Goodwill, Capitalized Software and Other Intangible Assets 3 (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Sep. 30, 2014
Goodwill activity by segment
Balance at March 31, 2014	$ 5,922
Divestiture adjustment	(109)
Foreign currency translation adjustment	(2)
Balance at September 30, 2014	5,811
Mainframe Solutions [Member]
Goodwill activity by segment
Balance at March 31, 2014	4,178
Divestiture adjustment	0
Foreign currency translation adjustment	0
Balance at September 30, 2014	4,178
Enterprise Solutions [Member]
Goodwill activity by segment
Balance at March 31, 2014	1,663
Divestiture adjustment	(109)
Foreign currency translation adjustment	(2)
Balance at September 30, 2014	1,552
Services [Member]
Goodwill activity by segment
Balance at March 31, 2014	81
Divestiture adjustment	0
Foreign currency translation adjustment	0
Balance at September 30, 2014	$ 81