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Description of Business - Additional Information (Details) - USD ($)
$ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Dec. 31, 2019
Apr. 30, 2020
Description Of Business [Line Items]        
Cash and cash equivalents $ 53,997   $ 75,708  
Accumulated deficit 270,465   250,087  
Cash flows from operating activities 23,131 $ 16,418 $ 30,500  
Paycheck Protection Program (the “PPP”) | Silicon Valley Bank        
Description Of Business [Line Items]        
Unsecured debt       $ 6,400
$35.0 Million Credit Facility | Oxford Finance LLC        
Description Of Business [Line Items]        
Borrowings outstanding under credit facility $ 35,000      
Credit facility maturity date Feb. 01, 2025