Share-Based Compensation (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Share-based compensation expense
Total share-based compensation expense	$ 127.2	$ 106.5	$ 88.9
Income tax benefit	(37.2)	(27.3)	(27.2)
Total share-based compensation expense after taxes	90.0	79.2	61.7
Cost of license revenue [Member]
Share-based compensation expense
Total share-based compensation expense	4.7	3.4	2.5
Cost of maintenance revenue [Member]
Share-based compensation expense
Total share-based compensation expense	15.2	9.8	7.9
Cost of professional services revenue [Member]
Share-based compensation expense
Total share-based compensation expense	5.3	5.1	3.9
Selling and marketing expenses [Member]
Share-based compensation expense
Total share-based compensation expense	39.7	35.1	31.6
Research and development expenses [Member]
Share-based compensation expense
Total share-based compensation expense	13.3	10.5	10.1
General and administrative expenses [Member]
Share-based compensation expense
Total share-based compensation expense	$ 49.0	$ 42.6	$ 32.9