Share Capital (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended				3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 31, 2018	May 31, 2018	Mar. 31, 2018	Mar. 31, 2018
Share Capital [Line Items]
Gain on termination of collaboration agreement						$ 4,398	$ 4,398
Series1 Preferred Shares
Share Capital [Line Items]
Conversion of shares		1,852,000
Common Shares [Member]
Share Capital [Line Items]
Conversion of shares		1,852,000
BVF Partners L.P [Member] | Exchange Agreement [Member]
Share Capital [Line Items]
Estimated weighted average cancellation price per share of common stock						$ 7.61
BVF Partners L.P [Member] | Exchange Agreement [Member] | Series1 Preferred Shares
Share Capital [Line Items]
Shares issued						2,868,000
Preferred shares convertible into common shares						one-for-one
Common shares issued on conversion of preferred stock						1	1
Maximum beneficial ownership limitation percentage for conversion of common stock issued and outstanding						9.99%	9.99%
Maximum beneficial ownership limitation upon notice, percentage for conversion of common stock issued and outstanding						19.99%	19.99%
Maximum beneficial percentage hold for conversion of number Of common stock issued and outstanding						5.00%	5.00%
Minimum beneficial percentage hold for conversion of number Of common stock issued and outstanding.						5.00%	5.00%
BVF Partners L.P [Member] | Exchange Agreement [Member] | Common Shares [Member]
Share Capital [Line Items]
Shares issued						2,868,000
Stifel [Member] | At-The-Market Equity Offering [Member]
Share Capital [Line Items]
Sale proceeds of common shares	$ 29,200
Stifel [Member] | At-The-Market Equity Offering [Member] | Maximum [Member]
Share Capital [Line Items]
Sale proceeds of common shares					$ 30,000
Stifel [Member] | At-The-Market Equity Offering [Member] | Common Shares [Member]
Share Capital [Line Items]
Shares issued	3,440,000
Jefferies and Stifel [Member] | At-The-Market Equity Offering Sales Agreement [Member]
Share Capital [Line Items]
Sale proceeds of common shares	$ 14,820
Jefferies and Stifel [Member] | Maximum [Member] | At-The-Market Equity Offering Sales Agreement [Member]
Share Capital [Line Items]
Sale proceeds of common shares				$ 50,000
Jefferies and Stifel [Member] | Common Shares [Member] | At-The-Market Equity Offering Sales Agreement [Member]
Share Capital [Line Items]
Shares issued	1,600,000
Jefferies and Stifel [Member] | Underwritten Public Offering [Member]
Share Capital [Line Items]
Sale proceeds of common shares			$ 59,220
Jefferies and Stifel [Member] | Underwritten Public Offering [Member] | Common Shares [Member]
Share Capital [Line Items]
Shares issued			4,500,000
Shares price			$ 14.00
Teva Pharmaceuticals International GmbH and Teva Canada Limited [Member]
Share Capital [Line Items]
Collaborative development and license agreement termination date						Mar. 31, 2018
Teva Canada Limited [Member]
Share Capital [Line Items]
Number of common shares transferred and assigned for cancellation						1,000,000