XML 55 R32.htm IDEA: XBRL DOCUMENT v2.4.0.6
Stock-Based Compensation (Tables)
 12 Months Ended
Dec. 31, 2011
Stock-Based Compensation [Abstract]  
Weighted average assumptions used to determine fair value for stock awards
   The fair value for stock awards was estimated at the date of grant using the Black-Scholes option valuation model with the following weighted average assumptions for the years ended December 31, 2011, 2010 and 2009:

 
2011
 
2010
 
2009
Expected life (years)                                                      
 
6.3
     
6.3
     
6.3
 
Interest rate                                                      
 
2.46
%
   
2.92
%
   
1.87
%
Volatility                                                      
 
30.93
%
   
28.80
%
   
28.01
%
Expected dividend yield                                                      
 
0.31
%
   
0.41
%
   
0.50
%
Summary of stock option activity
  The following table summarizes stock option activity for the year ended December 31, 2011:

   
Shares
       
Weighted Average Exercise Price Per Share
 
Weighted Average Remaining Contractual Life (Years)
   
Aggregate Intrinsic      Value                 (in thousands)
Balance December 31, 2010
 
820,030
     
$
52.11
         
Granted
 
122,323
       
64.12
         
Exercised
 
(120,598
)
     
50.02
         
Canceled
 
(34,768
)
     
53.59
         
Balance December 31, 2011
 
786,987
     
$
54.19
 
5.71
 
$
10,087
                         
Exercisable, December 31, 2011
 
559,670
     
$
54.16
 
4.63
 
$
2,639
Non-vested stock option activity
    Non-vested stock option activity for the year ended December 31, 2011 is as follows:
   
Shares
   
Weighted Average Exercise Price Per Share
 
Nonvested options outstanding at December 31, 2010
 
269,315
 
$
47.13
 
Options granted                                                                           
 
122,323
   
64.12
 
Options vested                                                                           
 
(133,864
)
 
48.76
 
Options forfeited .
 
(30,457
)
 
54.78
 
Nonvested options outstanding, December 31, 2011 
 
227,317
 
$
54.29
 
Summary of outstanding options by exercise price
   The following table summarizes additional information concerning options outstanding at December 31, 2011:

Options Outstanding
 
Options Exercisable
Range of
 Exercise Prices
 
Number Outstanding at 12/31/11
 
Weighted Average Remaining Contractual Term (Years)
 
Weighted Average Exercise Price
 
Number Exercisable
at 12/31/11
 
Weighted Average Exercise Price
$
38.620
-
$
49.505
 
302,241
 
6.4
 
$
44.69
 
183,199
 
$
44.24
$
50.785
-
$
59.330
 
158,162
 
2.8
 
$
54.09
 
154,402
 
$
54.09
$
60.195
-
$
69.315
 
326,584
 
6.5
 
$
63.04
 
222,069
 
$
62.38
$
38.620
-
$
69.315
 
786,987
 
5.2
 
$
54.19
 
559,670
 
$
54.15
Summary of restricted stock activity
 The following table summarizes the restricted stock activity for the Plan:

       
Shares
     
Weighted Average Grant Date Fair Value
 
Unvested balance at December 31, 2010
     
150,270
   
$
47.19
 
Granted
     
68,489
   
$
64.17
 
Vested
     
(47,123
)
 
$
63.98
 
Canceled
     
(45,624
)
 
$
60.44
 
Unvested balance at December 31, 2011
     
126,012
   
$
54.42