Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity At-the-Market Offering (Details)

v3.20.2
Stockholders' Equity At-the-Market Offering (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Sep. 30, 2020
Sep. 30, 2019
Subsidiary, Sale of Stock [Line Items]                
Number of shares authorized to be sold under equity distribution agreement (in shares) 35,000,000           35,000,000  
Number of common shares issued under equity distribution agreement and outstanding as of period-end (in shares) 7,490,235           7,490,235  
Accumulated proceeds from issuance of common shares under equity distribution agreement $ 128,600           $ 128,600  
Issuance of stock, net of offering costs $ 75 $ 95 $ 142 $ 217 $ 171 $ 335,278    
At the Market Offering [Member]                
Subsidiary, Sale of Stock [Line Items]                
Number of shares of stock issued during period (in shares) 0     0     0 3,665,300
Issuance of stock, net of offering costs $ 0     $ 0     $ 0 $ 50,600