Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation (Status Of Unvested Shares Of Stock Issued To Employees And Directors) (Details)

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Stock Based Compensation (Status Of Unvested Shares Of Stock Issued To Employees And Directors) (Details) (USD $)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Stock Based Compensation [Abstract]      
Unvested at beginning of year, Non-vested Shares 192,776 154,593 130,807
Granted, Non-vested Shares 106,602 78,152 59,590
Vested, Non-vested Shares (52,744) (39,969) (35,349)
Forfeited, Non-vested Shares     (455)
Unvested at end of year, Non-vested Shares 246,634 192,776 154,593
Unvested at beginning of year, Weighted average grant date fair value $ 39.34 $ 39.79 $ 44.79
Granted, Weighted average grant date fair value $ 35.02 $ 37.03 $ 29.70
Vested, Weighted average grant date fair value $ 37.19 $ 36.55 $ 41.25
Forfeited, Weighted average grant date fair value     $ 43.95
Unvested at end of year, Weighted average grant date fair value $ 37.93 $ 39.34 $ 39.79