Changes in Accrued Warranty Balances (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 28, 2013		Feb. 29, 2012		Feb. 28, 2013		Feb. 29, 2012
Product Liability Contingency [Line Items]
Beginning Balance	$ 15,138		$ 16,330		$ 14,751		$ 17,196
Deductions	(4,908)	[1]	(4,497)	[1]	(12,895)	[1]	(13,402)	[1]
Provision charged to SG&A expense	3,407		3,295		11,781		11,334
Ending Balance	$ 13,637		$ 15,128		$ 13,637		$ 15,128

[1] Primarily claims paid during the year.