Annual report pursuant to Section 13 and 15(d)

Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Details)

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Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
transaction
Dec. 31, 2017
USD ($)
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments $ 471,044,000 $ 522,615,000
Receivables 945,000,000  
Real estate 387,000,000  
Investments 170,000,000  
Total 1,951,000,000  
Average remaining balance 10,000,000  
Financing receivables on non accrual status $ 0 $ 0
Number of transactions | transaction 170  
Total aggregate remaining balance $ 64,000,000  
Maximum [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Average remaining balance 1,000,000  
Investment Grade by Independent Rating Agency [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Total financing receivable 9,000,000  
Renewable Energy Projects [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments 449,000,000  
Commercial Investment Grade [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Receivables 148,000,000  
Real estate 365,000,000  
Investments 68,000,000  
Total 581,000,000  
Average remaining balance $ 6,000,000  
Commercial Investment Grade [Member] | Credit Concentration Risk [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and real estate portfolio 39.00%  
Commercial Investment Grade [Member] | Renewable Energy Projects [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments $ 0  
Commercial Non-Investment Grade [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Receivables 299,000,000  
Real estate 0  
Investments 0  
Total 299,000,000  
Average remaining balance 14,000,000  
Increase in finance receivables 18,000,000  
Financing receivables on non accrual status $ 8,000,000  
Commercial Non-Investment Grade [Member] | Credit Concentration Risk [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and real estate portfolio 20.00%  
Commercial Non-Investment Grade [Member] | Renewable Energy Projects [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments $ 0  
Government [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Receivables 498,000,000  
Real estate 0  
Investments 102,000,000  
Total 600,000,000  
Average remaining balance $ 12,000,000  
Government [Member] | Credit Concentration Risk [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and real estate portfolio 41.00%  
Government [Member] | Renewable Energy Projects [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments $ 0  
Subtotal, Debt and Real Estate [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Receivables 945,000,000  
Real estate 365,000,000  
Investments 170,000,000  
Total 1,480,000,000  
Average remaining balance $ 9,000,000  
Subtotal, Debt and Real Estate [Member] | Credit Concentration Risk [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and real estate portfolio 100.00%  
Subtotal, Debt and Real Estate [Member] | Renewable Energy Projects [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments $ 0  
Equity Method Investments [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Receivables 0  
Real estate 22,000,000  
Investments 0  
Total 471,000,000  
Average remaining balance 16,000,000  
Equity Method Investments [Member] | Renewable Energy Projects [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments 449,000,000  
U.S. Federal Government [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Total financing receivable 384,000,000  
State, Local, Institutions [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Total financing receivable 216,000,000  
Residential Solar Loan [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Loans receivable $ 273,000,000