Consolidated Statements of Shareholders' (Deficit) Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Ordinary shares	Preferred shares	Additional paid-in capital	Additional paid-in capital Cumulative Effect, Period of Adoption, Adjustment	Accumulated deficit	Accumulated deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive loss
Beginning balance (in shares) at Dec. 31, 2020			58,396	488			(384,187)
Beginning balance at Dec. 31, 2020	$ 162,266	$ (12,939)	$ 583	$ 5	$ 566,916	$ (26,699)		$ 13,760	$ (21,051)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(77,329)						$ (77,329)
Other comprehensive loss	(2,889)								(2,889)
Exercise of stock options (in shares)			48
Exercise of stock options	169		$ 1		168
Vesting of restricted shares (in shares)			159
Vesting of restricted shares	0		$ 2		(2)
Employee share purchase plan share issuance (in shares)			17
Employee share purchase plan share issuance	94				94
Share-based compensation expense	8,872				8,872
Ending balance (in shares) at Dec. 31, 2021			58,620	488
Ending balance at Dec. 31, 2021	78,244		$ 586	$ 5	549,349		(447,756)		(23,940)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(137,464)						(137,464)
Other comprehensive loss	(2,401)								(2,401)
Change in fair value of October 2023 Notes conversion feature	5,508				5,508
Issuance of common stock under at-the-market offering program, net of issuance costs (in shares)			3,588
Issuance of common stock under at-the-market offering program, net of issuance costs	25,318		$ 36		25,282
Amortization of deferred issuance costs	$ (45)				(45)
Exercise of stock options (in shares)	450		451
Exercise of stock options	$ 2,460		$ 4		2,456
Vesting of restricted shares (in shares)			144
Vesting of restricted shares	0		$ 1		(1)
Employee share purchase plan share issuance (in shares)			75
Employee share purchase plan share issuance	222		$ 1		221
Share-based compensation expense	7,013				7,013
Ending balance (in shares) at Dec. 31, 2022			62,878	488
Ending balance at Dec. 31, 2022	$ (21,145)		$ 628	$ 5	$ 589,783		$ (585,220)		$ (26,341)