Financial Instruments (Notional Amounts of Derivatives) (Details) (USD $) In Millions, unless otherwise specified	Mar. 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	865	1,107
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative notional amounts	358	606
Not Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member]
Derivative [Line Items]
Derivative notional amounts	10,822	9,553
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative notional amounts	$ 238	$ 281