Quarterly report pursuant to Section 13 or 15(d)

Debt (Details Textual)

v3.21.2
Debt (Details Textual) - USD ($)
3 Months Ended 9 Months Ended
May 20, 2021
Apr. 22, 2021
Apr. 12, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Jun. 30, 2016
Jun. 02, 2016
Senior Notes | Senior Secured Green Bonds Due 2028                
Debt Instrument [Line Items]                
Face amount $ 550,000,000              
Interest rate 5.875%              
Fees and offering expenses $ 14,619,000              
Default, percentage of principal amount outstanding held 25.00%              
Senior Notes | Senior Secured Green Bonds Due 2028 | Debt Instrument, Redemption, Period One                
Debt Instrument [Line Items]                
Percentage of principal amount redeemed 35.00%              
Redemption price, percentage 105.875%              
Percentage of principal amount outstanding remaining after redemption 65.00%              
Senior Notes | Senior Secured Green Bonds Due 2028 | Debt Instrument, Redemption, Period Two                
Debt Instrument [Line Items]                
Redemption price, percentage 100.00%              
Senior Notes | Senior Secured Green Bonds Due 2028 | Debt Instrument, Redemption, Period Three                
Debt Instrument [Line Items]                
Redemption price, percentage 102.938%              
Senior Notes | Senior Secured Green Bonds Due 2028 | Debt Instrument, Redemption, Period Four                
Debt Instrument [Line Items]                
Redemption price, percentage 101.469%              
Senior Notes | Senior Secured Green Bonds Due 2028 | Debt Instrument, Redemption, Period Five                
Debt Instrument [Line Items]                
Redemption price, percentage 100.00%              
Senior Notes | Senior Secured Green Bonds Due 2028 | Debt Instrument, Redemption, Period Six                
Debt Instrument [Line Items]                
Redemption price, percentage 101.00%              
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%
Redemption price, percentage     100.00%          
Debt paid off       $ 5,000,000   $ 30,008,000    
REG Ralston term loan                
Debt Instrument [Line Items]                
Debt paid off   $ 12,556,000            
REG Capital term loan                
Debt Instrument [Line Items]                
Debt paid off   $ 6,596,000            
Wells Fargo Revolver                
Debt Instrument [Line Items]                
Line of credit         $ 250,000,000      
Line of Credit Facility Additional Increase in Maximum Borrowing Capacity         $ 100,000,000      
Debt instrument, variable rate minimum         0.00%      
Amount required of total current revolving loan commitments         $ 25,000,000      
Wells Fargo Revolver | Minimum                
Debt Instrument [Line Items]                
LIBOR rate margin         1.50%      
Fixed charge coverate ratio         1.0      
Wells Fargo Revolver | Maximum                
Debt Instrument [Line Items]                
LIBOR rate margin         2.00%      
Fixed charge coverate ratio         1.0      
Percentage required of total current revolving loan commitments         10.00%