Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended		9 Months Ended																3 Months Ended		9 Months Ended
	May 31, 2013	Aug. 31, 2012	May 31, 2013 Revenues Customer concentration risk Top ten customers	May 31, 2012 Revenues Customer concentration risk Top ten customers	May 31, 2013 Revenues Customer concentration risk Top ten customers	May 31, 2012 Revenues Customer concentration risk Top ten customers	May 31, 2013 United States U.S. Dollars	Aug. 31, 2012 United States U.S. Dollars	May 31, 2013 Taiwan U.S. Dollars	Aug. 31, 2012 Taiwan U.S. Dollars	May 31, 2013 Taiwan New Taiwan Dollars	Aug. 31, 2012 Taiwan New Taiwan Dollars	May 31, 2013 Taiwan Other currencies	Aug. 31, 2012 Taiwan Other currencies	May 31, 2013 China (including Hong Kong) U.S. Dollars	Aug. 31, 2012 China (including Hong Kong) U.S. Dollars	May 31, 2013 China (including Hong Kong) Renminbi	Aug. 31, 2012 China (including Hong Kong) Renminbi	May 31, 2013 China (including Hong Kong) H.K. dollars	Aug. 31, 2012 China (including Hong Kong) H.K. dollars	May 31, 2013 China, Taiwan, Russia and the United States Revenues Customer concentration risk	May 31, 2012 China, Taiwan, Russia and the United States Revenues Customer concentration risk	May 31, 2013 China, Taiwan, Russia and the United States Revenues Customer concentration risk	May 31, 2012 China, Taiwan, Russia and the United States Revenues Customer concentration risk
Concentration of Credit Risk
Cash, cash equivalents and short-term investments	$ 41,367	$ 56,059					$ 18,684	$ 18,744	$ 20,811	$ 34,477	$ 958	$ 2,193	$ 221	$ 235	$ 345	$ 376	$ 347	$ 33	$ 1	$ 1
Concentration risk (as a percent)			40.00%	57.00%	36.00%	55.00%															65.00%	78.00%	63.00%	80.00%