Accounts Payable and Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2012	Aug. 31, 2012	Nov. 30, 2011	Aug. 31, 2011
Accounts Payable and Accrued Liabilities [Line Items]
Trade payables and other accrued liabilities	$ 222,520	$ 258,316
Accrued payroll and related liabilities	31,137	37,915
Accrued maintenance	10,713	11,475
Accrued warranty	10,102	9,221	8,943	8,645
Income taxes payable	5,827	9,625
Other	2,626	2,956
Accounts payable and accrued liabilities	$ 282,925	$ 329,508