Fair Value Measurements Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, Assets	$ 27	$ 15
Derivatives, Liabilities	(182)	(305)
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	2,817	4,504
Commercial Paper, at Carrying Value	199	87
Available-for-sale Securities, Debt Securities	210	79
Available for Sale Securities, Government Agencies	88	83
Available-for-sale Securities, Equity Securities	47	20
Derivatives, Assets	27	15
Total assets	3,388	4,788
Derivatives, Liabilities	(182)	(305)
Total liabilities	(182)	(305)
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	2,817	4,504
Available-for-sale Securities, Equity Securities	47	20
Total assets	2,864	4,524
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Paper, at Carrying Value	199	87
Available-for-sale Securities, Debt Securities	210	79
Available for Sale Securities, Government Agencies	88	83
Derivatives, Assets	27	15
Total assets	524	264
Derivatives, Liabilities	(182)	(305)
Total liabilities	$ (182)	$ (305)