Stock incentive plans - Plans (Details) - shares |
12 Months Ended | 60 Months Ended |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| 2011 Plan | ||
| Stock incentive plans | ||
| Common stock shares reserved for issuance | 13,739,820 | |
| 2001 Plan | ||
| Stock incentive plans | ||
| Number of options outstanding | 0 | |
| Number of awards made | 0 | |
| Stock options | ||
| Stock incentive plans | ||
| Number of options outstanding | 109,000 | 235,000 |
| Number of awards made | 0 | 0 |
| Stock options | 2011 Plan | ||
| Stock incentive plans | ||
| Number of options outstanding | 109,000 | 228,000 |
| Stock options | 2001 Plan | ||
| Stock incentive plans | ||
| Number of options outstanding | 7,000 | |
| RSUs | ||
| Stock incentive plans | ||
| RSUs outstanding | 951,000 |