Employee Benefit Plans (Summary Of Stock Option Activity) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Employee Benefit Plans [Abstract]
Options Outstanding, beginning balance	289,544	293,817
Options, Granted	15,475	16,876
Options, Exercised	(42,250)	(16,899)
Options, Forfeited	(1,500)
Options Outstanding, ending balance	261,269	293,794
Weighted-Average Exercise Price, Outstanding, beginning balance	$ 34.38	$ 33.95
Weighted-Average Exercise Price, Granted	$ 37.74	$ 35.39
Weighted-Average Exercise Price, Exercised	$ 33.06	$ 28.87
Weighted-Average Exercise Price, Forfeited	$ 36.90
Weighted-Average Exercise Price, Outstanding, ending balance	$ 34.77	$ 34.32