Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($)	May 31, 2022	May 31, 2021
Deferred tax assets
Accounts receivable	$ 1,695,000	$ 1,244,000
Inventories	6,291,000	4,946,000
Accrued expenses	28,981,000	24,714,000
Net operating loss carry forwards	8,178,000	9,907,000
Stock-based compensation	5,432,000	6,076,000
Operating lease - ROU liability	10,443,000	7,642,000
Other	1,588,000	2,309,000
Total deferred tax assets	62,608,000	56,838,000
Valuation allowance for deferred tax assets	(5,878,000)	(9,124,000)
Net deferred tax assets	56,730,000	47,714,000
Deferred tax liabilities
Property, plant and equipment	(127,859,000)	(111,789,000)
Investment in affiliated companies, principally due to undistributed earnings	(28,274,000)	(24,034,000)
Operating lease - ROU asset	(10,354,000)	(7,102,000)
Derivative contracts	(412,000)	(15,343,000)
Other	(4,963,000)	(3,197,000)
Total deferred tax liability	(171,862,000)	(161,465,000)
Net deferred tax liability	$ (115,132,000)	$ (113,751,000)