Fair Value Measurements and Financial Instruments - Schedule of assets and liabilities that are measured at fair value on a recurring basis (Details) - Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	$ 1,618	$ 1,396
Corporate bonds [Member]
Assets:
Other investments	0	0
Government bonds [Member]
Assets:
Other investments	1	1
Equity investments [Member]
Assets:
Other investments	10	10
Foreign exchange contracts [Member]
Assets:
Derivatives	23	32
Liabilities:
Derivatives	17	18
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	1,618	1,396
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
Assets:
Other investments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Government bonds [Member]
Assets:
Other investments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity investments [Member]
Assets:
Other investments	6	6
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign exchange contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Significant Other Observable Inputs (Level 2) [Member] | Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	0	0
Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Other investments	0	0
Significant Other Observable Inputs (Level 2) [Member] | Government bonds [Member]
Assets:
Other investments	1	1
Significant Other Observable Inputs (Level 2) [Member] | Equity investments [Member]
Assets:
Other investments	4	4
Significant Other Observable Inputs (Level 2) [Member] | Foreign exchange contracts [Member]
Assets:
Derivatives	23	32
Liabilities:
Derivatives	17	18
Significant Unobservable Inputs (Level 3) [Member] | Money market funds and highly liquid debt securities
Assets:
Money market funds and highly liquid debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Other investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Government bonds [Member]
Assets:
Other investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Equity investments [Member]
Assets:
Other investments	0	0
Significant Unobservable Inputs (Level 3) [Member] | Foreign exchange contracts [Member]
Assets:
Derivatives	0	0
Liabilities:
Derivatives	$ 0	$ 0