XML 45 R23.htm IDEA: XBRL DOCUMENT v2.4.0.8
Asset Retirement Obligation (Tables)
 9 Months Ended
Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]  
Changes to the Company's asset retirement obligation liability
The following table describes the changes to the Company’s asset retirement obligation liability (in thousands):
 
Nine Months Ended September 30,
 
2013
 
2012
Asset retirement obligation, beginning of period
$
27,260

 
$
30,427

Liabilities incurred
498

 
867

Liabilities assumed
15,319

 
—

Liabilities settled
(2,415
)
 
(2,519
)
Accretion expense
1,203

 
1,542

Revisions in estimated cash flows
987

 
(42
)
Asset retirement obligation, end of period
42,852

 
30,275

Less: current portion of asset retirement obligation
(1,502
)
 
(1,034
)
Long-term asset retirement obligation
$
41,350

 
$
29,241