Share-based compensation - Options (Details) - $ / shares |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2019 |
Sep. 30, 2018 |
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| Share-based compensation | ||||
| Number of options granted (in shares) | 3,733,359 | 757,273 | 15,477,255 | 12,187,614 |
| Weighted average fair value (in dollars per share) | $ 0.31 | $ 1.09 | $ 0.48 | $ 0.82 |
| Number of additional options with a nominal exercise price granted | 743,292 | 1,259,760 | 7,700,658 | 7,966,716 |
| Weighted average fair value of options with a nominal exercise price | $ 0.51 | $ 1.67 | $ 0.89 | $ 1.40 |
| X | ||||||||||
- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the nominal exercise price. No definition available.
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- Definition Gross number of share options (or share units) granted with nominal exercise price during the period. No definition available.
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- References No definition available.
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- Definition Gross number of share options (or share units) granted during the period. No definition available.
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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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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