Equity Activity - Reclassifications and Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	$ 9,447	$ 9,130	$ 28,714	$ 28,202
SG&A expense	4,860	4,647	15,368	15,849
Other (income) and expense	234	253	911	614
Interest expense	291	323	852	971
Provision for/(benefit from) income taxes	188	128	365	(888)
Net (income) loss	(1,130)	(1,698)	(3,410)	(4,234)
Other comprehensive income/(loss)	350	172	2,035	12
Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	7,770	7,357	23,416	22,720
Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	1,513	1,601	4,792	4,964
Financing
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	165	172	506	517
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			382	(1,242)
Reclassification/amortization, Net of Tax Amount			1,654	1,255
Other comprehensive income/(loss), Before Tax Amount	683	66	3,014	187
Other comprehensive income/(loss), Tax (Expense)/Benefit	(333)	106	(978)	(175)
Other comprehensive income/(loss)	350	172	2,035	12
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			160	(1,094)
Other comprehensive income/(loss), Before Tax Amount	(114)	(439)	463	(1,354)
Other comprehensive income/(loss), Tax (Expense)/Benefit	(120)	247	(304)	260
Other comprehensive income/(loss)	(234)	(192)	160	(1,094)
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	0	(1)	0	0
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0	0	0	0
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0	(1)	0	0
Other comprehensive income/(loss), Before Tax Amount	0	(1)	0	0
Other comprehensive income/(loss), Tax (Expense)/Benefit	0	0	0	0
Other comprehensive income/(loss)	0	(1)	0	0
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	109	(32)	262	(249)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(28)	8	(66)	63
Unrealized gains/(losses) arising during the period, Net of Tax Amount	82	(24)	196	(186)
Reclassification/amortization, Net of Tax Amount			211	(27)
Other comprehensive income/(loss), Before Tax Amount	141	(101)	545	(285)
Other comprehensive income/(loss), Tax (Expense)/Benefit	(35)	26	(138)	73
Other comprehensive income/(loss)	106	(75)	407	(212)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications
Reclassifications and Taxes Related to Items of Other Comprehensive Income
SG&A expense	1	5	32	(12)
Other (income) and expense	22	(93)	187	(74)
Interest expense	16	19	48	60
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	(12)	(10)	(33)	(18)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	(1)	4	30	(14)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Financing
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	6	6	17	21
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	3	2	8	5
Net (income) loss	(9)	(7)	(25)	(14)
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	1	(1)	(8)	4
Net (income) loss	(1)	3	23	(10)
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	(1)	(2)	(4)	(5)
Net (income) loss	4	5	13	16
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	0	(1)	(8)	3
Net (income) loss	1	4	24	(9)
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	(6)	23	(47)	19
Net (income) loss	17	(70)	140	(55)
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	(4)	(5)	(12)	(15)
Net (income) loss	12	14	36	45
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			26	37
Reclassification/amortization, Net of Tax Amount			1,442	1,281
Other comprehensive income/(loss), Before Tax Amount	656	607	2,006	1,826
Other comprehensive income/(loss), Tax (Expense)/Benefit	(178)	(167)	(537)	(507)
Other comprehensive income/(loss)	478	440	1,469	1,319
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	0	(1)	0	(5)
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	0	0	0	(3)
Reclassification/amortization, Before Tax Amount	3	0	8	1
Reclassification/amortization, Tax (Expense)/Benefit	0	1	0	2
Reclassification/amortization, Net of Tax Amount	3	1	8	3
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	1	0	23	65
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0	0	4	(24)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	1	0	27	41
Reclassification/amortization, Before Tax Amount	638	586	1,929	1,722
Reclassification/amortization, Tax (Expense)/Benefit	(174)	(161)	(526)	(473)
Reclassification/amortization, Net of Tax Amount	464	425	1,403	1,249
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	21	46	42
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(4)	(6)	(14)	(12)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	$ 9	$ 14	$ 32	$ 30