License, collaboration and commercial agreements - Sanofi (Details) - License and Collaboration Agreement - Sanofi - USD ($) $ in Millions		1 Months Ended	9 Months Ended
Jul. 25, 2019	Aug. 31, 2019	Sep. 30, 2021
License and collaboration agreements
Proceeds received		$ 5.0
Maximum aggregate payments entitled to receive if all milestones successfully achieved	$ 42.0
Percentage of future milestone payments and royalties entitled			50.00%

Cash received from collaborators during the current period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585

Name:	us-gaap_ProceedsFromCollaborators
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration