Stock incentive plans - Plans (Details) - shares |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| 2011 Plan | ||
| Stock incentive plans | ||
| Common stock shares reserved for issuance | 13,739,820 | |
| Number of options outstanding | 290,000 | 1,128,000 |
| 2001 Plan | ||
| Stock incentive plans | ||
| Number of options outstanding | 14,000 | 155,000 |
| Stock options | ||
| Stock incentive plans | ||
| Number of options outstanding | 304,000 | 1,283,000 |
| Stock options | 2011 Plan | ||
| Stock incentive plans | ||
| Number of options outstanding | 290,000 | |
| Stock options | 2001 Plan | ||
| Stock incentive plans | ||
| Number of options outstanding | 14,000 | |
| RSUs | 2011 Plan | ||
| Stock incentive plans | ||
| RSUs outstanding | 3,119,000 |