Cleveland-Cliffs Inc. Quarterly report [Sections 13 or 15(d)]

REVENUES - Revenues By Product Line (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Revenues	$ 4,629	$ 5,199
Steelmaking [Member]
Disaggregation of Revenue [Line Items]
Revenues	4,495	5,053
Steelmaking [Member] \| Third Party
Disaggregation of Revenue [Line Items]
Revenues	4,467	5,027
Steelmaking [Member] \| Hot-rolled steel
Disaggregation of Revenue [Line Items]
Revenues	1,166	1,128
Steelmaking [Member] \| Cold-rolled steel
Disaggregation of Revenue [Line Items]
Revenues	591	749
Steelmaking [Member] \| Coated steel
Disaggregation of Revenue [Line Items]
Revenues	1,361	1,623
Steelmaking [Member] \| Stainless and electrical steel
Disaggregation of Revenue [Line Items]
Revenues	444	461
Steelmaking [Member] \| Plate
Disaggregation of Revenue [Line Items]
Revenues	247	333
Steelmaking [Member] \| Slab and other steel products
Disaggregation of Revenue [Line Items]
Revenues	247	335
Steelmaking [Member] \| Other
Disaggregation of Revenue [Line Items]
Revenues	411	398
Other Businesses [Member]
Disaggregation of Revenue [Line Items]
Revenues	162	172
Other Businesses [Member] \| Other
Disaggregation of Revenue [Line Items]
Revenues	$ 162	$ 172