XML 73 R59.htm IDEA: XBRL DOCUMENT v3.6.0.2
Stock award plan (Details 4)
12 Months Ended
Dec. 31, 2016
$ / shares
shares
Number of Shares  
Granted (in shares) | shares 141,185
Weighted Average Grant Date Fair Value  
Granted (in dollars per share) | $ / shares $ 30.86
Unvested restricted stock  
Number of Shares  
Balance at the beginning of the period (in shares) | shares 344,335
Vested (in shares) | shares (163,635)
Forfeited (in shares) | shares (50,234)
Balance at the end of the period (in shares) | shares 271,651
Weighted Average Grant Date Fair Value  
Balance at the beginning of the period (in dollars per share) | $ / shares $ 10.85
Vested (in dollars per share) | $ / shares 10.85
Forfeited (in dollars per share) | $ / shares 18.93
Balance at the end of the period (in dollars per share) | $ / shares $ 19.76