Stock-based compensation - Summary of significant valuation assumptions (Details)	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
2020 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	3.56%	3.45%
Risk-free interest rate, maximum	4.46%	4.73%
Expected volatility, minimum	102.82%	81.99%
Expected volatility, maximum	104.41%	86.15%
Expected dividend yield	0.00%	0.00%
2020 Stock Option and Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	5 years 6 months	5 years 6 months
2020 Stock Option and Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	6 years 1 month 9 days	6 years 1 month 9 days
Inducement Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	3.63%	3.96%
Risk-free interest rate, maximum	4.64%	4.19%
Expected volatility, minimum	103.11%	83.35%
Expected volatility, maximum	103.85%	83.50%
Expected dividend yield	0.00%	0.00%
Inducement Grants \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	6 years 29 days	6 years 1 month 9 days
Inducement Grants \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	6 years 1 month 9 days	6 years 1 month 9 days

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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