Share-based compensation - Schedule of management and director options activity (Details) - $ / shares |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2016 |
Dec. 31, 2015 |
|
| Number of options (in shares) | ||
| Outstanding (in shares) | 10,250,586 | 10,990,841 |
| Forfeited (in shares) | (139,534) | (306,976) |
| Exercised (in shares) | (104,652) | (433,279) |
| Outstanding (in shares) | 10,006,400 | 10,250,586 |
| Weighted average exercise price (in dollars per share) | ||
| Outstanding (in dollars per share) | $ 13.52 | $ 13.41 |
| Forfeited (in dollars per share) | 18.00 | 14.36 |
| Exercised (in dollars per share) | 10.00 | 10.00 |
| Outstanding (in dollars per share) | $ 13.50 | $ 13.52 |
| X | ||||||||||
- 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
|
| X | ||||||||||
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
|
| X | ||||||||||
- Definition Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. No definition available.
|
| X | ||||||||||
- Definition Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|