Quarterly report pursuant to Section 13 or 15(d)

Share-Based Payments - Stock Option Activity (Details)

v3.2.0.727
Share-Based Payments - Stock Option Activity (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense $ 1,890 $ 1,677 $ 3,676 $ 3,329
Employee Stock Option [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense 342 331 678 646
Tax benefit related to share-based expense 132 126 261 246
Unrecognized share-based compensation, net of estimated forfeitures $ 2,266 $ 2,314 $ 2,266 $ 2,314
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   31.60% 33.90% 38.80%
Weighted Average Risk Free Interest Rate   1.50% 1.60% 1.60%
Expected life of options (in years)   4 years 6 months 11 days 6 years 1 month 11 days 5 years 3 months 11 days
Weighted-average fair value of options (dollars per share)   $ 11 $ 16 $ 14
Outstanding, beginning of period (in shares) 950   1,363  
Granted (in shares) 0   82  
Exercised (in shares) (48)   (529)  
Forfeited (in shares) 0   (14)  
Outstanding, end of period (in shares) 902   902  
Exercisable, end of period (in shares) 712   712  
Outstanding, beginning of period (in dollars per share) $ 30   $ 28  
Grants in Period (in dollars per share) 0   51  
Exercises in Period (in dollars per share) 25   27  
Forfeited in period (in dollars per share) 0   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 $ 19,747   $ 19,747  
Aggregate Intrinsic Value Exercisable, end of period $ 18,363   $ 18,363  
Weighted-average remaining contractual term Outstanding, end of period (in years) 2 years 11 months 11 days   2 years 11 months 11 days  
Weighted-average remaining contractual term Exercisable, end of period (in years) 2 years 1 month 11 days   2 years 1 month 11 days