Nature of Business, Liquidity, Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Additional Information) (Details) - USD ($)	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Contract with customer, liability	$ 214,720,000				$ 177,575,000								$ 214,720,000	$ 177,575,000
Revenue related to sales-type leases													2,900,000	3,400,000	$ 4,000,000
Revenue	213,543,000	$ 224,307,000	$ 200,326,000	$ 147,001,000	157,145,000	$ 168,619,000	$ 138,302,000	$ 168,582,000	$ 347,327,000	$ 306,884,000	$ 571,634,000	$ 475,503,000	$ 785,177,000	632,648,000	365,623,000
Benefit of ITC															45,500,000
ITC recapture period													5 years
ITC recaptured amount													$ 0	0	0
Minimum
Disaggregation of Revenue [Line Items]
Term of PPA													10 years
Term during which the Company is responsible for the installation, operation and maintenance of the Energy Servers													10 years
Incentives received by the Company																1.00%
Maximum
Disaggregation of Revenue [Line Items]
Term of PPA													21 years
Term during which the Company is responsible for the installation, operation and maintenance of the Energy Servers													15 years
Incentives received by the Company																10.00%
Product
Disaggregation of Revenue [Line Items]
Revenue related to sales-type leases													$ 0	0	0
Revenue	158,427,000	163,902,000	144,081,000	90,926,000	103,937,000	102,433,000	78,497,000	115,771,000	235,007,000	194,268,000	398,909,000	296,701,000	557,336,000	400,638,000	157,192,000
Electricity
Disaggregation of Revenue [Line Items]
Operating lease revenue													60,389,000	57,525,000
Revenue	15,059,000	15,638,000	20,143,000	20,389,000	20,364,000	20,439,000	19,863,000	19,882,000	40,532,000	39,745,000	56,170,000	60,184,000	71,229,000	80,548,000	75,602,000
Service
Disaggregation of Revenue [Line Items]
Revenue	$ 25,628,000	$ 23,665,000	$ 23,026,000	$ 23,467,000	$ 21,778,000	$ 21,056,000	$ 20,299,000	$ 20,134,000	$ 46,493,000	$ 40,433,000	$ 70,158,000	$ 61,489,000	95,786,000	83,267,000	74,892,000
Electricity sales | Power generation
Disaggregation of Revenue [Line Items]
Revenue													11,300,000	23,000,000	23,300,000
Service revenue | Power generation
Disaggregation of Revenue [Line Items]
Revenue													6,800,000	13,700,000	13,900,000
PPA II | Variable Interest Entity, Primary Beneficiary
Disaggregation of Revenue [Line Items]
Increase (decrease) in restricted cash													108,700,000
Power Purchase Agreement Program Leases | Electricity
Disaggregation of Revenue [Line Items]
Operating lease revenue													29,700,000	30,900,000	29,900,000
Power Purchase Agreement Program Leases | Service
Disaggregation of Revenue [Line Items]
Operating lease revenue													$ 14,600,000	$ 15,200,000	$ 15,600,000