Summary of significant accounting policies - Concentrations of credit risk and off-balance sheet risk (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
Aug. 31, 2022	May 31, 2022	Mar. 31, 2024	Mar. 31, 2023
Concentrations of credit risk and off-balance sheet risk
Off-balance sheet concentrations of credit risk description			As of March 31, 2024, the Company’s cash, cash equivalents and investments were deposited at four financial institutions and it has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.
Grant awarded, amount		$ 3,800
Cash proceeds	$ 500		$ 3,500
Reduction of research and development expense			1,400	$ 100
Deferred liabilities			$ (327)	$ 693

Description of financial instruments, excluding certain derivatives, with off-balance sheet credit risk (for example, standby letters of credit or financial guarantees), including (1) information about the (shared) activity, region or economic characteristic that identifies the concentration, (2) the face or contract amount of the instrument, (3) the nature and terms of the instrument, including the market risk, cash requirements and accounting policies for it, (4) the maximum amount of loss due to credit risk that would be incurred if the counterparties failed completely to perform according to the terms of the contracts, and any security or collateral that proved to be of no value, (5) the entity's policy of requiring collateral or other security to support financial instruments subject to credit risk, information about access to collateral or other security, and a brief description of the security supporting those financial instruments, and (6) the policy of entering into and a brief description of master netting arrangements to mitigate the credit risk, and the extent to which such arrangements would reduce the maximum amount of loss due to credit risk.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-21

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480981/942-825-50-1

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- Definition

Change during the period in carrying value for all deferred liabilities due within one year or operating cycle.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (a)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

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- References

No definition available.

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- Definition

The amount of grant awarded.

+ References

No definition available.

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- Definition

The cash inflow associated with amount received from grants.

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- Definition

The proceeds recorded as a reduction of research and development expenses.

+ References

No definition available.

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