Total Proceeds Received related to Insurance Claims since Date of Loss (Detail) (USD $)	3 Months Ended	6 Months Ended
	Nov. 30, 2014	Nov. 30, 2014
Unusual or Infrequent Item [Line Items]
Total insurance proceeds	$ 1,089,000	$ 11,721,000
Property and equipment
Unusual or Infrequent Item [Line Items]
Total insurance proceeds		6,780,000
Business interruption
Unusual or Infrequent Item [Line Items]
Total insurance proceeds		3,940,000
Other expenses
Unusual or Infrequent Item [Line Items]
Total insurance proceeds		$ 1,001,000