Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011
Income Taxes [Line Items]
U.S. income (loss) before income taxes	$ 5,000,000	$ (4,900,000)	$ (4,200,000)
Foreign income (loss) before income taxes	500,000	100,000	(600,000)
Foreign tax expense	0	0	0
Valuation allowance	12,537,000	12,797,000
Net deferred tax assets	6,466,000	13,275,000
Total amount of gross unrecognized tax benefits, if recognized that would impact effective tax rate	700,000
Accrued interest and penalties included in long-term tax liability	100,000	200,000
Liability decreased relating to unrecognized tax benefits, interest	44,000
Liability decreased relating to unrecognized tax benefits, penalties	51,000
Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating Loss Carryforwards	10,800,000
Net operating loss carryforward, expiration year	2030
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Research and development credit carryforward expiration period	2014
Research and development credit carryforward expiration period	2030
Operating Loss Carryforwards	19,800,000
Australia and New Zealand Discontinued Operations [Member]
Income Taxes [Line Items]
Valuation allowance	10,900,000
Deferred tax benefit, net	10,900,000
Federal Alternative Minimum [Member]
Income Taxes [Line Items]
Tax Credit Carryforward Amount	3,500,000
Research and Development [Member]
Income Taxes [Line Items]
Tax Credit Carryforward Amount	1,700,000
Research and development credit carryforward expiration period	2025
Research and development credit carryforward expiration period	2032
Small Ethanol Producer [Member]
Income Taxes [Line Items]
Tax Credit Carryforward Amount	2,600,000
Tax credit carryforward, expiration year	2014
Valuation allowance		1,800,000
Valuation allowance, amount reduced	100,000
Charitable Contributions [Member]
Income Taxes [Line Items]
Research and development credit carryforward expiration period	2013
Research and development credit carryforward expiration period	2015
Valuation allowance		44,000
Valuation allowance, amount reduced	$ 22,000
Charitable contribution deduction limitation as a percentage of taxable income	10.00%
Carry forward period allowed	5 years