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, 2012	Mar. 31, 2011
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	367,936	192,581
Estimated fair value (in millions)	$ 15.6	$ 10.0
Percentage of shares granted expected to be distributed	89.00%	93.00%