Discontinued development of drug candidates - Additional Information (Detail) $ in Millions	Jun. 30, 2022 USD ($)
STOPS
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-cancellable purchase commitments	$ 3.8
Antisense Oligonucleotide
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-cancellable purchase commitments	$ 3.4

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