DERIVATIVES (Gain (Loss) Recognized in Income) (Details) - Cost of Sales [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Designated as Hedging Instrument [Member] | Inventory Intermediation Agreement Obligation [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income on Derivatives	$ (25.4)	$ 31.8	$ (13.8)
Designated as Hedging Instrument [Member] | Intermediates and Refined Products Inventory [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income on Derivatives	25.4	(31.8)	13.8
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income on Derivatives	$ 36.5	$ (123.8)	$ (85.4)