Stock Plans 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Recognized share-based compensation
Share-based compensation expense before tax	$ 108	$ 97	$ 87
Income tax benefit	(35)	(31)	(28)
Net share-based compensation expense	73	66	59
Costs of Licensing and Maintenance
Recognized share-based compensation
Share-based compensation expense before tax	7	7	5
Cost of Professional Services
Recognized share-based compensation
Share-based compensation expense before tax	3	4	4
Selling and Marketing
Recognized share-based compensation
Share-based compensation expense before tax	37	34	30
General and Administrative
Recognized share-based compensation
Share-based compensation expense before tax	38	35	29
Product Development and Enhancements
Recognized share-based compensation
Share-based compensation expense before tax	$ 23	$ 17	$ 19