Financing Receivables (Lease Assets And Locations) (Details) (Energy Holdings [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2011 mW
Powerton Station Units 5 And 6 [Member]
Property, Plant and Equipment [Line Items]
Lease Receivable, Asset Location	IL
Lease Receivable, Gross Investment	$ 135
Lease Receivable, Percent Owned	64.00%
Lease Receivable, Total, MW's	1,538
Lease Receivable, Asset, Fuel Type	Coal
Lease Receivable, Counterparties' S&P Credit Rating	B-
Lease Receivable, Counterparty	Edison Mission Energy
Joliet Station Units 7 And 8 [Member]
Property, Plant and Equipment [Line Items]
Lease Receivable, Asset Location	IL
Lease Receivable, Gross Investment	84
Lease Receivable, Percent Owned	64.00%
Lease Receivable, Total, MW's	1,044
Lease Receivable, Asset, Fuel Type	Coal
Lease Receivable, Counterparties' S&P Credit Rating	B-
Lease Receivable, Counterparty	Edison Mission Energy
Keystone Station Units 1 And 2 [Member]
Property, Plant and Equipment [Line Items]
Lease Receivable, Asset Location	PA
Lease Receivable, Gross Investment	112
Lease Receivable, Percent Owned	17.00%
Lease Receivable, Total, MW's	1,711
Lease Receivable, Asset, Fuel Type	Coal
Lease Receivable, Counterparties' S&P Credit Rating	B
Lease Receivable, Counterparty	GenOn REMA, LLC
Conemaugh Station Units 1 And 2 [Member]
Property, Plant and Equipment [Line Items]
Lease Receivable, Asset Location	PA
Lease Receivable, Gross Investment	112
Lease Receivable, Percent Owned	17.00%
Lease Receivable, Total, MW's	1,711
Lease Receivable, Asset, Fuel Type	Coal
Lease Receivable, Counterparties' S&P Credit Rating	B
Lease Receivable, Counterparty	GenOn REMA, LLC
Shawville Station Units 1, 2, 3 And 4 [Member]
Property, Plant and Equipment [Line Items]
Lease Receivable, Asset Location	PA
Lease Receivable, Gross Investment	$ 107
Lease Receivable, Percent Owned	100.00%
Lease Receivable, Total, MW's	603
Lease Receivable, Asset, Fuel Type	Coal
Lease Receivable, Counterparties' S&P Credit Rating	B
Lease Receivable, Counterparty	GenOn REMA, LLC