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Nature of Business (Details) - USD ($)
$ in Thousands
1 Months Ended 12 Months Ended
Feb. 28, 2021
Jan. 31, 2021
Jun. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
May 31, 2020
Liquidity              
Number of common stock issued     6,900,000        
Proceeds from offering of common stock, net of issuance costs     $ 203,700 $ 203,726 $ 116,341 $ 76,789  
Accumulated deficit       665,197 $ 549,221    
At Market Offering | Cowen and Company LLC ("Cowen")              
Liquidity              
Sales agreement amount of aggregate sale proceeds of common stock agreed to be issued             $ 150,000
Overallotment Option              
Liquidity              
Number of common stock issued     900,000        
Overallotment Option | Subsequent Event              
Liquidity              
Proceeds from offering of common stock, net of issuance costs $ 32,600            
Public and Market Offering              
Liquidity              
Aggregate net proceeds       $ 648,700      
Public Offering | Subsequent Event              
Liquidity              
Number of common stock issued   3,500,000          
Proceeds from offering of common stock, net of issuance costs   $ 216,900