CONDENSED 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) income
Beginning balance (in shares) at Dec. 31, 2020			58,396	488
Beginning balance at Dec. 31, 2020	$ 162,266	$ (12,939)	$ 583	$ 5	$ 566,916	$ (26,699)	$ (384,187)	$ 13,760	$ (21,051)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(13,445)						(13,445)
Other comprehensive loss	(1,255)								(1,255)
Exercise of stock options (in shares)			23
Exercise of stock options	106				106
Vesting of restricted shares (in shares)			61
Vesting of restricted shares	0		$ 1		(1)
Employee share purchase plan share issuance (in shares)			8
Employee share purchase plan share issuance	43				43
Share-based compensation expense	1,728				1,728
Ending balance (in shares) at Mar. 31, 2021			58,488	488
Ending balance at Mar. 31, 2021	136,504		$ 584	$ 5	542,093		(383,872)		(22,306)
Beginning balance (in shares) at Dec. 31, 2020			58,396	488
Beginning balance at Dec. 31, 2020	162,266	$ (12,939)	$ 583	$ 5	566,916	$ (26,699)	(384,187)	$ 13,760	(21,051)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(55,028)
Ending balance (in shares) at Sep. 30, 2021			58,616	488
Ending balance at Sep. 30, 2021	98,957		$ 586	$ 5	546,565		(425,455)		(22,744)
Beginning balance (in shares) at Mar. 31, 2021			58,488	488
Beginning balance at Mar. 31, 2021	136,504		$ 584	$ 5	542,093		(383,872)		(22,306)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(19,581)						(19,581)
Other comprehensive loss	(44)								(44)
Share-based compensation expense	2,001				2,001
Ending balance (in shares) at Jun. 30, 2021			58,488	488
Ending balance at Jun. 30, 2021	118,880		$ 584	$ 5	544,094		(403,453)		(22,350)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(22,002)						(22,002)
Other comprehensive loss	(394)								(394)
Exercise of stock options (in shares)			25
Exercise of stock options	63		$ 1		62
Vesting of restricted shares (in shares)			94
Vesting of restricted shares	0		$ 1		(1)
Employee share purchase plan share issuance (in shares)			9
Employee share purchase plan share issuance	51				51
Share-based compensation expense	2,359				2,359
Ending balance (in shares) at Sep. 30, 2021			58,616	488
Ending balance at Sep. 30, 2021	98,957		$ 586	$ 5	546,565		(425,455)		(22,744)
Beginning balance (in shares) at Dec. 31, 2021			58,620	488
Beginning balance at Dec. 31, 2021	78,244		$ 586	$ 5	549,349		(447,756)		(23,940)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(26,424)						(26,424)
Other comprehensive loss	(1,102)								(1,102)
Exercise of stock options (in shares)			275
Exercise of stock options	1,906		$ 3		1,903
Vesting of restricted shares (in shares)			119
Vesting of restricted shares	0		$ 1		(1)
Employee share purchase plan share issuance (in shares)			18
Employee share purchase plan share issuance	103				103
Share-based compensation expense	2,505				2,505
Ending balance (in shares) at Mar. 31, 2022			59,032	488
Ending balance at Mar. 31, 2022	55,232		$ 590	$ 5	553,859		(474,180)		(25,042)
Beginning balance (in shares) at Dec. 31, 2021			58,620	488
Beginning balance at Dec. 31, 2021	78,244		$ 586	$ 5	549,349		(447,756)		(23,940)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(110,014)
Ending balance (in shares) at Sep. 30, 2022			60,885	488
Ending balance at Sep. 30, 2022	(12,440)		$ 608	$ 5	572,626		(557,770)		(27,909)
Beginning balance (in shares) at Mar. 31, 2022			59,032	488
Beginning balance at Mar. 31, 2022	55,232		$ 590	$ 5	553,859		(474,180)		(25,042)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(63,444)						(63,444)
Other comprehensive loss	(1,286)								(1,286)
Vesting of restricted shares (in shares)			6
Change in fair value of October 2023 Notes conversion feature	5,508				5,508
Share-based compensation expense	658				658
Ending balance (in shares) at Jun. 30, 2022			59,038	488
Ending balance at Jun. 30, 2022	(3,332)		$ 590	$ 5	560,025		(537,624)		(26,328)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(20,146)						(20,146)
Other comprehensive loss	(1,581)								(1,581)
Exercise of stock options (in shares)			14
Exercise of stock options	64				64
Vesting of restricted shares (in shares)			8
Vesting of restricted shares	0
Issuance of common stock under at-the-market offering program, net of issuance costs (in shares)			1,768
Issuance of common stock under at-the-market offering program, net of issuance costs	10,532		$ 17		10,515
Amortization of deferred issuance costs	(19)				(19)
Employee share purchase plan share issuance (in shares)			57
Employee share purchase plan share issuance	119		$ 1		118
Share-based compensation expense	1,923				1,923
Ending balance (in shares) at Sep. 30, 2022			60,885	488
Ending balance at Sep. 30, 2022	$ (12,440)		$ 608	$ 5	$ 572,626		$ (557,770)		$ (27,909)