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ACQUISITIONS - Pro Forma Information (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2020
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma adjustments | $ 10 |
Pro forma tax rate |  | 24.30%
Pro forma income tax expense | (6) | $ (2)
AK Steel |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma revenue | 1,646 | 4,265
Pro forma net income (loss) | (6) | (124)
Fair Value Adjustment to Inventory |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma net income (loss) | 15 | 74
Acquisition-related Costs |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma net income (loss) | 1 | 29
Intersegment Eliminations |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma revenue | $ 136 | $ 395

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