Fair Value - Estimated Fair Values and Carrying Values for Customer Receivables and Debt Instruments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	May 01, 2020	Mar. 31, 2020	Mar. 30, 2020	Dec. 31, 2019
Senior secured notes | Senior Secured Notes due March 2030, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	$ 77,846				$ 80,016
Senior secured notes | Senior Secured Notes due March 2030, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument					87,618
Senior secured notes | 2.5% green convertible senior notes due August 2025 | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	98,212
Senior secured notes | 2.5% green convertible senior notes due August 2025 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	293,135
Term loan | Term Loan due November 2020, Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	278				1,536
Term loan | Term Loan due November 2020, Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	287				1,590
Term loan | Term Loan due September 2028, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	32,717				34,969
Term loan | Term Loan due September 2028, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	36,665				41,108
Term loan | Term Loan due December 2021, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	117,145				120,437
Term loan | Term Loan due December 2021, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	117,457				120,510
Convertible promissory notes | Convertible Promissory Notes due December 2019 and 2020, Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	0				36,482
Convertible promissory notes | Convertible Promissory Notes due December 2019 and 2020, Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	0				32,070
Convertible promissory notes | 10% convertible promissory notes due December 20211 | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	99,379				273,410
Convertible promissory notes | 10% convertible promissory notes due December 20211 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	234,816				302,047
Notes | 10% notes due July 2024 | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	76,743				89,962
Notes | 10% notes due July 2024 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	71,385				97,512
Notes | 10.25% senior secured notes due March 2027 | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	68,526				0
Notes | 10.25% senior secured notes due March 2027 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	59,747				0
Customer financing receivables | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Customer financing receivables	52,066				55,855
Customer financing receivables | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Customer financing receivables	$ 43,623				$ 44,002
Term Loan due November 2020, Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	4.00%				4.00%
Term Loan due November 2020, Recourse | Term loan | LIBOR
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
LIBOR margin (as a percentage)	4.00%
10% notes due July 2024 | Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	10.00%				10.00%
Term Loan due September 2028, Non-Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	7.50%				7.50%
Senior Secured Notes due March 2030, Non-Recourse | Senior secured notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	6.07%				6.07%
Senior Secured Notes due March 2030, Non-Recourse | Senior secured notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	$ 89,079
Term Loan due December 2021, Non-Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	2.50%				2.50%
10% convertible promissory notes due December 20211 | Convertible promissory notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	10.00%
10.25% senior secured notes due March 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage		10.25%
10.25% senior secured notes due March 2027 | Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	10.25%
Convertible Promissory Notes Interest Rate 5% Due December 2020, Recourse | Convertible promissory notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	5.00%		10.00%	5.00%	5.00%