Stock-Based Compensation (Schedule Of Fair Value Of The Restricted Stock Awards Granted During The Periods) (Details) (Restricted Stock [Member], USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	448,549	367,936
Estimated fair value (in millions)	$ 21.0	$ 15.6
Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	448,549	367,936
Estimated fair value (in millions)	21.0	15.6
Percentage of shares granted expected to be distributed	94.00%	89.00%
Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0
Estimated fair value (in millions)	$ 0	$ 0