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Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2012
Table Text Block Supplement [Abstract]  
Changes In Asset Retirement Obligations [Text Block]
The following table summarizes the changes in our asset retirement obligations for the years ended December 31, 2012 and 2011:
 
 
Year Ended December 31,
In thousands
 
2012
 
2011
Beginning asset retirement obligation
 
$
93,468

 
$
85,744

Liabilities incurred and assumed during period
 
50,956

 
12,477

Revisions in estimated retirement obligations
 
5,334

 
12,217

Liabilities settled and sold during period
 
(50,556
)
 
(23,257
)
Accretion expense
 
7,228

 
6,287

Ending asset retirement obligation
 
106,430

 
93,468

Less: current asset retirement obligation (1)
 
(3,700
)
 
(4,742
)
Long-term asset retirement obligation
 
$
102,730

 
$
88,726