Share-based Compensation and Non-Qualified Deferred Compensation Plan (Summary Of Share Options Outstanding And Exercisable) (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
Outstanding and Exercisable Options, Number | shares	198,123	[1]
Aggregate intrinsic value of outstanding options | $	$ 8.5
Aggregate Intrinsic Value of Exercisable Options | $	$ 8.5
Closing share price per share for calculation of aggregate intrinsic values	$ 88.42
Options outstanding at June 30, 2016, Weighted Average Exercise/Grant Price	45.71	[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]
Outstanding and Exercisable Options, Weighted Average Price	$ 30.06	[1]
Range Of Exercise Prices Forty One Point Sixteen To Forty Three Point Ninety Four [Domain]
Range of exercise prices, minimum	41.16
Range of exercise prices, maximum	$ 43.94
Outstanding and Exercisable Options, Number | shares	85,788	[1]
Outstanding and Exercisable Options, Weighted Average Price	$ 42.37	[1]
Range Of Exercise Prices Forty Eight Point Zero Two To Eighty Five Point Zero FIveMember [Domain] [Domain]
Range of exercise prices, minimum	48.02
Range of exercise prices, maximum	$ 85.05
Outstanding and Exercisable Options, Number | shares	46,875	[1]
Outstanding and Exercisable Options, Weighted Average Price	$ 73.67	[1]

[1] The aggregate intrinsic value of options outstanding and exercisable at June 30, 2016 was $8.5 million. The aggregate intrinsic value was calculated as the excess, if any, between our closing share price of $88.42 per share on June 30, 2016 and the strike price of the underlying award.