Changes in Accrued Warranty Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Commitments And Contingencies Disclosure [Abstract]
Beginning Balance		$ 10,112	$ 7,421	$ 11,663	$ 14,741
Deductions	[1]	(4,890)	(5,066)	(9,550)	(19,741)
Provision charged to SG&A expense		4,218	6,603	7,327	13,958
Ending Balance		$ 9,440	$ 8,958	$ 9,440	$ 8,958

[1] Primarily claims paid during the year.