SEGMENT INFORMATION (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Sales	$ 1,644.2	$ 1,635.3
Transferred over Time
Disaggregation of Revenue [Line Items]
Sales	58.4	19.8
United States
Disaggregation of Revenue [Line Items]
Sales	1,137.2	1,188.9
Europe
Disaggregation of Revenue [Line Items]
Sales	147.6	138.0
Other foreign
Disaggregation of Revenue [Line Items]
Sales	359.4	308.4
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	924.5	884.6
Chlor Alkali Products and Vinyls | Caustic soda
Disaggregation of Revenue [Line Items]
Sales	386.8	355.7
Chlor Alkali Products and Vinyls | Chlorine, chlorine-derivatives and other co-products
Disaggregation of Revenue [Line Items]
Sales	537.7	528.9
Chlor Alkali Products and Vinyls | United States
Disaggregation of Revenue [Line Items]
Sales	646.9	635.6
Chlor Alkali Products and Vinyls | Europe
Disaggregation of Revenue [Line Items]
Sales	33.2	35.8
Chlor Alkali Products and Vinyls | Other foreign
Disaggregation of Revenue [Line Items]
Sales	244.4	213.2
Epoxy
Disaggregation of Revenue [Line Items]
Sales	331.7	341.3
Epoxy | Aromatics and allylics
Disaggregation of Revenue [Line Items]
Sales	141.0	154.9
Epoxy | Epoxy resins
Disaggregation of Revenue [Line Items]
Sales	190.7	186.4
Epoxy | United States
Disaggregation of Revenue [Line Items]
Sales	144.1	171.3
Epoxy | Europe
Disaggregation of Revenue [Line Items]
Sales	101.8	89.3
Epoxy | Other foreign
Disaggregation of Revenue [Line Items]
Sales	85.8	80.7
Winchester
Disaggregation of Revenue [Line Items]
Sales	388.0	409.4
Winchester | Commercial
Disaggregation of Revenue [Line Items]
Sales	155.9	242.8
Winchester | Military and law enforcement
Disaggregation of Revenue [Line Items]
Sales	232.1	166.6
Winchester | United States
Disaggregation of Revenue [Line Items]
Sales	346.2	382.0
Winchester | Europe
Disaggregation of Revenue [Line Items]
Sales	12.6	12.9
Winchester | Other foreign
Disaggregation of Revenue [Line Items]
Sales	29.2	14.5
Corporate/ other
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Corporate/ other | United States
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Corporate/ other | Europe
Disaggregation of Revenue [Line Items]
Sales	0.0	0.0
Corporate/ other | Other foreign
Disaggregation of Revenue [Line Items]
Sales	$ 0.0	$ 0.0