Changes in Accrued Warranty Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015
Commitments And Contingencies Disclosure [Abstract]
Beginning Balance		$ 15,233	$ 10,112	$ 13,314	$ 11,663
Deductions	[1]	(5,942)	(4,890)	(8,432)	(9,550)
Provision charged to expense		6,663	4,218	11,072	7,327
Ending Balance		$ 15,954	$ 9,440	$ 15,954	$ 9,440

[1] Primarily claims paid during the year.