Financial Instruments - Fair Value of Derivatives Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 239	$ 288
Fair Value of Derivative, Liability	298	97
U.S Dollar Notional Amount	27,151	30,666
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	158	222
Fair Value of Derivative, Liability	105	24
U.S Dollar Notional Amount	12,654	14,728
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	81	66
Fair Value of Derivative, Liability	193	73
U.S Dollar Notional Amount	14,497	15,938
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	6	0
U.S Dollar Notional Amount	1,150	0
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	63	15
U.S Dollar Notional Amount	2,250	3,400
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	0	1
U.S Dollar Notional Amount	0	1,250
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	30	152
U.S Dollar Notional Amount	4,120	6,117
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	59	55
U.S Dollar Notional Amount	1,881	2,160
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	104	22
U.S Dollar Notional Amount	3,096	1,748
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	1
U.S Dollar Notional Amount	157	53
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	81	66
U.S Dollar Notional Amount	5,455	7,245
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	171	73
U.S Dollar Notional Amount	8,042	8,693
Forward Contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	22	0
U.S Dollar Notional Amount	$ 1,000	$ 0