Stock-Based Compensation - Schedule of Employee Service Share-Based Compensation, Allocation of Recognized Period Costs (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,404	$ 1,387	$ 1,117
Income tax benefit	(534)	(527)	(424)
Total stock-based compensation expense, net of tax	870	860	693
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		48	130
Operating Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,404	1,324	949
Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 15	$ 38