Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Fixed Rate Debt:
Carrying amount - liability	$ 2,978	$ 2,843
Fair value - liability	3,057	2,891
Variable Rate Debt:
Carrying amount - liability	2,491	2,071
Fair value - liability	2,432	2,029
Total Carrying Value in the Consolidated Balance Sheet [Member]
Assets:
Investments	48	44
Foreign Exchange Contracts	25	37
Total Assets at Fair Value	73	81
Liabilities:
Foreign Exchange Contracts	12	6
Total Liabilities at Fair Value	12	6
Quoted Prices in Active Markets for Identical Assets/Liabilities, Level 1 [Member]
Assets:
Investments	48	44
Foreign Exchange Contracts	0	0
Total Assets at Fair Value	48	44
Liabilities:
Foreign Exchange Contracts	0	0
Total Liabilities at Fair Value	0	0
Significant Other Observable Inputs, Level 2 [Member]
Assets:
Investments	0	0
Foreign Exchange Contracts	25	37
Total Assets at Fair Value	25	37
Liabilities:
Foreign Exchange Contracts	12	5
Total Liabilities at Fair Value	12	5
Significant Unobservable Inputs, Level 3 [Member]
Assets:
Investments	0	0
Foreign Exchange Contracts	0	0
Total Assets at Fair Value	0	0
Liabilities:
Foreign Exchange Contracts	0	1
Total Liabilities at Fair Value	$ 0	$ 1