Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Sale-Leaseback (Details)

v3.7.0.1
Summary of Significant Accounting Policies - Sale-Leaseback (Details)
 3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
project
Jun. 30, 2016
USD ($)
project
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Sep. 30, 2016
USD ($)
Sale Leaseback Transaction [Line Items]          
Sale Price     $ 21,454,000 $ 11,008,000  
Solar Photovoltaic Projects          
Sale Leaseback Transaction [Line Items]          
Maximum combined funding amount         $ 100,000,000
Number of Solar PV Projects Sold | project 4 3      
Sale Price $ 12,671,000 $ 7,467,000      
Deferred Gain Recorded 932,000 0 932,000 0  
Deferred Loss Recorded 144,000 124,000      
Capital Lease Asset/Liability Recorded $ 5,774,000 $ 4,266,000 $ 5,774,000 $ 4,266,000  
Initial Lease Term 20 years 20 years   20 years  
Percentage of fair value threshold, integral equipment     10.00%    
Net amortization expense $ (15,000) $ (8,000) $ (24,000) $ (31,000)  
Solar Photovoltaic Projects | Minimum          
Sale Leaseback Transaction [Line Items]          
Initial Lease Term     10 years    
Lease Payment 4,000 8,000      
Solar Photovoltaic Projects | Maximum          
Sale Leaseback Transaction [Line Items]          
Initial Lease Term     20 years    
Lease Payment $ 252,000 $ 389,000