Total Proceeds Received related to Insurance Claims since Date of Loss (Detail) (USD $)	3 Months Ended
	Aug. 31, 2014
Unusual or Infrequent Item [Line Items]
Total insurance proceeds	$ 10,088,000
Property and equipment
Unusual or Infrequent Item [Line Items]
Total insurance proceeds	5,547,000
Business interruption
Unusual or Infrequent Item [Line Items]
Total insurance proceeds	3,747,000
Other expenses
Unusual or Infrequent Item [Line Items]
Total insurance proceeds	$ 794,000