Share-based compensation - Summary of Status of Company's Stock Option Plan (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Shares
Outstanding at beginning of period	7,042,377	4,415,397
-Cancelled		(527,820)
-Exercised	(1,967,562)	(10,000)
-Granted	254,700	3,164,800
Outstanding at end of period	5,329,515	7,042,377
Weighted Average Exercise Price
Outstanding at beginning of period	$ 1.01	$ 1.20
-Cancelled		1.23
-Exercised	0.91	0.89
-Granted	1.11	0.79
Outstanding at end of period	$ 1.06	$ 1.01

No definition available.

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- Definition

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

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- Definition

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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- Definition

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

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- Definition

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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- Definition

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

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- Definition

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

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- Definition

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

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

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