Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Feb. 28, 2013	Feb. 29, 2012	May 31, 2012
Income Tax Contingency [Line Items]
Federal statutory corporate rate	35.00%
Estimated annualized income tax rate			2.50%
Income tax payments	$ 0	$ 0.1
Received income tax refunds (less than $0.1 million in the nine-month period ending February 29, 2012)	0
Net deferred tax assets	12.4		13.7
Net deferred tax assets classified as current	9.7		10.7
Valuation allowances			5.2
Significant reserves for uncertain tax positions including related interest and penalties	0
Fiscal Year 2013
Income Tax Contingency [Line Items]
Estimated annualized income tax rate	7.90%
Tax Years 2007 Through 2010
Income Tax Contingency [Line Items]
Adjustment following IRS review of tax returns	0
Maximum
Income Tax Contingency [Line Items]
Received income tax refunds (less than $0.1 million in the nine-month period ending February 29, 2012)		$ 0.1