Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	May 31, 2017	May 31, 2016
Deferred tax assets
Accounts receivable	$ 2,157	$ 2,786
Inventories	6,624	6,418
Accrued expenses	30,065	34,035
Net operating loss carry forwards	13,256	12,756
Tax credit carry forwards	3,206	3,127
Stock-based compensation	17,668	22,452
Other	205	210
Total deferred tax assets	73,181	81,784
Valuation allowance for deferred tax assets	(12,987)	(11,796)
Net deferred tax assets	60,194	69,988
Deferred tax liabilities
Property, plant and equipment	(42,599)	(35,521)
Investment in affiliated companies, principally due to undistributed earnings	(46,001)	(42,967)
Derivative contracts	(1,745)	(6,395)
Other	(4,149)	(2,484)
Total deferred tax liabilities	(94,494)	(87,367)
Net deferred tax liability	$ (34,300)	$ (17,379)