Inventories (Summary of Inventory) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Summary of inventories
Crude oil and petroleum products	$ 3,452	$ 3,238
Materials and supplies	324	305
Inventories	$ 3,776	$ 3,543

Carrying amount as of the balance sheet date of finished goods inventories for petroleum products, crude oil, petrochemical products, and other oil and gas inventories.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount, after of valuation reserves and allowances, of inventory, classified as other, expected to be sold, or consumed within one year or operating cycle, if longer.

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