Accrued Expenses and Other Current Liabilities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2012	Oct. 31, 2009	Apr. 30, 2014 Accrued Liabilities	Apr. 30, 2013 Accrued Liabilities	Apr. 30, 2014 Other Long Term Liabilities	Apr. 30, 2013 Other Long Term Liabilities
Accrued Expenses and Other Current Liabilities [Line Items]
Leasehold improvement incentives received	$ 0.6	$ 2.9	$ 1.2	$ 0.7	$ 1.2	$ 2.3