Quarterly report pursuant to Section 13 or 15(d)

Our Portfolio - Equity Method Investments, Additional Information (Details)

v3.10.0.1
Our Portfolio - Equity Method Investments, Additional Information (Details) - USD ($)
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2018
Mar. 31, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]            
Equity method investments $ 461,159,000     $ 461,159,000   $ 522,615,000
Loss from equity method investment (10,583,000)   $ (8,377,000) (8,298,000) $ (12,548,000)  
OTTI on equity method investments       0   0
Investment Contracts [Member]            
Schedule of Equity Method Investments [Line Items]            
Investment in project 11,000,000     11,000,000    
Investment Contracts [Member] | Wind Projects [Member]            
Schedule of Equity Method Investments [Line Items]            
Equity method investments $ 15,000,000     $ 15,000,000   $ 25,000,000
Loss from equity method investment   $ 8,000,000