Accrued Expenses and Other Current Liabilities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2013	Oct. 31, 2009	Apr. 30, 2012 Accrued Liabilities	Apr. 30, 2012 Other Long Term Liabilities
Accrued Liabilities And Other Non Current Liabilities [Line Items]
Leasehold improvement incentives received		$ 2.9
Lease incentive liability			0.7	2.3
Leasehold improvement incentives received	$ 0.6