Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Noncontrolling Interests in Consolidated Entities
Balance at Dec. 31, 2009	$ 30,202	$ 12	$ 604,571	$ (630,032)	$ 55,651
Balance, shares at Dec. 31, 2009		11,821
Net income	(5,350)	0	0	19,933	(25,283)
Capital contributions for noncontrolling interests in consolidated entities	23,871	0	0	0	23,871
Issuance of common stock under stock plans, net of stock award forfeitures	15	0	15	0	0
Issuance of common stock under stock plans, net of stock award forfeitures, shares		16
Issuance of common stock from convertible debt	3,227	0	3,227	0	0
Issuance of common stock from convertible debt, shares		773
Deconsolidation of Vercipia Biofuels LLC upon the adoption of authoritative accounting guidance	(6,527)	0	0	4,124	(10,651)
Sale of noncontrolling interest	(43,588)	0	0	0	(43,588)
Share-based compensation	1,320	0	1,320	0	0
Balance at Dec. 31, 2010	3,170	12	609,133	(605,975)	0
Balance, shares at Dec. 31, 2010		12,610
Net income	5,518	0	0	5,518	0
Issuance of common stock under stock plans, net of stock award forfeitures	2	0	2	0	0
Issuance of common stock under stock plans, net of stock award forfeitures, shares		1
Share-based compensation	1,437	0	1,437	0	0
Balance at Dec. 31, 2011	10,127	12	610,572	(600,457)	0
Balance, shares at Dec. 31, 2011	12,611	12,611
Net income	18,213	0	0	18,213	0
Issuance of common stock under stock plans, net of stock award forfeitures	501	1	500	0	0
Issuance of common stock under stock plans, net of stock award forfeitures, shares		172
Derecognition of warrant derivative liability	744	0	744	0	0
Share-based compensation	1,068	0	1,068	0	0
Balance at Dec. 31, 2012	$ 30,653	$ 13	$ 612,884	$ (582,224)	$ 0
Balance, shares at Dec. 31, 2012	12,783	12,783