Annual report pursuant to Section 13 and 15(d)

Leases - Narrative (Details)

v3.20.4
Leases - Narrative (Details)
 1 Months Ended 12 Months Ended
Dec. 31, 2020
USD ($)
project
Dec. 31, 2020
USD ($)
renewal_option
project
Dec. 31, 2019
USD ($)
project
Dec. 31, 2018
USD ($)
Jan. 31, 2020
USD ($)
Lessee, Lease, Description [Line Items]          
Number of renewal options | renewal_option   1      
Net amortization expense (gains)   $ 228,000 $ 230,000 $ (109,000)  
Proceeds from sale-leaseback financings   $ 0 $ 0 $ 5,145,000  
Maximum combined funding amount         $ 150,000,000
Revolving Credit Facility | Line of Credit          
Lessee, Lease, Description [Line Items]          
Stated interest rate (percent) 3.75% 3.75%      
Remaining borrowing capacity $ 50,011,000 $ 50,011,000      
Solar PV project          
Lessee, Lease, Description [Line Items]          
Solar PV projects sold | project   2 3    
Proceeds from sale-leaseback financings   $ 4,342,000 $ 13,700,000    
Available funding under lending commitment $ 111,705,000 111,705,000      
Solar PV project | Revolving Credit Facility          
Lessee, Lease, Description [Line Items]          
Proceeds from sale-leaseback financings   $ 19,717,000      
Solar PV project | December 2020 Long Term Finance Liability          
Lessee, Lease, Description [Line Items]          
Stated interest rate (percent) 0.00% 0.00%      
Solar PV project | Long-term financing facilities in quarterly installments          
Lessee, Lease, Description [Line Items]          
Solar PV projects sold | project 2        
Stated interest rate (percent) 0.00% 0.00%      
Solar PV project | Long-term financing facilities in quarterly installments | Revolving Credit Facility | Line of Credit          
Lessee, Lease, Description [Line Items]          
Available funding under lending commitment $ 158,000 $ 158,000      
Minimum          
Lessee, Lease, Description [Line Items]          
Operating lease renewal term 6 months 6 months      
Minimum | Long Term Financing Facility          
Lessee, Lease, Description [Line Items]          
Stated interest rate (percent)     0.00%    
Maximum          
Lessee, Lease, Description [Line Items]          
Operating lease renewal term 7 years 7 years      
Maximum | Long Term Financing Facility          
Lessee, Lease, Description [Line Items]          
Stated interest rate (percent)     0.28%