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Nature of Business (Details) - USD ($)
Dec. 31, 2021
Jan. 10, 2020
Dec. 31, 2019
Dec. 31, 2018
Debt Instrument [Line Items]        
Accumulated deficit     $ 1,236,614,000 $ 1,103,621,000
Cash, cash equivalents and marketable securities     $ 160,900,000  
Subsequent Event | Medium-term Notes | Term Facility | Forecast        
Debt Instrument [Line Items]        
Aggregate principal amount $ 55,000,000.0      
Revolving Credit Facility | Subsequent Event | Line of Credit        
Debt Instrument [Line Items]        
Maximum borrowing capacity   $ 20,000,000.0    
Accordian feature, increase limit   $ 20,000,000.0