COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Environmental liability	$ 150.7	$ 151.9
Martinez Acquisition [Member]
Loss Contingencies [Line Items]
Term of Agreement	4 years
Business Combination, Contingent Consideration, Liability	$ 29.5	0.0
Other Noncurrent Liabilities [Member]
Loss Contingencies [Line Items]
Environmental liability	139.5	140.5
Environmental Issue [Member] | Torrance Refinery [Member]
Loss Contingencies [Line Items]
Environmental liability	$ 112.3	$ 113.7