Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity / (Deficit) - Additional Information (Details)

Shareholders' Equity / (Deficit) - Additional Information (Details) $ / shares in Units, $ in Thousands											1 Months Ended	5 Months Ended	6 Months Ended	12 Months Ended
	Feb. 12, 2021 $ / shares shares	Feb. 10, 2021 USD ($) $ / shares shares	Feb. 09, 2021 USD ($) $ / shares shares	Feb. 08, 2021 $ / shares shares	Feb. 03, 2021 $ / shares shares	Oct. 31, 2020 $ / shares shares	Oct. 27, 2020 USD ($) $ / shares shares	Jul. 02, 2020 $ / shares shares	Jun. 05, 2020 $ / shares shares	Jun. 03, 2020 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) Vote $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Jan. 28, 2021 $ / shares shares	Jun. 10, 2020 $ / shares shares	Apr. 27, 2018 $ / shares shares
Class Of Stock [Line Items]
Ordinary shares, shares issued												182,594,282	182,594,282	49,431,028
Ordinary shares, par value \| $ / shares												$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Proceeds from registered direct offerings, net of transaction costs \| $													$ 500
Number of warrants to purchase ordinary shares												380,000	380,000
Ordinary shares, shares authorized												300,000,000	300,000,000	150,000,000	150,000,000	100,000,000
Number of vote per common share \| Vote													1
Common stock rights and preferences													The holders of ordinary shares currently have no preemptive or other subscription rights, and there are no redemption or sinking fund provisions with respect to such shares
Undesignated preferred shares, par value \| $ / shares												$ 0.01	$ 0.01	$ 0.01
Undesignated preferred shares, authorized												100,000,000	100,000,000	100,000,000
Undesignated preferred shares issued												0	0	0
Undesignated Preferred Shares
Class Of Stock [Line Items]
Undesignated preferred shares, par value \| $ / shares												$ 0.01	$ 0.01
Undesignated preferred shares, authorized												100,000,000	100,000,000
Designated Preferred Shares
Class Of Stock [Line Items]
Undesignated preferred shares issued												0	0	0
Silicon Valley Bank and Life Sciences Fund II LLC \| Series B Convertible Preferred Shares
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares												19,890	19,890				19,890
Warrants to purchase ordinary shares, exercise price \| $ / shares												$ 18.85	$ 18.85				$ 18.85
Exchangeable Notes
Class Of Stock [Line Items]
Ordinary shares, shares issued												53,888,331	53,888,331
Aggregate principal amount of exchangeable notes \| $												$ 39,200
Aggregate principal amount \| $												$ 12,600	$ 12,600
Ordinary Shares
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares												19,890	19,890				19,890
June 3 SPA
Class Of Stock [Line Items]
Ordinary shares, par value \| $ / shares												$ 0.01	$ 0.01
February Registered Direct Offering
Class Of Stock [Line Items]
Ordinary shares, shares issued			17,500,000
Ordinary shares, par value \| $ / shares			$ 0.01
Offering price per share \| $ / shares			$ 2.00
Aggregate gross proceeds from ordinary shares \| $			$ 35,000
Proceeds from registered direct offerings, net of transaction costs \| $			$ 32,200
Offering closing date			Feb. 12, 2021
June 3 Offering \| June 3 SPA
Class Of Stock [Line Items]
Ordinary shares, shares issued										2,971,770
Ordinary shares, par value \| $ / shares										$ 0.01
Offering price per share \| $ / shares										$ 1.6825
Aggregate gross proceeds from ordinary shares \| $										$ 5,000
Proceeds from registered direct offerings, net of transaction costs \| $										$ 4,300
Warrants closing date										Jun. 05, 2020
June 30 Offering \| June 30 SPA
Class Of Stock [Line Items]
Ordinary shares, shares issued											3,372,686
Ordinary shares, par value \| $ / shares											$ 0.01
Offering price per share \| $ / shares											$ 1.4825
Aggregate gross proceeds from ordinary shares \| $											$ 5,000
Proceeds from registered direct offerings, net of transaction costs \| $											$ 4,200
Warrants closing date											Jul. 02, 2020
October Offering
Class Of Stock [Line Items]
Ordinary shares, shares issued							15,511,537
Ordinary shares, par value \| $ / shares							$ 0.01					$ 0.01	$ 0.01
Aggregate gross proceeds from ordinary shares \| $							$ 17,400
Proceeds from registered direct offerings, net of transaction costs \| $							$ 15,500						$ 13,900
Number of warrants to purchase ordinary shares						1,884,615						20,890,516	20,890,516
Warrants to purchase ordinary shares, exercise price \| $ / shares						$ 0.8125	$ 0.65
Warrants expiry date						Oct. 22, 2025	Oct. 27, 2025
Percentage of ordinary shares issued to purchase warrants						7.00%
October Offering \| Maximum
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares							20,192,307
October Offering \| Pre-Funded Warrants
Class Of Stock [Line Items]
Offering price per share \| $ / shares							$ 0.01
Proceeds from registered direct offerings, net of transaction costs \| $														$ 110
Number of warrants to purchase ordinary shares							11,411,539
Warrants to purchase ordinary shares, exercise price \| $ / shares							$ 0.64
October Offering \| Warrant
Class Of Stock [Line Items]
Offering price per share \| $ / shares							$ 0.65
Number of warrants to purchase ordinary shares							20,192,307
Warrants to purchase ordinary shares, exercise price \| $ / shares							$ 0.65
February Underwritten Offering
Class Of Stock [Line Items]
Warrants to purchase ordinary shares, exercise price \| $ / shares		$ 1.4375		$ 1.4375
Offering closing date		Feb. 10, 2021		Feb. 08, 2021
Additional ordinary shares that can be purchased by underwriter		5,217,391
Warrants expiry date		Feb. 03, 2026		Feb. 03, 2026
Percentage of ordinary shares issued to purchase warrants		7.00%		7.00%
February Underwritten Offering \| Maximum
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares		365,217		2,434,783
February Underwritten Offering \| Underwriting Agreement
Class Of Stock [Line Items]
Ordinary shares, shares issued					34,782,609
Ordinary shares, par value \| $ / shares					$ 0.01
Offering price per share \| $ / shares					$ 1.15
Offering closing date					Feb. 08, 2021
February Underwritten Offering \| Pursuant to the Underwriting Agreement
Class Of Stock [Line Items]
Ordinary shares, shares issued		40,000,000
Aggregate gross proceeds from ordinary shares \| $		$ 46,000
Proceeds from registered direct offerings, net of transaction costs \| $		$ 42,100
Additional ordinary shares that can be purchased by underwriter		5,217,391
Percentage of ordinary shares issued to purchase warrants		7.00%
February Underwritten Offering \| Pursuant to the Underwriting Agreement \| Warrant
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares		2,800,000
Warrants to purchase ordinary shares, exercise price \| $ / shares		$ 1.4375
Private Placement \| Securities Purchase Agreement
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares									208,023
Warrants to purchase ordinary shares, exercise price \| $ / shares									$ 2.1031	$ 1.62
Warrants expiry date									Jun. 03, 2025	Dec. 05, 2025
Percentage of ordinary shares issued to purchase warrants									7.00%
Private Placement \| Securities Purchase Agreement \| Maximum
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares										1,485,885
Private Placement \| June 30 SPA
Class Of Stock [Line Items]
Proceeds from registered direct offerings, net of transaction costs \| $													$ 1,800
Number of warrants to purchase ordinary shares								236,088				1,264,757	1,264,757
Warrants to purchase ordinary shares, exercise price \| $ / shares								$ 1.8531			$ 1.42
Warrants expiry date								Jun. 30, 2025			Jan. 02, 2026
Percentage of ordinary shares issued to purchase warrants								7.00%
Private Placement \| June 30 SPA \| Maximum
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares											1,686,343
Private Placement \| Exchangeable Notes
Class Of Stock [Line Items]
Aggregate principal amount of exchangeable notes \| $												$ 39,200
Private Placement \| June 3 SPA
Class Of Stock [Line Items]
Warrants closing date										Jun. 05, 2020
Number of warrants to purchase ordinary shares									208,023
Warrants to purchase ordinary shares, exercise price \| $ / shares									$ 2.1031	$ 1.62
Warrants expiry date									Jun. 03, 2025	Dec. 05, 2025
Percentage of ordinary shares issued to purchase warrants									7.00%
Private Placement \| June 3 SPA \| Maximum
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares										1,485,885
February Registered Direct Offering
Class Of Stock [Line Items]
Warrants to purchase ordinary shares, exercise price \| $ / shares	$ 2.50
Offering closing date	Feb. 12, 2021
Warrants expiry date	Feb. 09, 2026
Percentage of ordinary shares issued to purchase warrants	7.00%
February Registered Direct Offering \| Maximum
Class Of Stock [Line Items]
Number of warrants to purchase ordinary shares	1,225,000