Share-Based Compensation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Share-based compensation expense
Total share-based compensation expense	$ 31.1	$ 25.3	$ 92.7	$ 76.3
Cost of license revenue [Member]
Share-based compensation expense
Total share-based compensation expense	1.1	0.9	3.4	2.4
Cost of maintenance revenue [Member]
Share-based compensation expense
Total share-based compensation expense	3.7	2.5	11.0	7.0
Cost of professional services revenue [Member]
Share-based compensation expense
Total share-based compensation expense	1.4	1.3	3.9	3.5
Selling and marketing expenses [Member]
Share-based compensation expense
Total share-based compensation expense	9.3	8.2	28.4	25.7
Research and development expenses [Member]
Share-based compensation expense
Total share-based compensation expense	3.1	2.3	9.6	7.1
General and administrative expenses [Member]
Share-based compensation expense
Total share-based compensation expense	$ 12.5	$ 10.1	$ 36.4	$ 30.6