Common Stock And Share-Based Compensation (Summary Of Share-Based Compensation Expense Recognized) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 3,412,000		$ 9,105,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	(943,000)	[1]	3,362,000	[1]
Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	2,573,000		5,030,000
Cash Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	469,000		209,000
Phantom Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	1,313,000		504,000
Revision To Forfeiture Rate [Member] | Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cumulative reduction to share-based compensation expense	$ 3,900,000

[1] The net credit to stock option expense for the three months ended March 31, 2012 is the result of a $3.9 million one-time cumulative reduction to share-based compensation expense for stock options based on our review of historical forfeiture activity in comparison to the estimated forfeiture rate originally applied to those awards.