XML 46 R25.htm IDEA: XBRL DOCUMENT v3.7.0.1
Asset Retirement Obligations (Tables)
 3 Months Ended
Mar. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]  
Changes in Asset Retirement Obligations
Changes in ARO are as follows:
 
Three Months Ended
March 31,
(millions)
2017
 
2016
Asset Retirement Obligations, Beginning Balance
$
935

 
$
989

Liabilities Incurred
1

 
2

Liabilities Settled
(9
)
 
(8
)
Revision of Estimate
(7
)
 
5

Accretion Expense (1)
12

 
12

Asset Retirement Obligations, Ending Balance
$
932

 
$
1,000

(1) 
Accretion expense is included in depreciation, depletion and amortization (DD&A) expense in the consolidated statements of operations.