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SEGMENT REPORTING (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |
NET INCOME | $ 437.8 | $ 165.1 | $ (84.3) | $ 52.9 | $ 30.1 | $ (29.8) | $ 518.6 | $ 53.2
Revenues | 741.8 |  |  | 596.7 |  |  | 1,636.1 | 1,354.2
SALES MARGIN | 261.6 |  |  | 157.8 |  |  | 607.6 | 351.5
Other operating expense | (36.1) |  |  | (29.1) |  |  | (97.6) | (74.2)
TOTAL OTHER INCOME (EXPENSE) | (25.2) |  |  | (113.6) |  |  | (79.8) | (256.9)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES | 200.3 |  |  | 15.1 |  |  | 430.2 | 20.4
Interest expense, net | (29.5) |  |  | (27.6) |  |  | (93.1) | (99.1)
Income Tax Expense (Benefit) | 0.5 |  |  | (7.2) |  |  | 14.4 | (7.2)
Depreciation, depletion and amortization |  |  |  |  |  |  | (68.6) | (66.3)
EBITDA | 487.2 |  |  | 95.7 |  |  | 697.1 | 215.8
INCOME FROM DISCONTINUED OPERATIONS, NET OF TAX | 238.0 |  |  | 30.6 |  |  | 102.8 | 25.6
Foreign currency transaction gain (loss), before tax | (0.2) |  |  | (1.3) |  |  | (0.7) | 14.0
Gain (loss) on extinguishment of debt | 0.0 |  |  | (88.6) |  |  | 0.2 | (165.4)
Impairment Charges | (1.1) |  |  | 0.0 |  |  | (1.1) | 0.0
Adjusted EBITDA | 250.3 |  |  | 150.8 |  |  | 578.3 | 325.9
Property, Plant and Equipment, Additions | 92.6 |  |  | 26.3 |  |  | 241.9 | 78.0
Payments To Acquire Property Plant And Equipment Net |  |  |  |  |  |  | (194.7) | (77.4)
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  | 83.3 | 16.2
Capital Expenditures Incurred but Not yet Paid |  |  |  |  |  |  | 42.2 | 0.6
Government grant rebate |  |  |  |  |  |  | 2.5 | 0.0
Capital Lease Obligations Incurred |  |  |  |  |  |  | 7.6 | 0.0
U.S. Iron Ore [Member] |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |
Revenues | $ 741.8 |  |  | $ 596.7 |  |  | $ 1,636.1 | $ 1,354.2
Percentage Of Segment Revenue | 100.00% |  |  | 100.00% |  |  | 100.00% | 100.00%
SALES MARGIN | $ 261.6 |  |  | $ 157.8 |  |  | $ 607.6 | $ 351.5
Depreciation, depletion and amortization | (17.8) |  |  | (16.5) |  |  | (49.2) | (49.6)
EBITDA | 273.1 |  |  | 168.9 |  |  | 641.6 | 381.8
Adjusted EBITDA | 279.5 |  |  | 174.2 |  |  | 657.9 | 399.8
Property, Plant and Equipment, Additions | 51.8 |  |  | 19.2 |  |  | 97.2 | 70.9
All Segments |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |
Depreciation, depletion and amortization | (19.2) |  |  | (18.2) |  |  | (53.4) | (55.0)
EBITDA | 214.1 |  |  | (73.2) |  |  | 55.5 | (166.0)
Adjusted EBITDA | (29.2) |  |  | (23.4) |  |  | (79.6) | (73.9)
Corporate and Other [Member] |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |
Depreciation, depletion and amortization | (1.4) |  |  | (1.7) |  |  | (4.2) | (5.4)
Property, Plant and Equipment, Additions | 40.8 |  |  | 7.1 |  |  | 144.7 | 7.1
EBITDA Calculation [Member] |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |
Interest expense, net | (29.7) |  |  | (28.9) |  |  | (95.5) | (103.1)
Income Tax Expense (Benefit) | (0.5) |  |  | 7.6 |  |  | (14.4) | 6.8
Depreciation, depletion and amortization | (19.2) |  |  | (21.5) |  |  | (68.6) | (66.3)
Adjusted EBITDA Calculation [Member] |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |
INCOME FROM DISCONTINUED OPERATIONS, NET OF TAX | $ 238.2 |  |  | $ 34.8 |  |  | $ 120.4 | $ 41.3

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