Significant Agreements - Additional Information (Detail) (USD $)	1 Months Ended			3 Months Ended		9 Months Ended		1 Months Ended					1 Months Ended		1 Months Ended		9 Months Ended	3 Months Ended		9 Months Ended		1 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		1 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2013 Boe	May 31, 2013 Boe	Mar. 31, 2013 Boe	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012 Maximum Boe	Sep. 30, 2011 Maximum Boe	Jul. 31, 2011 Sasol	Sep. 30, 2014 Sasol	Sep. 30, 2014 Lanxess	Aug. 31, 2011 Mansfield	Sep. 30, 2014 Mansfield	Aug. 31, 2011 C And N	Sep. 30, 2014 C And N	Sep. 30, 2014 Ethanol Marketing Agreement with Subsidiary of Mansfield Oil Company	Sep. 30, 2014 Biojet Fuel	Sep. 30, 2013 Biojet Fuel	Sep. 30, 2014 Biojet Fuel	Sep. 30, 2013 Biojet Fuel	Aug. 31, 2011 Development and Commercialization Agreements with ICM Inc	Sep. 30, 2014 Development and Commercialization Agreements with ICM Inc	Sep. 30, 2014 Joint Research Development License and Commercialization Agreement with Coca-Cola Company	Sep. 30, 2013 Joint Research Development License and Commercialization Agreement with Coca-Cola Company	Sep. 30, 2014 Joint Research Development License and Commercialization Agreement with Coca-Cola Company	Sep. 30, 2013 Joint Research Development License and Commercialization Agreement with Coca-Cola Company	Mar. 31, 2013 Cargill License Agreement	Mar. 31, 2010 Cargill License Agreement	Sep. 30, 2014 Cargill License Agreement Installment	Dec. 31, 2009 Cargill License Agreement	Sep. 30, 2014 Toray Industries, Inc.	May 31, 2014 Toray Industries, Inc.	Dec. 31, 2013 Toray Industries, Inc.
Parties To Contract [Line Items]
Agreement term										3 years			5 years		3 years
Amount recorded for resale agreement											$ 0
Amount recorded for supply agreement												0		0		0
Terms of agreement																	The ethanol purchase and marketing agreement with C&N was entered into on April 1, 2009 and automatically renews for subsequent one-year terms unless either party terminates the agreement 60 days before the end of a term.						In December 2011, the development agreement was amended to extend the term indefinitely. The development agreement, as amended, may be cancelled by either party with 30 days’ prior written notice.							The Company may terminate the license agreement at any time upon 90 days’ prior written notice. Unless terminated earlier, the license agreement remains in effect until the later of December 31, 2025 and the date that no licensed patent rights remain.
Production, barrels of oil Equivalents	20,000		3,650					45,000	11,000
Hydrocarbon revenue				778,000	704,000	3,426,000	2,016,000											800,000	400,000	1,600,000	1,100,000
Increase Decrease In Production Barrels Of Oil Equivalents		12,500
Commercialization Agreement Period																						2018-10
Grant and other revenue				166,000	406,000	620,000	1,168,000																	0	300,000	0	900,000
Milestone payment																														5
Royalty expense																														4,300,000
Research and development expense				3,723,000	5,476,000	11,414,000	16,280,000																						2,000,000		900,000
Present value of license fee																													1,600,000
Royalty fee payable																														1,000,000
Royalty fee payable, due date																														2015-12
License fees																														500,000
Common stock shares issued																												250,000
Amount received for pilot plant																																1,000,000
Amount refund from pilot plant																																	1,000,000
Refund amount as component of other long term liabilities																																		$ 1,000,000