DISCONTINUED OPERATIONS (Schedule of Disposal Groups, including Discontinued Operations, Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ 0.0	$ (70.9)
Asia Pacific Iron Ore [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues from product sales and services	0.0	59.0
Cost of goods sold and operating expenses	0.0	124.1
Sales margin	0.0	(65.1)
Other operating expense	(0.4)	(2.5)
Other expense	(0.1)	(1.1)
Impairment of long-lived assets	0.0	(2.6)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ (0.5)	$ (71.3)