Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Ordinary Shares Ionis Share Purchase Agreement	Ordinary Shares	Additional Paid-in Capital Ionis Share Purchase Agreement	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Ionis Share Purchase Agreement	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 ordinary shares upon exercise of warrants		$ 1						1
Issuance of ordinary shares upon exercise of warrants (in shares)		92,885
Issuance of ADSs upon exercise of share options		$ 1		270				271
Issuance of ADSs upon exercise of share options (in shares)		79,158
Issuance of ADSs, net of commissions and offering expenses		$ 37		48,107				48,144
Issuance of ADSs, net of commissions and offering expenses (in shares)		2,928,813
Share-based compensation expense				6,514				6,514
Foreign currency translation adjustment					(1,658)			(1,658)
Net loss						(51,010)		(51,010)
Ending balance at Dec. 31, 2020		$ 266		249,947	(3,193)	(151,560)		95,460
Ending balance (in shares) at Dec. 31, 2020		21,094,557
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options		$ 10		7,173				7,183
Issuance of ADSs upon exercise of share options (in shares)		703,786
Issuance of ADSs, net of commissions and offering expenses	$ 4	$ 104	$ 7,554	290,880			$ 7,558	290,984
Issuance of ADSs, net of commissions and offering expenses (in shares)	282,485	7,498,536
Share-based compensation expense				12,083				12,083
Foreign currency translation adjustment					(195)			(195)
Net loss						(66,819)		(66,819)
Ending balance at Dec. 31, 2021		$ 384		567,637	(3,388)	(218,379)		$ 346,254
Ending balance (in shares) at Dec. 31, 2021		29,579,364						29,579,364
Increase (decrease) in shareholders' equity (deficit)
Issuance of ADSs upon exercise of share options		$ 1		988				$ 989
Issuance of ADSs upon exercise of share options (in shares)		78,074
Issuance of ADSs, net of commissions and offering expenses		$ 2		5,701				5,703
Issuance of ADSs, net of commissions and offering expenses (in shares)		181,455
Issuance of ADSs upon vesting of restricted share units (in shares)		35,000
Share-based compensation expense				26,779				26,779
Foreign currency translation adjustment					3,775			3,775
Net loss						(112,717)		(112,717)
Ending balance at Dec. 31, 2022		$ 387		$ 601,105	$ 387	$ (331,096)		$ 270,783
Ending balance (in shares) at Dec. 31, 2022		29,873,893						29,873,893