Components of Inventory Balances (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule Of Inventory [Line Items]
Finished goods	$ 247	$ 192
Work in process	209	224
Spare parts	1,382	1,195
Total inventories	3,723	3,581
Corn
Schedule Of Inventory [Line Items]
Raw materials	1,301	1,456
Enzymes And Other Inputs
Schedule Of Inventory [Line Items]
Raw materials	$ 584	$ 514