Commitments and contingencies - Neurocrine Collaboration Agreement - (Details) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($) shares	Mar. 31, 2019 USD ($) item Program $ / shares shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Allocation of Transaction Price
Revenue recognized					$ 269
Deferred revenue			$ 11,827	$ 12,096	11,827	$ 12,096
Neurocrine Collaboration Agreement | FA Program
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of profit or loss under co-co option		40.00%
Neurocrine Collaboration Agreement | Neurocrine
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of collaboration programs | item		4
Number of discovery programs | Program		2
Programs added later | item		2
Discovery programs under development | item		2
Number of targets | item		8
Upfront payment	$ 115,000	$ 115,000
Purchase of common stock, shares | shares	4,179,728	4,179,728
Purchase of common stock	$ 5,000	$ 50,000
Price per share | $ / shares		$ 11.9625
Aggregate maximum milestone payments to be received from collaborative partner		$ 170,000
Estimated cost reimbursement	431,100		81,700	$ 80,000
Termination period		10 years
Period of advance notice for termination prior to first commercial sale		180 days
Period of advance notice for termination after first commercial sale		1 year
Discount related to equity investment	27,600
Equity investment	50,000
Allocation of Transaction Price
Allocation of variable consideration			81,671		81,671
Allocation of fixed consideration	92,400		92,382		92,382
Cumulative catch up of revenue recognized					900
Reimbursement costs expected to be received					300
Costs to obtain collaboration agreement			800		800
Consideration received	$ 5,000
Revenue recognized					900	$ 37,400
Deferred revenue			11,800		11,800
Neurocrine Collaboration Agreement | Neurocrine | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of reduction in royalty payments		50.00%
Neurocrine Collaboration Agreement | Neurocrine | VY-AADC
Allocation of Transaction Price
Allocation of variable consideration			53,863		53,863
Allocation of fixed consideration			49,045		49,045
Neurocrine Collaboration Agreement | Neurocrine | FA Program
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of profit or loss under co-co option		60.00%
Allocation of Transaction Price
Allocation of variable consideration			18,868		18,868
Allocation of fixed consideration			20,647		20,647
Neurocrine Collaboration Agreement | Neurocrine | Discovery and FA Programs
Allocation of Transaction Price
Allocation of fixed consideration			42,200		42,200
Neurocrine Collaboration Agreement | Neurocrine | Discovery program 1
Allocation of Transaction Price
Allocation of variable consideration			5,336		5,336
Allocation of fixed consideration			14,443		14,443
Neurocrine Collaboration Agreement | Neurocrine | Discovery program 2
Allocation of Transaction Price
Allocation of variable consideration			3,605		3,605
Allocation of fixed consideration			$ 8,247		$ 8,247
Neurocrine Collaboration Agreement | Neurocrine | Development and regulatory milestones | FA Program
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate maximum milestone payments to be received from collaborative partner		$ 195,000
Neurocrine Collaboration Agreement | Neurocrine | Development and regulatory milestones | Discovery program 1
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate maximum milestone payments to be received from collaborative partner		130,000
Neurocrine Collaboration Agreement | Neurocrine | Commercial Milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Per Milestone, maximum milestone payments to be received from collaborative partner		275,000
Aggregate maximum milestone payments to be received from collaborative partner		$ 1,100,000