Changes in Accrued Warranty Balances (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 29, 2012		Feb. 28, 2011		Feb. 29, 2012		Feb. 28, 2011
Product Liability Contingency [Line Items]
Beginning Balance	$ 16,330		$ 15,931		$ 17,196		$ 17,602
Deductions	(4,497)	[1]	(3,434)	[1]	(13,402)	[1]	(14,717)	[1]
Provision charged to SG&A expense	3,295		4,440		11,334		14,052
Ending Balance	$ 15,128		$ 16,937		$ 15,128		$ 16,937

[1] Primarily claims paid during the period.