SEGMENT INFORMATION (Details 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Sales	$ 2,616.1	$ 2,221.3	$ 5,077.5	$ 4,140.1
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	1,403.5	967.3	2,648.7	1,834.3
Chlor Alkali Products and Vinyls | Caustic soda
Disaggregation of Revenue [Line Items]
Sales	635.1	400.8	1,154.0	747.8
Chlor Alkali Products and Vinyls | Chlorine, chlorine-derivatives and other co-products
Disaggregation of Revenue [Line Items]
Sales	768.4	566.5	1,494.7	1,086.5
Epoxy
Disaggregation of Revenue [Line Items]
Sales	772.7	850.0	1,562.2	1,512.6
Epoxy | Aromatics and allylics
Disaggregation of Revenue [Line Items]
Sales	384.1	366.5	776.1	678.5
Epoxy | Epoxy resins
Disaggregation of Revenue [Line Items]
Sales	388.6	483.5	786.1	834.1
Winchester
Disaggregation of Revenue [Line Items]
Sales	439.9	404.0	866.6	793.2
Winchester | Commercial
Disaggregation of Revenue [Line Items]
Sales	320.6	281.5	634.8	542.5
Winchester | Military and law enforcement
Disaggregation of Revenue [Line Items]
Sales	$ 119.3	$ 122.5	$ 231.8	$ 250.7