Financial Instruments - Non-U.S. Dollar Debt Designated as Net Investment Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Euro notes
Derivative Instruments, Gain (Loss) [Line Items]
After-tax gains/(losses) related to hedges of net investments in international operations	$ (55)	$ (36)	$ (13)	$ 22
British pound sterling notes
Derivative Instruments, Gain (Loss) [Line Items]
After-tax gains/(losses) related to hedges of net investments in international operations	0	7	17	1
Swiss franc notes
Derivative Instruments, Gain (Loss) [Line Items]
After-tax gains/(losses) related to hedges of net investments in international operations	(14)	(21)	(20)	(8)
Canadian dollar notes
Derivative Instruments, Gain (Loss) [Line Items]
After-tax gains/(losses) related to hedges of net investments in international operations	$ (12)	$ (7)	$ 15	$ (14)