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

ACQUISITIONS - Pro Forma Information (Details)

v3.21.2

ACQUISITIONS - Pro Forma Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma adjustments	$ 10
Pro forma tax rate		24.30%
Pro forma income tax expense	(6)	$ (2)
AK Steel
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma revenue	1,646	4,265
Pro forma net income (loss)	(6)	(124)
Fair Value Adjustment to Inventory
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma net income (loss)	15	74
Acquisition-related Costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma net income (loss)	1	29
Intersegment Eliminations
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma revenue	$ 136	$ 395

- Definition

Business Acquisition, Pro Forma Expenses

+ References

No definition available.

+ Details

Name:	clf_BusinessAcquisitionProFormaExpenses
Namespace Prefix:	clf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Income Tax Benefit (Expense)

+ References

No definition available.

+ Details

Name:	clf_BusinessAcquisitionProFormaIncomeTaxBenefitExpense
Namespace Prefix:	clf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Income Tax, Statutory Rate

+ References

No definition available.

+ Details

Name:	clf_BusinessAcquisitionProFormaIncomeTaxStatutoryRate
Namespace Prefix:	clf_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=clf_AKSteelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_NonrecurringAdjustmentAxis=us-gaap_FairValueAdjustmentToInventoryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_NonrecurringAdjustmentAxis=us-gaap_AcquisitionRelatedCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: