Benefit Plans (Summary Of Restricted Stock Activity) (Details) - Performance Contingent Restricted Stock [Member] - $ / shares		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested, January 1 (in shares/awards)		98,812	158,922
Nonvested, January 1, weighted average fair value (in dollars per share)		$ 50.69	$ 42.71
Granted (in shares/awards)		45,403	51,221
Granted, weighted average fair value (in dollars per share)		$ 65.09	$ 53.77
Vested (in shares/awards)	[1]	(49,093)	(90,847)
Vested, weighted average fair value (in dollars per share)	[1]	$ 47.58	$ 40.91
Forfeited (in shares/awards)		0	(20,484)
Forfeited, weighted average fair value (in dollars per share)		$ 0.00	$ 39.85
Nonvested, June 30 (in shares/awards)		95,122	98,812
Nonvested, June 30, weighted average fair value (in dollars per share)		$ 59.17	$ 50.69
2013 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Vested (in shares/awards)	[1]	(49,093)
2012 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Vested (in shares/awards)	[1]		(45,612)
2011 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Vested (in shares/awards)	[1]		(45,235)

[1] In 2015, 49,093 performance contingent restricted shares granted in 2013 vested because the specified performance criteria for such shares were met. In 2014, 45,612 and 45,235 performance contingent restricted shares granted in 2012 and 2011, respectively, vested because the specified performance criteria for such shares were met.