Financial Instruments (Fair Values of Outstanding Derivative Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivative Assets:
Derivative Assets	$ 365	$ 569
Derivative Liabilities:
Derivative Liabilities	390	289
Level 2
Derivative Assets:
Derivative Assets	344	513
Derivative Liabilities:
Derivative Liabilities	369	233
Level 2 | Foreign exchange contracts | Other current and non-current assets
Derivative Assets:
Derivative Assets	344	513
Level 2 | Foreign exchange contracts | Accrued expenses and other liabilities, current and non-current
Derivative Liabilities:
Derivative Liabilities	369	233
Fair Value of Derivatives Designated as Hedging Instruments | Level 2
Derivative Assets:
Derivative Assets	91	459
Derivative Liabilities:
Derivative Liabilities	173	5
Fair Value of Derivatives Designated as Hedging Instruments | Level 2 | Foreign exchange contracts | Other current and non-current assets
Derivative Assets:
Derivative Assets	91	459
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	173	5
Fair Value of Derivatives Not Designated as Hedging Instruments | Level 2
Derivative Assets:
Derivative Assets	253	54
Derivative Liabilities:
Derivative Liabilities	196	228
Fair Value of Derivatives Not Designated as Hedging Instruments | Level 2 | Foreign exchange contracts | Other current and non-current assets
Derivative Assets:
Derivative Assets	253	54
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	$ 196	$ 228