Equity Activity - Reclassifications and Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost of sales	$ 1,605		$ 1,536	$ 4,839	$ 4,496
Cost of services	8,426		8,418	25,502	25,492
SG&A expense	4,648		4,732	14,959	16,093
Other (income) and expense	(114)		(8)	(218)	281
Interest expense	168		158	451	473
Provision for/(benefit from) income taxes	339	$ (329)	409	120	(31)
Net (income) loss	(2,726)		(2,853)	(6,807)	(7,371)
Other comprehensive income/(loss)				1,877	1,442
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				721	117
Reclassification/amortization, Net of Tax Amount				1,155	1,326
Other comprehensive income/(loss), Before Tax Amount	658		632	1,869	1,656
Other comprehensive income/(loss), Tax (Expense)/Benefit	11		(192)	7	(213)
Other comprehensive income/(loss)	669		440	1,877	1,442
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				794	303
Reclassification/amortization, Net of Tax Amount				0	0
Other comprehensive income/(loss), Before Tax Amount	89		(99)	213	(109)
Other comprehensive income/(loss), Tax (Expense)/Benefit	195		50	581	411
Other comprehensive income/(loss)	284		(49)	794	303
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)		(1)	2	(36)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	1		0	0	14
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0		(1)	1	(22)
Reclassification/amortization, Net of Tax Amount				0	22
Other comprehensive income/(loss), Before Tax Amount	(2)		(2)	2	0
Other comprehensive income/(loss), Tax (Expense)/Benefit	1		1	0	0
Other comprehensive income/(loss)	(1)		(1)	2	0
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)	1	36
Provision for/(benefit from) income taxes	0		0	0	(14)
Net (income) loss	0		(1)	0	22
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	(70)		35	(198)	(221)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	20		(14)	53	82
Unrealized gains/(losses) arising during the period, Net of Tax Amount	(50)		21	(146)	(139)
Reclassification/amortization, Net of Tax Amount				(219)	12
Other comprehensive income/(loss), Before Tax Amount	(143)		50	(545)	(195)
Other comprehensive income/(loss), Tax (Expense)/Benefit	49		(22)	180	68
Other comprehensive income/(loss)	(94)		29	(365)	(127)
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Reclassifications
Reclassifications and Taxes Related to Items of Other Comprehensive Income
Cost of sales	(1)		7	(23)	5
Cost of services	(20)		(3)	(47)	9
SG&A expense	6		(2)	(23)	1
Other (income) and expense	(64)		6	(275)	(6)
Interest expense	7		7	21	17
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		(3)	6	(4)
Net (income) loss	(1)		4	(17)	2
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	8		1	18	(3)
Net (income) loss	(12)		(2)	(29)	5
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	(1)		(1)	6	(3)
Net (income) loss	4		(3)	(17)	(1)
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	25		(2)	106	2
Net (income) loss	(39)		4	(169)	(4)
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	(3)		(3)	(8)	(6)
Net (income) loss	4		4	13	10
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				72	(25)
Reclassification/amortization, Net of Tax Amount				1,374	1,292
Other comprehensive income/(loss), Before Tax Amount	713		683	2,200	1,960
Other comprehensive income/(loss), Tax (Expense)/Benefit	(235)		(222)	(754)	(693)
Other comprehensive income/(loss)	479		461	1,446	1,267
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
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0			0
Unrealized gains/(losses) arising during the period, Net of Tax Amount	0			0
Reclassification/amortization, Before Tax Amount	(22)		(28)	(66)	(81)
Reclassification/amortization, Tax (Expense)/Benefit	7		9	23	29
Reclassification/amortization, Net of Tax Amount	(15)		(19)	(43)	(52)
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		11	106	(57)
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	0		(5)	(36)	20
Unrealized gains/(losses) arising during the period, Net of Tax Amount	1		6	70	(37)
Reclassification/amortization, Before Tax Amount	733		696	2,156	2,079
Reclassification/amortization, Tax (Expense)/Benefit	(242)		(225)	(739)	(735)
Reclassification/amortization, Net of Tax Amount	491		471	1,417	1,344
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		4	3	19
Unrealized gains/(losses) arising during the period, Tax (Expense)/Benefit	(1)		(1)	(1)	(7)
Unrealized gains/(losses) arising during the period, Net of Tax Amount	$ 1		$ 3	$ 2	$ 12