Derivative Financial Instruments - Effect of Hedge Activity on Income and Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss)
Cost	$ 9,741	$ 9,423	$ 19,266	$ 19,071
SG&A expense	5,334	5,248	10,508	11,203
Other (income) and expense	315	179	676	361
Interest expense	281	323	562	649
Cost of services
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	7	(1)	21	9
Cost of sales
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	(10)	9	(32)	18
Cost of financing
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	0	2	2	6
SG&A expense
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	67	157	101	(34)
Other (income) and expense
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	(79)	92	(239)	(9)
Interest expense
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	(1)	7	4	16
Services
Derivative Instruments, Gain (Loss)
Cost	7,871	7,520	15,646	15,363
Sales
Derivative Instruments, Gain (Loss)
Cost	1,694	1,739	3,279	3,363
Financing
Derivative Instruments, Gain (Loss)
Cost	$ 176	$ 165	$ 341	$ 345