Derivative Financial Instruments - Effect of Hedge Activity on Income and Expense (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)
Cost	$ 9,423	$ 10,151		$ 19,071	$ 20,290
SG&A expense	5,248	5,456		11,203	10,147
Other (income) and expense	179	(747)		361	(820)
Interest expense	323	348		649	558
Cost of services
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	(1)	20		9	29
Cost of sales
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	9	11		18	30
Cost of financing
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	2	(18)		6	(36)
SG&A expense
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	157	38		(34)	179
Other (income) and expense
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	92	271		(9)	202
Interest expense
Derivative Instruments, Gain (Loss)
Gains/(losses) of total hedge activity	7	(39)		16	(59)
Services
Derivative Instruments, Gain (Loss)
Cost	7,520	8,181	[1]	15,363	16,453	[1]
Sales
Derivative Instruments, Gain (Loss)
Cost	1,739	1,741	[1]	3,363	3,344	[1]
Financing
Derivative Instruments, Gain (Loss)
Cost	$ 165	$ 228		$ 345	$ 492

[1] Reclassified to conform to current period presentation. Refer to note 1, “Basis of Presentation,” for additional information.