Fair Value Measurements Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, Assets	$ 36	$ 15
Derivatives, Liabilities	(144)	(305)
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	3,232	4,504
Commercial Paper, at Carrying Value	168	87
Available-for-sale Securities, Debt Securities	252	79
Available for Sale Securities, Government Agencies	78	83
Available-for-sale Securities, Equity Securities	52	20
Derivatives, Assets	36	15
Total assets	3,818	4,788
Derivatives, Liabilities	(144)	(305)
Total liabilities	(144)	(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	3,232	4,504
Available-for-sale Securities, Equity Securities	52	20
Total assets	3,284	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	168	87
Available-for-sale Securities, Debt Securities	252	79
Available for Sale Securities, Government Agencies	78	83
Derivatives, Assets	36	15
Total assets	534	264
Derivatives, Liabilities	(144)	(305)
Total liabilities	$ (144)	$ (305)