Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 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	(26)		(69)
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(26)		(69)
Interest rate swaps	(13)		(14)
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
Fair Value, Measurements, Recurring [Member]
Derivatives designated as cash flow hedging instruments
Total assets	73		81
Total liabilities	(39)		(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	9		4
Total liabilities	(39)		(83)
Fair Value, Measurements, Recurring [Member] | US Corporate Debt Securities [Member]
Marketable securities, at fair value
Marketable securities, at fair value			1
Fair Value, Measurements, Recurring [Member] | US Corporate Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Marketable securities, at fair value
Marketable securities, at fair value			0
Fair Value, Measurements, Recurring [Member] | US Corporate Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Marketable securities, at fair value
Marketable securities, at fair value			1
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Marketable securities, at fair value
Marketable securities, at fair value	64		77
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Marketable securities, at fair value
Marketable securities, at fair value	64		77
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Marketable securities, at fair value
Marketable securities, at fair value	0		0
Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(21)	[1]	(59)	[1]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(21)	[1]	(59)	[1]
Interest rate swaps	13	[2]	(14)	[2]
Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	0	[1]	0	[1]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	0	[1]	0	[1]
Interest rate swaps	0	[2]	0	[2]
Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(21)	[1]	(59)	[1]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(21)	[1]	(59)	[1]
Interest rate swaps	13	[2]	(14)	[2]
Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(2)	[1]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(2)	[1]
Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	0	[1]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	0	[1]
Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives not designated as hedging instruments
Interest rate swaps	(2)	[1]
Derivatives designated as cash flow hedging instruments
Interest rate swaps	(2)	[1]
Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Foreign Currency Forwards and Swaps [Member]
Derivatives not designated as hedging instruments
Foreign currency forwards and swaps	9	[3]	3	[3]
Foreign currency forwards and swaps	(3)	[1]	(10)	[1]
Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Foreign Currency Forwards and Swaps [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Derivatives not designated as hedging instruments
Foreign currency forwards and swaps	0	[3]	0	[3]
Foreign currency forwards and swaps	0	[1]	0	[1]
Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member] | Foreign Currency Forwards and Swaps [Member] | Significant Other Observable Inputs (Level 2) [Member]
Derivatives not designated as hedging instruments
Foreign currency forwards and swaps	9	[3]	3	[3]
Foreign currency forwards and swaps	$ (3)	[1]	$ (10)	[1]

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

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

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