Quarterly report pursuant to Section 13 or 15(d)

Nature of Business (Details)

v3.19.3
Nature of Business (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]              
Net Loss $ 19,793 $ 15,737 $ 55,709 $ 44,247 $ 62,300 $ 54,000 $ 47,700
Accumulated deficit (273,254)   (273,254)   $ (217,545)    
Cash equivalents and marketable securities $ 108,100   $ 108,100