Nature of Business and Basis of Presentation - Amendment to Certificate of Incorporation (Details)	Oct. 30, 2015 shares	Dec. 31, 2017 item $ / shares shares	Dec. 31, 2016 $ / shares shares	Nov. 24, 2015 $ / shares shares	Apr. 30, 2015 shares	Dec. 31, 2014 $ / shares shares
Nature of Business and Basis of Presentation
Number of late-stage candidates in Company's product candidate portfolio | item		5
Common stock, shares authorized | shares	25,000,000	150,000,000	150,000,000	150,000,000	22,033,500	14,689,000
Stock split ratio	7.3445
Preferred stock, shares authorized | shares		10,000,000	10,000,000	10,000,000
Common stock, par value | $ / shares		$ 0.0001	$ 0.0001	$ 0.0001		$ 0.0001
Preferred stock, par value | $ / shares		$ 0.0001	$ 0.0001	$ 0.0001