Equity Activity - Reclassifications and Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Reclassifications and Taxes Related to Items of Other Comprehensive Income
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
Provision for/(benefit from) income taxes	209	269		(1,017)	558
Net (income) loss	(1,361)	(2,498)		(2,536)	(4,089)
Other comprehensive income/(loss)	527	340		(160)	649
Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	7,520	8,181	[1]	15,363	16,453	[1]
Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	1,739	1,741	[1]	3,363	3,344	[1]
Financing
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	165	228		345	492
Accumulated Other Comprehensive Income/(Loss)
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Net of Tax Amount				(1,025)	29
Reclassification/amortization, Net of Tax Amount				866	620
Other comprehensive income/(loss), Before Tax Amount	548	405		121	779
Other comprehensive income/(loss), Tax (Expense)/Benefit	(21)	(64)		(281)	(131)
Other comprehensive income/(loss)	527	340		(160)	649
Foreign Currency Translation Adjustments
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Net of Tax Amount				(902)	214
Other comprehensive income/(loss), Before Tax Amount	4	5		(915)	176
Other comprehensive income/(loss), Tax (Expense)/Benefit	135	37		13	38
Other comprehensive income/(loss)	139	42		(902)	214
Net Unrealized Gains/(Losses) on Available-For-Sale Securities
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Before Tax Amount	1	(2)		1	(3)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0	0		0	1
Unrealized gains/(losses) arising during the period, Net of Tax Amount	1	(1)		1	(2)
Other comprehensive income/(loss), Before Tax Amount	1	(2)		1	(3)
Other comprehensive income/(loss), Tax (Expense)/Benefit	0	0		0	1
Other comprehensive income/(loss)	1	(1)		1	(2)
Net Unrealized Gains/(Losses) on Cash Flow Hedges
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Before Tax Amount	(36)	(6)		(216)	(359)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	9	2		55	87
Unrealized gains/(losses) arising during the period, Net of Tax Amount	(26)	(4)		(162)	(272)
Reclassification/amortization, Net of Tax Amount				25	(51)
Other comprehensive income/(loss), Before Tax Amount	(94)	(175)		(184)	(429)
Other comprehensive income/(loss), Tax (Expense)/Benefit	25	45		47	106
Other comprehensive income/(loss)	(70)	(129)		(137)	(323)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications
Reclassifications and Taxes Related to Items of Other Comprehensive Income
SG&A expense	(7)	(12)		(17)	(34)
Other (income) and expense	(70)	(202)		19	(115)
Interest expense	19	52		41	86
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	1	(20)		(9)	(29)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	(9)	(11)		(18)	(30)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Financing
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	7	25		15	53
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Cost of services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Provision for/(benefit from) income taxes	0	5		2	8
Net (income) loss	1	(15)		(6)	(22)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Cost of sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Provision for/(benefit from) income taxes	3	3		5	8
Net (income) loss	(7)	(8)		(13)	(21)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Cost of financing
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Provision for/(benefit from) income taxes	(2)	(6)		(4)	(13)
Net (income) loss	5	18		11	40
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | SG&A expense
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Provision for/(benefit from) income taxes	2	3		4	9
Net (income) loss	(5)	(9)		(13)	(25)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Other (income) and expense
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Provision for/(benefit from) income taxes	18	51		(5)	29
Net (income) loss	(52)	(151)		15	(86)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Interest expense
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Provision for/(benefit from) income taxes	(5)	(13)		(10)	(22)
Net (income) loss	15	39		31	64
Net Change Retirement-Related Benefit Plans
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Net of Tax Amount				38	89
Reclassification/amortization, Net of Tax Amount				841	671
Other comprehensive income/(loss), Before Tax Amount	637	576		1,219	1,035
Other comprehensive income/(loss), Tax (Expense)/Benefit	(180)	(147)		(341)	(275)
Other comprehensive income/(loss)	457	430		879	760
Retirement-Related Benefit Plans, Prior Service Costs/(Credits)
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Before Tax Amount				(4)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0			1
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0			(3)
Reclassification/amortization, Before Tax Amount	0	(3)		1	(6)
Reclassification/amortization, Tax (Expense)/Benefit	1	0		1	1
Reclassification/amortization, Net of Tax Amount	1	(3)		2	(5)
Retirement-Related Benefit Plans, Net Gains/(Losses)
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Before Tax Amount	57	116		65	113
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(22)	(25)		(24)	(24)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	35	92		41	89
Reclassification/amortization, Before Tax Amount	566	460		1,136	924
Reclassification/amortization, Tax (Expense)/Benefit	(155)	(123)		(312)	(252)
Reclassification/amortization, Net of Tax Amount	411	337		824	671
Retirement-Related Benefit Plans, Curtailments and Settlements
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Unrealized gains/(losses) arising during the period, Before Tax Amount	13	3		21	4
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(4)	0		(6)	0
Unrealized gains/(losses) arising during the period, Net of Tax Amount	$ 9	$ 3		$ 15	$ 4

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