Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012 Y	Mar. 31, 2011	Mar. 31, 2010
Summary of Significant Accounting Policies (Textual) [Abstract]
Interest income on finance receivables	$ 7.2	$ 12.9	$ 11.4
Allowance for doubtful trade accounts receivable	5.1	3.6
Allowance for doubtful trade finance receivables	0.6	0.5
Provision (recovery) for bad debts	1.6	1.7	(0.3)
Amounts charged against allowance for doubtful accounts	0.1	0.2	1.3
Estimated useful lives of property and equipment, excluding leasehold improvements, minimum	3
Estimated useful lives of property and equipment, excluding leasehold improvements, maximum	5
Estimated useful lives of leasehold improvements, minimum	3
Estimated useful lives of leasehold improvements, maximum	10
Estimated useful lives of internal-use software development costs, minimum	3
Estimated useful lives of internal-use software development costs, maximum	7
Capitalized software development costs	144.5	124.0	85.9
Amortized software development costs	93.6	75.7	63.1
Effect of change in foreign currency rates on capitalized software development costs	0	0	0.1
Interest capitalized on software development costs	4.9	4.4	2.3
Capitalized share-based compensation costs	12.0	8.2	4.9
Estimated economic lives of intangible assets, minimum	1
Estimated economic lives of intangible assets, maximum	5
Minimum term of maintenance arrangements	1
Maximum term of maintenance arrangements	3
Extended term of maintenance arrangements	up to five years
Deferred sales commission	$ 69.8	$ 78.7
Maturity period to classify investments as short-term investments	twelve months or less
Maturity period to classify investments as long-term investments	more than twelve months