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Schedule of Change in Asset Retirement Obligations (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Asset Retirement Obligation Disclosure [Abstract]      
Asset Retirement Obligation $ 94 $ 87 $ 64
Asset Retirement Obligation, Liabilities Incurred 4 0 1
Asset Retirement Obligation, Liabilities Settled (4) (3) (4)
Asset Retirement Obligation, Accretion Expense 6 6 4
Asset Retirement Obligation, Revision of Estimate 0 (4) 22
Asset Retirement Obligation $ 100 $ 94 $ 87