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ACQUISITIONS - Pro Forma Information (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2020
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma adjustments | $ 12 | $ 1
Pro forma tax rate |  | 24.30%
Pro forma income tax expense | (2) | $ (3)
AK Steel |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma revenue | 979 | 2,428
Pro forma net income (loss) | (125) | (164)
Fair Value Adjustment to Inventory |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma net income (loss) | 36 | 59
Acquisition-related Costs |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma net income (loss) | 2 | 28
Intersegment Eliminations |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Pro forma revenue | $ 114 | $ 259

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