Goodwill, Capitalized Software and Other Intangible Assets 3 (Details) $ in Millions	9 Months Ended
	Dec. 31, 2015 USD ($)
Goodwill activity by segment
Balance at March 31, 2015	$ 5,806
Acquisitions	321
Foreign currency translation adjustment	(4)
Balance at December 31, 2015	6,123
Mainframe Solutions
Goodwill activity by segment
Balance at March 31, 2015	4,178
Acquisitions	0
Foreign currency translation adjustment	0
Balance at December 31, 2015	4,178
Enterprise Solutions
Goodwill activity by segment
Balance at March 31, 2015	1,547
Acquisitions	321
Foreign currency translation adjustment	(4)
Balance at December 31, 2015	1,864
Services
Goodwill activity by segment
Balance at March 31, 2015	81
Acquisitions	0
Foreign currency translation adjustment	0
Balance at December 31, 2015	$ 81