Segments (Details 1) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014		Jun. 30, 2015	Jun. 30, 2014
Segment Information
Revenue	$ 20,813	$ 24,047	[1]	$ 40,403	$ 46,283	[1]
Pre-tax income/(loss) from continuing operations	4,224	5,348	[1]	7,225	8,531	[1]
Total Segments
Segment Information
Revenue	20,778	23,955		40,301	46,083
Global Technology Services
Segment Information
Revenue	8,068	9,010		15,953	17,859
Global Business Services
Segment Information
Revenue	4,345	4,938		8,663	9,902
Software
Segment Information
Revenue	5,830	6,488		11,028	12,149
Systems Hardware
Segment Information
Revenue	2,058	3,014		3,717	5,157
Global Financing
Segment Information
Revenue	478	504		939	1,016
Business Segments | Total Segments
Segment Information
Revenue	22,693	26,074		44,184	50,301
Pre-tax income/(loss) from continuing operations	$ 5,044	$ 6,160		$ 9,110	$ 10,191
Revenue year-to-year change (as a percent)	(13.00%)			(12.20%)
Pre-tax income year-to-year change (as a percent)	(18.10%)			(10.60%)
Pre-tax income margin (as a percent)	22.20%	23.60%		20.60%	20.30%
Business Segments | Global Technology Services
Segment Information
Revenue	$ 8,272	$ 9,257		$ 16,353	$ 18,346
Pre-tax income/(loss) from continuing operations	$ 1,248	$ 1,669		$ 2,242	$ 2,885
Revenue year-to-year change (as a percent)	(10.60%)			(10.90%)
Pre-tax income year-to-year change (as a percent)	(25.20%)			(22.30%)
Pre-tax income margin (as a percent)	15.10%	18.00%		13.70%	15.70%
Business Segments | Global Business Services
Segment Information
Revenue	$ 4,475	$ 5,078		$ 8,923	$ 10,183
Pre-tax income/(loss) from continuing operations	$ 656	$ 1,013		$ 1,253	$ 1,772
Revenue year-to-year change (as a percent)	(11.90%)			(12.40%)
Pre-tax income year-to-year change (as a percent)	(35.30%)			(29.30%)
Pre-tax income margin (as a percent)	14.70%	20.00%		14.00%	17.40%
Business Segments | Software
Segment Information
Revenue	$ 6,600	$ 7,345		$ 12,762	$ 13,939
Pre-tax income/(loss) from continuing operations	$ 2,272	$ 2,683		$ 4,208	$ 4,601
Revenue year-to-year change (as a percent)	(10.10%)			(8.40%)
Pre-tax income year-to-year change (as a percent)	(15.30%)			(8.50%)
Pre-tax income margin (as a percent)	34.40%	36.50%		33.00%	33.00%
Business Segments | Systems Hardware
Segment Information
Revenue	$ 2,165	$ 3,204		$ 3,916	$ 5,515
Pre-tax income/(loss) from continuing operations	$ 255	$ 202		$ 279	$ (255)
Revenue year-to-year change (as a percent)	(32.40%)			(29.00%)
Pre-tax income year-to-year change (as a percent)	26.20%
Pre-tax income margin (as a percent)	11.80%	6.30%		7.10%	(4.60%)
Business Segments | Global Financing
Segment Information
Revenue	$ 1,182	$ 1,189		$ 2,229	$ 2,318
Pre-tax income/(loss) from continuing operations	$ 613	$ 593		$ 1,128	$ 1,188
Revenue year-to-year change (as a percent)	(0.60%)			(3.80%)
Pre-tax income year-to-year change (as a percent)	3.50%			(5.10%)
Pre-tax income margin (as a percent)	51.90%	49.80%		50.60%	51.30%
Internal transactions
Segment Information
Pre-tax income/(loss) from continuing operations	$ (508)	$ (507)		$ (915)	$ (1,031)
Internal transactions | Total Segments
Segment Information
Revenue	(1,915)	(2,119)		(3,883)	(4,218)
Internal transactions | Global Technology Services
Segment Information
Revenue	(204)	(247)		(399)	(488)
Internal transactions | Global Business Services
Segment Information
Revenue	(130)	(140)		(261)	(281)
Internal transactions | Software
Segment Information
Revenue	(770)	(857)		(1,734)	(1,789)
Internal transactions | Systems Hardware
Segment Information
Revenue	(107)	(190)		(199)	(358)
Internal transactions | Global Financing
Segment Information
Revenue	$ (704)	$ (685)		$ (1,290)	$ (1,303)

[1] Reclassified to reflect discontinued operations presentation.