License, Collaboration and Other Significant Agreements - Janssen Pharmaceutica NV Research and License Agreement (Details) - Development And Commercialize Research And License Agreement - USD ($) $ / shares in Units, $ in Millions	Feb. 09, 2017	Mar. 31, 2017
Janssen Pharmaceutica NV
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative arrangement, term	3 years
Upfront payment made in cash	$ 1.0
Potential milestone revenue from developmental milestones (up to)	16.5
Potential milestone revenue from commercial milestones (up to)	$ 215.0
Johnson & Johnson Innovation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Warrant to purchase common stock (in shares)	509,611
Exercise price (in dollars per share)	$ 9.81
Fair value of warrant at issuance		$ 3.4