Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE INSTRUMENTS - Schedule Of Derivatives Not Designated As Hedging Instruments (Details)

v3.20.2
DERIVATIVE INSTRUMENTS - Schedule Of Derivatives Not Designated As Hedging Instruments (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net $ 33.1 $ (40.9) $ 41.6 $ 43.4
Customer Supply Agreement [Member] | Sales [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net 8.8 7.6 14.4 82.2
Provisional Pricing Arrangements [Member] | Sales [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net 20.4 (48.5) 28.0 (38.8)
Commodity Contract [Member] | Cost of Sales [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net $ 3.9 $ 0.0 $ (0.8) $ 0.0