Financial Instruments (Fair Value of Derivative Contracts) (Details) - Derivative Contract [Member] - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative asset fair value	$ 377	$ 220
Derivative liability fair value	663	631
Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset fair value	275	54
Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset fair value	38	99
Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability fair value	66	47
Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability fair value	491	525
Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset fair value	64	67
Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset fair value	0	0
Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability fair value	79	46
Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability fair value	$ 27	$ 13