Fair Value Measurements (Schedule of Carrying Value and Estimated Fair Value of Debt Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Eight Point Six Two Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	$ 600,000	$ 600,000
Seven Point Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	300,000	300,000
Other Long Term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	4,425	4,425
Reported Value Measurement [Member] | Eight Point Six Two Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	596,366	595,822
Reported Value Measurement [Member] | Seven Point Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	300,000	300,000
Reported Value Measurement [Member] | Other Long Term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	4,425	4,425
Estimate of Fair Value Measurement [Member] | Eight Point Six Two Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	627,750	644,978
Estimate of Fair Value Measurement [Member] | Seven Point Five Percent Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	312,750	327,000
Estimate of Fair Value Measurement [Member] | Other Long Term Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt	$ 4,027	$ 4,115