Fair Values Of Assets And Liabilities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value	$ 1,831	$ 1,830
Interest Rate Cap Agreements Purchased	7
Investment Foreign Currency, Contract, Amount Purchased	17
Interest Rate Swap Agreements - Assets	7
Derivative Assets	1,862
Interest Rate Swap Agreements - Liabilities	20
Interest Rate Cap Agreements - Sold	7
Investment Foreign Currency, Contract, Amount Sold	3
Derivative Liabilities	30
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value	1,831	1,830
Derivative Assets	1,831
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Cap Agreements Purchased	7
Investment Foreign Currency, Contract, Amount Purchased	17
Derivative Assets	24
Interest Rate Cap Agreements - Sold	7
Investment Foreign Currency, Contract, Amount Sold	3
Derivative Liabilities	10
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Swap Agreements - Assets	7
Derivative Assets	7
Interest Rate Swap Agreements - Liabilities	20
Derivative Liabilities	$ 20