Annual report pursuant to Section 13 and 15(d)

Leases - Narrative (Details)

v3.19.3.a.u2
Leases - Narrative (Details)
12 Months Ended
Dec. 31, 2019
USD ($)
project
Dec. 31, 2018
USD ($)
project
Dec. 31, 2017
USD ($)
project
Jan. 31, 2020
USD ($)
Aug. 31, 2019
USD ($)
Jul. 31, 2019
Jan. 01, 2019
USD ($)
Lessee, Lease, Description [Line Items]              
Operating lease assets $ 32,791,000           $ 31,639,000
Current portions of operating lease liabilities 5,802,000           5,084,000
Long-term portions of operating lease liabilities 29,101,000           28,480,000
Operating leases, rent expense 8,179,000 $ 6,463,000 $ 6,362,000        
Maximum combined funding amount         $ 100,000,000    
Proceeds from sale-leaseback financings 0 $ 5,145,000 $ 51,204,000        
Available funding under lending commitment $ 81,000,000            
Minimum              
Lessee, Lease, Description [Line Items]              
Operating lease renewal term 6 months            
Maximum              
Lessee, Lease, Description [Line Items]              
Operating lease renewal term 7 years            
Solar PV project              
Lessee, Lease, Description [Line Items]              
Number of projects sold then leased back to separate investor | project   2 1        
Solar PV projects sold | project 3 2 13        
Proceeds from sale-leaseback financings $ 13,700,000            
Long Term Financing Facility              
Lessee, Lease, Description [Line Items]              
Stated interest rate (percent)           0.28%  
Long Term Financing Facility | Minimum              
Lessee, Lease, Description [Line Items]              
Stated interest rate (percent) 0.00%            
Long Term Financing Facility | Maximum              
Lessee, Lease, Description [Line Items]              
Stated interest rate (percent) 0.28%            
Subsequent Event              
Lessee, Lease, Description [Line Items]              
Maximum combined funding amount       $ 150,000,000      
Accounting Standards Update 2016-02              
Lessee, Lease, Description [Line Items]              
Operating lease assets             31,639,000
Current portions of operating lease liabilities             5,084,000
Long-term portions of operating lease liabilities             $ 28,480,000