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	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 288	$ 454
Fair Value of Derivative, Liability	97	160
U.S. Dollar Notional	30,666	29,742
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	222	338
Fair Value of Derivative, Liability	24	89
U.S. Dollar Notional	14,728	14,390
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	66	116
Fair Value of Derivative, Liability	73	71
U.S. Dollar Notional	15,938	15,352
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	15	0
U.S. Dollar Notional	3,400	0
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	0
U.S. Dollar Notional	1,250	0
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	0	81
U.S. Dollar Notional	0	4,650
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	55	75
Fair Value of Derivative, Liability	0	0
U.S. Dollar Notional	2,160	2,655
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	152	263
U.S. Dollar Notional	6,117	6,222
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	22	7
U.S. Dollar Notional	1,748	774
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	53	89
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	66	116
U.S. Dollar Notional	7,245	5,430
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	73	71
U.S. Dollar Notional	$ 8,693	$ 9,922