Financial Instruments Notional Amounts (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 145	$ 587
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	3,866	3,922
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 8	$ 6