Quarterly report pursuant to Section 13 or 15(d)

Debt (Details Textual)

v3.19.2
Debt (Details Textual)
1 Months Ended 3 Months Ended 6 Months Ended
Jul. 09, 2019
USD ($)
Jun. 15, 2019
USD ($)
$ / shares
shares
Jun. 02, 2016
USD ($)
d
$ / shares
Jun. 30, 2019
USD ($)
shares
Jun. 30, 2014
USD ($)
$ / shares
Jun. 30, 2019
USD ($)
shares
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Jun. 30, 2016
USD ($)
Debt Instrument [Line Items]                      
Termination of capped call options (in shares) | shares           625,558          
Debt liability component       $ 116,841,000   $ 116,841,000   $ 116,841,000   $ 185,817,000  
Convertible Notes | 2019 Senior Convertible Notes Repurchases                      
Debt Instrument [Line Items]                      
Face amount         $ 143,800,000            
Interest rate       2.75% 2.75% 2.75%   2.75%      
Initial conversion rate         75.3963            
Initial conversion price (in dollars per share) | $ / shares         $ 13.26            
Payment of outstanding principal   $ 67,380,000                  
Settlement of 2019 Convertible Senior Notes conversion premium (in shares) | shares   1,902,781       1,902,781          
Settlement of 2019 Convertible Senior Notes conversion premium share price (in dollars per share)) | $ / shares   $ 9.87                  
Percentage of capped call options purchased that relate to common stock underlying the convertible notes   92.50%                  
Cap price (in dollars per share) | $ / shares   $ 16.02                  
Termination of capped call options (in shares) | shares       625,558              
Net proceeds from debt issuance             $ 0   $ 6,689,000    
Convertible Notes | 2036 Senior Convertible Notes Repurchases                      
Debt Instrument [Line Items]                      
Face amount     $ 152,000,000               $ 152,000,000
Interest rate     4.00%               4.00%
Percentage of convertible senior notes principal required for repurchase     100.00%                
Initial conversion rate     92.8074                
Initial conversion price (in dollars per share) | $ / shares     $ 10.78                
Convertible debt instrument, closing price minimum | $ / shares     $ 14.01                
Convertible debt instrument, threshold percentage of stock price trigger     130.00%                
Convertible debt instrument, threshold trading days | d     20                
Convertible debt instrument, threshold consecutive trading days | d     30                
Net proceeds from debt issuance     $ 147,118,000     $ 0 $ 41,763,000 $ 0 $ 41,763,000    
Fees and offering expenses     $ 4,882,000                
Effective interest rate     2.45%                
Convertible Notes                      
Debt Instrument [Line Items]                      
Face amount       $ 67,380,000   $ 67,380,000   $ 67,380,000      
Interest rate       2.75%   2.75%   2.75%      
Debt liability component       $ 0   $ 0   $ 0   66,361,000  
REG Ralston term loan                      
Debt Instrument [Line Items]                      
Debt liability component       17,350,000   17,350,000   $ 17,350,000   18,948,000  
REG Ralston term loan | Prime Rate                      
Debt Instrument [Line Items]                      
Basis spread on variable rate               2.25%      
REG Danville                      
Debt Instrument [Line Items]                      
Debt liability component       $ 7,924,000   $ 7,924,000   $ 7,924,000   8,964,000  
REG Danville | LIBOR                      
Debt Instrument [Line Items]                      
Basis spread on variable rate               4.00%      
REG Capital term loan                      
Debt Instrument [Line Items]                      
Interest rate       3.99%   3.99%   3.99%      
Debt liability component       $ 7,058,000   $ 7,058,000   $ 7,058,000   $ 7,185,000  
BNP Master Banking Facility Agreement                      
Debt Instrument [Line Items]                      
Line of credit       $ 25,000,000   $ 25,000,000   $ 25,000,000      
BNP Master Banking Facility Agreement | Minimum                      
Debt Instrument [Line Items]                      
Effective interest rate       1.50%   1.50%   1.50%      
BNP Master Banking Facility Agreement | Maximum                      
Debt Instrument [Line Items]                      
Effective interest rate       4.39%   4.39%   4.39%      
Wells Fargo Revolver                      
Debt Instrument [Line Items]                      
Line of credit facility limitation amount       $ 40,000,000   $ 40,000,000   $ 40,000,000      
Debt instrument, variable rate minimum               0.00%      
Percentage required of total current revolving loan commitments               10.00%      
Amount required of total current revolving loan commitments               $ 15,000,000      
Line of credit       150,000,000   150,000,000   $ 150,000,000      
Wells Fargo Revolver | Minimum                      
Debt Instrument [Line Items]                      
LIBOR rate margin               1.75%      
Fixed charge coverate ratio               1.0      
Wells Fargo Revolver | Minimum | Subsequent Event                      
Debt Instrument [Line Items]                      
Additional Increase in maximum borrowing capacity $ 175,000                    
Wells Fargo Revolver | Maximum                      
Debt Instrument [Line Items]                      
Line of credit facility limitation amount       $ 50,000,000   $ 50,000,000   $ 50,000,000      
LIBOR rate margin               2.25%      
Fixed charge coverate ratio               1.0      
Wells Fargo Revolver | Maximum | Subsequent Event                      
Debt Instrument [Line Items]                      
Additional Increase in maximum borrowing capacity $ 200,000