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ACQUISITION OF AK STEEL (Pro Forma Information Tables) (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended
--- | --- | ---
Mar. 31, 2020 | Mar. 31, 2020 | Mar. 31, 2019
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Business Acquisition, Pro Forma Revenue |  |  | $ 1,526.4 | $ 1,787.3
Business Acquisition, Pro Forma Net Income (Loss) |  |  | (17.4) | (79.7)
Revenues | [1] |  | 359.1 | 157.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  | $ (48.6) | (22.1)
AK Steel Holding Corporation [Member] |  |  |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Revenues |  | $ 217.5 |  |
Business Acquisition, Pro Forma Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  |  | 24.30% |
Business Acquisition, Pro Forma Income Tax Expense (Benefit) |  |  | $ 11.6 | 18.3
Fair Value Adjustment to Inventory [Member] |  |  |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  | 23.2 | 84.8
Acquisition-related Costs [Member] |  |  |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  | 26.6 |
Other Adjustments [Member] |  |  |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  | 13.1 |
Other Adjustments [Member] | AK Steel Holding Corporation [Member] |  |  |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest |  |  |  | 4.2
Intersegment Eliminations [Member] |  |  |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |  |  |
Revenues |  |  | $ 67.8 | $ 67.4
[1] | 1 Includes Realization of deferred revenue of $34.6 million for the three months ended March 31, 2020.

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