Debt (Schedule Of Debt) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term debt	$ 900,425,000	$ 900,247,000
Senior Secured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility amount outstanding	0	0
Eight Point Six Two Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes	600,000,000	600,000,000
Unamortized discount	(4,000,000)	(4,178,000)
Seven Point Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes	300,000,000	300,000,000
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Other long-term debt	$ 4,425,000	$ 4,425,000