Power Purchase Agreement Programs - Additional Information (Details)		1 Months Ended	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 14, 2019 USD ($) MW	Jul. 31, 2019 USD ($)	Jun. 30, 2019 USD ($) variable_interest_entity	Jun. 30, 2018 USD ($)	Dec. 31, 2019 MW	Jun. 30, 2019 USD ($) variable_interest_entity MW	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Variable Interest Entity [Line Items]
Standard warranty period (years)						1 year
Number of variable interest entities | variable_interest_entity			6			6
Redeemable noncontrolling interest			$ 505,000			$ 505,000		$ 57,261,000
Sale of Energy Savers | MW						9.7
Revenue			233,782,000	$ 168,881,000		$ 434,489,000	$ 338,242,000
Energy Server repurchased | MW						10
Cost of revenue			(192,109,000)	(136,110,000)		$ (377,061,000)	(261,805,000)
Energy servers installed | MW						9
Debt payoff make-whole penalty						$ 5,934,000	0
Interest expense			$ 18,300,000	25,200,000
Revenue from related parties						93,204,000	30,925,000
Payments to acquire equity method investments	$ 57,500,000
Possible indemnification amount						97,200,000
Possible indemnification, tax expense (benefit) amount						(7,500,000)
Purchase Agreement, Possible Indemnification, Cash Collateral						(20,000,000)
Tariff Damages Collateral						57,200,000
Forced outage event, purchase price of REC						45
Distributions to noncontrolling and redeemable noncontrolling interests						(7,753,000)	(11,582,000)
Decrease in inventories						(27,542,000)	46,172,000
Decrease in property plant and equipment						19,800,000
Increase in deferred revenue and customer current liabilities						(25,411,000)	(31,817,000)
Increase in accrued other current liabilities						7,213,000	(12,815,000)
Commitment to redeem noncontrolling interest						$ 18,690,000	0
Minimum
Variable Interest Entity [Line Items]
Term of power purchase agreements (years)			10 years			10 years
Maximum
Variable Interest Entity [Line Items]
Term of power purchase agreements (years)			21 years			21 years
PPA II
Variable Interest Entity [Line Items]
Number of megawatts available for purchase | MW	18
Number of megawatts decommissioned | MW	19
Number of megawatts available for repurchase | MW	11
Number of replacement megawatts | MW	9
Additional funding needed to complete upgrade						$ 92,000,000
Variable Interest Entity, Primary Beneficiary | PPA II
Variable Interest Entity [Line Items]
Energy Server repurchased | MW						10
Adjustment for hypothetical liquidation at book value						$ 300,000
Repayments of debt and interest						77,700,000
Repayments of debt						(11,300,000)
Debt payoff make-whole penalty						5,900,000
Debt issuance costs written-off						1,000,000
Interest expense						100,000
Increase in cash and cash equivalents						4,600,000
Revenue from related parties						115,600,000
Repayments of long-term debt						(72,300,000)
Increase in restricted cash						(20,000,000)
Distributions to noncontrolling and redeemable noncontrolling interests						(18,700,000)
Decrease in inventories						(27,000,000)
Decrease in property plant and equipment						(33,700,000)
Increase in long-term restricted cash						8,700,000
Decrease in current portion of non-recourse debt						(12,200,000)
Increase in deferred revenue and customer current liabilities						23,800,000
Increase in accrued other current liabilities						400,000
Increase in accrued installation cost						1,100,000
Payoff of accrued interest						(700,000)
Decrease in noncontrolling interest						(18,400,000)
Commitment to redeem noncontrolling interest						37,000,000
Sale Of Energy Servers
Variable Interest Entity [Line Items]
Revenue			$ 87,800,000
Installation Services Of Energy Servers
Variable Interest Entity [Line Items]
Revenue			3,900,000
Write Off Of Energy Servers
Variable Interest Entity [Line Items]
Cost of revenue			(25,600,000)
Product
Variable Interest Entity [Line Items]
Revenue			179,899,000	108,654,000		321,633,000	229,961,000
Cost of revenue			(131,952,000)	$ (70,802,000)		(255,952,000)	$ (151,157,000)
Repurchase Of Energy Servers
Variable Interest Entity [Line Items]
Cost of revenue			(26,300,000)
Energy Servers, Change In Useful Lives
Variable Interest Entity [Line Items]
Cost of revenue			$ (8,100,000)
Scenario, Forecast
Variable Interest Entity [Line Items]
Sale of Energy Savers | MW					8
PPA II
Variable Interest Entity [Line Items]
Repayments of debt						(144,813,000)		$ (65,114,000)
Distributions to noncontrolling and redeemable noncontrolling interests						(18,700,000)
Non-recourse debt | Variable Interest Entity, Primary Beneficiary | PPA II
Variable Interest Entity [Line Items]
Repayments of long-term debt						$ (63,700,000)
Subsequent Event
Variable Interest Entity [Line Items]
Purchase Agreement, Possible Indemnification, Cash Collateral		$ (20,000,000)