Financing (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 13, 2016	Feb. 19, 2015
Class of Stock
Stock issued (in shares)		23,000,000
Stock price (in dollars per share)		$ 3.75
Gross proceeds from offering of common stock		$ 86.3
Net proceeds from offering of common stock	$ 48.9	$ 80.6
Baker Bros. Advisors LP | Directors
Class of Stock
Stock issued (in shares)		5,333,333
Stock price (in dollars per share)		$ 3.75