Stock-Based Compensation - Schedule of Share Based Compensation Stock Options Activity (Detail) (USD $)	6 Months Ended				6 Months Ended
	Feb. 28, 2013	Feb. 28, 2013 Outstanding Ending Balance Option Price Range [Member]	Feb. 28, 2013 Exercisable Ending Balance Option Price Range [Member]	Aug. 31, 2012 Outstanding Beginning Balance Option Price Range [Member]	Feb. 28, 2013 Granted During Period Option Price Range [Member]	Feb. 28, 2013 Cancelled During Period Option Price Range [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, beginning of period, Shares				1,824,916
Options outstanding, end of period, Shares		1,819,452		1,824,916
Shares, Granted					100,000
Weighted-Average Exercise Price, Options Outstanding end of period (in USD per share)		$ 10.79		$ 10.94
Shares, Exercised	(35,500)
Weighted Average Remaining Term, Outstanding, Ending Balance (in years)		3 years 9 months 4 days
Shares, Cancelled						(69,964)
Options exercisable, end of period, Shares			1,216,453
Weighted-Average Exercise Price, Options Outstanding beginning of period (in USD per share)				$ 10.94
Weighted-Average Exercise Price, Granted (in USD per share)					$ 7.97
Weighted-Average Exercise Price, Exercised (in USD per share)	$ 5.65
Weighted-Average Exercise Price, Cancelled (in USD per share)						$ 13.43
Weighted-Average Exercise Price, Options Exercisable, end of period (in USD per share)			$ 13.16
Weighted Average Remaining Term, Options Exercisable (in years)			2 years 7 months 17 days
Aggregate Intrinsic value, Outstanding, Ending Balance		$ 3,841,500
Aggregate Intrinsic value, Options Exercisable			$ 1,341,700