Annual report pursuant to Section 13 and 15(d)

Our Portfolio - Receivables and Investments, Additional Information (Details)

v3.10.0.1
Our Portfolio - Receivables and Investments, Additional Information (Details) - USD ($)
1 Months Ended 12 Months Ended
Nov. 30, 2018
Jan. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]          
Principal payments on non-recourse debt $ 250,000,000   $ 390,537,000 $ 79,459,000 $ 69,097,000
Proceeds from pre-payment premium 9,000,000        
Unamortized loan costs and fees 4,000,000        
Costs related to debt repayment 9,000,000   9,245,000 0 $ 0
Financing receivables on non accrual status     0 0  
Provision for credit losses     0 0  
Loan modifications that qualify as troubled debt restructurings     0 $ 0  
Land [Member]          
Financing Receivable, Recorded Investment, Past Due [Line Items]          
Proceeds from lease payments   $ 1,600,000      
American Wind Capital Company, LLC [Member]          
Financing Receivable, Recorded Investment, Past Due [Line Items]          
Commercial receivables, carrying value that became past due     8,000,000    
Residential Solar Loan [Member]          
Financing Receivable, Recorded Investment, Past Due [Line Items]          
Loans receivable     273,000,000    
Commercial Non-Investment Grade [Member]          
Financing Receivable, Recorded Investment, Past Due [Line Items]          
Financing receivables on non accrual status     $ 8,000,000    
SunStrong [Member] | Investment Grade [Member]          
Financing Receivable, Recorded Investment, Past Due [Line Items]          
Collections of loans $ 307,000,000