Share-Based Compensation (Share-Based Compensation Expense) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 147.4	$ 127.2	$ 106.5
Income tax benefit	(40.2)	(37.2)	(27.3)
Total share-based compensation expense after taxes	107.2	90.0	79.2
Cost Of License Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	7.1	4.7	3.4
Cost Of Maintenance Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	16.5	15.2	9.8
Cost Of Professional Services Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	5.9	5.3	5.1
Selling And Marketing Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	54.9	39.7	35.1
Research And Development Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	13.0	13.3	10.5
General And Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 50.0	$ 49.0	$ 42.6