Derivative Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 1,376	$ 7,017
Embedded derivative | Change in fair value of preferred stock conversion feature embedded derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives		11,975
Interest rate swap | Other income (loss)
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	9	(10)
Commodity futures | Cost of goods sold - Biodiesel
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	(2)
Commodity swaps | Cost of goods sold - Biodiesel
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	1,134	(5,001)
Commodity options | Cost of goods sold - Biodiesel
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 235	$ 53