Segment and Geographic Information 1 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Mar. 31, 2011
Segment information
Revenue	$ 4,643		$ 4,814		$ 4,429
Income from continuing operations before interest and income taxes	1,362		1,389		1,254
Depreciation and amortization	477		401		379
Reconciliation of segment profit to income from continuing operations before income taxes
Segment profit	1,362		1,389		1,254
Depreciation and amortization	477		401		379
Share-based compensation expense	78		89		80
Other (gains) expenses, net	0	[1]	1	[1]	(6)	[1]
Interest expense, net	44		35		45
Income from continuing operations before income taxes	1,318		1,354		1,209
Mainframe Solutions [Member]
Segment information
Revenue	2,489		2,612		2,479
Expenses	1,016		1,140		1,129
Income from continuing operations before interest and income taxes	1,473		1,472		1,350
Segment operating margin	59.00%		56.00%		54.00%
Depreciation and amortization	103		99		102
Reconciliation of segment profit to income from continuing operations before income taxes
Segment profit	1,473		1,472		1,350
Depreciation and amortization	103		99		102
Enterprise Solutions [Member]
Segment information
Revenue	1,772		1,820		1,623
Expenses	1,612		1,668		1,501
Income from continuing operations before interest and income taxes	160		152		122
Segment operating margin	9.00%		8.00%		8.00%
Depreciation and amortization	157		134		116
Reconciliation of segment profit to income from continuing operations before income taxes
Segment profit	160		152		122
Depreciation and amortization	157		134		116
Services [Member]
Segment information
Revenue	382		382		327
Expenses	358		359		310
Income from continuing operations before interest and income taxes	24		23		17
Segment operating margin	6.00%		6.00%		5.00%
Depreciation and amortization	0		0		0
Reconciliation of segment profit to income from continuing operations before income taxes
Segment profit	24		23		17
Depreciation and amortization	0		0		0
Total Reportable Segments [Member]
Segment information
Revenue	4,643		4,814		4,429
Expenses	2,986		3,167		2,940
Income from continuing operations before interest and income taxes	1,657		1,647		1,489
Segment operating margin	36.00%		34.00%		34.00%
Depreciation and amortization	260		233		218
Reconciliation of segment profit to income from continuing operations before income taxes
Segment profit	1,657		1,647		1,489
Depreciation and amortization	260		233		218
Amortization of Intangible Assets [Member] | Purchased Software Products [Member]
Segment information
Depreciation and amortization	163	[2]	103		88
Reconciliation of segment profit to income from continuing operations before income taxes
Depreciation and amortization	163	[2]	103		88
Amortization of Intangible Assets [Member] | Other Intangible Assets [Member]
Segment information
Depreciation and amortization	54		65		73
Reconciliation of segment profit to income from continuing operations before income taxes
Depreciation and amortization	$ 54		$ 65		$ 73

[1] Other (gains) expenses, net consists of other unallocated costs including foreign exchange derivative (gains) losses, and other miscellaneous costs

[2] Amount includes impairment recorded in the fourth quarter of fiscal year 2013 of $55 million relating to purchased software (see Note 6, “Long Lived Assets,” in the Notes to the Consolidated Financial Statements for additional information).