Net loss per share - Securities excluded from the diluted per share calculation (Details) - shares	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022
Antidilutive securities
Antidilutive securities (in shares)	7,647,124	5,972,306
Restricted ordinary shares
Antidilutive securities
Antidilutive securities (in shares)	335,104	187,725
Options to purchase ordinary shares
Antidilutive securities
Antidilutive securities (in shares)	7,312,020	5,784,581

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration