Derivatives (Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 12
Derivative Liability, Fair Value, Gross Liability	6
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	6
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	10	$ 131
Derivative Liability, Fair Value, Gross Liability	6	4
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		(127)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	4
Other Current Assets [Member] \| Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	9	131
Derivative Liability, Fair Value, Gross Liability	1
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	8	131
Other Noncurrent Assets [Member] \| Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1
Other Current Liabilities [Member] \| Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0
Derivative Liability, Fair Value, Gross Liability	5	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(5)
Other Noncurrent Liabilities [Member] \| Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability		4
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		$ (4)
Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2
Derivative Liability, Fair Value, Gross Liability	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	2
Cash Flow Hedging [Member] \| Other Noncurrent Assets [Member] \| Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2
Derivative Liability, Fair Value, Gross Liability	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 2

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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