Debt - Additional Information (Detail) (USD $)	3 Months Ended			1 Months Ended	3 Months Ended		3 Months Ended				1 Months Ended						3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	May 11, 2011	Jan. 24, 2013 Convertible Senior Subordinated Notes	Mar. 31, 2013 Convertible Senior Subordinated Notes	Jan. 24, 2013 Convertible Senior Subordinated Notes Early Conversion Payment	Mar. 31, 2013 HSBC Facility	Mar. 26, 2013 HSBC Facility	Mar. 31, 2013 HSBC Facility U.S Dollar	Mar. 31, 2013 HSBC Facility Foreign Currency	May 31, 2011 Manufacturing facility l T	Jun. 30, 2010 Promissory note Purchased equipment	May 31, 2011 Promissory note Manufacturing facility	May 11, 2011 Term loan	Mar. 26, 2013 Facility	May 11, 2011 Facility	Mar. 31, 2013 Silicon valley bank term loan	Dec. 31, 2012 Silicon valley bank term loan
Debt Instrument [Line Items]
Interest costs related to the Company's total debt	$ 1,600,000	$ 200,000
Amount borrowed												265,000	5,500,000	15,000,000
Final payment due												Jan. 01, 2015
Interest rate												9.00%
Credit facility maximum borrowing			20,000,000					30,000,000						15,000,000		5,000,000
Outstanding balance under the credit facility							10,400,000											11,200,000
Loan and security agreement termination date																	March 26, 2013
Fermenters production facility											128,000
Annual oil production capacity											1,820
Annual oil production capacity, in units											2,000,000
Purchase price of production facility											11,500,000
First payment due date of principal													2012-03
Second payment due date of principal													2013-02
Imputed interest rate													3.25%
Amount of discount	8,132,000			5,300,000									300,000
Aggregate principal amount of debt				125,000,000
Debt instrument, fixed interest rate				6.00%
Interest payment, beginning date				Aug. 01, 2013
Maturity date of debt				Feb. 01, 2018			Mar. 26, 2015
Net proceeds from Note offering	119,750,000			119,300,000
Debt issuance costs					400,000		200,000
Conversion rate of convertible note into shares of common stock				121.1240
Principal amount of convertible notes, denominator				1,000		1,000
Conversion price of per share				$ 8.26
Conversion price of per principal amount						$ 83.33
Upon a fundamental change, Company to pay a percentage of the principal amount				100.00%
Cash and unrestricted cash equivalents															$ 30,000,000
Additional percent of aggregate letter of credit under revolving facility															110.00%
Commitment fee	2.50%
Line of credit facility maturity date	Mar. 26, 2015
Outstanding balance under the credit facility							2.00%		105.00%	110.00%
Interest rate for total debt outstanding							2.80%