Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Income Taxes [Line Items]
Loss from continuing operations before income taxes related to domestic operations		$ 4,800,000	$ 4,800,000	$ 14,300,000
Tax Credit Carryforward Amount	1,800,000	1,800,000
Research and development credit carryforward expiration peiod	2013
Research and development credit carryforward expiration peiod	2015
Valuation allowance	44,000	44,000
Tax credit carryforwards related to expiration period		2014
Charitable contribution deduction limitation as a percentage of taxable income	10.00%
Carry forward period allowed	5 years
Net deferred tax assets	13,275,000	13,275,000	13,604,000
Total amount of gross unrecognized tax benefits, if recognized that would impact effective tax rate	1,100,000	1,100,000
Accrued interest and penalties included in long-term tax liability	200,000	200,000	200,000
Liability increase relating to unrecognized tax benefits, interest		11,000
Liability increase relating to unrecognized tax benefits, penalties		6,000
Tax refund	3,500,000	3,500,000
Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating Loss Carryforwards	18,700,000	18,700,000
Net operating loss carryforward, expiration year		2030
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Research and development credit carryforward expiration peiod		2013
Research and development credit carryforward expiration peiod		2030
Operating Loss Carryforwards	20,800,000	20,800,000
Federal Alternative Minimum [Member]
Income Taxes [Line Items]
Tax Credit Carryforward Amount	3,400,000	3,400,000
Research and Development [Member]
Income Taxes [Line Items]
Tax Credit Carryforward Amount	1,400,000	1,400,000
Research and development credit carryforward expiration peiod		2025
Research and development credit carryforward expiration peiod		2032
Small Ethanol Producer [Member]
Income Taxes [Line Items]
Tax Credit Carryforward Amount	$ 2,800,000	$ 2,800,000
Tax credit carryforward, expiration year		2014