Fair Value (Quantitative Information) (Details) (USD $)	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	$ (275,000,000)	$ (286,000,000)	$ (148,000,000)	$ (209,000,000)	$ 10,000,000	$ 49,000,000
Interest Rate Derivatives
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	(297,000,000)	(281,000,000)	(128,000,000)	(191,000,000)	(60,000,000)	(1,000,000)
Interest Rate Derivatives | Minimum
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Subsidiaries' credit risk	3.00%
Interest Rate Derivatives | Maximum
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Subsidiaries' credit risk	3.75%
Interest Rate Derivatives | Weighted Average
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Subsidiaries' credit risk	3.43%
Foreign Currency Embedded Derivative Argentine Peso [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Argentine Peso to U.S. Dollar currency exchange rate after 2 years	8.2
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	61,000,000
Foreign Currency Derivative Other [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	(1,000,000)
Commodity And Other Embedded Derivative Philippine Peso [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	11,000,000
Commodity And Other Embedded Derivative Philippine Peso [Member] | Minimum
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
U.S. Producer Price Index after 5 years (where base year of 2005 = 100)	141.3
Commodity And Other Embedded Derivative Philippine Peso [Member] | Maximum
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
U.S. Producer Price Index after 5 years (where base year of 2005 = 100)	174.54
Commodity And Other Embedded Derivative Philippine Peso [Member] | Weighted Average
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
U.S. Producer Price Index after 5 years (where base year of 2005 = 100)	152.74
Commodity And Other Derivative Other [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	1,000,000
Commodity And Other Embedded Derivative Aluminum [Member]
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets Liabilities Value	(50,000,000)
Commodity And Other Embedded Derivative Aluminum [Member] | Minimum
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Market Price of Power for Customer in Cameroon (per KWh)	0.06
Commodity And Other Embedded Derivative Aluminum [Member] | Maximum
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Market Price of Power for Customer in Cameroon (per KWh)	0.14
Commodity And Other Embedded Derivative Aluminum [Member] | Weighted Average
Fair Value Derivative Assets Liabilities Measured On Recurring Basis Unobservable Inputs [Abstract]
Market Price of Power for Customer in Cameroon (per KWh)	$ 0.12