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ASSET RETIREMENT OBLIGATIONS (Tables)
 12 Months Ended
Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]  
Changes in Asset Retirement Obligations
The change in our asset retirement obligations during the years ended December 31, 2015, 2014 and 2013 is set forth below:
 
Year Ended December 31,
 
2015
 
2014
 
2013
Asset retirement obligations as of the beginning of the year, including current portion
$
316,409

 
$
502,513

 
$
488,302

Liabilities incurred
15,933

 
28,606

 
19,043

Liabilities settled
(72,713
)
 
(55,839
)
 
(79,695
)
Divestment of properties
(248
)
 
(137,801
)
 
(9,245
)
Accretion expense
25,988

 
28,411

 
33,575

Revision of estimates
(59,503
)
 
(49,481
)
 
50,533

Asset retirement obligations as of the end of the year, including current portion
$
225,866

 
$
316,409

 
$
502,513