Schedule of Progression of Liabilities Associated with Restructuring Activities, Combined with Reconciliation to Restructuring and Other Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014
Restructuring Cost and Reserve [Line Items]
Beginning Balance			$ 7,029
Expense			3,078
Payments			(6,516)
Adjustments			125
Ending Balance	3,716		3,716
Gain on asset disposal			(313)
Less: joint venture transactions	(84)	(120)	(274)	(1,048)
Restructuring and other expense	2,093	1,398	2,491	(3,781)
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance			6,495
Expense			2,169
Payments			(5,313)
Adjustments			46
Ending Balance	3,397		3,397
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance			534
Expense			909
Payments			(1,203)
Adjustments			79
Ending Balance	$ 319		$ 319