Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Sales Leaseback (Details)

v3.6.0.2
Summary of Significant Accounting Policies - Sales Leaseback (Details) - Solar Photovaltaic Projects
 12 Months Ended
Dec. 31, 2016
USD ($)
project
Dec. 31, 2015
USD ($)
project
Sep. 30, 2016
USD ($)
Sale Leaseback Transaction [Line Items]      
Maximum combined funding amount     $ 100,000,000
Number of Solar-PV Projects Sold | project 6 3  
Sale Price $ 17,045,000 $ 12,506,000  
Deferred Gain Recorded 906,000 933,000  
Deferred Loss Recorded 145,000 924,000  
Capital Lease Asset/Liability Recorded $ 8,830,000 $ 6,810,000  
Initial Lease Term   20 years  
Percentage of fair value threshold integral equipment 10.00%    
Net amortization expense $ (24,000)    
Minimum      
Sale Leaseback Transaction [Line Items]      
Initial Lease Term 20 years    
Lease Payment $ 2,000 $ 7,000  
Maximum      
Sale Leaseback Transaction [Line Items]      
Initial Lease Term 25 years    
Lease Payment $ 397,000 $ 348,000