Stock incentive plan (Details 1)
|
12 Months Ended |
|
Dec. 31, 2016
$ / shares
shares
|
|---|
| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
| Outstanding Number of Options (in shares) | shares |
2,337
|
| Outstanding Weighted Average Remaining Years of Contractual Life |
6 years 22 days
|
| Outstanding Weighted Average Exercise Price (in dollars per share) | $ / shares |
$ 24.21
|
| Exercisable Number of Options (in shares) | shares |
2,337
|
| Exercisable Weighted Average Exercise Price (in dollars per share) | $ / shares |
$ 24.21
|
| $16.00-$25.76 [Member] |
|
| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] |
|
| Outstanding Number of Options (in shares) | shares |
2,337
|
| Outstanding Weighted Average Remaining Years of Contractual Life |
6 years 22 days
|
| Outstanding Weighted Average Exercise Price (in dollars per share) | $ / shares |
$ 24.21
|
| Exercisable Number of Options (in shares) | shares |
2,337
|
| Exercisable Weighted Average Exercise Price (in dollars per share) | $ / shares |
$ 24.21
|