Fair Value - Estimated Fair Values and Carrying Values for Customer Receivables and Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Jul. 01, 2017	Dec. 31, 2016	Sep. 30, 2016	Jul. 31, 2014	Mar. 31, 2013	Dec. 31, 2012
Senior secured notes | Senior Secured Notes due March 2025, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	$ 78,566	$ 89,564
Senior secured notes | Senior Secured Notes due March 2025, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	80,838	95,114
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	82,337	84,032
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	85,917	93,264
Term loan | Term Loan due September 2028, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	36,319	36,940
Term loan | Term Loan due September 2028, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	39,892	46,713
Term loan | Senior Secured Notes due October 2020, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	23,916	24,364
Term loan | Senior Secured Notes due October 2020, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	25,441	27,206
Term loan | Term Loan due December 2021, Non-Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	123,384	125,596
Term loan | Term Loan due December 2021, Non-Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	123,040	131,817
Term loan | Term Loan due November 2020, Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	3,214	4,887
Term loan | Term Loan due November 2020, Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	3,311	5,148
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	34,706	0
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	31,546	0
Convertible promissory notes | Convertible Promissory Notes One due December 2020 | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	263,284	236,724
Convertible promissory notes | Convertible Promissory Notes One due December 2020 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	353,368	219,094
Notes | Notes due July 2024, Recourse | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	95,555	94,517
Notes | Notes due July 2024, Recourse | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument	99,260	106,124
Customer financing receivables | Net Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Customer financing receivables	72,676	77,885
Customer financing receivables | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Customer financing receivables	51,541	55,255
Affiliated entity | 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	244,717
Affiliated entity | 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	$ 211,000
Term Loan due November 2020, Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	4.00%
Term Loan due November 2020, Recourse | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	4.00%
Term Loan due December 2021, Non-Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	2.50%
Term Loan due December 2021, Non-Recourse | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	2.50%
Senior Secured Notes due October 2020, Non-Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	5.25%
Senior Secured Notes due October 2020, Non-Recourse | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	5.25%
Senior Secured Notes due March 2025, Non-Recourse | Senior secured notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	5.22%
Term Loan due September 2028, Non-Recourse | Term loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	7.50%
Convertible Promissory Notes Interest Rate 8% Due December 2019 And 2020, Recourse | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	8.00%
Convertible Promissory Notes Interest Rate 5% Due December 2019 And 2020, Recourse [Member] | Convertible promissory notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	5.00%
Convertible Promissory Notes due December 2020, Recourse | Convertible promissory notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	6.00%		6.00%
Convertible Promissory Notes due December 2020, Recourse | Affiliated entity | Convertible promissory notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage			6.00%	6.00%	5.00%
Notes due July 2024, Recourse
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	10.00%
Notes due July 2024, Recourse | Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	10.00%
PPA Company II | Senior Secured Notes due March 2025, Non-Recourse | Senior secured notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate percentage	5.22%						5.22%
PPA Company IIIa | 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%
PPA Company IV | 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%