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Asset Retirement Obligations (Tables)
6 Months Ended
Jun. 30, 2012
Asset Retirement Obligations [Abstract]  
Information related to asset retirement obligation
         

Balance at December 31, 2011

  $ 180,662  

Additions to asset retirement obligations

    441  

Accretion expense

    5,066  

Liabilities settled

    (2,833
   

 

 

 

Balance at June 30, 2012

  $ 183,336