Share-Based Compensation (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Share-based compensation expense
Total share-based compensation expense	$ 30.8	$ 25.9	$ 61.6	$ 51.0
Cost of license revenue [Member]
Share-based compensation expense
Total share-based compensation expense	1.2	0.7	2.3	1.5
Cost of maintenance revenue [Member]
Share-based compensation expense
Total share-based compensation expense	3.8	2.2	7.3	4.5
Cost of professional services revenue [Member]
Share-based compensation expense
Total share-based compensation expense	1.2	1.3	2.5	2.2
Selling and marketing expenses [Member]
Share-based compensation expense
Total share-based compensation expense	10.0	8.8	19.1	17.5
Research and development expenses [Member]
Share-based compensation expense
Total share-based compensation expense	3.6	2.7	6.5	4.8
General and administrative expenses [Member]
Share-based compensation expense
Total share-based compensation expense	$ 11.0	$ 10.2	$ 23.9	$ 20.5