Commitments And Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
May 31, 2013	May 31, 2012	May 31, 2011
Operating Leased Assets [Line Items]
Rental expenses	$ 1,125	$ 1,007	$ 1,057
Maximum
Operating Leased Assets [Line Items]
Operating lease agreements Period	5 years

Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

No definition available.

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration