Condensed Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common shares	Accumulated deficit	Accumulated other comprehensive loss	Additional paid-in capital
Beginning balance (in shares) at Dec. 31, 2019		39,564,529
Beginning balance at Dec. 31, 2019	$ 245,681	$ 450,210	$ (290,709)	$ (6,659)	$ 92,839
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares on exercise of options		122,492
Issuance of common shares on exercise of options	2,013	$ 2,767			(754)
Issuance of common shares through employee stock purchase plan		21,451
Issuance of common shares through employee stock purchase plan	615	$ 615
Fair value adjustments upon reclassification of options to liabilities	(110)				(110)
Stock-based compensation	4,446				4,446
Issuance of common shares and pre-funded warrants in connection with public offering (Note 8)		5,824,729
Issuance of common shares and pre-funded warrants in connection with public offering (Note 8)	300,910	$ 254,018			46,892
Net loss	(31,136)		(31,136)
Ending balance (in shares) at Mar. 31, 2020		45,533,201
Ending balance at Mar. 31, 2020	$ 522,419	$ 707,610	(321,845)	(6,659)	143,313
Beginning balance (in shares) at Dec. 31, 2020	46,035,389	46,035,389
Beginning balance at Dec. 31, 2020	$ 409,922	$ 724,219	(471,261)	(6,659)	163,623
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares on exercise of options		78,736
Issuance of common shares on exercise of options	1,962	$ 2,624			(662)
Issuance of common shares through employee stock purchase plan		26,807
Issuance of common shares through employee stock purchase plan	1,321	$ 1,321
Issuance of common shares upon vesting of restricted stock units ("RSUs")		23,956
Issuance of common shares upon vesting of restricted stock units ("RSUs")	0	$ 843			(843)
Stock-based compensation	8,530				8,530
Net loss	$ (44,590)		(44,590)
Ending balance (in shares) at Mar. 31, 2021	46,164,888	46,164,888
Ending balance at Mar. 31, 2021	$ 377,145	$ 729,007	$ (515,851)	$ (6,659)	$ 170,648