Annual report pursuant to Section 13 and 15(d)

Indebtedness - Schedule of Debt (Details)

v3.8.0.1
Indebtedness - Schedule of Debt (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]    
Long term debt, Current $ 21,529,000 $ 14,153,000
Long term debt, Noncurrent 1,273,416,000 883,870,000
Total 1,294,945,000 898,023,000
Unused Borrowing Capacity 13,191,000 18,738,000
Recourse Debt    
Debt Instrument [Line Items]    
Long term debt, Current 0 0
Long term debt, Noncurrent 247,000,000 244,000,000
Total 247,000,000 244,000,000
Unused Borrowing Capacity 406,000 3,406,000
Recourse Debt | Bank line of credit    
Debt Instrument [Line Items]    
Long term debt, Current 0 0
Long term debt, Noncurrent 247,000,000 244,000,000
Total 247,000,000 244,000,000
Unused Borrowing Capacity 406,000 3,406,000
Recourse Debt | Bank line of credit | Minimum    
Debt Instrument [Line Items]    
Unused Borrowing Capacity 0.0458 0.0396
Recourse Debt | Bank line of credit | Maximum    
Debt Instrument [Line Items]    
Unused Borrowing Capacity 0.0487 0.0575
Non Recourse Debt    
Debt Instrument [Line Items]    
Long term debt, Current 21,529,000 14,153,000
Long term debt, Noncurrent 1,026,416,000 639,870,000
Total 1,047,945,000 654,023,000
Unused Borrowing Capacity 12,785,000 15,332,000
Non Recourse Debt | Senior    
Debt Instrument [Line Items]    
Long term debt, Current 3,561,000 3,020,000
Long term debt, Noncurrent 804,894,000 439,400,000
Total 808,455,000 442,420,000
Unused Borrowing Capacity 12,758,000 14,300,000
Non Recourse Debt | Senior | Minimum    
Debt Instrument [Line Items]    
Unused Borrowing Capacity 0.0363 0.0286
Non Recourse Debt | Senior | Maximum    
Debt Instrument [Line Items]    
Unused Borrowing Capacity 0.0469 0.0450
Non Recourse Debt | Subordinated    
Debt Instrument [Line Items]    
Long term debt, Current 4,301,000 116,000
Long term debt, Noncurrent 107,187,000 42,869,000
Total 111,488,000 42,985,000
Unused Borrowing Capacity 27,000 $ 0
Interest Rate (1)   6.00%
Non Recourse Debt | Subordinated | Minimum    
Debt Instrument [Line Items]    
Unused Borrowing Capacity 0.0636  
Non Recourse Debt | Subordinated | Maximum    
Debt Instrument [Line Items]    
Unused Borrowing Capacity 0.0713  
Non Recourse Debt | Note Payable    
Debt Instrument [Line Items]    
Long term debt, Current   $ 0
Long term debt, Noncurrent   36,232,000
Total   36,232,000
Unused Borrowing Capacity   $ 0
Interest Rate (1)   12.00%
Non Recourse Debt | Securitization Class A    
Debt Instrument [Line Items]    
Long term debt, Current 3,534,000 $ 3,315,000
Long term debt, Noncurrent 82,203,000 87,483,000
Total 85,737,000 90,798,000
Unused Borrowing Capacity $ 0 $ 0
Interest Rate (1) 4.40% 4.40%
Non Recourse Debt | Securitization Class B    
Debt Instrument [Line Items]    
Long term debt, Current $ 440,000 $ 416,000
Long term debt, Noncurrent 9,644,000 10,084,000
Total 10,084,000 10,500,000
Unused Borrowing Capacity $ 0 $ 0
Interest Rate (1) 5.38% 5.38%
Non Recourse Debt | SREC Loans    
Debt Instrument [Line Items]    
Long term debt, Current $ 9,693,000 $ 7,286,000
Long term debt, Noncurrent 22,488,000 23,802,000
Total 32,181,000 31,088,000
Unused Borrowing Capacity $ 0 $ 1,032,000
Interest Rate (1) 7.28% 6.88%