XML 28 R29.htm IDEA: XBRL DOCUMENT v2.4.0.8
Asset Retirement Obligations (Tables)
 9 Months Ended
Sep. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]  
Changes in Asset Retirement Obligations
Changes in ARO are as follows:
 
Nine Months Ended
September 30,
(millions)
2014
 
2013
Asset Retirement Obligations, Beginning Balance
$
586

 
$
402

Liabilities Incurred
38

 
4

Liabilities Settled
(77
)
 
(15
)
Revision of Estimate
123

 
5

Accretion Expense (1)
28

 
21

Asset Retirement Obligations, Ending Balance
$
698

 
$
417

(1) Accretion expense is included in DD&A expense in the consolidated statements of operations.