Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Aug. 31, 2020
Tax Credit Carryforward [Line Items]
Income tax provision	$ 1,046,000	$ 256,000	$ 633,000
Pre-tax loss	$ 192,323,000	$ 178,831,000	$ 322,833,000
Effective income tax rate	(0.50%)	(0.10%)	(0.20%)
Valuation allowance	$ 689,257,000	$ 614,958,000
Increase (decrease) in valuation allowance		(74,300,000)	$ 18,600,000
Uncertain tax positions increase	4,300,000
Unrecognized tax benefits that would impact valuation allowance	38,700,000
Interest and penalties accrued	$ 0	$ 0
2.5% Green Convertible Senior Notes due August 2025 | Senior secured notes
Tax Credit Carryforward [Line Items]
Interest Rate	2.50%	2.50%		2.50%
Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 2,100,000,000
Tax credit carryforwards	32,800,000
Domestic Tax Authority | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	26,200,000
Domestic Tax Authority | Investment Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	6,600,000
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	1,300,000,000
Operating loss carryforwards, subject to expiration	366,100,000
Tax credit carryforwards	15,900,000
State and Local Jurisdiction | Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 15,900,000