Changes in Accrued Warranty Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Commitments And Contingencies Disclosure [Abstract]
Beginning Balance		$ 10,555	$ 9,863	$ 10,414	$ 11,721
Deductions	[1]	(4,622)	(4,283)	(16,002)	(17,557)
Provision charged to expense		4,804	4,091	16,325	15,507
Ending Balance		$ 10,737	$ 9,671	$ 10,737	$ 9,671

[1] Primarily claims paid during the year.