Financial Instruments (Notional Amounts of Derivatives) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of interest rate swaps	$ 1,000	$ 1,000
Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member]
Derivative [Line Items]
Notional amount of foreign currency contracts	1,389	2,032
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Notional amount of commodity contracts	8	553
Not Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member]
Derivative [Line Items]
Notional amount of foreign currency contracts	7,692	6,444
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Notional amount of commodity contracts	$ 21	$ 437