Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	May 31, 2020	May 31, 2019
Deferred tax assets
Accounts receivable	$ 1,246	$ 1,516
Inventories	5,554	5,649
Accrued expenses	21,214	21,195
Net operating loss carry forwards	11,732	16,433
Stock-based compensation	6,931	10,989
Derivative contracts	1,920	2,054
Operating lease - ROU liability	7,294
Other	3,549	316
Total deferred tax assets	59,440	58,152
Valuation allowance for deferred tax assets	(11,178)	(14,619)
Net deferred tax assets	48,262	43,533
Deferred tax liabilities
Property, plant and equipment	(95,553)	(91,732)
Investment in affiliated companies, principally due to undistributed earnings	(15,884)	(23,035)
Operating lease - ROU asset	(6,241)
Other	(2,526)	(2,868)
Total deferred tax liability	(120,204)	(117,635)
Net deferred tax liability	$ (71,942)	$ (74,102)