XML 54 R39.htm IDEA: XBRL DOCUMENT v3.5.0.2
Asset Retirement Obligation - Asset Retirement Obligation (Detail) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset retirement obligation at December 31, 2015 $ 2,598  
Liabilities incurred 6  
Liabilities acquired 34  
Liabilities settled (31)  
Accretion expense 76  
Revisions in estimated liabilities 59  
Asset retirement obligation at June 30, 2016 2,742  
Less current portion 36 $ 36
Asset retirement obligation, long-term $ 2,706 $ 2,562