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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