Equity Activity - Reclassifications and Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	$ 10,804	$ 10,321	[1]	$ 21,629	$ 20,531	[1]
SG&A expense	4,857	5,033	[1]	10,302	10,060	[1]
Other (income) and expense	280	273	[1]	692	592	[1]
Interest expense	173	147		338	283
Continuing operations provision for (benefit from) income taxes	373	111		(166)	(218)
Net (income) loss	(2,404)	(2,331)		(4,083)	(4,082)
Other comprehensive income/(loss)				724	1,208
Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	1,869	1,664	[1]	3,591	3,195	[1]
Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	8,645	8,368	[1]	17,479	16,769	[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				(681)	486
Reclassification/amortization, Net of Tax Amount				1,405	723
Other comprehensive income/(loss), Before Tax Amount	748	432		1,322	1,211
Other comprehensive income/(loss), Tax (Expense)/Benefit	(455)	88		(598)	(3)
Other comprehensive income/(loss)	294	520		724	1,208
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				(620)	510
Reclassification/amortization, Net of Tax Amount				0	0
Other comprehensive income/(loss), Before Tax Amount	(347)	(38)		(513)	124
Other comprehensive income/(loss), Tax (Expense)/Benefit	(158)	278		(106)	386
Other comprehensive income/(loss)	(505)	240		(620)	510
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	4		(2)	3
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0	(1)		0	(1)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0	2		(1)	2
Reclassification/amortization, Net of Tax Amount				0	1
Other comprehensive income/(loss), Before Tax Amount	0	3		(2)	4
Other comprehensive income/(loss), Tax (Expense)/Benefit	0	(1)		0	(1)
Other comprehensive income/(loss)	0	2		(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		0	1
Continuing operations provision for (benefit from) income taxes		0		0	0
Net (income) loss		0		0	1
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	(149)	(96)		(89)	(128)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	38	24		29	32
Unrealized gains/(losses) arising during the period, Net of Tax Amount	(111)	(71)		(60)	(96)
Reclassification/amortization, Net of Tax Amount				284	(175)
Other comprehensive income/(loss), Before Tax Amount	285	(272)		292	(402)
Other comprehensive income/(loss), Tax (Expense)/Benefit	(71)	90		(68)	131
Other comprehensive income/(loss)	214	(183)		224	(271)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications
Reclassifications and Taxes Related to Items of Other Comprehensive Income
SG&A expense	3	(8)		21	(29)
Other (income) and expense	397	(146)		293	(211)
Interest expense	38	7		71	14
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	6	(10)		23	(22)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost	(9)	(18)		(28)	(27)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Cost of Sales
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Continuing operations provision for (benefit from) income taxes	(2)	3		(6)	6
Net (income) loss	5	(8)		17	(16)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Cost of Services
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Continuing operations provision for (benefit from) income taxes	2	7		7	10
Net (income) loss	(7)	(11)		(21)	(17)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | SG&A Expense
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Continuing operations provision for (benefit from) income taxes	(1)	2		(6)	7
Net (income) loss	2	(6)		15	(22)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Other (Income) and Expense
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Continuing operations provision for (benefit from) income taxes	(100)	56		(74)	81
Net (income) loss	297	(90)		219	(130)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications | Interest Expense
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Continuing operations provision for (benefit from) income taxes	(9)	(3)		(18)	(6)
Net (income) loss	28	4		53	9
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				64	70
Reclassification/amortization, Net of Tax Amount				1,057	897
Other comprehensive income/(loss), Before Tax Amount	810	738		1,545	1,486
Other comprehensive income/(loss), Tax (Expense)/Benefit	(226)	(278)		(424)	(519)
Other comprehensive income/(loss)	584	461		1,121	967
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
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0			0	0
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0			(1)	0
Reclassification/amortization, Before Tax Amount	(19)	(22)		(37)	(44)
Reclassification/amortization, Tax (Expense)/Benefit	5	8		10	15
Reclassification/amortization, Net of Tax Amount	(13)	(14)		(27)	(28)
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	82	44		84	105
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(23)	(17)		(23)	(37)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	59	27		61	69
Reclassification/amortization, Before Tax Amount	741	713		1,494	1,423
Reclassification/amortization, Tax (Expense)/Benefit	(207)	(268)		(410)	(497)
Reclassification/amortization, Net of Tax Amount	534	445		1,084	926
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	6	3		6	1
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(2)	(1)		(2)	(1)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	$ 4	$ 2		$ 4	$ 1

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