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Asset Retirement Obligation Disclosure (Tables)
 12 Months Ended
Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Change in Asset Retirement Obligation
The table below summarizes the changes in our asset retirement obligations (in thousands):
 
Year Ended December 31,
 
2014
 
2013
Asset retirement obligation – beginning of period
$
3,172

 
$
512

Obligation acquired
—

 
2,601

Accretion expense
239

 
59

Change in estimate
(831
)
 
—

Asset retirement obligation – end of period
$
2,580

 
$
3,172