Schedule of Progression of Liabilities Associated with Restructuring Activities, Combined with Reconciliation to Restructuring and Other Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2017	Aug. 31, 2016
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 789
Expense	2,161
Payments	(1,132)
Adjustments	258
Ending Balance	2,076
Net (gain) loss on sale of assets	143
Restructuring and other expense	2,304	$ 1,328
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance	253
Expense	1,877
Payments	(182)
Adjustments	127
Ending Balance	2,075
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance	536
Expense	284
Payments	(950)
Adjustments	131
Ending Balance	$ 1