Derivatives and Other Hedging Instruments (Notional Amounts of Derivatives) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional amounts	$ 1,000	$ 1,000
Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member]
Derivative [Line Items]
Derivative notional amounts	434	1,107
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative notional amounts	388	606
Not Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member]
Derivative [Line Items]
Derivative notional amounts	10,586	9,553
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative notional amounts	$ 166	$ 281