Outstanding Loans and Security Agreements - Schedule of Debt (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Unpaid principal balance	$ 691,541	$ 786,495
Current portion of debt	27,161	29,848
Long-term portion of debt	636,808	711,433
Total	663,969	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	$ 81,686	83,457
Current portion of debt	2,975	2,469
Long-term portion of debt	77,702	79,868
Total	80,677	82,337
Term loan \| Term Loan due November 2020, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	2,000	3,286
Current portion of debt	1,678	1,686
Long-term portion of debt	278	1,528
Total	1,956	3,214
Term loan \| Term Loan due September 2028, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	38,847	40,538
Current portion of debt	3,500	2,200
Long-term portion of debt	31,781	34,119
Total	$ 35,281	36,319
Interest rate percentage	7.50%
Term loan \| Senior Secured Notes due October 2020, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 24,068	24,723
Current portion of debt	987	827
Long-term portion of debt	22,584	23,089
Total	23,571	23,916
Term loan \| Term Loan due December 2021, Non-Recourse
Debt Instrument [Line Items]
Unpaid principal balance	122,603	125,456
Current portion of debt	4,021	3,672
Long-term portion of debt	117,048	119,712
Total	$ 121,069	123,384
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	$ 267,204	353,872
Current portion of debt	11,483	21,162
Long-term portion of debt	249,115	323,360
Total	260,598	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	36,026	34,706
Total	$ 36,026	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	275,716	263,284
Total	$ 275,716	263,284
Interest rate percentage	6.00%
Notes \| Notes due July 2024, Recourse
Debt Instrument [Line Items]
Unpaid principal balance	$ 93,000	100,000
Current portion of debt	14,000	7,000
Long-term portion of debt	75,673	88,555
Total	$ 89,673	95,555
Interest rate percentage	10.00%		10.00%
Recourse debt
Debt Instrument [Line Items]
Unpaid principal balance	$ 424,337	432,623
Current portion of debt	15,678	8,686
Long-term portion of debt	387,693	388,073
Total	403,371	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	11,483	21,162
Long-term portion of debt	$ 249,115	$ 323,360
LIBOR \| Term loan \| Term Loan due November 2020, Recourse
Debt Instrument [Line Items]
LIBOR margin (as a percentage)	4.00%
LIBOR \| Term loan \| Senior Secured Notes due October 2020, Non-Recourse
Debt Instrument [Line Items]
LIBOR margin (as a percentage)	5.25%
LIBOR \| Term loan \| Term Loan due December 2021, Non-Recourse
Debt Instrument [Line Items]
LIBOR margin (as a percentage)	2.50%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebtNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant