Outstanding Loans and Security Agreements - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unpaid principal balance	$ 786,495	$ 1,008,104
Current portion of debt	29,848	20,136
Long-term portion of debt	711,433	921,205
Total	741,281	941,341
Unused Borrowing Capacity	$ 1,220	1,784
Notes due July 2024, Recourse
Debt Instrument [Line Items]
Interest rate percentage	10.00%
Senior secured notes | Senior Secured Notes due March 2025, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 79,698	91,086
Current portion of debt	11,994	11,389
Long-term portion of debt	66,572	78,175
Total	$ 78,566	89,564
Interest rate percentage	5.22%
Term loan | Term Loan due September 2028, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 40,538	41,927
Current portion of debt	2,200	1,389
Long-term portion of debt	34,119	35,551
Total	$ 36,319	36,940
Interest rate percentage	7.50%
Term loan | Senior Secured Notes due October 2020, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 24,723	25,599
Current portion of debt	827	876
Long-term portion of debt	23,089	23,488
Total	$ 23,916	24,364
Interest rate percentage	5.25%
Term loan | Term Loan due December 2021, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 125,456	128,403
Current portion of debt	3,672	2,946
Long-term portion of debt	119,712	122,650
Total	$ 123,384	125,596
Interest rate percentage	2.50%
Term loan | Term Loan due November 2020, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 3,286	5,000
Current portion of debt	1,686	1,690
Long-term portion of debt	1,528	3,197
Total	$ 3,214	4,887
Interest rate percentage	4.00%
Non-recourse debt
Debt Instrument [Line Items]
Unpaid principal balance	$ 353,872	372,318
Current portion of debt	21,162	18,446
Long-term portion of debt	323,360	342,050
Total	344,522	360,496
Unused Borrowing Capacity	$ 1,220	1,784
Convertible promissory notes | Convertible Promissory Notes Interest Rate 8% Due December 2018
Debt Instrument [Line Items]
Unpaid principal balance		244,717
Current portion of debt		0
Long-term portion of debt		244,717
Total		244,717
Interest rate percentage	8.00%
Convertible promissory notes | Convertible Promissory Notes Interest Rate 5% Due December 2020, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 33,104
Current portion of debt	0
Long-term portion of debt	34,706
Total	$ 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	286,069
Current portion of debt	0	0
Long-term portion of debt	263,284	236,724
Total	$ 263,284	236,724
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	7,000	0
Long-term portion of debt	88,555	94,517
Total	$ 95,555	94,517
Interest rate percentage	10.00%
Recourse debt
Debt Instrument [Line Items]
Unpaid principal balance	$ 432,623	635,786
Current portion of debt	8,686	1,690
Long-term portion of debt	388,073	579,155
Total	396,759	580,845
Senior Secured Notes due March 2030, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	83,457	85,303
Current portion of debt	2,469	1,846
Long-term portion of debt	79,868	82,186
Total	$ 82,337	84,032
Interest rate percentage	6.07%
Letters of Credit | Letter of Credit due December 2021, Non-Recourse
Debt Instrument [Line Items]
Unused Borrowing Capacity	$ 1,220	1,784
Variable Interest Entity, Primary Beneficiary
Debt Instrument [Line Items]
Current portion of debt	21,162	18,446
Long-term portion of debt	$ 323,360	$ 342,050