Accounts Payable and Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2013	Feb. 28, 2013	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Aug. 31, 2011
Accounts Payable and Accrued Liabilities [Line Items]
Trade payables and other accrued liabilities	$ 214,883		$ 258,316
Accrued payroll and related liabilities	35,643		37,915
Income taxes payable	13,166		9,625
Accrued maintenance	10,951		11,475
Accrued warranty	9,983	10,289	9,221	10,447	9,297	8,645
Other	2,338		2,956
Accounts payable and accrued liabilities	$ 286,964		$ 329,508