Commitments and Contingencies (Sale-Leaseback Commitments) (Details) (Midwest Generation LLC, USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended
Jan. 02, 2013	Sep. 30, 2013	Jul. 02, 2013
Midwest Generation LLC
Sale Leaseback Transaction [Line Items]
Lease payments not paid	$ 76		$ 76
Rent Paid for Sales Leaseback Transaction	7
Sale Leaseback Transaction, Monthly Rental Payments		3.75
PoJoCureAmount		$ 150

The amount of the monthly rental payments due under the lease entered into in connection with the transactions involving the sale of property to another party and the lease of the property back to the seller.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6456341&loc=d3e50796-112755

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 98

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_SaleLeasebackTransactionMonthlyRentalPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration