Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

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Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Impairments		$ 171		$ 2,321
Gain on sale of assets, net		$ 17	$ 6
Long-term Debt [Member] \| 4.05% Senior Notes due January 2020 [Member]
Debt Instrument [Line Items]
Stated interest rate		4.05%
Debt, maturity date		Jan. 31, 2020
Other Non-Core Assets [Member]
Debt Instrument [Line Items]
Impairments		$ 11
Midstream Services [Member]
Debt Instrument [Line Items]
Impairments		155
Gain on sale of assets, net		35
Exploration and Production [Member]
Debt Instrument [Line Items]
Impairments		15
Gain on sale of assets, net		(18)
Discontinued Operations, Held-for-sale [Member]
Debt Instrument [Line Items]
Impairments	$ 160	160
Discontinued Operations, Held-for-sale [Member] \| Midstream Services [Member]
Debt Instrument [Line Items]
Impairments	145	145
Discontinued Operations, Held-for-sale [Member] \| Exploration and Production [Member]
Debt Instrument [Line Items]
Impairments	$ 15	$ 15