INVENTORIES (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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U.S. Iron Ore [Member] | |||
Inventory [Line Items] | |||
Inventory, LIFO Reserve |
$ 119.0us-gaap_InventoryLIFOReserve / us-gaap_StatementBusinessSegmentsAxis = clf_USIronOreMember |
$ 115.3us-gaap_InventoryLIFOReserve / us-gaap_StatementBusinessSegmentsAxis = clf_USIronOreMember |
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Effect of LIFO Inventory Liquidation on Income |
44.8us-gaap_EffectOfLIFOInventoryLiquidationOnIncome / us-gaap_StatementBusinessSegmentsAxis = clf_USIronOreMember |
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Increase in Inventories due to build up of LIFO layers |
7.4clf_IncreaseInInventoriesDueToBuildUpOfLifoLayers / us-gaap_StatementBusinessSegmentsAxis = clf_USIronOreMember |
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Cost of Sales [Member] | Eastern Canadian Iron Ore [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
38.9us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_StatementBusinessSegmentsAxis = clf_EasternCanadianIronOreMember |
0us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_StatementBusinessSegmentsAxis = clf_EasternCanadianIronOreMember |
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Cost of Sales [Member] | North American Coal [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
44.5us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_StatementBusinessSegmentsAxis = clf_NorthAmericanCoalMember |
11.1us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_StatementBusinessSegmentsAxis = clf_NorthAmericanCoalMember |
24.4us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_StatementBusinessSegmentsAxis = clf_NorthAmericanCoalMember |
Work in process inventory [Member] | Bloom Lake [Member] | Cost of Sales [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
0us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_WorkinprocessinventoryMember / clf_ReportingUnitAxis = clf_BloomLakeMember |
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Work in process inventory [Member] | Wabush [Member] | Cost of Sales [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
0us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_WorkinprocessinventoryMember / clf_ReportingUnitAxis = clf_WabushMember |
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Finished goods inventory [Member] | Bloom Lake [Member] | Cost of Sales [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
0us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_FinishedgoodsinventoryMember / clf_ReportingUnitAxis = clf_BloomLakeMember |
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Finished goods inventory [Member] | Wabush [Member] | Cost of Sales [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
0us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_FinishedgoodsinventoryMember / clf_ReportingUnitAxis = clf_WabushMember |
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Pellets [Member] | Cost of Sales [Member] | Eastern Canadian Iron Ore [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
11.1us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_PelletsMember / us-gaap_StatementBusinessSegmentsAxis = clf_EasternCanadianIronOreMember |
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Pellets [Member] | Wabush [Member] | Cost of Sales [Member] | |||
Inventory [Line Items] | |||
Unsaleable Inventory Impairment Charge |
10.6clf_UnsaleableInventoryImpairmentCharge / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_PelletsMember / clf_ReportingUnitAxis = clf_WabushMember |
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Concentrate [Member] | Cost of Sales [Member] | Eastern Canadian Iron Ore [Member] | |||
Inventory [Line Items] | |||
Inventory Write-down |
13.2us-gaap_InventoryWriteDown / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_ConcentrateMember / us-gaap_StatementBusinessSegmentsAxis = clf_EasternCanadianIronOreMember |
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Concentrate [Member] | Wabush [Member] | Cost of Sales [Member] | |||
Inventory [Line Items] | |||
Unsaleable Inventory Impairment Charge |
$ 7.9clf_UnsaleableInventoryImpairmentCharge / us-gaap_IncomeStatementLocationAxis = us-gaap_CostOfSalesMember / us-gaap_PublicUtilitiesInventoryAxis = clf_ConcentrateMember / clf_ReportingUnitAxis = clf_WabushMember |
X | ||||||||||
- Definition
Increase in Inventories due to build up of LIFO layers No definition available.
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X | ||||||||||
- Definition
Unsaleable Inventory Impairment Charge No definition available.
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X | ||||||||||
- Definition
The effect of liquidating LIFO (last in first out) inventory layers on income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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X | ||||||||||
- Definition
Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Charge to cost of goods sold that represents the reduction of the carrying amount of inventory, generally attributable to obsolescence or market conditions. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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