Derivative Financial Instruments (Derivatives Balance Sheet Location) (Details) - Commodity contracts - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	[1]	$ 0	$ 0
Derivative liability, fair value, gross liability	[1]	(60)	(61)
Not Designated as Hedging Instrument | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	[1]	0	0
Not Designated as Hedging Instrument | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value, gross liability	[1]	(5)	(7)
Not Designated as Hedging Instrument | Other noncurrent assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	[1]	0	0
Not Designated as Hedging Instrument | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value, gross liability	[1]	$ (55)	$ (54)

[1] Includes embedded derivatives in commodity contracts as discussed above.