Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Ordinary Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2019	$ 227	$ 195,056	$ (1,535)	$ (100,550)	$ 93,198
Beginning balance (in shares) at Dec. 31, 2019	17,993,701
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options		2			2
Issuance of ADSs upon exercise of share options (in shares)	1,071
Issuance of ordinary shares upon exercise of warrants (in shares)	21,435
Share based compensation expense		2,121			2,121
Foreign currency translation adjustment			(2,184)		(2,184)
Net loss				(11,324)	(11,324)
Ending balance at Mar. 31, 2020	$ 227	197,179	(3,719)	(111,874)	81,813
Ending balance (in shares) at Mar. 31, 2020	18,016,207
Beginning balance at Dec. 31, 2019	$ 227	195,056	(1,535)	(100,550)	93,198
Beginning balance (in shares) at Dec. 31, 2019	17,993,701
Increase (decrease) in shareholders' equity (deficit)
Foreign currency translation adjustment					(2,185)
Net loss					(23,438)
Ending balance at Jun. 30, 2020	$ 228	198,507	(3,720)	(123,989)	71,026
Ending balance (in shares) at Jun. 30, 2020	18,091,657
Beginning balance at Mar. 31, 2020	$ 227	197,179	(3,719)	(111,874)	81,813
Beginning balance (in shares) at Mar. 31, 2020	18,016,207
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options		9			9
Issuance of ADSs upon exercise of share options (in shares)	4,000
Issuance of ordinary shares upon exercise of warrants	$ 1				1
Issuance of ordinary shares upon exercise of warrants (in shares)	71,450
Share based compensation expense		1,319			1,319
Foreign currency translation adjustment			(1)		(1)
Net loss				(12,115)	(12,115)
Ending balance at Jun. 30, 2020	$ 228	198,507	(3,720)	(123,989)	71,026
Ending balance (in shares) at Jun. 30, 2020	18,091,657
Beginning balance at Dec. 31, 2020	$ 266	249,947	(3,193)	(151,560)	$ 95,460
Beginning balance (in shares) at Dec. 31, 2020	21,094,557				21,094,557
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options	$ 1	283			$ 284
Issuance of ADSs upon exercise of share options (in shares)	63,545
Issuance of ADSs, net of commissions and offering expenses	$ 33	58,742			58,775
Issuance of ADSs, net of commissions and offering expenses (in shares)	2,358,485
Share based compensation expense		3,821			3,821
Foreign currency translation adjustment			(58)		(58)
Net loss				(16,191)	(16,191)
Ending balance at Mar. 31, 2021	$ 300	312,793	(3,251)	(167,751)	142,091
Ending balance (in shares) at Mar. 31, 2021	23,516,587
Beginning balance at Dec. 31, 2020	$ 266	249,947	(3,193)	(151,560)	$ 95,460
Beginning balance (in shares) at Dec. 31, 2020	21,094,557				21,094,557
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options (in shares)					189,211
Foreign currency translation adjustment					$ (313)
Net loss					(34,104)
Ending balance at Jun. 30, 2021	$ 309	330,911	(3,506)	(185,664)	$ 142,050
Ending balance (in shares) at Jun. 30, 2021	24,124,552				24,124,552
Beginning balance at Mar. 31, 2021	$ 300	312,793	(3,251)	(167,751)	$ 142,091
Beginning balance (in shares) at Mar. 31, 2021	23,516,587
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options	$ 2	1,573			1,575
Issuance of ADSs upon exercise of share options (in shares)	125,666
Issuance of ADSs, net of commissions and offering expenses	$ 7	13,970			13,977
Issuance of ADSs, net of commissions and offering expenses (in shares)	482,299
Share based compensation expense		2,575			2,575
Foreign currency translation adjustment			(255)		(255)
Net loss				(17,913)	(17,913)
Ending balance at Jun. 30, 2021	$ 309	$ 330,911	$ (3,506)	$ (185,664)	$ 142,050
Ending balance (in shares) at Jun. 30, 2021	24,124,552				24,124,552