ÐÇ¿Õ´«Ã½

Annual report pursuant to Section 13 and 15(d)

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Revenue Reimbursement) (Details)

v3.8.0.1
BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Revenue Reimbursement) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Freight and venture partners' cost reimbursements $ 241.0 $ 195.5 $ 180.9
U.S. Iron Ore [Member] Ìý Ìý Ìý
Freight and venture partners' cost reimbursements 221.4 174.8 157.3
U.S. Iron Ore [Member] | Freight Revenue [Member] Ìý Ìý Ìý
Freight and venture partners' cost reimbursements 166.7 106.8 105.3
U.S. Iron Ore [Member] | Co-venturer [Member] Ìý Ìý Ìý
Freight and venture partners' cost reimbursements $ 54.7 $ 68.0 $ 52.0