Financial Instruments Notional Amounts (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 264	$ 587
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	9,959	10,454
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 34	$ 6