Share-based compensation - Options (Details) |
12 Months Ended | |||
|---|---|---|---|---|
|
Dec. 31, 2018
$ / shares
shares
|
Dec. 31, 2018
£ / shares
shares
|
Dec. 31, 2017
$ / shares
shares
|
Dec. 31, 2016
$ / shares
shares
|
|
| Number of options granted (in shares) | 20,771,970 | 20,771,970 | 29,924,787 | 19,404,373 |
| Weighted average fair value (in dollars per share) | $ / shares | $ 0.87 | $ 0.35 | $ 0.74 | |
| Number of options outstanding (in shares) | 87,564,719 | 87,564,719 | 74,943,667 | |
| Exercise price | £ / shares | £ 0.42 | |||
| RSU | ||||
| Number of options granted (in shares) | 8,603,676 | 8,603,676 | ||
| Weighted average fair value (in dollars per share) | $ / shares | $ 1.37 | |||
| Vesting period (in years) | 4 years | 4 years | ||
| Vesting percentage (as a percent) | 25.00% | 25.00% | ||
| 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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| X | ||||||||||
- Definition Gross number of share options (or share units) granted during the period. No definition available.
|
| X | ||||||||||
- 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
|
| X | ||||||||||
- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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| X | ||||||||||
- Definition Percentage of vesting of share-based compensation awards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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