Outstanding Loans and Security Agreements - Schedule of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Unpaid principal balance	$ 701,278	$ 786,495
Current portion of debt	26,224	29,848
Long-term portion of debt	641,983	711,433
Total	668,207	741,281
Unused Borrowing Capacity	$ 1,220	1,220
Senior secured notes \| Senior Secured Notes due March 2025, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance		79,698
Current portion of debt		11,994
Long-term portion of debt		66,572
Total		78,566
Interest rate percentage	5.22%
Senior secured notes \| Senior Secured Notes due March 2030, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 82,269	83,457
Current portion of debt	2,803	2,469
Long-term portion of debt	78,420	79,868
Total	81,223	82,337
Term loan \| Term Loan due September 2028, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	39,317	40,538
Current portion of debt	2,889	2,200
Long-term portion of debt	32,643	34,119
Total	$ 35,532	36,319
Interest rate percentage	7.50%
Term loan \| Senior Secured Notes due October 2020, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 24,262	24,723
Current portion of debt	957	827
Long-term portion of debt	22,704	23,089
Total	$ 23,661	23,916
Interest rate percentage	5.25%
Term loan \| Term Loan due December 2021, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 123,664	125,456
Current portion of debt	3,894	3,672
Long-term portion of debt	118,058	119,712
Total	$ 121,952	123,384
Interest rate percentage	2.50%
Term loan \| Term Loan due November 2020, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 2,429	3,286
Current portion of debt	1,681	1,686
Long-term portion of debt	695	1,528
Total	$ 2,376	3,214
Interest rate percentage	4.00%
Senior Secured Notes due March 2030, Non-Recourse
Debt Instrument [Line Items]
Interest rate percentage	6.07%
Non-recourse debt
Debt Instrument [Line Items]
Unpaid principal balance	$ 269,512	353,872
Current portion of debt	10,543	21,162
Long-term portion of debt	251,825	323,360
Total	262,368	344,522
Unused Borrowing Capacity	1,220	1,220
Convertible promissory notes \| Convertible Promissory Notes Interest Rate 5% Due December 2020, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	33,104	33,104
Current portion of debt	0	0
Long-term portion of debt	35,576	34,706
Total	$ 35,576	34,706
Interest rate percentage	5.00%
Convertible promissory notes \| Convertible Promissory Notes Interest Rate 6% Due December 2020, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 296,233	296,233
Current portion of debt	0	0
Long-term portion of debt	271,503	263,284
Total	$ 271,503	263,284
Interest rate percentage	6.00%
Notes \| Notes due July 2024, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 100,000	100,000
Current portion of debt	14,000	7,000
Long-term portion of debt	82,384	88,555
Total	$ 96,384	95,555
Interest rate percentage	10.00%		10.00%
Recourse debt
Debt Instrument [Line Items]
Unpaid principal balance	$ 431,766	432,623
Current portion of debt	15,681	8,686
Long-term portion of debt	390,158	388,073
Total	405,839	396,759
Letters of Credit \| Letter of Credit due December 2021, Non-Recourse
Debt Instrument [Line Items]
Unused Borrowing Capacity	1,220	1,220
Variable Interest Entity, Primary Beneficiary
Debt Instrument [Line Items]
Current portion of debt	10,544	21,162
Long-term portion of debt	$ 251,826	$ 323,360

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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