Financial Instruments (Fair Values of Outstanding Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative Assets:
Derivative Assets	$ 183	$ 596
Derivative Liabilities:
Derivative Liabilities	599	13
Level 2
Derivative Assets:
Derivative Assets	166	596
Derivative Liabilities:
Derivative Liabilities	582	13
Level 2 | Foreign exchange contracts | Other current and non-current assets
Derivative Assets:
Derivative Assets	166	596
Level 2 | Foreign exchange contracts | Accrued expenses and other liabilities, current and non-current
Derivative Liabilities:
Derivative Liabilities	582	13
Fair Value of Derivatives Designated as Hedging Instruments | Level 2
Derivative Assets:
Derivative Assets	53	539
Derivative Liabilities:
Derivative Liabilities	459	4
Fair Value of Derivatives Designated as Hedging Instruments | Level 2 | Foreign exchange contracts | Other current and non-current assets
Derivative Assets:
Derivative Assets	53	539
Fair Value of Derivatives Designated as Hedging Instruments | Level 2 | Foreign exchange contracts | Accrued expenses and other liabilities, current and non-current
Derivative Liabilities:
Derivative Liabilities	459	4
Fair Value of Derivatives Not Designated as Hedging Instruments | Level 2
Derivative Assets:
Derivative Assets	113	57
Derivative Liabilities:
Derivative Liabilities	123	9
Fair Value of Derivatives Not Designated as Hedging Instruments | Level 2 | Foreign exchange contracts | Other current and non-current assets
Derivative Assets:
Derivative Assets	113	57
Fair Value of Derivatives Not Designated as Hedging Instruments | Level 2 | Foreign exchange contracts | Accrued expenses and other liabilities, current and non-current
Derivative Liabilities:
Derivative Liabilities	$ 123	$ 9