Portfolio Financings - Schedule of VIEs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) MWh	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Variable Interest Entity [Line Items]
Distributions to Equity Investor	$ 0	$ 373	$ 576
PPA IIIa
Variable Interest Entity [Line Items]
Maximum size of installation (in megawatts) | MWh	10
Installed size (in megawatts) | MWh	10
Term of power purchase agreements (in years)	15 years
Income (loss) and tax benefits allocation to Equity Investor	99.00%
Cash allocation to Equity Investor	99.00%
Income (loss), tax and cash allocations to Equity Investor after the flip date	5.00%
Company cash contributions	$ 32,223
Company non-cash contributions	8,655
Equity Investor cash contributions	36,967
Debt financing	44,968
Distributions to Equity Investor	4,847	4,803	4,063
Debt repayment—principal	$ 10,513	6,631	4,431
PPA IV
Variable Interest Entity [Line Items]
Maximum size of installation (in megawatts) | MWh	21
Installed size (in megawatts) | MWh	19
Term of power purchase agreements (in years)	15 years
Income (loss) and tax benefits allocation to Equity Investor	90.00%
Cash allocation to Equity Investor	90.00%
Company cash contributions	$ 11,669
Company non-cash contributions	0
Equity Investor cash contributions	84,782
Debt financing	99,000
Distributions to Equity Investor	8,852	6,692	4,568
Debt repayment—principal	$ 21,163	18,012	15,543
PPA V
Variable Interest Entity [Line Items]
Maximum size of installation (in megawatts) | MWh	40
Installed size (in megawatts) | MWh	37
Term of power purchase agreements (in years)	15 years
Income (loss) and tax benefits allocation to Equity Investor	99.00%
Cash allocation to Equity Investor	90.00%
Company cash contributions	$ 27,932
Company non-cash contributions	0
Equity Investor cash contributions	227,344
Debt financing	131,237
Distributions to Equity Investor	24,809	70,591	66,745
Debt repayment—principal	$ 16,475	$ 9,453	$ 5,780