v3.21.1

Shareholders' equity - Share-based compensation - Outstanding and exercisable options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Outstanding and exercisable options, number of shares
Forfeited	0	(7,728)
Cancelled	0	0
Exercisable at end of period		1,333,297
Outstanding and exercisable options, weighted average exercise price
Granted	$ 4.79
Exercised	$ 1.08	$ 1.44
Forfeited		$ 2.12
Weighted average remaining contractual life (in years)	8 years 4 months 24 days	8 years 2 months 12 days
Weighted average remaining contractual life for vested options (in years)	7 years 1 month 6 days	7 years
Weighted average fair values of options granted		$ 15.19
Share-based compensation expense	$ 1,368	$ 981
Unrecognized compensation cost	$ 20,573	$ 17,442
Expected period for recognition	3 years 1 month 6 days	2 years 10 months 24 days
Option Plans 2011 and 2019
Outstanding and exercisable options, number of shares
Outstanding at end of period	5,632,224	3,288,376
Exercisable at end of period	2,205,114
Outstanding and exercisable options, weighted average exercise price
Outstanding at end of period	$ 6.99	$ 7.89
Exercisable at end of period	$ 4.86	$ 1.92
2011 Plan
Outstanding and exercisable options, number of shares
Outstanding at beginning of period	2,080,087	2,364,526
Exercised	(16,753)	(53,722)
Forfeited		(4,978)
Outstanding at end of period	2,063,334	2,305,826
Exercisable at end of period	1,613,229	1,327,637
Outstanding and exercisable options, weighted average exercise price
Outstanding at beginning of period	$ 2.15	$ 2.15
Exercised	0.88	1.44
Outstanding at end of period	2.16	2.17
Exercisable at end of period	$ 2.05	$ 1.85
2019 Plan
Outstanding and exercisable options, number of shares
Outstanding at beginning of period	1,706,190	220,140
Granted	1,863,950	765,160
Exercised	(1,250)
Forfeited		(2,750)
Outstanding at end of period	3,568,890	982,550
Exercisable at end of period	591,885	5,660
Outstanding and exercisable options, weighted average exercise price
Outstanding at beginning of period	$ 13.55	$ 20.78
Granted	6.31	21.49
Exercised	3.74
Forfeited		21.48
Outstanding at end of period	9.77	21.33
Exercisable at end of period	12.55	18.43
Weighted average fair values of options granted	$ 4.79	$ 15.19

X

- Definition

The number of shares under options that were cancelled during the reporting period pertaining to the stock option plan.

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

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for 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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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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Weighted average price of options that were either forfeited or expired.

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

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

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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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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. 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 share options (or share units) exercised during the current period.

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