Total Proceeds Received related to Insurance Claims since Date of Loss (Detail) - USD ($) $ in Thousands	12 Months Ended	45 Months Ended
	May 31, 2015	May 31, 2017
Unusual or Infrequent Item, or Both [Line Items]
Total insurance proceeds	$ 1,248	$ 13,414
Property and equipment
Unusual or Infrequent Item, or Both [Line Items]
Total insurance proceeds		6,892
Business interruption
Unusual or Infrequent Item, or Both [Line Items]
Total insurance proceeds		5,521
Other expenses
Unusual or Infrequent Item, or Both [Line Items]
Total insurance proceeds		$ 1,001