Share-Based Compensation (Summary Of Share Options Outstanding And Exercisable) (Details) (USD $) In Millions, except Share data, unless otherwise specified						12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 $30.06-$31.48 [Member]		Dec. 31, 2012 $41.16-$43.94 [Member]		Dec. 31, 2012 $45.53-$73.32 [Member]
Range of exercise prices, minimum						$ 30.06		$ 41.16		$ 45.53
Range of exercise prices, maximum						$ 31.48		$ 43.94		$ 73.32
Outstanding Options, Number	838,754	[1]	1,339,536	1,847,136	1,983,358	210,750	[1]	255,632	[1]	372,372	[1]
Outstanding Options, Weighted Average Price	$ 42.36	[1]	$ 42.27	$ 42.37	$ 41.39	$ 30.06	[1]	$ 42.72	[1]	$ 49.07	[1]
Exercisable Options, Number	551,206	[1]				14,943	[1]	237,000	[1]	299,263	[1]
Exercisable Options, Weighted Average Price	$ 45.92	[1]				$ 30.12	[1]	$ 42.62	[1]	$ 49.33	[1]
Aggregate intrinsic value of outstanding options	$ 21.8
Aggregate Intrinsic Value of Exercisable Options	$ 12.4
Closing share price per share for calculation of aggregate intrinsic values	$ 68.21

[1] (1)The aggregate intrinsic value of outstanding and exercisable options at December 31, 2012 was approximately $21.8 million and $12.4 million, respectively. The aggregate intrinsic values were calculated as the excess, if any, between our closing share price of $68.21 per share on December 31, 2012 and the strike price of the underlying award.