Convertible Preferred Shares (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	May 31, 2017	Feb. 28, 2017	Oct. 31, 2016	Mar. 31, 2017
Preferred Shares
Accretion of beneficial conversion feature on Series A preferred shares				$ (4,000)
Series A Convertible Preferred Shares
Preferred Shares
Preferred stock issued and sold		4,305,182	4,305,209
Accretion of beneficial conversion feature on Series A preferred shares		$ 2,406
Shares issued on conversion of preferred stock	9,358,560
Series A Convertible Preferred Shares | AstraZeneca
Preferred Shares
Preferred stock issued and sold			538,150