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Acquisitions - Additional Information (Details) - USD ($)
1 Months Ended 3 Months Ended
Jul. 14, 2016
Jun. 30, 2016
Jun. 30, 2017
Sep. 30, 2017
Wyoming Refining Company        
Business Acquisition [Line Items]        
Consideration transferred $ 209,400,000      
Adjustment to WRC environmental liability (other non-current liabilities)     $ 2,000,000  
Adjustment to inventory     500,000  
Adjustments to goodwill     $ 1,500,000  
Other Long Term Assets | Wyoming Refining Company        
Business Acquisition [Line Items]        
Acquisition deposit   $ 5,000,000    
Secured Debt | Wyoming Refining Company        
Business Acquisition [Line Items]        
Aggregate principal amount 65,000,000      
Wyoming Refining Senior Secured Term Loan | Secured Debt | Wyoming Refining Company        
Business Acquisition [Line Items]        
Long-term debt 58,036,000      
Wyoming Refining Senior Secured Revolver | Revolving Credit Facility | Wyoming Refining Company        
Business Acquisition [Line Items]        
Long-term debt $ 10,100,000      
Convertible Subordinated Bridge Notes        
Business Acquisition [Line Items]        
Debt instrument, interest rate 2.50%      
5.00% Convertible Senior Notes due 2021        
Business Acquisition [Line Items]        
Debt instrument, interest rate 5.00%     5.00%
5.00% Convertible Senior Notes due 2021 | Convertible Debt        
Business Acquisition [Line Items]        
Debt instrument, interest rate       5.00%
Aggregate principal amount $ 115,000,000