Quarterly report pursuant to Section 13 or 15(d)

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES (Intangible Assets and Liabilities) (Details)

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GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES (Intangible Assets and Liabilities) (Details) - USD ($)
$ in Millions
Mar. 31, 2020
Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross $ 235.2  
Finite-Lived Intangible Assets, Accumulated Amortization (25.2)  
Finite-Lived Intangible Assets, Net 210.0  
Finite-Lived Intangible Liability, Gross (140.0)  
Finite-Lived Intangible Liability, Accumulated Amortization 2.1  
Finite-Lived Intangible Liability, Net (137.9)  
Customer Relationships [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross 91.0  
Finite-Lived Intangible Assets, Accumulated Amortization (0.5)  
Finite-Lived Intangible Assets, Net 90.5  
Technology-Based Intangible Assets [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross 61.0  
Finite-Lived Intangible Assets, Accumulated Amortization (0.3)  
Finite-Lived Intangible Assets, Net 60.7  
Trademarks and Trade Names [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross 11.0  
Finite-Lived Intangible Assets, Accumulated Amortization (0.1)  
Finite-Lived Intangible Assets, Net 10.9  
Mining Permits [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Gross 72.2 $ 72.2
Finite-Lived Intangible Assets, Accumulated Amortization (24.3) (24.1)
Finite-Lived Intangible Assets, Net $ 47.9 $ 48.1