Segments: (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013		Sep. 30, 2014	Sep. 30, 2013
Segment Information
Revenue	$ 22,397	$ 23,338	[1]	$ 68,680	$ 70,982	[1]
Income from continuing operations before income taxes	4,361	4,972	[1]	12,891	13,142	[1]
Global Technology Services
Segment Information
Revenue	9,218	9,494		27,962	28,634
Global Business Services
Segment Information
Revenue	4,459	4,558		13,476	13,649
Software
Segment Information
Revenue	5,708	5,798		17,857	17,792
Systems and Technology
Segment Information
Revenue	2,434	2,864	[2]	7,590	9,041	[2]
Global Financing
Segment Information
Revenue	487	502		1,502	1,488
Total Segments
Segment Information
Revenue	22,305	23,216	[2]	68,387	70,604	[2]
Business Segments
Segment Information
Revenue	24,334	25,079	[2]	74,635	76,314	[2]
Income from continuing operations before income taxes	5,195	5,738	[2]	15,386	15,583	[2]
Business Segments | Global Technology Services
Segment Information
Revenue	9,470	9,755		28,701	29,435
Income from continuing operations before income taxes	1,680	1,895		4,876	4,994
Revenue year-to-year change (as a percent)	(2.90%)			(2.50%)
Pre-tax income year-to-year change (as a percent)	(11.30%)			(2.40%)
Pre-tax income margin (as a percent)	17.70%	19.40%		17.00%	17.00%
Business Segments | Global Business Services
Segment Information
Revenue	4,594	4,735		13,892	14,194
Income from continuing operations before income taxes	805	948		2,266	2,274
Revenue year-to-year change (as a percent)	(3.00%)			(2.10%)
Pre-tax income year-to-year change (as a percent)	(15.00%)			(0.30%)
Pre-tax income margin (as a percent)	17.50%	20.00%		16.30%	16.00%
Business Segments | Software
Segment Information
Revenue	6,570	6,542		20,508	20,105
Income from continuing operations before income taxes	2,333	2,410		6,935	6,867
Revenue year-to-year change (as a percent)	0.40%			2.00%
Pre-tax income year-to-year change (as a percent)	(3.20%)			1.00%
Pre-tax income margin (as a percent)	35.50%	36.80%		33.80%	34.20%
Business Segments | Systems and Technology
Segment Information
Revenue	2,616	3,032	[2]	8,131	9,464	[2]
Income from continuing operations before income taxes	(99)	(8)	[2]	(354)	(133)	[2]
Revenue year-to-year change (as a percent)	(13.70%)			(14.10%)
Pre-tax income year-to-year change (as a percent)				167.10%
Pre-tax income margin (as a percent)	(3.80%)	(0.30%)	[2]	(4.40%)	(1.40%)	[2]
Business Segments | Global Financing
Segment Information
Revenue	1,084	1,015		3,403	3,116
Income from continuing operations before income taxes	475	494		1,664	1,582
Revenue year-to-year change (as a percent)	6.90%			9.20%
Pre-tax income year-to-year change (as a percent)	(3.70%)			5.20%
Pre-tax income margin (as a percent)	43.90%	48.70%		48.90%	50.80%
Business Segments | Total Segments
Segment Information
Revenue	24,334	25,079	[2]	74,635	76,314	[2]
Income from continuing operations before income taxes	5,195	5,738	[2]	15,386	15,583	[2]
Revenue year-to-year change (as a percent)	(3.00%)			(2.20%)
Pre-tax income year-to-year change (as a percent)	(9.50%)			(1.30%)
Pre-tax income margin (as a percent)	21.30%	22.90%	[2]	20.60%	20.40%	[2]
Internal transactions
Segment Information
Revenue	(2,029)	(1,863)	[2]	(6,248)	(5,710)	[2]
Income from continuing operations before income taxes	(402)	(280)	[2]	(1,433)	(998)	[2]
Internal transactions | Global Technology Services
Segment Information
Revenue	(252)	(262)		(739)	(801)
Internal transactions | Global Business Services
Segment Information
Revenue	(135)	(177)		(416)	(545)
Internal transactions | Software
Segment Information
Revenue	(862)	(744)		(2,652)	(2,312)
Internal transactions | Systems and Technology
Segment Information
Revenue	(182)	(168)	[2]	(541)	(423)	[2]
Internal transactions | Global Financing
Segment Information
Revenue	(598)	(512)		(1,900)	(1,628)
Internal transactions | Total Segments
Segment Information
Revenue	$ (2,029)	$ (1,863)	[2]	$ (6,248)	$ (5,710)	[2]

[1] Reclassified to reflect discontinued operations presentation. See note 1 on page 9 for additional information.

[2] Reclassified to reflect discontinued operations presentation.