Nature of Operations and Significant Accounting Policies (Details) (USD $)
 3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2012
Jun. 30, 2011
Nature of Operations and Significant Accounting Policies (Textual) [Abstract]      
Reclassification from other assets to treasury stock, Amount $ 6,200,000    
Reclassification from other assets to treasury stock, Shares 188,621    
Increase to cash flows from financing activities due to identification of errors reported in cash flow   19,364,000 18,243,000
Error Correction [Member]
      
Nature of Operations and Significant Accounting Policies (Textual) [Abstract]      
Error related to amortization period resulting in reduction to net periodic pension expense   2,000,000  
Error related to amortization period resulting in reduction to net periodic pension expense after tax   1,300,000  
Decrease to cash flows from operating activities due to identification of errors reported in cash flow   900,000  
Increase to cash flows from financing activities due to identification of errors reported in cash flow   $ 900,000