Cleveland-Cliffs Inc. Quarterly report pursuant to Section 13 or 15(d)

DISCONTINUED OPERATIONS (Narrative) (Details)

DISCONTINUED OPERATIONS (Narrative) (Details) $ in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2018 CAD ($)	Sep. 30, 2017 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loans to and accounts receivable from the Canadian Entities	$ 0.0						$ 0.0			$ 51.6	$ 51.6
Cash contribution								$ 19.0
Asia Pacific Iron Ore [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense	0.0			$ (0.4)			0.0		$ 0.4
Unrealized Net Gain (Loss) on Foreign Currency Translation [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (228.1)	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Discontinued Operations [Member] \| Asia Pacific Iron Ore [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-cash financing activities							$ 27.1

- Definition

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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