Share Capital (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended				12 Months Ended
	Jan. 01, 2019	Jun. 25, 2014	Sep. 30, 2018	Jul. 31, 2018	May 31, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Share Capital [Line Items]
Sale proceeds of common shares							$ 102,850
Number of Options Exercisable							1,566,435
Options Exercisable Weighted Average Remaining Contractual Life in Years							5 years 3 months
Aggregate fair value of options vested							$ 2,861	$ 2,047
Unrecognized stock-based compensation cost							$ 3,919
Unrecognized stock-based compensation expected to be recognized over a period							2 years 4 months 28 days
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
Maximum beneficial ownership limitation percentage for conversion of common stock issued and outstanding						9.99%
Maximum beneficial ownership limitation upon notice, percentage for conversion of common stock issued and outstanding						19.99%
Maximum beneficial percentage hold for conversion of number Of common stock issued and outstanding						5.00%
Minimum beneficial percentage hold for conversion of number Of common stock issued and outstanding.						5.00%
BVF Partners L.P [Member] | Exchange Agreement [Member] | Common Shares [Member]
Share Capital [Line Items]
Shares issued						2,868,000
Two Thousand Fourteen Plan [Member]
Share Capital [Line Items]
Number of Options, Granted							153,209
Two Thousand Fourteen Plan [Member] | Subsequent Event [Member]
Share Capital [Line Items]
Common stock reserved for issuance	900,000
Maximum [Member] | Amended And Restated Stock Option Plan [Member]
Share Capital [Line Items]
Options exercise term							10 years
Options vesting period							4 years
Maximum [Member] | Two Thousand Fourteen Plan [Member]
Share Capital [Line Items]
Options exercise term		10 years
Options vesting period		4 years
Common Shares [Member]
Share Capital [Line Items]
Shares issued							9,540,000
Conversion of shares							1,852,000
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