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Quarterly report pursuant to Section 13 or 15(d)

Statements Of Condensed Consolidated Financial Position (Parenthetical)

v2.4.1.9
Statements Of Condensed Consolidated Financial Position (Parenthetical) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Class of Stock [Line Items] Ìý Ìý
Preferred stock, par value $ 0us-gaap_PreferredStockParOrStatedValuePerShare $ 0.000us-gaap_PreferredStockParOrStatedValuePerShare
Common shares, par value $ 0.125us-gaap_CommonStockParOrStatedValuePerShare $ 0.125us-gaap_CommonStockParOrStatedValuePerShare
Common shares, authorized (in shares) 400,000,000us-gaap_CommonStockSharesAuthorized 400,000,000us-gaap_CommonStockSharesAuthorized
Common shares, issued (in shares) 159,546,224us-gaap_CommonStockSharesIssued 159,546,224us-gaap_CommonStockSharesIssued
Common shares, outstanding 153,279,552us-gaap_CommonStockSharesOutstanding 153,246,754us-gaap_CommonStockSharesOutstanding
Common shares in treasury 6,266,672us-gaap_TreasuryStockShares 6,299,470us-gaap_TreasuryStockShares
Preferred Class A [Member] Ìý Ìý
Class of Stock [Line Items] Ìý Ìý
Preferred Stock, Liquidation Preference Per Share $ 1,000us-gaap_PreferredStockLiquidationPreference
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
$ 1,000us-gaap_PreferredStockLiquidationPreference
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
Cumulative Mandatory Convertible 7.00%clf_CumulativeMandatoryConvertible
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
7.00%clf_CumulativeMandatoryConvertible
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
Preferred stock, shares authorized (in shares) 3,000,000us-gaap_PreferredStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
3,000,000us-gaap_PreferredStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
Preferred Shares, Issued and Outstanding, Shares 731,223us-gaap_PreferredStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
731,223us-gaap_PreferredStockSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassAMember
Preferred Class B [Member] Ìý Ìý
Class of Stock [Line Items] Ìý Ìý
Preferred stock, shares authorized (in shares) 4,000,000us-gaap_PreferredStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember
4,000,000us-gaap_PreferredStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_PreferredClassBMember