Annual report pursuant to Section 13 and 15(d)

SEGMENT REPORTING SEGMENT REPORTING (Revenue from External Customers by Products and Services) (Details)

betfred games-free to play_SEGMENT REPORTING SEGMENT v2.4.1.9
betfred sportsbook
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenue from External Customer [Line Items]      
Concentration Risk, Percentage 100.00%us-gaap_ConcentrationRiskPercentage1 100.00%us-gaap_ConcentrationRiskPercentage1 100.00%us-gaap_ConcentrationRiskPercentage1
Iron Ore Revenue [Member]
      
Revenue from External Customer [Line Items]      
Concentration Risk, Percentage 78.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_IronOreRevenueMember 		80.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_IronOreRevenueMember 		81.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_IronOreRevenueMember
Coal Revenue [Member]
      
Revenue from External Customer [Line Items]      
Concentration Risk, Percentage 12.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_CoalRevenueMember 		13.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_CoalRevenueMember 		13.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_CoalRevenueMember
Freight and Venture Partners' Cost Reimbursements [Member]
      
Revenue from External Customer [Line Items]      
Concentration Risk, Percentage 10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_FreightAndVenturePartnersCostReimbursementsMember 		7.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_FreightAndVenturePartnersCostReimbursementsMember 		6.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_ProductConcentrationRiskMember
/ clf_RevenueTypeAxis
= clf_FreightAndVenturePartnersCostReimbursementsMember