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Stock-Based Compensation Plans (Tables)
9 Months Ended
Sep. 30, 2011
Stock-Based Compensation Plans [Abstract] 
Weighted-Average Assumptions For The ESOP
                                 
    Three Months Ended     Nine Months Ended  
    September 30,     September 30, 2011  
    2011     2010     2011     2010  
Dividend yield
     2.65 %     2.74 %     2.69 %     2.72 %
Expected volatility
     42.21 %     41.16 %     41.13 %     40.93 %
Risk-free interest rate
     0.98 %     1.27 %     1.61 %     1.87 %
Expected term of options (in years)
     4.05       4.18       4.05       4.19  
Weighted-average grant-date fair value
   $ 7.10     $ 5.46     $ 7.82     $ 5.34