Equity Activity - Reclassifications and Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	$ 9,953	$ 10,172	[1]	$ 31,582	$ 30,703	[1]
SG&A expense	4,363	4,606	[1]	14,665	14,666	[1]
Other (income) and expense	275	159	[1]	968	751	[1]
Interest expense	191	168		530	451
Provision for (benefit from) income taxes	304	339		138	120
Net (income) loss	(2,694)	(2,726)		(6,777)	(6,807)
Other comprehensive income/(loss)				1,194	1,877
Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	1,625	1,584	[1]	5,216	4,779	[1]
Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	8,040	8,265	[1]	25,519	25,034	[1]
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				(695)	721
Reclassification/amortization, Net of Tax Amount				1,889	1,155
Other comprehensive income/(loss), Before Tax Amount	678	658		2,001	1,869
Other comprehensive income/(loss), Tax (Expense)/Benefit	(209)	11		(807)	7
Other comprehensive income/(loss)	470	669		1,194	1,877
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				(663)	794
Other comprehensive income/(loss), Before Tax Amount	(22)	89		(535)	213
Other comprehensive income/(loss), Tax (Expense)/Benefit	(22)	195		(128)	581
Other comprehensive income/(loss)	(44)	284		(663)	794
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)		(2)	2
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0	1		1	0
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0	0		(1)	1
Reclassification/amortization, Net of Tax Amount					0
Other comprehensive income/(loss), Before Tax Amount	0	(2)		(2)	2
Other comprehensive income/(loss), Tax (Expense)/Benefit	0	1		1	0
Other comprehensive income/(loss)	0	(1)		(1)	2
Net Unrealized Gains/(Losses) on Available-For-Sale Securities | Reclassifications
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Other (income) and expense		0			1
Provision for (benefit from) income taxes		0			0
Net (income) loss		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	(46)	(70)		(134)	(198)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	11	20		39	53
Unrealized gains/(losses) arising during the period, Net of Tax Amount	(35)	(50)		(95)	(146)
Reclassification/amortization, Net of Tax Amount				305	(219)
Other comprehensive income/(loss), Before Tax Amount	(18)	(143)		274	(545)
Other comprehensive income/(loss), Tax (Expense)/Benefit	4	49		(63)	180
Other comprehensive income/(loss)	(14)	(94)		210	(365)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications
Reclassifications and Taxes Related to Items of Other Comprehensive Income
SG&A expense	(7)	6		14	(23)
Other (income) and expense	8	(64)		301	(275)
Interest expense	36	7		108	21
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	(8)	(1)		15	(23)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	(1)	(20)		(29)	(47)
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	1		(4)	6
Net (income) loss	(6)	(1)		11	(17)
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	8		7	18
Net (income) loss	(1)	(12)		(22)	(29)
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	(1)		(4)	6
Net (income) loss	(5)	4		10	(17)
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	(2)	25		(76)	106
Net (income) loss	6	(39)		225	(169)
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	(9)	(3)		(27)	(8)
Net (income) loss	27	4		81	13
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				65	72
Reclassification/amortization, Net of Tax Amount				1,584	1,374
Other comprehensive income/(loss), Before Tax Amount	719	713		2,264	2,200
Other comprehensive income/(loss), Tax (Expense)/Benefit	(191)	(235)		(616)	(754)
Other comprehensive income/(loss)	527	479		1,648	1,446
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	0		(1)	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	0		(1)	0
Reclassification/amortization, Before Tax Amount	(18)	(22)		(55)	(66)
Reclassification/amortization, Tax (Expense)/Benefit	5	7		15	23
Reclassification/amortization, Net of Tax Amount	(13)	(15)		(40)	(43)
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)	1		83	106
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	1	0		(22)	(36)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	(1)	1		60	70
Reclassification/amortization, Before Tax Amount	737	733		2,231	2,156
Reclassification/amortization, Tax (Expense)/Benefit	(196)	(242)		(607)	(739)
Reclassification/amortization, Net of Tax Amount	540	491		1,624	1,417
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	2	2		7	3
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0	(1)		(2)	(1)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	$ 1	$ 1		$ 5	$ 2

[1] Recast to reflect adoption of the FASB guidance on presentation of net periodic pension and nonpension postretirement benefit costs.