Changes in Accrued Warranty Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Commitments And Contingencies Disclosure [Abstract]
Beginning Balance		$ 9,440	$ 8,958	$ 11,663	$ 14,741
Acquisition of SPHC and subsidiaries			2,978		2,978
Deductions	[1]	(4,268)	(4,128)	(13,818)	(23,869)
Provision charged to SG&A expense		8,790	3,907	16,117	17,865
Ending Balance		$ 13,962	$ 11,715	$ 13,962	$ 11,715

[1] Primarily claims paid during the year.