Fair Values Of Assets And Liabilities Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value	$ 1,439	[1]	$ 1,830	[2]
Interest Rate Swap Agreements - Assets	8
Interest Rate Cap Agreements Purchased	5
Investment Foreign Currency, Contract, Amount Purchased	1
Assets Fair Value disclosure	1,453
Interest Rate Swap Agreements - Liabilities	16
Interest Rate Cap Agreements - Sold	6
Investment Foreign Currency, Contract, Amount Sold	19
Liabilities Fair Value Disclosure	41
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Cap Agreements Purchased	5
Investment Foreign Currency, Contract, Amount Purchased	1
Assets Fair Value disclosure	6
Interest Rate Cap Agreements - Sold	6
Investment Foreign Currency, Contract, Amount Sold	19
Liabilities Fair Value Disclosure	25
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Swap Agreements - Assets	8
Assets Fair Value disclosure	8
Interest Rate Swap Agreements - Liabilities	16
Liabilities Fair Value Disclosure	16
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	1,439	[1]	1,830	[2]
Assets Fair Value disclosure	$ 1,439

[1] Excludes cash in banks of $1.7 billion.

[2] Excludes cash in banks of $228 million.