Fair Value Measurements (Schedule Of Estimated Fair Value Of Other Financial Instruments) (Details) (7.5% Senior Unsecured Notes 2018 [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
2018 Notes	$ 673,125	$ 705,000
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
2018 Notes	673,125	705,000
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
2018 Notes
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
2018 Notes