Share-based compensation - Options (Details) |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
|
Sep. 30, 2018
$ / shares
shares
|
Sep. 30, 2017
$ / shares
shares
|
Sep. 30, 2018
$ / shares
shares
|
Sep. 30, 2018
£ / shares
shares
|
Sep. 30, 2017
$ / shares
shares
|
|
| Number of options granted (in shares) | shares | 757,273 | 8,756,211 | 12,187,614 | 12,187,614 | 28,959,363 |
| Weighted average fair value (in dollars per share) | $ / shares | $ 1.09 | $ 0.34 | $ 0.82 | $ 0.34 | |
| RSU | |||||
| Number of options granted (in shares) | shares | 1,259,760 | 7,966,716 | 7,966,716 | ||
| Weighted average fair value (in dollars per share) | $ / shares | $ 1.67 | $ 1.40 | |||
| Exercise price | £ / shares | £ 0.001 | ||||
| Vesting period (in years) | 4 years | 4 years | |||
| Contractual term (in years) | 10 years | 10 years | |||
| First anniversary | RSU | |||||
| Vesting percentage (as a percent) | 25.00% | 25.00% | |||
| Annual installments over the following three years | RSU | |||||
| Vesting percentage (as a percent) | 75.00% | 75.00% | |||
| X | ||||||||||
- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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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- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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- Definition Percentage of vesting of share-based compensation awards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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