Financial Instruments - Location and Amount of Pretax (Gains) Losses of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 12,551	$ 12,397	$ 35,479	$ 34,972
Other (income) expense, net	(312)	35	(630)	362
Other comprehensive income (loss)	10	(28)	(190)	155
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI on derivatives	(1)	(1)	(3)	(6)
Interest rate swap contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(14)	13	54	101
Derivatives designated as hedging instruments	0	(6)	(76)	(74)
Amount of gain recognized in Other (income) expense, net on derivatives	(1)	(1)	(3)	(3)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI on derivatives	(195)	186	(126)	183
Increase (decrease) in Sales as a result of AOCI reclassifications	23	(70)	(65)	(189)
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	$ (23)	$ 70	$ 65	$ 189