Changes in Accrued Warranty Balances (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2014		Nov. 30, 2013		Nov. 30, 2014		Nov. 30, 2013
Product Liability Contingency [Line Items]
Beginning Balance	$ 7,421		$ 9,842		$ 14,741		$ 9,330
Deductions	(5,066)	[1]	(7,179)	[1]	(19,741)	[1]	(11,975)	[1]
Provision charged to SG&A expense	6,603		5,916		13,958		11,224
Ending Balance	$ 8,958		$ 8,579		$ 8,958		$ 8,579

[1] Primarily claims paid during the year.