Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE INSTRUMENTS - Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value (Details)

v3.20.2
DERIVATIVE INSTRUMENTS - Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value (Details) - USD ($)
$ in Millions
Jun. 30, 2020
Dec. 31, 2019
Commodity Contract [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset $ 5.4  
Commodity Contract [Member] | Other Noncurrent Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 0.7  
Commodity Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (17.2) $ (3.2)
Commodity Contract [Member] | Other Noncurrent Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (1.1)  
Foreign Exchange Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (1.0)  
Foreign Exchange Contract [Member] | Other Noncurrent Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (0.4)  
Customer Supply Agreement [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 27.3 44.5
Provisional Pricing Arrangements [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 8.0 1.3
Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability   (1.1)
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 1.6 0.0
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 0.6 0.0
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (14.2) (3.2)
Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (0.9) 0.0
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (1.0) 0.0
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Noncurrent Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (0.4) 0.0
Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 0.0 0.0
Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 0.0 0.0
Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 0.0 0.0
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 3.8 0.0
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 0.1 0.0
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (3.0) 0.0
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability (0.2) 0.0
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 0.0 0.0
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Noncurrent Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability 0.0 0.0
Not Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 27.3 44.5
Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative Asset 8.0 1.3
Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liability $ 0.0 $ (1.1)