RESTRUCTURING CHARGES (Details 3) - USD ($) $ in Millions	3 Months Ended		37 Months Ended	38 Months Ended	52 Months Ended	96 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2024	Mar. 31, 2024	Mar. 31, 2024
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 8.3	$ 60.9				$ 201.5
Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	0.0				17.9
Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	39.7				35.5
Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8.3	8.4				68.2
Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	12.8				79.9
McIntosh Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1.9	1.4	$ 20.5
McIntosh Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			0.0
McIntosh Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			6.4
McIntosh Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			11.4
McIntosh Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 2.7
Freeport 2021 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.4	0.7		$ 13.5
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				0.0
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				0.0
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges				13.5
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 0.0
Freeport 2019 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.5	1.0			$ 82.6
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					2.1
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					0.0
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					21.6
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges					$ 58.9
Epoxy Optimization Plan | Epoxy
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 3.5	$ 57.8				84.9
Epoxy Optimization Plan | Epoxy | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						15.8
Epoxy Optimization Plan | Epoxy | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						29.1
Epoxy Optimization Plan | Epoxy | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						21.7
Epoxy Optimization Plan | Epoxy | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges						$ 18.3