XML 75 R55.htm IDEA: XBRL DOCUMENT
v3.21.1

ACQUISITIONS - Pro Forma Information (Details) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2020 USD ($)
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |
Pro forma adjustments | $ 13
Pro forma tax rate | 24.30%
Pro forma income tax expense | $ 12
AK Steel |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |
Pro forma revenue | 1,526
Pro forma net income (loss) | (17)
Fair Value Adjustment to Inventory |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |
Pro forma net income (loss) | 23
Acquisition-related Costs |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |
Pro forma net income (loss) | 27
Intersegment Eliminations |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |
Pro forma revenue | $ 68

X
- 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

X
- 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

X
- Definition Business Acquisition, Pro Forma Income Tax, Statutory Rate + References No definition available. + Details
Name: | clf_BusinessAcquisitionProFormaIncomeTaxStatutoryRate
Namespace Prefix: | clf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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

X
- 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

X
- 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

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

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

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

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