Inventory valuation (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Hydrocarbon Inventory [Member]
Disclosure of financial assets [line items]
Inventory valuation reserve	$ 289	$ 290

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

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