Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity, Stock Options and Net Income per Share - Stock Option Activity (Details)

v2.4.0.6
Shareholders' Equity, Stock Options and Net Income per Share - Stock Option Activity (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation $ 6,050 $ 5,971 $ 6,284
Employee Stock Option [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at beginning of year (shares) 3,363 3,702 3,086
Granted (shares) 94 117 664
Exercise of stock options (in shares) (570) (451) (35)
Forfeited (shares) (13) (5) (13)
Outstanding at end of year (shares) 2,874 3,363 3,702
Weighted Average Outstanding at beginning of year (per share) $ 26 $ 26 $ 26
Weighted average exercise price for options granted in the period $ 37 $ 29 $ 22
Weighted average exercise price for options exercised in the period $ 27 $ 23 $ 21
Weighted average exercise price for options forfeited in the period $ 29 $ 24 $ 26
Weighted Average Outstanding at end of year (per share) $ 26 $ 26 $ 26
Exercisable at end of year 2,487 2,585 2,475
Weighted average exercise price for options exercisable at year end $ 26 $ 27 $ 27
Weighted-average fair value of options granted during the year (dollars per share) $ 13 $ 11 $ 8
Aggregate intrinsic value of options exercised 3,924 3,771 268
Average aggregate intrinsic value for options outstanding 20,059    
Average aggregate instrinsic value for exercisable options 17,628    
Share-based compensation 2,585 3,981 5,689
Tax benefit related to share-based compensation expense 713 1,042 1,707
Unrecognized compensation cost 1,461    
Non-employee Director Activity - Options [Abstract]      
Term of options issued under the plan 7    
Non-employee Director Stock Options [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at beginning of year (shares) 41 63 74
Exercise of stock options (in shares) (12) (22) (11)
Outstanding at end of year (shares) 29 41 63
Weighted Average Outstanding at beginning of year (per share) $ 21 $ 22 $ 22
Weighted average exercise price for options exercised in the period $ 16 $ 23 $ 24
Weighted Average Outstanding at end of year (per share) $ 23 $ 21 $ 22
Aggregate intrinsic value of options exercised 207 202 37
Average aggregate intrinsic value for options outstanding and exercisable $ 302    
Non-employee Director Activity - Options [Abstract]      
Weighted average remaining contractual term for options outstanding 1.9    
Term of options issued under the plan   10  
Exercise Price Range 13.25 thru 18.82 [Member] | Employee Stock Option [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 250    
Weighted Average Outstanding at end of year (per share) $ 14.97    
Exercisable at end of year 250    
Weighted average exercise price for options exercisable at year end $ 14.97    
Range of exercise price, lower range limit $ 13.25    
Range of exercise price, upper range limit $ 18.82    
Weighted average remaining contractual life 0.4    
Exercise Price Range 20.21 thru 29.44 [Member] | Employee Stock Option [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 1,995    
Weighted Average Outstanding at end of year (per share) $ 25.91    
Exercisable at end of year 1,702    
Weighted average exercise price for options exercisable at year end $ 26.23    
Range of exercise price, lower range limit $ 20.21    
Range of exercise price, upper range limit $ 29.44    
Weighted average remaining contractual life 3.0    
Exercise Price Range 30.35 thru 36.90 [Member] | Employee Stock Option [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 629    
Weighted Average Outstanding at end of year (per share) $ 32.47    
Exercisable at end of year 535    
Weighted average exercise price for options exercisable at year end $ 31.75    
Range of exercise price, lower range limit $ 30.35    
Range of exercise price, upper range limit $ 36.90    
Weighted average remaining contractual life 1.9    
Exercise Price Range 13.25 thru 36.90 [Member] | Employee Stock Option [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Outstanding at end of year (shares) 2,874    
Weighted Average Outstanding at end of year (per share) $ 26.40    
Exercisable at end of year 2,487    
Weighted average exercise price for options exercisable at year end $ 26.29    
Range of exercise price, lower range limit $ 13.25    
Range of exercise price, upper range limit $ 36.90    
Weighted average remaining contractual life 2.5