Basis of Presentation (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
Basis of Presentation [Abstract]
Standard perpetual license sales, minimum term of maintenance agreement (in years)	1Y		1Y
Multi-product contracts, minimum term of maintenance agreement (in years)	2Y		2Y
Multi-product contracts, maximum term of maintenance agreement (in years)	5Y		5Y
Minimum term over which maintenance fees ratably recognized (in years)	1Y		1Y
Maximum term over which maintenance fees ratably recognized (in years)	5Y		5Y
Research and development costs	$ 22.6	$ 16.2	$ 62.2	$ 51.8
Effective tax rate (in hundredths)			33.10%	37.30%
Reduction to income tax provision			5.0
Valuation allowance				2.2
Cash paid for income taxes			$ 11.6	$ 28.1