Quarterly report pursuant to Section 13 or 15(d)

EARNINGS PER SHARE (Earnings Per Share Computation) (Details)

v3.10.0.1
EARNINGS PER SHARE (Earnings Per Share Computation) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Earnings Per Share [Abstract]        
Income from Continuing Operations $ 199.8 $ 22.3 $ 415.8 $ 27.6
LOSS ATTRIBUTABLE TO NONCONTROLLING INTEREST 0.0 0.5 0.0 3.9
Net Income from Continuing Operations Attributable to Cliffs Shareholders 199.8 22.8 415.8 31.5
INCOME FROM DISCONTINUED OPERATIONS, NET OF TAX 238.0 30.6 102.8 25.6
NET INCOME ATTRIBUTABLE TO CLIFFS SHAREHOLDERS $ 437.8 $ 53.4 $ 518.6 $ 57.1
Weighted Average Number of Shares:        
Basic 297,878 296,100 297,587 285,771
Weighted Average Number of Shares Oustanding, Depositary 8,000 0 1,900 0
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements 4,300 5,000 4,000 4,700
Diluted 310,203 301,100 303,518 290,512
Income per Common Share Attributable to Cliffs Common Shareholders - Basic:        
Continuing operations (in dollars per share) $ 0.67 $ 0.08 $ 1.40 $ 0.11
Discontinued operations (in dollars per share) 0.80 0.10 0.35 0.09
Earnings (Loss) per Common Share Attributable to Cliffs Common Shareholders - Basic (in dollars per share) 1.47 0.18 1.75 0.20
Income per Common Share Attributable to Cliffs Common Shareholders - Diluted:        
Continuing operations (in dollars per share) 0.64 0.08 1.37 0.11
Discontinued operations (in dollars per share) 0.77 0.10 0.34 0.08
Earnings (Loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted (in dollars per share) $ 1.41 $ 0.18 $ 1.71 $ 0.19