Benefit Plans (Summary Of Non-Qualified Stock Option Activity) (Details) (Non-Qualified Stock Options [Member], USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Non-Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, Jan. 1, Shares (in shares)	63,889	163,680
Outstanding, Jan. 1, Weighted Average Exercise Price (in dollars per share)	$ 24.21	$ 24.51
Exercised, Shares (in shares)	(27,453)	(60,481)
Exercised, Weighted Average Exercise Price (in dollars per share)	$ 23.79	$ 27.08
Outstanding and exercisable, June 30, Shares (in shares)	36,436	103,199
Outstanding and exercisable, June 30, Weighted Average Exercise Price (in dollars per share)	$ 24.52	$ 23.01