Stock Plans 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Recognized share-based compensation
Share-based compensation expense before tax	$ 120	$ 108	$ 97
Income tax benefit	(37)	(35)	(31)
Net share-based compensation expense	83	73	66
Costs of Licensing and Maintenance
Recognized share-based compensation
Share-based compensation expense before tax	8	7	7
Cost of Professional Services
Recognized share-based compensation
Share-based compensation expense before tax	3	3	4
Selling and Marketing
Recognized share-based compensation
Share-based compensation expense before tax	38	37	34
General and Administrative
Recognized share-based compensation
Share-based compensation expense before tax	45	38	35
Product Development and Enhancements
Recognized share-based compensation
Share-based compensation expense before tax	$ 26	$ 23	$ 17