Derivative Financial Instruments, Fair Value (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Foreign Currency Swaps Cash Flow Hedge Maximum Term	8 years
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives	$ 247	$ 255
Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives	50	58
Designated as Hedging Instrument [Member] | Foreign Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives	133	133
Designated as Hedging Instrument [Member] | Interest Rate And Foreign Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives	64	64
Designated as Hedging Instrument [Member] | Other Long Term Investments [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	6	5
Designated as Hedging Instrument [Member] | Other Long Term Investments [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	3	4
Designated as Hedging Instrument [Member] | Other Long Term Investments [Member] | Foreign Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	3	1
Designated as Hedging Instrument [Member] | Other Long Term Investments [Member] | Interest Rate And Foreign Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	0	0
Designated as Hedging Instrument [Member] | Accounts Payable Accrued Expenses And Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	28	31
Designated as Hedging Instrument [Member] | Accounts Payable Accrued Expenses And Other Liabilities [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	0	0
Designated as Hedging Instrument [Member] | Accounts Payable Accrued Expenses And Other Liabilities [Member] | Foreign Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	14	18
Designated as Hedging Instrument [Member] | Accounts Payable Accrued Expenses And Other Liabilities [Member] | Interest Rate And Foreign Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value	$ 14	$ 13