Accounting for Share-Based Compensation 1 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Recognized share-based compensation
Share-based compensation expense before tax	$ 25	$ 23	$ 54	$ 45
Income tax benefit	(8)	(7)	(18)	(14)
Net share-based compensation expense	17	16	36	31
Costs of Licensing and Maintenance
Recognized share-based compensation
Share-based compensation expense before tax	1	1	3	3
Cost of Professional Services
Recognized share-based compensation
Share-based compensation expense before tax	1	1	2	2
Selling and Marketing
Recognized share-based compensation
Share-based compensation expense before tax	9	8	19	16
General and Administrative
Recognized share-based compensation
Share-based compensation expense before tax	8	9	19	16
Product Development and Enhancements
Recognized share-based compensation
Share-based compensation expense before tax	$ 6	$ 4	$ 11	$ 8