Schedule of Progression of Liabilities Associated with Restructuring Activities, Combined with Reconciliation to Restructuring and Other Expense (Income) (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 2,541	$ 7,029
Expense	14,104	4,589
Payments	(13,228)	(9,262)
Adjustments	(933)	185
Ending Balance	2,484	2,541	$ 7,029
Net (gain) loss on sale of assets	(6,927)	2,338
Restructuring and other expense	7,177	6,927	(1,876)
Early Retirement And Severance
Restructuring Cost and Reserve [Line Items]
Beginning Balance	2,170	6,495
Expense	6,137	3,323
Payments	(5,746)	(7,694)
Adjustments	(730)	46
Ending Balance	1,831	2,170	6,495
Facility Exit And Other Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance	371	534
Expense	7,967	1,266
Payments	(7,482)	(1,568)
Adjustments	(203)	139
Ending Balance	$ 653	$ 371	$ 534