Consolidated Statement Of Changes In Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statement Of Changes In Shareholders' Equity [Abstract]
Stock option exercises/deferred stock unit conversions	148,203	820,853	426,625
Purchase of treasury stock, shares	37,464	18,424	15,777
Treasury stock issued/sold to the 401(k) stock purchase plan, shares		40,019	154,695
Common stock issued/sold to the 401(k) stock purchase plan, shares	22,680	205,100
Cash dividends, per share	$ 1.83	$ 1.78	$ 1.71
Non-vested stock awards, shares	22,360	22,360	56,300