Share-Based Compensation and Benefit Plans (Summary Of Share Incentive Plans) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding Options, Number	295,205		321,811	634,361
Granted, Options Outstanding	12,854		26,752	84,452
Exercised/Vested, Options Outstanding	(202,993)		(53,358)	(375,316)
Forfeited, Options Outstanding	0		0	(21,686)
Outstanding Options, Number	105,066	[1]	295,205	321,811
Weighted Average Exercise/Grant Price, balance	$ 42.49		$ 38.97	$ 41.59
Granted, Weighted Average Exercise/Grant Price	85.05		75.17	64.75
Exercised/Vested, Weighted Average Exercise/Grant Price	42.19		37.69	47.85
Forfeited, Weighted Average Exercise/Grant Price	0.00		0.00	62.32
Weighted Average Exercise/Grant Price, balance	$ 48.27		$ 42.49	$ 38.97
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested share awards outstanding, Share Awards Outstanding	750,246		818,943	831,298
Granted, Share Awards Outstanding	270,978		257,749	314,614
Exercised/Vested, Share Awards Outstanding	(398,492)		(313,628)	(305,372)
Forfeited, Share Awards Outstanding	(18,245)		(12,818)	(21,597)
Nonvested share awards outstanding, Share Awards Outstanding	604,487		750,246	818,943
Nonvested share awards outstanding, Weighted Average Exercise/Grant Price	$ 68.09		$ 63.39	$ 59.77
Granted, Weighted Average Exercise/Grant Price	74.92		74.53	65.78
Exercised/Vested, Weighted Average Exercise/Grant Price	68.16		61.10	55.97
Forfeited, Weighted Average Exercise/Grant Price	70.63		67.96	64.14
Nonvested share awards outstanding, Weighted Average Exercise/Grant Price	$ 71.03		$ 68.09	$ 63.39

[1] The aggregate intrinsic value of options outstanding and exercisable at December 31, 2016 was approximately $3.8 million. The aggregate intrinsic value was calculated as the excess, if any, between our closing share price of $84.07 per share on December 31, 2016 and the strike price of the underlying award.