Schedule of Progression of Liabilities Associated with Restructuring Activities, Combined with Reconciliation to Restructuring and Other Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 7,029
Expense (Income)	100
Payments	(2,968)
Adjustments	243
Ending Balance	4,404
Less: joint venture transactions	(107)	(142)
Restructuring and other expense (income)	(7)	(3,997)
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance	6,495
Expense (Income)	(30)
Payments	(2,334)
Adjustments	30
Ending Balance	4,161
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance	534
Expense (Income)	130
Payments	(634)
Adjustments	213
Ending Balance	$ 243