XML 85 R65.htm IDEA: XBRL DOCUMENT
v3.21.1

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES - Intangible Assets and Liabilities (Details) - USD ($) $ in Millions | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Finite-Lived Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross | $ 220 | $ 220
Finite-Lived Intangible Assets, Accumulated Amortization | (35) | (32)
Finite-Lived Intangible Assets, Net | 185 | 188
Above-market supply contracts, Gross Amount | (71) | (71)
Above-market supply contracts, Accumulated Amortization | 8 | 7
Above-market supply contracts, Net | (63) | (64)
Customer relationships |  |
Finite-Lived Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross | 77 | 77
Finite-Lived Intangible Assets, Accumulated Amortization | (5) | (3)
Finite-Lived Intangible Assets, Net | 72 | 74
Developed technology |  |
Finite-Lived Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross | 60 | 60
Finite-Lived Intangible Assets, Accumulated Amortization | (4) | (3)
Finite-Lived Intangible Assets, Net | 56 | 57
Trade names and trademarks |  |
Finite-Lived Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross | 11 | 11
Finite-Lived Intangible Assets, Accumulated Amortization | (1) | (1)
Finite-Lived Intangible Assets, Net | 10 | 10
Mining permits |  |
Finite-Lived Intangible Assets [Line Items] |  |
Finite-Lived Intangible Assets, Gross | 72 | 72
Finite-Lived Intangible Assets, Accumulated Amortization | (25) | (25)
Finite-Lived Intangible Assets, Net | $ 47 | $ 47

X
- Definition Finite-Lived Intangible Liability, Accumulated Amortization + References No definition available. + Details
Name: | clf_FiniteLivedIntangibleLiabilityAccumulatedAmortization
Namespace Prefix: | clf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Finite-Lived Intangible Liability, Gross + References No definition available. + Details
Name: | clf_FiniteLivedIntangibleLiabilityGross
Namespace Prefix: | clf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Finite-Lived Intangible Liability, Net + References No definition available. + Details
Name: | clf_FiniteLivedIntangibleLiabilityNet
Namespace Prefix: | clf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 928 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 926 -SubTopic 20 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TechnologyBasedIntangibleAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TrademarksAndTradeNamesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=clf_MiningPermitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |