v3.25.3
RESTRUCTURING CHARGES (Details 3) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended 52 Months Ended
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2024
Jun. 30, 2024
Mar. 31, 2024
Sep. 30, 2025
Sep. 30, 2024
Jun. 30, 2025
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges $ 2.9 $ 7.4 $ 4.0 $ 7.9 $ 6.8 $ 8.3 $ 14.3 $ 23.0 $ 240.7
Write-off of equipment and facility                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 79.9
Employee severance and related benefit costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges 0.6 3.8 1.6 0.0 0.0 0.0     23.7
Facility exit costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges 2.3 3.6 2.2 5.0 5.1 8.3     96.4
Lease and other contract termination costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges 0.0 $ 0.0 $ 0.2 2.9 $ 1.7 $ 0.0     40.7
Chlor Alkali Products and Vinyls                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges 0.0     0.0     0.0 0.0 128.9
Chlor Alkali Products and Vinyls | Write-off of equipment and facility                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 61.6
Chlor Alkali Products and Vinyls | Employee severance and related benefit costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 2.1
Chlor Alkali Products and Vinyls | Facility exit costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 58.8
Chlor Alkali Products and Vinyls | Lease and other contract termination costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 6.4
Epoxy                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges 0.0     0.0     0.0 0.0 111.8
Epoxy | Write-off of equipment and facility                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 18.3
Epoxy | Employee severance and related benefit costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 21.6
Epoxy | Facility exit costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 37.6
Epoxy | Lease and other contract termination costs                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges                 $ 34.3
Winchester                  
Restructuring Cost and Reserve [Line Items]                  
Restructuring charges $ 0.0     $ 0.0     $ 0.0 $ 0.0