Stock incentive plan (Details) - USD ($) |
9 Months Ended | |
|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Options | ||
| Outstanding | 2,337 | 2,929 |
| Granted | 0 | 0 |
| Forfeited | 0 | 0 |
| Exercised | 0 | 0 |
| Outstanding | 2,337 | 2,929 |
| Exercisable | 2,337 | 1,730 |
| Weighted Average Exercise Price | ||
| Options Outstanding | $ 24.21 | $ 24.47 |
| Granted | 0 | 0 |
| Forfeited | 0 | 0 |
| Exercised | 0 | 0 |
| Options Outstanding | 24.21 | 24.47 |
| Fair Value Per Share | ||
| Options Outstanding | 12.76 | 12.74 |
| Granted | 0 | 0 |
| Forfeited | 0 | 0 |
| Exercised | 0 | 0 |
| Options Outstanding | $ 12.76 | $ 12.74 |
| Intrinsic Value Options outstanding | $ 0 | $ 0 |