Interest Costs (Details) (USD $) In Thousands  | 
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2011  | 
Sep. 30, 2010  | 
Sep. 30, 2011  | 
Sep. 30, 2010  | 
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| Interest Cost | ||||
| Interest costs charged to expense | $ 75,316 | $ 68,559 | $ 229,730 | $ 223,230 | 
| Interest costs capitalized | 8,906 | 19,040 | 24,224 | 49,470 | 
| Total interest costs incurred | 84,222 | 87,599 | 253,954 | 272,700 | 
| Interest Costs (Textual) [Abstract] | ||||
| Non cash interest expense included in interest costs | $ 9,977 | $ 10,689 | $ 29,211 | $ 32,983 | 
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- Definition Interest Cost. 
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- Definition Interest Costs. 
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- Definition The amount of interest that was capitalized during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Total interest costs incurred during the period and either capitalized or charged against earnings. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The cost of borrowed funds accounted for as interest that was charged against earnings during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Interest paid other than in cash for example by issuing additional debt securities. As a noncash item, it is added to net income when calculating cash provided by or used in operations using the indirect method. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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