v3.20.1

Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Finished goods	$ 259	$ 237
Work-in-process	738	738
Purchased raw materials	72	85
Operating supplies	68	69
Inventory, gross	1,137	1,129
LIFO reserve	(293)	(309)
Inventory, net	844	820
LIFO inventory	$ 764	$ 753
LIFO inventory	67.00%	67.00%

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

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Amount by which inventory stated at last-in first-out (LIFO) is less than (in excess of) inventory stated at other inventory cost methods.

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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 before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

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Amount before valuation and LIFO reserves of other supplies used within the manufacturing or production process expected to be consumed within one year or operating cycle, if longer.

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The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

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