The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 45

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-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

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-Name Accounting Standards Codification

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_AssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Summary of Significant Accounting Policies (Chapter 11 Cases) (Details) (USD $) In Millions, unless otherwise specified				3 Months Ended			9 Months Ended
	Jul. 25, 2013	May 02, 2013 subsidiaries	Dec. 17, 2012 subsidiaries	Sep. 30, 2013 Midwest Generation LLC	Sep. 30, 2013 Unsecured Notes	Dec. 31, 2012 Unsecured Notes	Sep. 30, 2013 Will County Station Midwest Generation LLC
Property, Plant and Equipment [Line Items]
Number of Subsidiaries Filing Voluntary Petitions for Relief Under Chapter Eleven of Bankruptcy Code		3	16
Unsecured debt					$ 3,700	$ 3,700
Asset Impairment Charges							464
Sale Leaseback Transaction, Monthly Rental Payments				$ 3.75
Percent Noteholders terminating Support Agreement	98.02%