Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - (Details Textual)

v3.7.0.1
Summary of Significant Accounting Policies - (Details Textual)
1 Months Ended 3 Months Ended 6 Months Ended 9 Months Ended 12 Months Ended 16 Months Ended 21 Months Ended
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
shares
Sep. 30, 2015
USD ($)
Apr. 30, 2015
USD ($)
Dec. 31, 2016
USD ($)
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
Mar. 31, 2016
USD ($)
Jun. 30, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
Dec. 31, 2016
USD ($)
renewable_identification_number
shares
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
customer
Dec. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Jun. 02, 2016
USD ($)
Feb. 28, 2015
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Estimated impaired fixed assets     $ 1,414,000 $ 11,027,000           $ 12,441,000              
Insurance recoveries                           $ 2,939,000 $ 19,037,000    
Gain on involuntary conversion                     $ 9,894,000 $ 0 $ 0 1,525,000 8,010,000    
Proceeds from business interruption insurance                     15,060,000            
Capitalization of interest incurred on debt during construction         $ 537,000         $ 897,000 537,000 897,000 1,345,000 537,000 537,000    
Impairment of property, plant and equipment, net         17,893,000 $ 0 $ 0 $ 0     17,893,000 0 0        
Impairment charges due to deteriorating physical condition                     2,300,000            
Change in fair value of convertible debt conversion liability                     $ 13,045,000 0 0        
Shares covered by rebalancing call options                     100.00%            
Revenues                     $ 434,000 624,000 600,000        
Advertising and promotional expenses                     $ 1,746,000 1,288,000 755,000        
Matching contributions                     50.00%            
Participants eligible earnings                     6.00%            
Total expense related to the Company's defined contribution plan                     $ 1,168,000 $ 1,071,000 $ 855,000        
Cash, coverage by U.S. FDIC         250,000           250,000     250,000 250,000    
Customer A                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Number of customers | customer                         1        
February 2015                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Stock repurchase program, amount authorized to be repurchased                                 $ 30,000,000
Stock repurchase program, amount repurchased                 $ 6,687,000                
Share repurchase program, shares repurchased (in shares) | shares                 738,448                
March 2016                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Stock repurchase program, amount authorized to be repurchased               $ 50,000,000                  
Stock repurchase program, amount repurchased                     $ 44,019,000            
Share repurchase program, shares repurchased (in shares) | shares                     5,070,375            
Convertible Senior Notes | 2036 Convertible Notes                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Face amount   $ 152,000,000         $ 152,000,000   $ 152,000,000             $ 152,000,000  
Interest rate   4.00%         4.00%   4.00%             4.00%  
Share repurchase program, shares repurchased (in shares) | shares   4,060,323                              
Net proceeds from debt issuance                               $ 147,118,000  
Convertible Senior Notes | 2019 Convertible Notes                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Net proceeds from debt issuance $ 5,584,000 $ 61,954,000     $ 5,584,000 $ 5,584,000 $ 61,954,000   $ 61,954,000   $ 5,584,000     $ 5,584,000 $ 5,584,000    
Principal amount of debt repurchased $ 6,000,000 $ 63,912,000                 $ 6,000,000            
Services                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Minimum percentage increase in fair value of each of the reporting units over its carrying value through annual impairment test                     16.00%            
Emporia                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Impairment of property, plant and equipment, net                     $ 15,593,000            
Minimum                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
RINs per gallon | renewable_identification_number                     1.5            
Allowed RINs per gallon | renewable_identification_number                     0            
Maximum                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
RINs per gallon | renewable_identification_number                     1.7            
Allowed RINs per gallon | renewable_identification_number                     2.5            
In-process research and development                                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Useful life                     15 years