Annual report pursuant to Section 13 and 15(d)

Energy Assets - Additional Information (Details)

v3.10.0.1
Energy Assets - Additional Information (Details)
 12 Months Ended
Dec. 31, 2018
USD ($)
project
developer
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Property, Plant and Equipment [Line Items]      
Energy assets, net $ 459,952,000 $ 356,443,000  
Capital lease assets 42,402,000 38,725,000  
Less - accumulated depreciation and amortization (4,139,000) (2,049,000)  
Capital lease assets, net 38,263,000 36,676,000  
Project asset depreciation 27,305,000 21,648,000 $ 19,377,000
Depreciation and amortization expense on capital lease assets $ 2,090,000 1,305,000 $ 570,000
Number of developers current year solar projects were purchased from | developer 2    
Asset retirement obligation, project assets $ 897,000    
Asset retirement obligation 897,000 0  
Renewal Energy Program      
Property, Plant and Equipment [Line Items]      
Energy assets 619,708,000 488,818,000  
Less - accumulated depreciation and amortization (159,756,000) (132,375,000)  
Energy assets, net $ 459,952,000 $ 356,443,000  
Solar Projects 2018      
Property, Plant and Equipment [Line Items]      
Number of projects acquired | project 12    
Fair value of consideration $ 72,921,000    
Contingent consideration liabilities 5,437,000    
Payments to acquire businesses $ 62,116,000    
Scenario, Plan      
Property, Plant and Equipment [Line Items]      
Number of projects acquired | project 6    
Scenario, Plan | Solar Projects 2018      
Property, Plant and Equipment [Line Items]      
Number of projects acquired | project 6