tax	1	1
Unrealized gains (losses) on derivatives qualified as cash flow hedges
Unrealized holding gain arising during period, net of income tax expense of $17 and $4 for the three months ended March 31, 2012 and 2011	25	6
Reclassification adjustments included in net loss, net of income tax benefit of $8 and $6 for the three months ended March 31, 2012 and 2011	(11)	(10)
Other comprehensive income (loss), net of tax	16	(3)
Comprehensive Loss	(66)	(23)
Comprehensive Income Attributable to Noncontrolling Interests	(2)	0
Comprehensive Loss Attributable to Edison Mission Energy Common Shareholder	$ (68)	$ (23)