Share-Based Compensation (Summary Of All RSU Awards Granted To Employees And Non-Employee Directors) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU outstanding at end of period, RSUs	206,685
RSU Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU outstanding at beginning of period, RSUs	109,281	115,949	176,084
Granted, RSUs	98,942	62,322	38,899
Settled, RSUs	(54,034)	(56,865)	(58,117)
Cancelled, RSUs	(22,527)	(19,088)	(40,917)
RSU outstanding at end of period, RSUs	138,761	109,281	115,949
RSU exercisable at end of period, RSUs	3,040	1,200	250
RSU outstanding at beginning of period, Weighted Average Price	$ 52.90	$ 52.97	$ 44.39
Granted, Weighted Average Price	41.09	51.53	72.11
Settled, Weighted Average Price	48.50	48.34	45.51
Cancelled, Weighted Average Price	$ 46.86	$ 55.08	44.86
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	7,099	6,963
RSU outstanding at end of period, Weighted Average Price	$ 46.60	$ 52.90	52.97
RSU exercisable at end of period, Weighted Average Price	60.92	59.29	$ 42.12
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 41.55	$ 32.76