Changes in Accrued Warranty Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 29, 2016
Commitments And Contingencies Disclosure [Abstract]
Beginning Balance		$ 15,954	$ 9,440	$ 13,314	$ 11,663
Deductions	[1]	(3,662)	(4,268)	(12,094)	(13,818)
Provision charged to expense		7,308	8,790	18,380	16,117
Ending Balance		$ 19,600	$ 13,962	$ 19,600	$ 13,962

[1] Primarily claims paid during the year.