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Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2013
Table Text Block Supplement [Abstract]  
Changes In Asset Retirement Obligations
The following table summarizes the changes in our asset retirement obligations for the years ended December 31, 2013 and 2012:
 
 
Year Ended December 31,
In thousands
 
2013
 
2012
Beginning asset retirement obligation
 
$
106,430

 
$
93,468

Liabilities incurred and assumed during period
 
22,216

 
50,956

Revisions in estimated retirement obligations
 
4,730

 
5,334

Liabilities settled and sold during period
 
(15,523
)
 
(50,556
)
Accretion expense
 
8,448

 
7,228

Ending asset retirement obligation
 
126,301

 
106,430

Less: current asset retirement obligation (1)
 
(6,413
)
 
(3,700
)
Long-term asset retirement obligation
 
$
119,888

 
$
102,730



(1)
Included in "Accounts payable and accrued liabilities" in our Consolidated Balance Sheets.