Accrued Loss Reserves (Detail) - USD ($) $ in Thousands	May 31, 2021	May 31, 2020
Schedule Of Accrued Liabilities [Line Items]
Accrued losses	$ 29,054	$ 20,021
Accrued Loss Reserves - Noncurrent	36,627	34,654
Accrued product liability reserves
Schedule Of Accrued Liabilities [Line Items]
Accrued losses	18,296	10,458
Accrued Loss Reserves - Noncurrent	26,614	27,016
Accrued warranty reserves
Schedule Of Accrued Liabilities [Line Items]
Accrued losses	9,429	7,593
Accrued Loss Reserves - Noncurrent	3,746	3,513
Accrued environmental reserves
Schedule Of Accrued Liabilities [Line Items]
Accrued losses	1,329	1,970
Accrued Loss Reserves - Noncurrent	$ 6,267	$ 4,125