XML 41 R28.htm IDEA: XBRL DOCUMENT v3.4.0.3
Asset Retirement Obligations (Tables)
 3 Months Ended
Mar. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]  
Changes in Asset Retirement Obligations
Changes in ARO are as follows:
 
Three Months Ended
March 31,
(millions)
2016
 
2015
Asset Retirement Obligations, Beginning Balance
$
989

 
$
751

Liabilities Incurred
2

 
10

Liabilities Settled
(8
)
 
(8
)
Revision of Estimate
5

 
24

Accretion Expense (1)
12

 
10

Asset Retirement Obligations, Ending Balance
$
1,000

 
$
787

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