Share-based Compensation and Non-Qualified Deferred Compensation Plan (Summary Of Share Options Outstanding And Exercisable) (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Outstanding and Exercisable Options, Number | shares	105,066	[1]
Aggregate intrinsic value of outstanding options | $	$ 3.7
Aggregate Intrinsic Value of Exercisable Options | $	$ 3.7
Closing share price per share for calculation of aggregate intrinsic values	$ 83.74
Options outstanding at September 30, 2016, Weighted Average Exercise/Grant Price	48.27	[1]
Exercise Price Thirty Point Zero Six Member [Domain]
Range of exercise prices, minimum	30.06
Range of exercise prices, maximum	$ 30.06
Outstanding and Exercisable Options, Number | shares	65,460	[1]
Exercise Price Seventy Five Point One Seven [Domain]
Range of exercise prices, minimum	$ 75.17
Range of exercise prices, maximum	$ 75.17
Outstanding and Exercisable Options, Number | shares	26,752	[1]
Exercise Price Five Point Zero FIve [Domain]
Range of exercise prices, minimum	$ 85.05
Range of exercise prices, maximum	$ 85.05
Outstanding and Exercisable Options, Number | shares	12,854	[1]

[1] The aggregate intrinsic value of options outstanding and exercisable at September 30, 2016 was $3.7 million. The aggregate intrinsic value was calculated as the excess, if any, between our closing share price of $83.74 per share on September 30, 2016 and the strike price of the underlying award.