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           Long-Term Debt (Schedule Of Long-Term Debt) (Details) (USD $) 
        In Thousands, unless otherwise specified  | 
        0 Months Ended | 12 Months Ended | |||||
|---|---|---|---|---|---|---|---|
| 
           Dec. 31, 2011 
         | 
        
           Dec. 31, 2010 
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           Jun. 10, 2011
 
          8.5% Senior Notes Due June 2019 [Member] 
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           Dec. 31, 2011
 
          8.5% Senior Notes Due June 2019 [Member] 
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           Dec. 31, 2010
 
          8.25% Senior Notes Due June 2014 [Member] 
         | 
        
           Dec. 31, 2011
 
          Revolving Bank Credit Facility Due May 2015 [Member] 
         | 
        
           Dec. 31, 2010
 
          Revolving Bank Credit Facility Due May 2015 [Member] 
         | 
      |
| Debt Instrument [Line Items] | |||||||
| Total long-term debt | $ 717,000 | $ 450,000 | $ 600,000 | $ 600,000 | $ 450,000 | $ 117,000 | |
| Current maturities of long-term debt | |||||||
| Long-term debt, less current maturities | $ 717,000 | $ 450,000 | |||||
| Senior notes interest rate | 8.50% | 8.50% | 8.25% | ||||
| Senior notes maturity date | Jun. 15, 2019 | Jun. 01, 2019 | Jun. 01, 2014 | May 01, 2015 | |||
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- Definition 
          Interest rate stated in the contractual debt agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
          
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- Definition 
          Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.). Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Total of the portions of the carrying amounts as of the balance sheet date of long-term debt, which may include notes payable, bonds payable, debentures, mortgage loans, and commercial paper, which are scheduled to be repaid within one year or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year (current maturities) or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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