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Summary of Significant Accounting Policies Asset Retirement Obligation (Details) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | ||
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Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2009
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| Asset Retirement Obligation, Roll Forward | |||
| Asset retirement obligation, beginning | $ 59,036 | $ 63,005 | |
| Asset retirement obligation, liabilities incurred | 1,084 | 6,484 | |
| Asset retirement obligation, liabilities settled | (218) | (512) | |
| Asset retirement obligation, revision of estimate | 0 | (13,004) | |
| Accretion expense, asset retirement obligation | 5,224 | 3,063 | 5,111 |
| Asset retirement obligation, ending | $ 65,126 | $ 59,036 | $ 63,005 |
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- Definition
The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of asset retirement obligations incurred during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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