Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTIES (Summary Of Related Party Transactions Table Disclosure) (Details)

v2.4.1.9
RELATED PARTIES (Summary Of Related Party Transactions Table Disclosure) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Related Party Transactions [Abstract]    
Product revenues from related parties $ 110.4us-gaap_RevenueFromRelatedParties $ 134.4us-gaap_RevenueFromRelatedParties
Product $ 399.5us-gaap_SalesRevenueGoodsNet $ 559.2us-gaap_SalesRevenueGoodsNet
Related party product revenue as a percent of total product revenue 27.60%clf_PercentageOfRelatedPartyRevenue 24.00%clf_PercentageOfRelatedPartyRevenue