Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
Marketable securities, at fair value
Marketable securities, at fair value	$ 64		$ 78
Derivatives not designated as hedging instruments
Interest rate swaps	(42)		(69)
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(42)		(69)
Interest rate swaps	(17)		(14)
US Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Marketable securities, at fair value
Marketable securities, at fair value			1
US Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Marketable securities, at fair value
Marketable securities, at fair value			0
US Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Marketable securities, at fair value
Marketable securities, at fair value			1
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member]
Marketable securities, at fair value
Marketable securities, at fair value	64		77
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Marketable securities, at fair value
Marketable securities, at fair value	64		77
Mutual Funds [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Marketable securities, at fair value
Marketable securities, at fair value	0		0
Foreign Currency Forwards and Swaps [Member] | Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member]
Derivatives not designated as hedging instruments
Foreign currency forwards and swaps	10	[1]	3	[1]
Foreign currency forwards and swaps	(7)	[2]	(10)	[2]
Foreign Currency Forwards and Swaps [Member] | Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives not designated as hedging instruments
Foreign currency forwards and swaps	0	[1]	0	[1]
Foreign currency forwards and swaps	0	[2]	0	[2]
Foreign Currency Forwards and Swaps [Member] | Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives not designated as hedging instruments
Foreign currency forwards and swaps	10	[1]	3	[1]
Foreign currency forwards and swaps	(7)	[2]	(10)	[2]
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(31)	[2]	(59)	[2]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(31)	[2]	(59)	[2]
Interest rate swaps	17	[3]	(14)	[3]
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	0	[2]	0	[2]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	0	[2]	0	[2]
Interest rate swaps	0	[3]	0	[3]
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(31)	[2]	(59)	[2]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(31)	[2]	(59)	[2]
Interest rate swaps	17	[3]	(14)	[3]
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(4)	[2]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(4)	[2]
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	0	[2]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	0	[2]
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(4)	[2]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(4)	[2]
Fair Value, Measurements, Recurring [Member]
Derivatives designated as cash flow hedging instruments
Total assets	74		81
Total liabilities	(59)		(83)
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives designated as cash flow hedging instruments
Total assets	64		77
Total liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives designated as cash flow hedging instruments
Total assets	10		4
Total liabilities	(59)		(83)
US Corporate Debt Securities [Member]
Marketable securities, at fair value
Marketable securities, at fair value			1
Mutual Funds [Member]
Marketable securities, at fair value
Marketable securities, at fair value	$ 64		$ 77

[1] Included in current Other assets in the unaudited consolidated balance sheets.

[2] Included in current Other liabilities in the unaudited consolidated balance sheets.

[3] Included in noncurrent Other liabilities in the unaudited consolidated balance sheets.