v3.8.0.1
ASSET RETIREMENT OBLIGATION (Tables)
9 Months Ended
Sep. 30, 2017
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Changes to Asset Retirement Obligation
Following is a table of the changes to our asset retirement obligation for the following periods (in thousands):
 
 
Three Months Ended September 30,
 
Nine Months Ended September 30,
 
 
2017
 
2016
 
2017
 
2016
Asset retirement obligation, at beginning of period
 
$
20,754

 
$
23,832

 
$
19,976

 
$
22,951

Liabilities settled
 

 

 

 
(3
)
Accretion of discount
 
390

 
442

 
1,168

 
1,326

Total asset retirement obligation, at end of period
 
$
21,144

 
$
24,274

 
$
21,144

 
$
24,274