Earnings per common share (Details Textual) - shares |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | 0 | 0 | 0 | 0 |
| Stock Option [Member] | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | 2,337 | 2,587 | 2,337 | 1,742 |