Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Schedule Of Significant Accounting Policies [Line Items]
Research and development costs	$ 6,993,000	$ 5,932,000	$ 4,844,000
International subsidiaries accumulated earnings and profits	640,072,000	498,653,000
Cash and Cash Equivalents,Temporary Investments, Maturity Period	90 days
Long-term debt, fair value	153,000	445,000
Minimum exercisable period for outstanding grants of stock options	Three
Maximum exercisable period for outstanding grants of stock options	Four
Maximum [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of Noncontrolling Interest of Consolidated Subsidiaries	10000.00%
Subsidiary [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of Noncontrolling Interest of Consolidated Subsidiaries	100.00%	100.00%	100.00%
Bolivian to U.S Dollar, exchange rate	2.15	4.30
International subsidiaries accumulated earnings and profits	$ 78,287,000	$ 67,287,000