Debt (Schedule Of Debt) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Debt	$ 967,808	$ 711,486
Senior Secured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility amount outstanding	0	47,000
Eight Point Six Two Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes	600,000	600,000
Unamortized discount	(4,849)	(5,465)
Seven Point Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes	300,000	0
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Unamortized discount	(1,093)	(3,799)
4.375% Convertible Senior Notes	$ 73,750	$ 73,750