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, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	$ (12)	$ (23)
Interest rate swaps	(3)	(8)
Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, at fair value	41	53
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	42	55
Total liabilities	(15)	(31)
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	41	53
Total liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1	2
Total liabilities	(15)	(31)
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, at fair value	41	53
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, at fair value	41	53
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities, at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Derivatives Designated as Cash Flow Hedges [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	(5)	(10)
Interest rate swaps	(3)	(7)
Fair Value, Measurements, Recurring [Member] | Derivatives Designated as Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	0	0
Interest rate swaps	0	0
Fair Value, Measurements, Recurring [Member] | Derivatives Designated as Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	(5)	(10)
Interest rate swaps	(3)	(7)
Fair Value, Measurements, Recurring [Member] | Derivatives Not Designated as Hedges [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	(2)	(5)
Interest rate swaps	0	(1)
Fair Value, Measurements, Recurring [Member] | Derivatives Not Designated as Hedges [Member] | Interest Rate Swaps [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	0	0
Interest rate swaps	0	0
Fair Value, Measurements, Recurring [Member] | Derivatives Not Designated as Hedges [Member] | Interest Rate Swaps [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	(2)	(5)
Interest rate swaps	0	(1)
Fair Value, Measurements, Recurring [Member] | Derivatives Not Designated as Hedges [Member] | Foreign Currency Forwards and Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	1	2
Foreign currency forwards and swaps	(5)	(8)
Fair Value, Measurements, Recurring [Member] | Derivatives Not Designated as Hedges [Member] | Foreign Currency Forwards and Swaps [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	0	0
Foreign currency forwards and swaps	0	0
Fair Value, Measurements, Recurring [Member] | Derivatives Not Designated as Hedges [Member] | Foreign Currency Forwards and Swaps [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forwards and swaps	1	2
Foreign currency forwards and swaps	$ (5)	$ (8)