Stock-Based Compensation - Schedule of Employee Service Share-Based Compensation, Allocation of Recognized Period Costs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Nov. 30, 2012	Nov. 30, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 417	$ 238
Total stock-based compensation expense	417	238
Income tax benefit	158	90
Total stock-based compensation expense, net of tax	259	148
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		25
Operating Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	417	203
Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 10