Derivative Instruments And Hedging Activities (Derivative Financial Instruments At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments And Hedging Activities [Line Items]
Total	$ 34	$ 130
Designated As Hedging Instrument [Member] | Derivative Assets Included Other Current Assets [Member]
Derivative Instruments And Hedging Activities [Line Items]
Derivative assets	64	128
Designated As Hedging Instrument [Member] | Derivative Liabilities Included Other Current Liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Derivative liabilities	(33)	(16)
Not Designated As Hedging Instrument [Member] | Derivative Assets Included Other Current Assets [Member]
Derivative Instruments And Hedging Activities [Line Items]
Derivative assets	20	35
Not Designated As Hedging Instrument [Member] | Derivative Liabilities Included Other Current Liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Derivative liabilities	$ (17)	$ (17)