Indebtedness - Schedule of Debt (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long term debt, current	$ 269,538	$ 14,153
Long term debt, noncurrent	846,257	883,870
Long term debt	1,115,795	898,023
Unused borrowing capacity	$ 27,141	$ 18,738
Line of Credit \| Minimum
Debt Instrument [Line Items]
Interest rate	3.73%	2.93%
Line of Credit \| Maximum
Debt Instrument [Line Items]
Interest rate	3.81%	3.39%
Recourse debt
Debt Instrument [Line Items]
Long term debt, current	$ 247,000
Long term debt, noncurrent	0	$ 244,000
Long term debt	247,000	244,000
Unused borrowing capacity	406	3,406
Recourse debt \| Bank line of credit
Debt Instrument [Line Items]
Long term debt, current	247,000
Long term debt, noncurrent	0	244,000
Long term debt	247,000	244,000
Unused borrowing capacity	$ 406	$ 3,406
Maturity date	Apr. 30, 2018	Apr. 30, 2018
Recourse debt \| Bank line of credit \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	3.25%	3.25%
Recourse debt \| Bank line of credit \| Minimum
Debt Instrument [Line Items]
Interest rate	4.49%	3.96%
Recourse debt \| Bank line of credit \| Maximum
Debt Instrument [Line Items]
Interest rate	4.52%	5.75%
Recourse debt \| Term loan due April 2024 \| Minimum
Debt Instrument [Line Items]
Interest rate	3.98%
Recourse debt \| Term loan due April 2024 \| Maximum
Debt Instrument [Line Items]
Interest rate	4.06%
Non recourse debt
Debt Instrument [Line Items]
Long term debt, current	$ 22,538	$ 14,153
Long term debt, noncurrent	846,257	639,870
Long term debt	868,795	654,023
Unused borrowing capacity	26,735	15,332
Non recourse debt \| Line of Credit
Debt Instrument [Line Items]
Long term debt, noncurrent	288,400	245,200
Long term debt	288,400	245,200
Unused borrowing capacity	$ 18,300	$ 9,300
Maturity date	Dec. 31, 2020	Dec. 31, 2020
Non recourse debt \| Line of Credit \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	2.50%	2.50%
Non recourse debt \| Term loan due April 2024
Debt Instrument [Line Items]
Long term debt, noncurrent	$ 131,508
Long term debt	131,508
Unused borrowing capacity	$ 3,435
Maturity date	Apr. 30, 2024
Non recourse debt \| Term loan due April 2024 \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	2.75%	2.75%
Non recourse debt \| Term Loan and Term Loan B
Debt Instrument [Line Items]
Long term debt, current	$ 6,179	$ 116
Long term debt, noncurrent	35,940	42,870
Long term debt	$ 42,119	$ 42,986
Interest rate	6.31%	6.00%
Non recourse debt \| Term Loan and Term Loan B \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	5.00%	5.00%
Non recourse debt \| Term Loan
Debt Instrument [Line Items]
Maturity date	Dec. 31, 2020	Dec. 31, 2020
Non recourse debt \| Term Loan \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	5.00%	5.00%
Non recourse debt \| Term Loan B
Debt Instrument [Line Items]
Maturity date	Dec. 31, 2021	Dec. 31, 2021
Non recourse debt \| Term Loan B \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	5.00%	5.00%
Non recourse debt \| Term Loan A
Debt Instrument [Line Items]
Long term debt, current	$ 586	$ 616
Long term debt, noncurrent	144,691	146,387
Long term debt	145,277	147,003
Unused borrowing capacity	$ 5,000	$ 5,000
Interest rate	4.06%	3.64%
Maturity date	Dec. 31, 2021	Dec. 31, 2021
Non recourse debt \| Term Loan A \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	2.75%	2.75%
Non recourse debt \| Bank loans
Debt Instrument [Line Items]
Long term debt, noncurrent	$ 35,661
Long term debt	$ 35,661
Maturity date	Sep. 30, 2020
Non recourse debt \| Bank loans \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	2.75%	2.75%
Non recourse debt \| Bank term loan
Debt Instrument [Line Items]
Long term debt, current	$ 8,839	$ 7,286
Long term debt, noncurrent	22,126	23,802
Long term debt	$ 30,965	31,088
Unused borrowing capacity		$ 1,032
Maturity date	Jul. 31, 2021	Jul. 31, 2021
Non recourse debt \| Bank term loan \| Minimum
Debt Instrument [Line Items]
Interest rate	6.82%	6.25%
Non recourse debt \| Bank term loan \| Maximum
Debt Instrument [Line Items]
Interest rate	10.32%	9.94%
Non recourse debt \| Bank term loan
Debt Instrument [Line Items]
Long term debt, current	$ 1,446	$ 1,331
Long term debt, noncurrent	24,016	26,565
Long term debt	$ 25,462	$ 27,896
Interest rate	4.50%	4.50%
Maturity date	Apr. 30, 2022	Apr. 30, 2022
Non recourse debt \| Bank term loans
Debt Instrument [Line Items]
Long term debt, current	$ 1,578	$ 1,074
Long term debt, noncurrent	31,338	21,249
Long term debt	32,916	$ 22,323
Non recourse debt \| Bank term loans due September 2022, Tranche One
Debt Instrument [Line Items]
Long term debt	$ 12,600
Interest rate	3.48%	2.86%
Maturity date	Sep. 30, 2022	Sep. 30, 2022
Non recourse debt \| Bank term loans due September 2022, Tranche One \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	2.25%	2.25%
Non recourse debt \| Bank term loans due September 2022, Tranche Two
Debt Instrument [Line Items]
Long term debt	$ 20,400
Interest rate	4.33%
Maturity date	Sep. 30, 2022
Non recourse debt \| Bank term loans due September 2022, Tranche Two \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Annual contractual interest rate	3.00%
Non recourse debt \| Solar asset-backed notes
Debt Instrument [Line Items]
Long term debt, current	$ 3,910	$ 3,730
Long term debt, noncurrent	93,359	97,565
Long term debt	$ 97,269	$ 101,295
Non recourse debt \| Solar asset-backed notes - Class A
Debt Instrument [Line Items]
Annual contractual interest rate	4.40%	4.40%
Interest rate	4.40%	4.40%
Maturity date	Jul. 31, 2024	Jul. 31, 2024
Non recourse debt \| Solar asset-backed notes - Class B
Debt Instrument [Line Items]
Annual contractual interest rate	5.38%	5.38%
Interest rate	5.38%	5.38%
Maturity date	Jul. 31, 2024	Jul. 31, 2024
Non recourse debt \| Note payable
Debt Instrument [Line Items]
Long term debt, noncurrent	$ 39,218	$ 36,232
Long term debt	$ 39,218	$ 36,232
Interest rate	12.00%	12.00%
Maturity date	Dec. 31, 2018	Dec. 31, 2018

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

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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

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- 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.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
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- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- 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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- 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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
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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

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-Name Accounting Standards Codification
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-Section S99
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