Goodwill, Capitalized Software and Other Intangible Assets 3 (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Sep. 30, 2013	Mar. 31, 2013
Goodwill activity by segment
Balance at March 31, 2013	$ 5,871
Revision to preliminary purchase price allocation of prior year acquisition	(6)
Balance at March 31, 2013 as revised		5,865
Acquisitions	54
Foreign currency translation adjustment	1
Balance at September 30, 2013	5,920
Mainframe Solutions [Member]
Goodwill activity by segment
Balance at March 31, 2013	4,178
Revision to preliminary purchase price allocation of prior year acquisition	0
Balance at March 31, 2013 as revised		4,178
Acquisitions	0
Foreign currency translation adjustment	0
Balance at September 30, 2013	4,178
Enterprise Solutions [Member]
Goodwill activity by segment
Balance at March 31, 2013	1,612
Revision to preliminary purchase price allocation of prior year acquisition	(6)
Balance at March 31, 2013 as revised		1,606
Acquisitions	54
Foreign currency translation adjustment	1
Balance at September 30, 2013	1,661
Services [Member]
Goodwill activity by segment
Balance at March 31, 2013	81
Revision to preliminary purchase price allocation of prior year acquisition	0
Balance at March 31, 2013 as revised		81
Acquisitions	0
Foreign currency translation adjustment	0
Balance at September 30, 2013	$ 81