Schedule of Progression of Liabilities Associated with Restructuring Activities, Combined with Reconciliation to Restructuring and Other Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015
Restructuring Cost and Reserve [Line Items]
Beginning Balance			$ 2,484
Expense			3,591
Payments			(4,002)
Adjustments			39
Ending Balance	$ 2,112		2,112
Net (gain) loss on sale of assets			1,009
Restructuring and other expense	3,272	$ 1,523	4,600	$ 4,592
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance			1,831
Expense			1,572
Payments			(2,707)
Adjustments			39
Ending Balance	735		735
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance			653
Expense			2,019
Payments			(1,295)
Ending Balance	$ 1,377		$ 1,377