Stock-based compensation - Determination of Fair Value (Details)	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Fair Value Assumptions and Methodology
Risk-free interest rate, minimum	0.80%	0.30%
Risk-free interest rate, maximum	2.20%	1.30%
Dividend Yield	0.00%	0.00%
Minimum
Fair Value Assumptions and Methodology
Expected term (in years)	5 years 8 months 12 days	3 years 6 months
Volatility	63.00%	45.00%
Maximum
Fair Value Assumptions and Methodology
Expected term (in years)	7 years	6 years 1 month 6 days
Volatility	67.00%	47.00%

No definition available.

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- Definition

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.

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The estimated measure of the 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.

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No definition available.

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- Definition

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

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No definition available.

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- Definition

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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 718
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