Segment Information 1 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Segment information
Revenue	$ 1,140		$ 1,152		$ 2,268		$ 2,297
Income before interest and income taxes	359		337		587		718
Reconciliation of segment profit to income before income taxes
Segment profit	359		337		587		718
Software development costs capitalized	(8)		(42)		(31)		(78)
Share-based compensation expense	21		21		41		44
Other (gains) expenses, net	7	[1]	8	[2]	125	[3]	2	[2]
Interest expense, net	13		10		24		21
Income before income taxes	346		327		563		697
Purchased Software Products [Member]
Reconciliation of segment profit to income before income taxes
Amortization of intangible ssets	31		27		59		54
Other Intangible Assets [Member]
Reconciliation of segment profit to income before income taxes
Amortization of intangible ssets	15		13		29		27
Internally Developed Software Products [Member]
Reconciliation of segment profit to income before income taxes
Amortization of intangible ssets	42		40		83		77
Mainframe Solutions [Member]
Segment information
Revenue	624		619		1,243		1,247
Expenses	228		250		470		511
Income before interest and income taxes	396		369		773		736
Segment operating margin	63.00%		60.00%		62.00%		59.00%
Depreciation	13		16		26		32
Reconciliation of segment profit to income before income taxes
Segment profit	396		369		773		736
Enterprise Solutions [Member]
Segment information
Revenue	419		438		830		864
Expenses	357		409		727		766
Income before interest and income taxes	62		29		103		98
Segment operating margin	15.00%		7.00%		12.00%		11.00%
Depreciation	9		11		18		22
Reconciliation of segment profit to income before income taxes
Segment profit	62		29		103		98
Services [Member]
Segment information
Revenue	97		95		195		186
Expenses	88		89		178		176
Income before interest and income taxes	9		6		17		10
Segment operating margin	9.00%		6.00%		9.00%		5.00%
Depreciation	0		0		0		0
Reconciliation of segment profit to income before income taxes
Segment profit	9		6		17		10
Total Reportable Segments [Member]
Segment information
Revenue	1,140		1,152		2,268		2,297
Expenses	673		748		1,375		1,453
Income before interest and income taxes	467		404		893		844
Segment operating margin	41.00%		35.00%		39.00%		37.00%
Depreciation	22		27		44		54
Reconciliation of segment profit to income before income taxes
Segment profit	$ 467		$ 404		$ 893		$ 844

[1] Other (gains) expenses, net consists of approximately $2 million of costs associated with the Fiscal 2014 Plan, certain foreign exchange derivative hedging gains and losses, and other miscellaneous costs.

[2] Other (gains) expenses, net consists of certain foreign exchange derivative hedging gains and losses, and other miscellaneous costs.

[3] Other (gains) expenses, net consists of approximately $122 million of costs associated with the Fiscal 2014 Plan, certain foreign exchange derivative hedging gains and losses, and other miscellaneous costs.Three Months Ended September 30, 2012 MainframeSolutions EnterpriseSolutions Services Total(dollars in millions)Revenue $619 $438 $95 $1,152Expenses 250 409 89 748Segment profit $369 $29 $6 $404Segment operating margin 60% 7% 6% 35%Depreciation $16 $11 $— $27