Derivative Financial Instruments and Risk Management (Details 6) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Offsetting Assets and Liabilities
Gross Amount of Recognized Assets	$ 101	$ 138	$ 238
Gross Amounts Offset	0	0	0
Net Amount of Assets	101	138	238
Gross Amounts Not Offset	(8)	(9)	(12)
Net Amount	93us-gaap_DerivativeAssets	129us-gaap_DerivativeAssets	226us-gaap_DerivativeAssets
Gross Amount of Recognized Liabilities	(23)	(10)	(15)
Gross Amounts Offset	0	0	0
Net Amount of Liabilities	(23)	(10)	(15)
Gross Amounts Not Offset	8	9	12
Net Amount	$ (15)us-gaap_DerivativeLiabilities	$ (1)us-gaap_DerivativeLiabilities	$ (3)us-gaap_DerivativeLiabilities

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