Share-based compensation - Share Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Additional Information
Total share-based compensation expense	$ 10,198	$ 3,821
Stock option
Number of Shares
Outstanding number of shares at beginning	4,603,486
Granted	899,747
Exercised	(30,074)
Forfeited	(93,818)
Outstanding number of shares at end	5,379,341		4,603,486
Number of shares, vested and expected to vest	5,379,341
Number of shares, options exercisable	2,750,276
Weighted Average Exercise Price
Weighted average exercise price at beginning	$ 14.97
Granted	58.96
Exercised	14.96
Forfeited	22.39
Weighted average exercise price at ending	22.20		$ 14.97
Weighted average exercise price, vested and expected to vest	22.20
Weighted average exercise price, options exercisable	$ 12.74
Weighted Average Contractual Term
Weighted average contractual term, outstanding	8 years 2 months 1 day		8 years 1 month 17 days
Weighted average contractual term, vested and expected to vest	8 years 2 months 1 day
Weighted average contractual term ,options exercisable	7 years 5 months 19 days
Aggregate Intrinsic Value
Aggregate intrinsic value outstanding	$ 130,435		$ 207,009
Aggregate intrinsic value, vested and expected to vest	130,435
Aggregate intrinsic value, options exercisable	$ 86,689
Additional Information
Granted	$ 40.94	$ 12.60
Exercised	$ 1,000	$ 1,500
Total share-based compensation expense	$ 7,400	$ 3,800

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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

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