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Asset Retirement Obligations
 12 Months Ended
Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligations
Asset Retirement Obligations

The following table presents the balance and activity of the asset retirement obligations for the years ended December 31, 2015, 2014 and 2013 (in thousands).
 
2015
 
2014
 
2013
Beginning balance
$
54,402

 
$
424,117

 
$
498,410

Liability incurred upon acquiring and drilling wells
1,662

 
4,968

 
5,078

Revisions in estimated cash flows(1)
44,060

 
(5,848
)
 
(3,077
)
Liability settled or disposed in current period(2)
(1,023
)
 
(377,927
)
 
(113,071
)
Accretion
4,477

 
9,092

 
36,777

Ending balance
103,578

 
54,402

 
424,117

Less: current portion
8,399

 
—

 
87,063

Asset retirement obligations, net of current
$
95,179

 
$
54,402

 
$
337,054

____________________
(1)
Revisions for the year ended December 31, 2015 relate primarily to changes in estimated well lives.
(2)
Liability settled or disposed for the year ended December 31, 2014, includes $366.0 million associated with the Gulf Properties sold in February 2014, as discussed in Note 3.