XML 103 R64.htm IDEA: XBRL DOCUMENT
v3.20.4

ACQUISITIONS - Pro Forma (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Business Acquisition, Pro Forma Revenue | $ 12,837 | $ 17,163
Business Acquisition, Pro Forma Net Income (Loss) | (520) | (11)
Business Acquisition, Pro Forma Expenses | $ 32 | 76
Business Acquisition, Pro Forma Income Tax, Statutory Rate | 24.30% |
Business Acquisition, Pro Forma Income Tax Benefit (Expense) | $ 170 | 117
Intersegment Eliminations [Member] |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Business Acquisition, Pro Forma Revenue | 844 | 1,499
Franchise |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Business Acquisition, Pro Forma Net Income (Loss) | 140 | 129
Fair Value Adjustment to Inventory |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Business Acquisition, Pro Forma Net Income (Loss) | 96 | 362
Acquisition-related Costs | ArcelorMittal USA and AK Steel [Member] |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Business Acquisition, Pro Forma Net Income (Loss) | 93 | $ 93
Restructuring Costs | ArcelorMittal USA [Member] |  |
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] |  |
Business Acquisition, Pro Forma Net Income (Loss) | $ 1,820 |

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

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

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

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