Benefit Plans (Summary Of Non-Qualified Stock Option Activity) (Details) (Non-Qualified Stock Options [Member], USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Non-Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, January 1, shares (in shares)	63,889	163,680
Outstanding, January 1, weighted average exercise price (in dollars per share)	$ 24.21	$ 24.51
Exercised, shares (in shares)	(38,711)	(62,481)
Exercised, weighted average exercise price (in dollars per share)	$ 24.41	$ 27.10
Outstanding and exercisable, September 30, shares (in shares)	25,178	101,199
Outstanding and exercisable, September 30, weighted average exercise price (in dollars per share)	$ 23.89	$ 22.92