XML 19 R42.htm IDEA: XBRL DOCUMENT v2.4.0.8
Asset Retirement Obligations (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Asset Retirement Obligations        
AROs $ 20,382   $ 20,382  
Changes in Company's asset retirement obligations        
Asset retirement obligations at the beginning of the period     26,308  
Liabilities incurred     844  
Liabilities settled     (47)  
Liabilities eliminated through asset sale     (7,652)  
Current period accretion expense 432 313 929 567
Asset retirement obligations at the end of the period $ 20,382   $ 20,382