Long-Term Debt - Schedule of Fair Value of Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Net deferred financing costs and debt discounts	$ 59,500	$ 54,800
Carrying Value
Debt Instrument [Line Items]
Long-term debt	1,671,772	1,498,711
Estimated Fair Value
Debt Instrument [Line Items]
Long-term debt	$ 1,790,372	1,517,778
SEI | 7.75% convertible senior notes
Debt Instrument [Line Items]
Stated interest rate	7.75%
SEI | Carrying Value | 7.75% convertible senior notes
Debt Instrument [Line Items]
Long-term debt	$ 55,000	55,000
SEI | Estimated Fair Value | 7.75% convertible senior notes
Debt Instrument [Line Items]
Long-term debt	31,408	37,964
Sunnova Energy Corporation | Carrying Value | Notes payable
Debt Instrument [Line Items]
Long-term debt	30	2,428
Sunnova Energy Corporation | Estimated Fair Value | Notes payable
Debt Instrument [Line Items]
Long-term debt	30	2,428
AP4 | Carrying Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	0	92,478
AP4 | Estimated Fair Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	0	92,478
HELI | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	217,420	222,305
HELI | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	228,905	223,895
LAPH | Carrying Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	10,743	42,876
LAPH | Estimated Fair Value | Secured term loan
Debt Instrument [Line Items]
Long-term debt	10,743	42,876
EZOP | Carrying Value | Warehouse credit facility
Debt Instrument [Line Items]
Long-term debt	168,450	121,400
EZOP | Estimated Fair Value | Warehouse credit facility
Debt Instrument [Line Items]
Long-term debt	168,450	121,400
HELII | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	244,914	254,314
HELII | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	299,601	281,850
RAYSI | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	130,546	133,155
RAYSI | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	155,092	139,004
HELIII | Carrying Value | Solar loan-backed notes
Debt Instrument [Line Items]
Long-term debt	149,059	154,573
HELIII | Estimated Fair Value | Solar loan-backed notes
Debt Instrument [Line Items]
Long-term debt	168,524	155,701
SOLI | Carrying Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	412,500	0
SOLI | Estimated Fair Value | Solar asset-backed notes
Debt Instrument [Line Items]
Long-term debt	444,509	0
Revolving credit facility | TEPIIH | Carrying Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	0	234,650
Revolving credit facility | TEPIIH | Estimated Fair Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	0	234,650
Revolving credit facility | TEPH | Carrying Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	193,950	90,325
Revolving credit facility | TEPH | Estimated Fair Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	193,950	90,325
Revolving credit facility | TEPINV | Carrying Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	89,160	95,207
Revolving credit facility | TEPINV | Estimated Fair Value | Line of credit
Debt Instrument [Line Items]
Long-term debt	$ 89,160	$ 95,207