Schedule of Progression of Liabilities Associated with Restructuring Activities, Combined with Reconciliation to Restructuring and Other Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2015
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 2,484
Expense	5,606
Payments	(7,421)
Adjustments	120
Ending Balance	789	$ 2,484
Net (gain) loss on sale of assets	805
Restructuring and other expense	6,411	7,177	$ 6,927
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,831
Expense	1,854
Payments	(3,505)
Adjustments	73
Ending Balance	253	1,831
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance	653
Expense	3,752
Payments	(3,916)
Adjustments	47
Ending Balance	$ 536	$ 653