根据第13或15(d)条提交的季度报告

股票补偿计划（用于估计业绩股票授予的公允价值的假设）（详细信息）

v2.4.1.9
股票薪酬计划（用于估计业绩股授予的公允价值的假设）（详细信息）（业绩股[成员]，美元）
3个月结束
2015年3月31日
2015年1月12日【会员】  
以股份为基础的薪酬安排（分项）  
授予日期市价 7.70美元clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantDatePrice
/ us-gaap_AwardDateAxis
= clf_January122015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
平均预期年期（年） 2年11个月20天
预期波动率 58.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardDateAxis
= clf_January122015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
无风险利率 0.91%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardDateAxis
= clf_January122015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
股息收益率 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardDateAxis
= clf_January122015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
公允价值 11.56美元us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardDateAxis
= clf_January122015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
公允价值（授予日市价的百分比） 150.13%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate
/ us-gaap_AwardDateAxis
= clf_January122015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
2015年2月9日【会员】  
以股份为基础的薪酬安排（分项）  
授予日期市价 6.57美元clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantDatePrice
/ us-gaap_AwardDateAxis
= clf_February92015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
平均预期年期（年） 2年10个月20天
预期波动率 58.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardDateAxis
= clf_February92015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
无风险利率 0.87%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardDateAxis
= clf_February92015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
股息收益率 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardDateAxis
= clf_February92015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
公允价值 9.86美元us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardDateAxis
= clf_February92015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
公允价值（授予日市价的百分比） 150.13%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate
/ us-gaap_AwardDateAxis
= clf_February92015Member
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember