Annual report pursuant to Section 13 and 15(d)

Stock Options, Stock Grants and New Stock (Stock Options by Exercise Price Range) (Details)

v3.8.0.1
Stock Options, Stock Grants and New Stock (Stock Options by Exercise Price Range) (Details)
 12 Months Ended
Dec. 31, 2017
$ / shares
shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Number of Outstanding options (shares) | shares 145,511
Number of exercisable options (shares) | shares 119,861
$11.55 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices (dollars per share) $ 11.55
Number of Outstanding options (shares) | shares 56,710
Weighted average exercise price (dollars per share) $ 11.55
Weighted average remaining contractual life in years (years) 3 years 23 days
Number of exercisable options (shares) | shares 56,710
Exercisable options, weighted average exercise price (dollars per share) $ 11.55
$11.35 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices (dollars per share) $ 11.35
Number of Outstanding options (shares) | shares 25,076
Weighted average exercise price (dollars per share) $ 11.35
Weighted average remaining contractual life in years (years) 4 years 1 month 5 days
Number of exercisable options (shares) | shares 25,076
Exercisable options, weighted average exercise price (dollars per share) $ 11.35
$13.70 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices (dollars per share) $ 13.70
Number of Outstanding options (shares) | shares 27,801
Weighted average exercise price (dollars per share) $ 13.70
Weighted average remaining contractual life in years (years) 5 years 1 month 6 days
Number of exercisable options (shares) | shares 22,084
Exercisable options, weighted average exercise price (dollars per share) $ 13.70
$14.76 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices (dollars per share) $ 14.76
Number of Outstanding options (shares) | shares 8,109
Weighted average exercise price (dollars per share) $ 14.76
Weighted average remaining contractual life in years (years) 6 years 1 month 19 days
Number of exercisable options (shares) | shares 4,865
Exercisable options, weighted average exercise price (dollars per share) $ 14.76
$16.01 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices (dollars per share) $ 16.01
Number of Outstanding options (shares) | shares 27,815
Weighted average exercise price (dollars per share) $ 16.01
Weighted average remaining contractual life in years (years) 7 years 1 month 10 days
Number of exercisable options (shares) | shares 11,126
Exercisable options, weighted average exercise price (dollars per share) $ 16.01