Fair Value and Financial Instruments (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Fair Value Money market funds and highly liquid debt securities Recurring	Dec. 31, 2011 Fair Value Money market funds and highly liquid debt securities Recurring	Mar. 31, 2012 Fair Value Corporate bonds Recurring	Dec. 31, 2011 Fair Value Corporate bonds Recurring	Mar. 31, 2012 Fair Value Government bonds. Recurring	Dec. 31, 2011 Fair Value Government bonds. Recurring	Mar. 31, 2012 Fair Value Interest rate contracts Recurring	Dec. 31, 2011 Fair Value Interest rate contracts Recurring	Mar. 31, 2012 Fair Value Foreign exchange contracts Recurring	Dec. 31, 2011 Fair Value Foreign exchange contracts Recurring	Mar. 31, 2012 Quoted Prices in Active Markets for Identical Assets (Level 1) Money market funds and highly liquid debt securities Recurring	Dec. 31, 2011 Quoted Prices in Active Markets for Identical Assets (Level 1) Money market funds and highly liquid debt securities Recurring	Mar. 31, 2012 Significant Other Observable Inputs (Level 2) Money market funds and highly liquid debt securities Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Money market funds and highly liquid debt securities Recurring	Mar. 31, 2012 Significant Other Observable Inputs (Level 2) Government bonds. Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Government bonds. Recurring	Mar. 31, 2012 Significant Other Observable Inputs (Level 2) Interest rate contracts Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Interest rate contracts Recurring	Mar. 31, 2012 Significant Other Observable Inputs (Level 2) Foreign exchange contracts Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Foreign exchange contracts Recurring	Mar. 31, 2012 Significant Unobservable (Level 3) Inputs Corporate bonds Recurring	Dec. 31, 2011 Significant Unobservable (Level 3) Inputs Corporate bonds Recurring
Fair Value and Financial Instruments
Net assets value (in dollar per share)	$ 1
Assets:
Money market funds and highly liquid debt securities		$ 2,563	$ 2,428									$ 2,538	$ 2,403	$ 25	$ 25
Other investments				12	12	3	3									3	3					12	12
Derivatives								18	16	170	141							18	16	170	141
Liabilities:
Derivatives										$ 206	$ 189									$ 206	$ 189