Accounting for Share-Based Compensation 1 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Recognized share-based compensation
Share-based compensation expense before tax	$ 35	$ 29	$ 68	$ 61
Income tax benefit	(8)	(9)	(16)	(20)
Net share-based compensation expense	27	20	52	41
Costs of Licensing and Maintenance
Recognized share-based compensation
Share-based compensation expense before tax	2	2	4	4
Cost of Professional Services
Recognized share-based compensation
Share-based compensation expense before tax	0	0	1	1
Selling and Marketing
Recognized share-based compensation
Share-based compensation expense before tax	11	10	21	20
General and Administrative
Recognized share-based compensation
Share-based compensation expense before tax	13	11	25	23
Product Development and Enhancements
Recognized share-based compensation
Share-based compensation expense before tax	$ 9	$ 6	$ 17	$ 13