$CLF
CLEVELAND-CLIFFS INC. Stock $clf

$clf Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-Q Financial Statement

#000076406520000231 Filed on October 23, 2020

Income Statement

Concept	2020 Q4	2020 Q3	2019 Q4
Revenue	$2.256B	$1.646B	$534.1M
YoY Change	322.43%	196.26%	-23.29%
Cost Of Revenue	$2.000B	$1.525B	$407.2M
YoY Change	391.18%	280.58%	-17.45%
Gross Profit	$256.1M	$121.0M	$126.9M
YoY Change	101.81%	-21.89%	-37.18%
Gross Profit Margin	11.35%	7.35%	23.76%
Selling, General & Admin	$92.80M	$59.00M	$37.20M
YoY Change	149.46%	131.37%	5.08%
% of Gross Profit	36.24%	48.76%	29.31%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$124.1M	$72.00M	$22.00M
YoY Change	464.09%	227.27%	7.84%
% of Gross Profit	48.46%	59.5%	17.34%
Operating Expenses	$114.3M	$59.00M	$45.20M
YoY Change	152.88%	77.18%	14.14%
Operating Profit	$141.8M	$38.00M	$81.70M
YoY Change	73.56%	-68.75%	-49.69%
Interest Expense	-$70.10M	-$68.00M	-$24.70M
YoY Change	183.81%	168.77%	-5.0%
% of Operating Profit	-49.44%	-178.95%	-30.23%
Other Income/Expense, Net	$25.80M	-$58.00M	$900.0K
YoY Change	2766.67%	132.0%	-78.05%
Pretax Income	$60.30M	-$20.00M	$57.90M
YoY Change	4.15%	-120.7%	-56.95%
Income Tax	-$12.50M	-$22.00M	-$5.500M
% Of Pretax Income	-20.73%		-9.5%
Net Earnings	$64.00M	-$10.00M	$63.20M
YoY Change	1.27%	-111.0%	-89.63%
Net Earnings / Revenue	2.84%	-0.61%	11.83%
Basic Earnings Per Share		-$0.02	$0.23
Diluted Earnings Per Share	$152.2K	-$0.02	$0.23
COMMON SHARES
Basic Shares Outstanding	399.2M shares	399.0M shares	270.1M shares
Diluted Shares Outstanding		399.0M shares

Balance Sheet

Concept	2020 Q4	2020 Q3	2019 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$112.0M	$56.00M	$353.0M
YoY Change	-68.27%	-85.96%	-57.11%
Cash & Equivalents	$112.0M	$56.00M	$353.0M
Short-Term Investments
Other Short-Term Assets	$189.0M	$115.0M	$75.00M
YoY Change	152.0%	182.56%	88.44%
Inventory	$3.828B	$1.795B	$317.0M
Prepaid Expenses
Receivables	$1.169B	$653.7M	$94.00M
Other Receivables	$24.00M	$9.000M	$59.00M
Total Short-Term Assets	$5.298B	$2.629B	$898.0M
YoY Change	489.98%	146.93%	-39.31%
LONG-TERM ASSETS
Property, Plant & Equipment	$8.743B	$4.551B	$1.929B
YoY Change	353.24%	157.12%	50.0%
Goodwill	$1.406B	$144.0M	$2.000M
YoY Change	70200.0%
Intangibles		$190.1M	$48.10M
YoY Change
Long-Term Investments
YoY Change
Other Assets	$1.324B	$240.1M	$215.0M
YoY Change	515.81%	108.96%	20.85%
Total Long-Term Assets	$11.47B	$5.852B	$2.606B
YoY Change	340.25%	141.16%	27.12%
TOTAL ASSETS
Total Short-Term Assets	$5.298B	$2.629B	$898.0M
Total Long-Term Assets	$11.47B	$5.852B	$2.606B
Total Assets	$16.77B	$8.481B	$3.504B
YoY Change	378.62%	142.92%	-0.73%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$1.575B	$710.7M	$193.0M
YoY Change	716.06%	233.98%	3.32%
Accrued Expenses	$664.0M	$279.4M	$126.3M
YoY Change	425.73%	207.03%	-20.52%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$34.00M
YoY Change
Total Short-Term Liabilities	$2.929B	$1.214B	$409.0M
YoY Change	616.14%	164.8%	-12.64%
LONG-TERM LIABILITIES
Long-Term Debt	$5.390B	$4.310B	$2.114B
YoY Change	154.97%	104.34%	1.01%
Other Long-Term Liabilities	$1.260B	$280.7M	$311.0M
YoY Change	305.14%	85.4%	151.62%
Total Long-Term Liabilities	$6.650B	$4.591B	$2.425B
YoY Change	174.23%	103.07%	9.41%
TOTAL LIABILITIES
Total Short-Term Liabilities	$2.929B	$1.214B	$409.0M
Total Long-Term Liabilities	$6.650B	$4.591B	$2.425B
Total Liabilities	$13.69B	$7.357B	$3.146B
YoY Change	335.22%	134.96%	1.31%
SHAREHOLDERS EQUITY
Retained Earnings	-$2.989B	-$3.053B	-$2.842B
YoY Change	5.17%	5.66%	-7.13%
Common Stock
YoY Change
Preferred Stock
YoY Change
Treasury Stock (at cost)	$354.0M	$354.8M	$391.0M
YoY Change	-9.46%	-9.24%	110.1%
Treasury Stock Shares	29.32M shares	29.42M shares	31.80M shares
Shareholders Equity	$2.018B	$810.6M	$358.0M
YoY Change
Total Liabilities & Shareholders Equity	$16.77B	$8.481B	$3.504B
YoY Change	378.62%	142.92%	-0.73%

Cashflow Statement

Concept	2020 Q4	2020 Q3	2019 Q4
OPERATING ACTIVITIES
Net Income	$64.00M	-$10.00M	$63.20M
YoY Change	1.27%	-111.0%	-89.63%
Depreciation, Depletion And Amortization	$124.1M	$72.00M	$22.00M
YoY Change	464.09%	227.27%	7.84%
Cash From Operating Activities	-$207.4M	$247.0M	$175.4M
YoY Change	-218.24%	3.69%	-40.14%
INVESTING ACTIVITIES
Capital Expenditures	-$146.1M	-$96.00M	-$191.1M
YoY Change	-23.55%	-37.46%	96.6%
Acquisitions
YoY Change
Other Investing Activities	-$655.7M	$8.200M	-$3.800M
YoY Change	17155.26%	-327.78%	72.73%
Cash From Investing Activities	-$801.8M	-$87.80M	-$194.9M
YoY Change	311.39%	-44.11%	96.08%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	1.065B	-176.9M	-27.20M
YoY Change	-4014.71%	199.83%	-89.83%
NET CHANGE
Cash From Operating Activities	-207.4M	247.0M	175.4M
Cash From Investing Activities	-801.8M	-87.80M	-194.9M
Cash From Financing Activities	1.065B	-176.9M	-27.20M
Net Change In Cash	55.60M	-17.70M	-46.70M
YoY Change	-219.06%	-180.09%	-36.81%
FREE CASH FLOW
Cash From Operating Activities	-$207.4M	$247.0M	$175.4M
Capital Expenditures	-$146.1M	-$96.00M	-$191.1M
Free Cash Flow	-$61.30M	$343.0M	$366.5M
YoY Change	-116.73%	-12.43%	-6.07%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Entity Central Index Key EntityCentralIndexKey	0000764065
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Amendment Flag AmendmentFlag	false
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2020-09-30
	dei	Entity Registrant Name EntityRegistrantName	CLEVELAND-CLIFFS INC.
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	1-8944
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	OH
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	34-1464672
	dei	Entity Address Address Line1 EntityAddressAddressLine1	200 Public Square,
	dei	Entity Address City Or Town EntityAddressCityOrTown	Cleveland,
	dei	Entity Address State Or Province EntityAddressStateOrProvince	OH
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	44114-2315
	dei	City Area Code CityAreaCode	216
	dei	Local Phone Number LocalPhoneNumber	694-5700
	dei	Security12b Title Security12bTitle	Common shares, par value $0.125 per share
	dei	Trading Symbol TradingSymbol	CLF
	dei	Security Exchange Name SecurityExchangeName	NYSE
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Shell Company EntityShellCompany	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
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	us-gaap	Profit Loss ProfitLoss	-154800000	USD
	us-gaap	Profit Loss ProfitLoss	229600000	USD
CY2020Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	11900000	USD
CY2019Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	31200000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-10000000.0	USD
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	90900000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-186000000.0	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	229600000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.02
CY2019Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.34
	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.51
	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.83
CY2020Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
CY2019Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.01
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.02
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.34
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.51
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
CY2020Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.02
CY2019Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.33
	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.51
	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.80
CY2020Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
CY2019Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.02
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.33
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.51
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.80
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	399399000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	269960000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	365245000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	278418000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	399399000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	276578000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	365245000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	287755000	shares
CY2020Q3	us-gaap	Profit Loss ProfitLoss	1900000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	90900000	USD
	us-gaap	Profit Loss ProfitLoss	-154800000	USD
	us-gaap	Profit Loss ProfitLoss	229600000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-6600000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-5800000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-18200000	USD
	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-17300000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	1600000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	0	USD
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	1400000	USD
	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	0	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	15700000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	400000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	17200000	USD
	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	1000000.0	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	23900000	USD
CY2019Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	6200000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	36800000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	18300000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	25800000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	97100000	USD
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-118000000.0	USD
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	247900000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	11900000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	0	USD
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	31200000	USD
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	0	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	13900000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	97100000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-149200000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	247900000	USD
	us-gaap	Profit Loss ProfitLoss	-154800000	USD
	us-gaap	Profit Loss ProfitLoss	229600000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	183900000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	63100000	USD
	clf	Amortizationof Inventory Stepup AmortizationofInventoryStepup	74000000.0	USD
	clf	Amortizationof Inventory Stepup AmortizationofInventoryStepup	0	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-89900000	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	22700000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	132600000	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-18200000	USD
	us-gaap	Unrealized Gain Loss On Derivatives And Commodity Contracts UnrealizedGainLossOnDerivativesAndCommodityContracts	19100000	USD
	us-gaap	Unrealized Gain Loss On Derivatives And Commodity Contracts UnrealizedGainLossOnDerivativesAndCommodityContracts	-48400000	USD
	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	13000000.0	USD
	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-49400000	USD
	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	-259800000	USD
	us-gaap	Increase Decrease In Accounts Receivable And Other Operating Assets IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets	-174100000	USD
	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	4200000	USD
	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	147000000.0	USD
	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-157300000	USD
	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-70400000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-53200000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	388100000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	378900000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	460700000	USD
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	869300000	USD
	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-8000000.0	USD
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-11200000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1240200000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-449500000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	252900000	USD
	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	1762900000	USD
	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	720900000	USD
	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	57500000	USD
	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	6800000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	999500000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	729300000	USD
	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	800000000.0	USD
	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	0	USD
	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	400000000.0	USD
	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	0	USD
	us-gaap	Payments Of Dividends PaymentsOfDividends	40800000	USD
	us-gaap	Payments Of Dividends PaymentsOfDividends	45100000	USD
	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-23300000	USD
	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-53700000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	994200000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-366900000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-299200000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-428300000	USD
	us-gaap	Net Cash Provided By Used In Discontinued Operations NetCashProvidedByUsedInDiscontinuedOperations	-2600000	USD
	us-gaap	Net Cash Provided By Used In Discontinued Operations NetCashProvidedByUsedInDiscontinuedOperations	-4400000	USD
	us-gaap	Net Cash Provided By Used In Continuing Operations NetCashProvidedByUsedInContinuingOperations	-296600000	USD
	us-gaap	Net Cash Provided By Used In Continuing Operations NetCashProvidedByUsedInContinuingOperations	-423900000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	352600000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	823200000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	56000000.0	USD
CY2019Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	399300000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	357900000	USD
CY2020Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-46900000	USD
CY2020Q1	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	2100000	USD
CY2020Q1	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	947400000	USD
CY2020Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.06
CY2020Q1	us-gaap	Dividends Common Stock DividendsCommonStock	24000000.0	USD
CY2020Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5500000	USD
CY2020Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1231000000.0	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-96900000	USD
CY2020Q2	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	2500000	USD
CY2020Q2	us-gaap	Dividends Common Stock DividendsCommonStock	100000	USD
CY2020Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	18300000	USD
CY2020Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1118200000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	25800000	USD
CY2020Q3	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	3800000	USD
CY2020Q3	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	24100000	USD
CY2020Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1123700000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	424200000	USD
CY2019Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-13700000	USD
	us-gaap	Revenues Revenues	3097800000	USD
	us-gaap	Revenues Revenues	1455800000	USD
CY2019Q1	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	-10000000.0	USD
CY2019Q1	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	124300000	USD
CY2019Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.05
CY2019Q1	us-gaap	Dividends Common Stock DividendsCommonStock	14500000	USD
CY2019Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	261700000	USD
CY2019Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	164500000	USD
CY2019Q2	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	4600000	USD
CY2019Q2	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	128600000	USD
CY2019Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.06
CY2019Q2	us-gaap	Dividends Common Stock DividendsCommonStock	16600000	USD
CY2019Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	285600000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	97100000	USD
CY2019Q3	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	4500000	USD
CY2019Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.10
CY2019Q3	us-gaap	Dividends Common Stock DividendsCommonStock	27300000	USD
CY2019Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	359900000	USD
CY2020Q3	us-gaap	Revenues Revenues	1646000000.0	USD
CY2020Q3	us-gaap	Revenues Revenues	1646000000.0	USD
	us-gaap	Basis Of Accounting BasisOfAccounting	<div style="text-align:justify;margin-bottom:9pt;"><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:120%;">Business, Consolidation and Presentation</span></div><div style="text-align:justify;margin-bottom:9pt;"><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;"> The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with SEC rules and regulations and, in the opinion of management, include all adjustments (consisting of normal recurring adjustments) necessary to present fairly the financial position, results of operations, comprehensive income (loss), cash flows and changes in equity for the periods presented. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management bases its estimates on various assumptions and historical experience, which are believed to be reasonable; however, due to the inherent nature of estimates, actual results may differ significantly due to changed conditions or assumptions. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020 or any other future period. Due to the acquisition of AK Steel, certain balances have become material and are no longer being condensed in our Statements of Unaudited Condensed Consolidated Financial Position, such as balances for </span><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%;">Right-of-use asset, operating lease</span><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;"> and </span><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%;">Operating lease liability, non-current</span><span style="background-color:rgb(255,255,255, 0.0);color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:120%;">. As a result, certain prior period amounts have been reclassified to conform with the current year presentation. These unaudited condensed consolidated financial statements should be read in conjunction with the financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2019 and in our Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2020 and June 30, 2020.</span></div>
CY2020Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.125
	us-gaap	Deferred Revenue Revenue Recognized1 DeferredRevenueRevenueRecognized1	34600000	USD
CY2019Q3	us-gaap	Revenues Revenues	555600000	USD
CY2020Q3	us-gaap	Inventory Finished Goods Net Of Reserves InventoryFinishedGoodsNetOfReserves	940500000	USD
CY2019Q3	us-gaap	Revenues Revenues	555600000	USD
	us-gaap	Revenues Revenues	3097800000	USD
	us-gaap	Revenues Revenues	1455800000	USD
	us-gaap	Deferred Revenue Revenue Recognized1 DeferredRevenueRevenueRecognized1	34600000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	0	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	0	USD
	us-gaap	Allowance For Doubtful Accounts Receivable Period Increase Decrease AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease	5200000	USD
	us-gaap	Allowance For Doubtful Accounts Receivable Period Increase Decrease AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease	0	USD
CY2020Q3	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	5200000	USD
CY2019Q3	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	0	USD
CY2019Q4	us-gaap	Inventory Raw Materials Net Of Reserves InventoryRawMaterialsNetOfReserves	9400000	USD
CY2020Q3	us-gaap	Inventory Finished Goods And Work In Process Net Of Reserves InventoryFinishedGoodsAndWorkInProcessNetOfReserves	1401000000.0	USD
CY2019Q4	us-gaap	Inventory Finished Goods Net Of Reserves InventoryFinishedGoodsNetOfReserves	114100000	USD
CY2020Q3	us-gaap	Inventory Work In Process Net Of Reserves InventoryWorkInProcessNetOfReserves	78200000	USD
CY2019Q4	us-gaap	Inventory Work In Process Net Of Reserves InventoryWorkInProcessNetOfReserves	68700000	USD
CY2020Q3	us-gaap	Inventory Raw Materials Net Of Reserves InventoryRawMaterialsNetOfReserves	382300000	USD
CY2019Q4	us-gaap	Inventory Finished Goods And Work In Process Net Of Reserves InventoryFinishedGoodsAndWorkInProcessNetOfReserves	192200000	USD
CY2020Q3	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	394100000	USD
CY2019Q4	us-gaap	Inventory Supplies Net Of Reserves InventorySuppliesNetOfReserves	125200000	USD
CY2020Q3	us-gaap	Inventory Net InventoryNet	1795100000	USD
CY2019Q4	us-gaap	Inventory Net InventoryNet	317400000	USD
	us-gaap	Deferred Revenue Revenue Recognized1 DeferredRevenueRevenueRecognized1	34600000	USD
CY2020Q3	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	146600000	USD
CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	61700000	USD
CY2020Q3	us-gaap	Interest Payable Current InterestPayableCurrent	81800000	USD
CY2019Q4	us-gaap	Interest Payable Current InterestPayableCurrent	29000000.0	USD
CY2020Q3	us-gaap	Dividends Payable Current DividendsPayableCurrent	1000000.0	USD
CY2019Q4	us-gaap	Dividends Payable Current DividendsPayableCurrent	17800000	USD
CY2020Q3	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	50000000.0	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	17800000	USD
CY2020Q3	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	279400000	USD
CY2019Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	126300000	USD
	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	333000000.0	USD
	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	505600000	USD
	clf	Capital Expenditures Incurredbut Notyet Paid Increase Decrease In Period CapitalExpendituresIncurredbutNotyetPaidIncreaseDecreaseInPeriod	-88400000	USD
	clf	Capital Expenditures Incurredbut Notyet Paid Increase Decrease In Period CapitalExpendituresIncurredbutNotyetPaidIncreaseDecreaseInPeriod	26100000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	42500000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	29300000	USD
	clf	Government Grant Received GovernmentGrantReceived	0	USD
	clf	Government Grant Received GovernmentGrantReceived	10500000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	378900000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	460700000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	3200000	USD
	us-gaap	Income Taxes Paid IncomeTaxesPaid	100000	USD
	us-gaap	Proceeds From Income Tax Refunds ProceedsFromIncomeTaxRefunds	119300000	USD
	us-gaap	Proceeds From Income Tax Refunds ProceedsFromIncomeTaxRefunds	117900000	USD
	us-gaap	Interest Paid Net InterestPaidNet	106000000.0	USD
	us-gaap	Interest Paid Net InterestPaidNet	71900000	USD
	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	38000000.0	USD
	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	16900000	USD
	us-gaap	Number Of Reporting Units NumberOfReportingUnits	2	unit
CY2020Q3	us-gaap	Revenues Revenues	1646000000.0	USD
CY2019Q3	us-gaap	Revenues Revenues	555600000	USD
	us-gaap	Revenues Revenues	3097800000	USD
	us-gaap	Revenues Revenues	1455800000	USD
CY2020Q3	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	126300000	USD
CY2019Q3	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	144100000	USD
	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	67000000.0	USD
	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	413700000	USD
	us-gaap	Deferred Revenue Revenue Recognized1 DeferredRevenueRevenueRecognized1	34600000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	1900000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	90900000	USD
	us-gaap	Profit Loss ProfitLoss	-154800000	USD
	us-gaap	Profit Loss ProfitLoss	229600000	USD
CY2020Q3	clf	Ebitda Earnings Loss EBITDAEarningsLoss	120100000	USD
CY2019Q3	clf	Ebitda Earnings Loss EBITDAEarningsLoss	143300000	USD
	clf	Ebitda Earnings Loss EBITDAEarningsLoss	98500000	USD
	clf	Ebitda Earnings Loss EBITDAEarningsLoss	392600000	USD
CY2020Q3	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	126300000	USD
CY2019Q3	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	144100000	USD
	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	67000000.0	USD
	clf	Adjusted Ebitda Earnings Loss AdjustedEBITDAEarningsLoss	413700000	USD
CY2020Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	11900000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	31200000	USD
CY2020Q3	clf	Depreciation Depletionand Amortization Attributableto Noncontrolling Interests DepreciationDepletionandAmortizationAttributabletoNoncontrollingInterests	4300000	USD
	clf	Depreciation Depletionand Amortization Attributableto Noncontrolling Interests DepreciationDepletionandAmortizationAttributabletoNoncontrollingInterests	10100000	USD
CY2020Q3	us-gaap	Assets Assets	8480900000	USD
CY2019Q4	us-gaap	Assets Assets	3503800000	USD
CY2020Q3	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	102300000	USD
CY2019Q3	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	184700000	USD
	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	333000000.0	USD
	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	505600000	USD
CY2020Q3	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	5958000000.0	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	3027400000	USD
CY2020Q3	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1407300000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1098400000	USD
CY2020Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	4550700000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	1929000000.0	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	97100000	USD
CY2019Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	49000000.0	USD
CY2020Q3	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	14700000	USD
	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	38000000.0	USD
CY2019Q3	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	7000000.0	USD
	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	16900000	USD
CY2020Q3	us-gaap	Depreciation Depreciation	71800000	USD
	us-gaap	Depreciation Depreciation	62500000	USD
	us-gaap	Depreciation Depreciation	182500000	USD
CY2019Q3	us-gaap	Depreciation Depreciation	22000000.0	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	220200000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	30100000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	190100000	USD
CY2020Q3	clf	Finite Lived Intangible Liability Gross FiniteLivedIntangibleLiabilityGross	70500000	USD
CY2020Q3	clf	Finite Lived Intangible Liability Accumulated Amortization FiniteLivedIntangibleLiabilityAccumulatedAmortization	4600000	USD
CY2020Q3	clf	Finite Lived Intangible Liability Net FiniteLivedIntangibleLiabilityNet	65900000	USD
CY2020Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2500000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	6000000.0	USD
CY2019Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	200000	USD
	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	600000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Remainder Of Fiscal Year FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear	2500000	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	10000000.0	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	10000000.0	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	10000000.0	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	10000000.0	USD
CY2020Q3	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	10000000.0	USD
CY2020Q3	clf	Amortizationof Intangible Liability AmortizationofIntangibleLiability	1900000	USD
	clf	Amortizationof Intangible Liability AmortizationofIntangibleLiability	4600000	USD
CY2020Q3	clf	Finite Lived Intangible Liabilities Amortization Credit Remainderof Fiscal Year FiniteLivedIntangibleLiabilitiesAmortizationCreditRemainderofFiscalYear	2000000.0	USD
CY2020Q3	clf	Finite Lived Intangible Liabilities Amortization Credit Next Twelve Months FiniteLivedIntangibleLiabilitiesAmortizationCreditNextTwelveMonths	7800000	USD
CY2020Q3	clf	Finite Lived Intangible Liabilities Amortization Credit Year Two FiniteLivedIntangibleLiabilitiesAmortizationCreditYearTwo	7800000	USD
CY2020Q3	clf	Finite Lived Intangible Liabilities Amortization Credit Year Three FiniteLivedIntangibleLiabilitiesAmortizationCreditYearThree	7800000	USD
CY2020Q3	clf	Finite Lived Intangible Liabilities Amortization Credit Year Four FiniteLivedIntangibleLiabilitiesAmortizationCreditYearFour	7800000	USD
CY2020Q3	clf	Finite Lived Intangible Liabilities Amortization Credit Year Five FiniteLivedIntangibleLiabilitiesAmortizationCreditYearFive	7800000	USD
CY2020Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	4309800000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	2113800000	USD
CY2020Q2	us-gaap	Extinguishment Of Debt Amount ExtinguishmentOfDebtAmount	736400000	USD
CY2020Q2	clf	Reductionof Principal Long Term Debt ReductionofPrincipalLongTermDebt	181200000	USD
	us-gaap	Extinguishment Of Debt Amount ExtinguishmentOfDebtAmount	1487500000	USD
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	us-gaap	Extinguishment Of Debt Amount ExtinguishmentOfDebtAmount	724000000.0	USD
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-18200000	USD
CY2020Q3	us-gaap	Line Of Credit Facility Maximum Borrowing Capacity LineOfCreditFacilityMaximumBorrowingCapacity	2000000000.0	USD
CY2020Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	0	USD
CY2020Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	33500000	USD
CY2020Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	0	USD
CY2020Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	12800000	USD
CY2020Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	456500000	USD
CY2020Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	3987900000	USD
CY2020Q3	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	4490700000	USD
CY2020Q3	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	79000000.0	USD
CY2020Q3	us-gaap	Financial Liabilities Fair Value Disclosure FinancialLiabilitiesFairValueDisclosure	9700000	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	233400000	USD
CY2019Q4	us-gaap	Financial Liabilities Fair Value Disclosure FinancialLiabilitiesFairValueDisclosure	4300000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	61400000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	72800000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	61400000	USD
CY2020Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	35300000	USD
CY2019Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	118100000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	45800000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	91400000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-29500000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	6500000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-43300000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	-83100000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	3400000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	38800000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	27700000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	101700000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	72800000	USD
CY2020Q3	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	27800000	USD
CY2019Q3	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-6500000	USD
	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	40400000	USD
	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	81800000	USD
CY2020Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	0	USD
CY2019Q2	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	0	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	1100000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	0	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Earnings FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings	-300000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Earnings FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings	-34400000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Earnings FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings	-900000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Gain Loss Included In Earnings FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings	-39700000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements	0	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements	4200000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements	1700000	USD
	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements	9500000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	300000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	30200000	USD
CY2020Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	300000	USD
CY2019Q3	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue	30200000	USD
CY2020Q3	us-gaap	Fair Value Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-300000	USD
CY2019Q3	us-gaap	Fair Value Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-30200000	USD
	us-gaap	Fair Value Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-300000	USD
	us-gaap	Fair Value Liabilities Measured On Recurring Basis Change In Unrealized Gain Loss FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-30200000	USD
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.355
	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.096
CY2020Q3	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-5000000.0	USD
	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-8600000	USD
CY2019Q3	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-500000	USD
	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-1300000	USD
CY2020Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	186400000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	165300000	USD
CY2020Q3	us-gaap	Asset Retirement Obligation Current AssetRetirementObligationCurrent	4400000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation Current AssetRetirementObligationCurrent	2100000	USD
CY2020Q3	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	182000000.0	USD
CY2019Q4	us-gaap	Asset Retirement Obligations Noncurrent AssetRetirementObligationsNoncurrent	163200000	USD
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CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	165300000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	172400000	USD
	clf	Asset Retirement Obligation Liabilities Assumed Acquisition AssetRetirementObligationLiabilitiesAssumedAcquisition	16700000	USD
	clf	Asset Retirement Obligation Liabilities Assumed Acquisition AssetRetirementObligationLiabilitiesAssumedAcquisition	0	USD
	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	7800000	USD
	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	7600000	USD
	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	3400000	USD
	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	500000	USD
	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	24400000	shares
CY2020Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	186400000	USD
CY2019Q3	us-gaap	Asset Retirement Obligation AssetRetirementObligation	179500000	USD
CY2020Q3	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	33100000	USD
CY2019Q3	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	-40900000	USD
	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	41600000	USD
	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	43400000	USD
CY2020Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.125
CY2020Q1	us-gaap	Business Acquisition Equity Interest Issued Or Issuable Value Assigned BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned	617600000	USD
CY2020Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.06
CY2020Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.06
CY2019Q4	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.10
CY2019Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.06
CY2019Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.05
CY2019Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.05
CY2019Q4	clf	Us Gaap Common Stock Special Dividends Per Share Cash Paid UsGaap_CommonStockSpecialDividendsPerShareCashPaid	0.04
CY2018Q4	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	200000000	USD
CY2019Q2	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	100000000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	252900000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	315700000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	0	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-3100000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-318800000	USD
CY2020Q1	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	310100000	USD
CY2020Q1	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-900000	USD
CY2020Q1	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-6100000	USD
CY2020Q1	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-317100000	USD
CY2020Q2	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	304100000	USD
CY2020Q2	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-200000	USD
CY2020Q2	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-1600000	USD
CY2020Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-305900000	USD
CY2020Q3	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	297500000	USD
CY2020Q3	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	1400000	USD
CY2020Q3	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	14100000	USD
CY2020Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-282000000.0	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	281100000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-2800000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-283900000	USD
CY2019Q1	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	275400000	USD
CY2019Q1	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-100000	USD
CY2019Q1	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-275500000	USD
CY2019Q2	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	269600000	USD
CY2019Q2	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-2200000	USD
CY2019Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-271800000	USD
CY2019Q3	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	263800000	USD
CY2019Q3	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-1800000	USD
CY2019Q3	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-265600000	USD
CY2020Q3	us-gaap	Revenue From Related Parties RevenueFromRelatedParties	294900000	USD
CY2019Q3	us-gaap	Revenue From Related Parties RevenueFromRelatedParties	293500000	USD
	us-gaap	Revenue From Related Parties RevenueFromRelatedParties	587500000	USD
	us-gaap	Revenue From Related Parties RevenueFromRelatedParties	792800000	USD
CY2020Q3	us-gaap	Revenues Revenues	1646000000.0	USD
CY2019Q3	us-gaap	Revenues Revenues	555600000	USD
	us-gaap	Revenues Revenues	3097800000	USD
	us-gaap	Revenues Revenues	1455800000	USD
CY2020Q3	clf	Percentage Of Related Party Revenue PercentageOfRelatedPartyRevenue	0.179
CY2019Q3	clf	Percentage Of Related Party Revenue PercentageOfRelatedPartyRevenue	0.528
	clf	Percentage Of Related Party Revenue PercentageOfRelatedPartyRevenue	0.190
	clf	Percentage Of Related Party Revenue PercentageOfRelatedPartyRevenue	0.545
CY2020Q3	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	8200000	USD
CY2019Q3	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	0	USD
	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	20400000	USD
	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	0	USD
	us-gaap	Deferred Revenue Revenue Recognized1 DeferredRevenueRevenueRecognized1	34600000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	2200000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	91800000	USD
	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-154800000	USD
	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	231100000	USD
CY2020Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	11900000	USD
CY2019Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	31200000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-9700000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	91800000	USD
	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-186000000.0	USD
	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	231100000	USD
CY2020Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-300000	USD
CY2019Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-900000	USD
	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	USD
	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-1500000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	-10000000.0	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	90900000	USD
	us-gaap	Net Income Loss NetIncomeLoss	-186000000.0	USD
	us-gaap	Net Income Loss NetIncomeLoss	229600000	USD
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	399400000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	270000000.0	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	365200000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	278400000	shares
CY2020Q3	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
CY2019Q3	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	3700000	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	5800000	shares
CY2020Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	0	shares
CY2019Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	2900000	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	0	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	3600000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	399400000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	276600000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	365200000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	287800000	shares
CY2020Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.02
CY2019Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.34
	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.51
	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.83
CY2020Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
CY2019Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Basic Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerBasicShare	-0.01
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.02
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.34
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.51
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.82
CY2020Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.02
CY2019Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.33
	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.51
	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.80
CY2020Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
CY2019Q3	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
	us-gaap	Discontinued Operation Income Loss From Discontinued Operation Net Of Tax Per Diluted Share DiscontinuedOperationIncomeLossFromDiscontinuedOperationNetOfTaxPerDilutedShare	0
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.02
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.33
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.51
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.80
CY2020Q3	clf	Estimated Project Capital Expenditures EstimatedProjectCapitalExpenditures	1000000000	USD
	clf	Total Project Expenditures Excluding Capitalized Interest TotalProjectExpendituresExcludingCapitalizedInterest	940200000	USD
CY2020Q3	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	40900000	USD
CY2019Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	2000000.0	USD
CY2020Q3	us-gaap	Accrued Environmental Loss Contingencies Current AccruedEnvironmentalLossContingenciesCurrent	6400000	USD
CY2019Q4	us-gaap	Accrued Environmental Loss Contingencies Current AccruedEnvironmentalLossContingenciesCurrent	300000	USD
CY2020Q3	us-gaap	Accrued Environmental Loss Contingencies Noncurrent AccruedEnvironmentalLossContingenciesNoncurrent	34500000	USD
CY2019Q4	us-gaap	Accrued Environmental Loss Contingencies Noncurrent AccruedEnvironmentalLossContingenciesNoncurrent	1700000	USD

Files In Submission

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$CLF
CLEVELAND-CLIFFS INC. Stock $clf

2020 Q4 Form 10-Q Financial Statement

#000076406520000231 Filed on October 23, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CLF CLEVELAND-CLIFFS INC. Stock $clf

2020 Q4 Form 10-Q Financial Statement

#000076406520000231 Filed on October 23, 2020

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CLF
CLEVELAND-CLIFFS INC. Stock $clf