Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.3
Stockholders' Equity At-the-Market Offering (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
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   10,000,000
Number of common shares issued under equity distribution agreement and outstanding as of period-end (in shares) 7,458,235   7,458,235    
Accumulated proceeds from issuance of common shares under equity distribution agreement $ 128,200   $ 128,200    
At the Market Offering [Member]          
Subsidiary, Sale of Stock [Line Items]          
Number of shares of stock issued during period (in shares) 0 0 3,665,300 0  
Issuance of stock, net of offering costs $ 0 $ 0 $ 50,600 $ 0