Financial Instruments - Location and Amount of Pretax (Gains) Losses of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 10,872	$ 11,760	$ 22,929	$ 22,575
Other (income) expense, net	(390)	140	(318)	327
Other comprehensive income (loss)	(2)	(16)	(200)	183
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI on derivatives	(1)	(1)	(2)	(5)
Interest rate swap contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	1	55	68	88
Derivatives designated as hedging instruments	(8)	(45)	(76)	(68)
Amount of gain recognized in Other (income) expense, net on derivatives	(1)	(1)	(2)	(2)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI on derivatives	(109)	10	69	(2)
Increase (decrease) in Sales as a result of AOCI reclassifications	(42)	(75)	(88)	(119)
Foreign exchange contracts | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 42	$ 75	$ 88	$ 119