Statements Of Unaudited Condensed Consolidated Comprehensive Income - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (48.6)	$ (22.1)
Other comprehensive income (loss):
Changes in pension and OPEB, net of tax	5.6	5.7
Changes in foreign currency translation	(0.9)	0.0
Changes in derivative financial instruments, net of tax	(3.0)	2.7
Total other comprehensive income	1.7	8.4
Comprehensive loss	(46.9)	(13.7)
Comprehensive income attributable to noncontrolling interests	(3.5)	0.0
Comprehensive loss attributable to Cliffs shareholders	$ (50.4)	$ (13.7)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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