XML 29 R29.htm IDEA: XBRL DOCUMENT v2.4.1.9
Asset Retirement Obligations (Tables)
 3 Months Ended
Mar. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]  
Changes in Asset Retirement Obligations
Changes in ARO are as follows:
 
Three Months Ended
March 31,
(millions)
2015
 
2014
Asset Retirement Obligations, Beginning Balance
$
751

 
$
586

Liabilities Incurred
10

 
1

Liabilities Settled
(8
)
 
(14
)
Revision of Estimate
24

 
72

Accretion Expense (1)
10

 
10

Asset Retirement Obligations, Ending Balance
$
787

 
$
655

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