Share-based compensation - Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
Oct. 02, 2023	Dec. 31, 2023	Dec. 31, 2022
Number of shares
Options, Beginning balance		2,519,405
Replacement options issued at asset acquisition		2,472,563
Options, Granted		4,007,552
Options, Forfeited		(314,319)
Options, Expired		(55,670)
Options, Exercised		(651,240)
Options, Ending balance		7,978,291	2,519,405
Options, Exercisable		3,151,799
Weighted Average Exercise price
Beginning price		$ 9.60
Replacement options issued at asset acquisition		1.29
Granted		6.42
Forfeited		6.67
Expired		16.59
Exercised		1.57
Ending price		6.15	$ 9.60
Exercisable		$ 5.86
Weighted average remaining contractual term
Weighted Average Remaining Contractual Term		8 years 7 months 13 days
Weighted Average Remaining Contractual Term, Exercisable		7 years 6 months 14 days
Weighted average grant date fair value		$ 6.09	$ 2.65
Intrinsic value, exercisable		$ 21.9
Intrinsic value, outstanding		45.4
Intrinsic value, exercised		$ 5.9	$ 0.2
Modification of stock options and recognized	$ 0.7
Morphimmune Inc
Weighted average remaining contractual term
Weighted average grant fair value	$ 7.55

Number of replacement options (or share units) issued at acquisition during the period.

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Weighted average exercise price per share amount of replacement options issued at asset acquisition.

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Amount of additional cost recognized for award under share-based payment arrangement from occurrence of event accelerating recognition of cost.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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