Changes in Accrued Warranty Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Beginning Balance		$ 12,836	$ 10,069	$ 11,106	$ 10,414
Deductions	[1]	(7,652)	(5,721)	(13,582)	(11,380)
Provision charged to expense		6,866	6,207	14,526	11,521
Ending Balance		$ 12,050	$ 10,555	$ 12,050	$ 10,555

[1] Primarily claims paid during the year.