Fair Value Measurement (Details 1) - Contingent Consideration for Acquisition - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
LS9, Inc.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 6,159	$ 8,593	$ 8,624	$ 16,666	$ 17,050	$ 0
Change in estimates included in earnings	1,099	(2,434)	(31)	(1,192)	(384)
Fair value of contingent consideration at measurement date	0				0	17,050
Settlements	0	0	0	0	0
Ending balance	7,258	6,159	8,593	15,474	16,666	17,050
Dynamic Fuels, LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	29,337	29,967	30,695	28,900	0	0
Change in estimates included in earnings	7	313	324	133	0
Fair value of contingent consideration at measurement date	0				28,900	0
Settlements	(111)	(943)	(1,052)	0	0
Ending balance	29,233	29,337	29,967	$ 29,033	$ 28,900	$ 0
Imperium Renewables, Inc.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	0	0
Change in estimates included in earnings	0	0	0
Fair value of contingent consideration at measurement date	5,000
Settlements	0	0	0
Ending balance	$ 5,000	$ 0	$ 0