Quarterly report pursuant to Section 13 or 15(d)

Share-Based Payments - Stock Option Activity (Details)

v3.3.0.814
Share-Based Payments - Stock Option Activity (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense $ 1,886 $ 1,676 $ 5,562 $ 5,005
Employee Stock Option [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense 352 343 1,029 989
Tax benefit related to share-based expense 137 131 403 377
Unrecognized share-based compensation, net of estimated forfeitures $ 1,977 $ 1,971 $ 1,977 $ 1,971
Employee activity - stock options [Abstract]        
Stock option grants expire (in years)     7 years  
Grants, vesting period (in years)     3 years  
Expected dividend yield (in hundredths) 1.20%   1.00% 1.20%
Expected stock price volatility 29.80%   33.70% 38.80%
Weighted Average Risk Free Interest Rate 1.40%   1.60% 1.60%
Expected life of options (in years) 4 years 6 months 11 days   6 years 11 days 5 years 3 months 11 days
Weighted-average fair value of options (dollars per share) $ 12   $ 16 $ 14
Outstanding, beginning of period (in shares) 902   1,363  
Granted (in shares) 5   87  
Exercised (in shares) 0   (530)  
Forfeited (in shares) (1)   (14)  
Outstanding, end of period (in shares) 906   906  
Exercisable, end of period (in shares) 713   713  
Outstanding, beginning of period (in dollars per share) $ 31   $ 28  
Grants in Period (in dollars per share) 52   51  
Exercises in Period (in dollars per share) 0   27  
Forfeited in period (in dollars per share) 23   29  
Outstanding, end of period (in dollars per share) 31   31  
Exercisable, end of period (in dollars per share) $ 27   $ 27  
Aggregate Intrinsic Value Outstanding, end of period $ 14,819   $ 14,819  
Aggregate Intrinsic Value Exercisable, end of period $ 14,507   $ 14,507  
Weighted-average remaining contractual term Outstanding, end of period (in years) 2 years 8 months 11 days   2 years 8 months 11 days  
Weighted-average remaining contractual term Exercisable, end of period (in years) 1 year 10 months 11 days   1 year 10 months 11 days