XML 92 R45.htm IDEA: XBRL DOCUMENT v2.4.0.6
Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2012
Asset Retirement Obligation Disclosure [Abstract]  
Reconciliation of Beginning and Ending Aggregate Carrying Amounts of Asset Retirement Obligation
The following table presents the balance and activity of the asset retirement obligations for the years ended December 31 (in thousands).
 
2012
 
2011
 
2010
Asset retirement obligations at January 1
$
128,116

 
$
119,877

 
$
111,137

Liability incurred upon acquiring and drilling wells
7,479

 
5,716

 
17,347

Liability assumed in acquisition
371,365

 
—

 
—

Revisions in estimated cash flows
34,654

 
7,574

 
(17,017
)
Liability settled or disposed in current period
(72,200
)
 
(14,419
)
 
(1,011
)
Accretion
28,996

 
9,368

 
9,421

Asset retirement obligations at December 31
498,410

 
128,116

 
119,877

Less: current portion
118,504

 
32,906

 
25,360

Asset retirement obligations, net of current
$
379,906

 
$
95,210

 
$
94,517