Fair Value and Financial Instruments (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 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	Sep. 30, 2012 Fair Value Money market funds Recurring	Dec. 31, 2011 Fair Value Money market funds Recurring	Sep. 30, 2012 Fair Value Highly liquid debt securities Recurring	Dec. 31, 2011 Fair Value Highly liquid debt securities Recurring	Sep. 30, 2012 Fair Value Corporate bonds Recurring	Dec. 31, 2011 Fair Value Corporate bonds Recurring	Sep. 30, 2012 Fair Value Government bonds. Recurring	Dec. 31, 2011 Fair Value Government bonds. Recurring	Sep. 30, 2012 Fair Value Interest rate contracts Recurring	Dec. 31, 2011 Fair Value Interest rate contracts Recurring	Sep. 30, 2012 Fair Value Foreign exchange contracts Recurring	Dec. 31, 2011 Fair Value Foreign exchange contracts Recurring	Sep. 30, 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	Sep. 30, 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	Sep. 30, 2012 Significant Other Observable Inputs (Level 2) Government bonds. Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Government bonds. Recurring	Sep. 30, 2012 Significant Other Observable Inputs (Level 2) Interest rate contracts Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Interest rate contracts Recurring	Sep. 30, 2012 Significant Other Observable Inputs (Level 2) Foreign exchange contracts Recurring	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) Foreign exchange contracts Recurring	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) Corporate bonds Recurring	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) 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		$ 2,612	$ 2,428	$ 2,587	$ 2,403	$ 25	$ 25									$ 2,587	$ 2,403	$ 25	$ 25
Other investments								12	12	6	3									6	3					12	12
Derivatives												16	16	226	141							16	16	226	141
Liabilities:
Derivatives														$ 284	$ 189									$ 284	$ 189