CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current Assets
Cash and cash equivalents	$ 1,138	$ 888
Accounts receivable-trade	81	73
Receivables from affiliates	6	8
Inventory	121	175
Derivative assets	35	53
Restricted cash and cash equivalents	15	11
Margin and collateral deposits	85	61
Prepaid expenses and other	44	54
Total current assets	1,525	1,323
Investments in Unconsolidated Affiliates	543	534
Property, Plant and Equipment, less accumulated depreciation	3,934	4,516
Other Assets
Deferred financing costs	35	44
Long-term derivative assets	21	37
Restricted deposits	103	102
Rent payments in excess of levelized rent expense under plant operating leases	799	836
Other long-term assets	94	128
Total other assets	1,052	1,147
Total Assets	7,054	7,520
Current Liabilities
Accounts payable	26	29
Payables to affiliates	32	34
Accrued liabilities and other	83	67
Interest payable	7	1
Current portion of long-term debt	90	307
Short-term debt	0	382
Total current liabilities	238	820
Liabilities subject to compromise	3,979	3,959
Long-term debt net of current portion	1,433	749
Deferred taxes and tax credits, net (Note 7)	53	81
Deferred revenues	513	533
Long-term derivative liabilities	69	118
Other long-term liabilities	510	528
Total Liabilities	6,795	6,788
Commitments and Contingencies (Notes 5, 6, 9 and 10)
Equity
Common stock and membership interests	64	64
Additional paid-in capital	1,137	1,095
Retained earnings (deficit)	(1,225)	(577)
Accumulated other comprehensive loss	(109)	(138)
Total Edison Mission Energy common shareholder's equity	(133)	444
Noncontrolling Interests	392	288
Total Equity	259	732
Total Liabilities and Equity	7,054	7,520
Midwest Generation LLC
Current Assets
Cash and cash equivalents	120	95
Receivables from affiliates	38	40
Inventory	102	165
Interest receivable from affiliate, net (Note 1)	0	0
Derivative assets	1	2
Prepaid expenses and other	20	20
Total current assets	281	322
Property, Plant and Equipment, less accumulated depreciation	1,542	2,078
Notes receivable from affiliate, net (Note 1)	0	0
Other Assets
Other long-term assets	10	28
Total Assets	1,833	2,428
Current Liabilities
Accounts payable	6	10
Payables to affiliates	4	3
Accrued liabilities and other	29	18
Derivative liabilities	2	3
Interest payable	6	1
Current portion of lease financings	0	6
Total current liabilities	47	41
Liabilities subject to compromise	542	529
Deferred taxes and tax credits, net (Note 7)	0	0
Other long-term liabilities	194	192
Total Liabilities	783	762
Commitments and Contingencies (Notes 5, 6, 9 and 10)
Equity
Common stock and membership interests	0	0
Additional paid-in capital	3,405	3,405
Retained earnings (deficit)	(2,308)	(1,689)
Accumulated other comprehensive loss	(47)	(50)
Total Equity	1,050	1,666
Total Liabilities and Equity	$ 1,833	$ 2,428