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Noncurrent Other Liabilities (Schedule of Changes in Asset Retirement Obligations Narrative) (Details) (Details) - USD ($)
$ in Millions
Dec. 31, 2015
Dec. 31, 2014
Other Liabilities, Noncurrent [Abstract]    
Asset retirement obligation, liability for assets or businesses acquired $ 10 $ 10
Asset retirement obligation, recoveries current receivable non-trade 1  
Asset retirement obligation, recoveries long-term receivable noncurrent other assets $ 9