Quarterly report pursuant to Section 13 or 15(d)

Indebtedness - Narrative (Details)

v3.19.2
Indebtedness - Narrative (Details) - USD ($)
6 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Debt Instrument [Line Items]    
Loan outstanding balance $ 1,963,182,000 $ 1,748,922,000
Recourse debt    
Debt Instrument [Line Items]    
Loan outstanding balance 239,035,000 247,000,000
Non-recourse debt    
Debt Instrument [Line Items]    
Loan outstanding balance $ 1,724,147,000 1,501,922,000
Non-recourse debt | London Interbank Offered Rate (LIBOR) | Line of credit | Aggregation facility, March 2023    
Debt Instrument [Line Items]    
Facility available period 3 years  
Facility available period, increase 2 years  
Bank line of credit | Recourse debt    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 250,000,000.0  
Minimum unencumbered liquid assets to be maintained 25,000,000  
Debt covenant, liability maintenance $ 30,000,000  
Interest coverage ratio 300.00%  
Loan outstanding balance $ 239,035,000 $ 247,000,000
Bank line of credit | Recourse debt | Minimum    
Debt Instrument [Line Items]    
Interest rate 5.72% 5.45%
Bank line of credit | Recourse debt | Maximum    
Debt Instrument [Line Items]    
Interest rate 5.83% 5.77%
Bank line of credit | Recourse debt | London Interbank Offered Rate (LIBOR)    
Debt Instrument [Line Items]    
Basis spread on variable rate 3.25%  
Bank line of credit | Recourse debt | Base Rate    
Debt Instrument [Line Items]    
Basis spread on variable rate 2.25%  
Bank line of credit | Recourse debt | Federal Funds Rate    
Debt Instrument [Line Items]    
Basis spread on variable rate 0.50%  
Bank line of credit | Recourse debt | LIBOR Floor Rate    
Debt Instrument [Line Items]    
Basis spread on variable rate 1.00%  
Term Loan Due in October 2024 | Non-recourse debt | Senior secured revolving letter of credit facility | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 321,500,000  
Loan outstanding balance 280,500,000  
Term Loan Due in October 2024 | Non-recourse debt | Term Loan | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity 309,000,000.0  
Term Loan Due in October 2024 | Non-recourse debt | Revolving debt | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 12,500,000  
Term Loan A | Non-recourse debt | London Interbank Offered Rate (LIBOR) | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 2.125%  
Term Loan A | Non-recourse debt | Base Rate | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 1.125%  
Term Loan B | Non-recourse debt | Aggregation facility, October 2024 | Minimum    
Debt Instrument [Line Items]    
Term loan prepayment penalty, percent 0.00%  
Term Loan B | Non-recourse debt | Aggregation facility, October 2024 | Maximum    
Debt Instrument [Line Items]    
Term loan prepayment penalty, percent 5.00%  
Term Loan B, Class A | Non-recourse debt | London Interbank Offered Rate (LIBOR) | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 7.03%  
Term Loan B, Class B | Non-recourse debt | London Interbank Offered Rate (LIBOR) | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 5.00%  
Basis spread on Federal Funds Rate 1.00%  
Term Loan B, Class B | Non-recourse debt | Base Rate | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 4.00%  
Term Loan B, Class B | Non-recourse debt | Federal Funds Rate | Aggregation facility, October 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 0.50%  
Term Loan due in April 2024 | Non-recourse debt | Senior secured revolving letter of credit facility | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 202,000,000.0  
Loan outstanding balance 183,400,000  
Term Loan due in April 2024 | Non-recourse debt | Revolving debt | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity 7,000,000.0  
Term Loan due in April 2024 | Non-recourse debt | Delayed draw term loan | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 195,000,000.0  
Term Loan due in April 2024 | Non-recourse debt | London Interbank Offered Rate (LIBOR) | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 2.25%  
Facility available period 4 years  
Term Loan due in April 2024 | Non-recourse debt | Base Rate | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 1.25%  
Term Loan due in April 2024 | Non-recourse debt | Federal Funds Rate | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 0.50%  
Term Loan due in April 2024 | Non-recourse debt | LIBOR Floor Rate | Aggregation facility, April 2024    
Debt Instrument [Line Items]    
Basis spread on variable rate 1.00%  
Term Loan due in March 2023 | Non-recourse debt | Aggregation facility, March 2023    
Debt Instrument [Line Items]    
Loan outstanding balance $ 455,700,000  
Term Loan due in March 2023 | Non-recourse debt | Line of credit | Aggregation facility, March 2023    
Debt Instrument [Line Items]    
Line of credit, maximum borrowing capacity $ 595,000,000.0  
Term Loan due in March 2023 | Non-recourse debt | London Interbank Offered Rate (LIBOR) | Line of credit | Aggregation facility, March 2023    
Debt Instrument [Line Items]    
Basis spread on variable rate 2.50%  
Debt instrument basis spread on variable rate, periodic increase 2.75%  
Subordinated debt | Non-recourse debt    
Debt Instrument [Line Items]    
Loan outstanding balance $ 315,913,000 $ 273,337,000
Subordinated debt | Non-recourse debt | Minimum    
Debt Instrument [Line Items]    
Interest rate 7.03% 7.03%
Subordinated debt | Non-recourse debt | Maximum    
Debt Instrument [Line Items]    
Interest rate 10.00% 10.00%
Subordinated debt | Non-recourse debt | Aggregation facility, March 2023 | Minimum    
Debt Instrument [Line Items]    
Term loan prepayment penalty, percent 0.00%  
Subordinated debt | Non-recourse debt | Aggregation facility, March 2023 | Maximum    
Debt Instrument [Line Items]    
Term loan prepayment penalty, percent 1.00%  
Subordinated debt | Non-recourse debt | London Interbank Offered Rate (LIBOR) | Aggregation facility, March 2023    
Debt Instrument [Line Items]    
Basis spread on variable rate 5.00%  
Facility available period 3 years  
Debt instrument basis spread on variable rate, periodic increase 6.50%  
Bank Term Loan due April 2022 | Non-recourse debt    
Debt Instrument [Line Items]    
Loan outstanding balance $ 19,100,000  
Interest rate 4.50%  
Bank Term Loan due September 2022 | Non-recourse debt    
Debt Instrument [Line Items]    
Basis spread on variable rate 2.25%  
Loan outstanding balance $ 15,400,000  
Bank Term Loan due January 2030 | Non-recourse debt    
Debt Instrument [Line Items]    
Loan outstanding balance $ 118,300,000  
Interest rate 10.00%  
Bank Term Loan due July 2030 | Non-recourse debt    
Debt Instrument [Line Items]    
Loan outstanding balance $ 62,300,000  
Interest rate, spread on stated percentage 6.75%  
Bank Term Loan due July 2030 | Non-recourse debt | Minimum    
Debt Instrument [Line Items]    
Interest rate 2.00%  
Bank Term Loan due July 2030 | Non-recourse debt | Maximum    
Debt Instrument [Line Items]    
Interest rate 3.25%  
Securitization loans | Non-recourse debt | Subsidiary one    
Debt Instrument [Line Items]    
Loan outstanding balance $ 87,700,000  
Secured borrowings assets carrying amount $ 160,900,000 $ 164,700,000
Debt Instrument Discount Rate 0.08%  
Securitization loans | Non-recourse debt | Subsidiary two    
Debt Instrument [Line Items]    
Loan outstanding balance $ 302,700,000  
Debt Instrument Discount Rate 1.47%  
Securitization loans | Non-recourse debt | Subsidiary three    
Debt Instrument [Line Items]    
Loan outstanding balance $ 199,000,000.0  
Debt Instrument Discount Rate 0.01%