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Asset Retirement Obligations (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Asset retirement obligation, beginning balance $ 90 $ 85
Accretion expense 10 9
Liabilities settled (9) (8)
Revision in estimate cash flows 0 5
Effect of foreign currency rate change (2) (1)
Asset retirement obligation, ending balance $ 89 $ 90