SEGMENT INFORMATION (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Sales	$ 1,425.1	$ 1,553.4
United States
Disaggregation of Revenue [Line Items]
Sales	866.8	909.4
Europe
Disaggregation of Revenue [Line Items]
Sales	227.1	276.8
Other foreign
Disaggregation of Revenue [Line Items]
Sales	331.2	367.2
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	759.9	872.2
Chlor Alkali Products and Vinyls | United States
Disaggregation of Revenue [Line Items]
Sales	533.9	604.0
Chlor Alkali Products and Vinyls | Europe
Disaggregation of Revenue [Line Items]
Sales	30.2	38.6
Chlor Alkali Products and Vinyls | Other foreign
Disaggregation of Revenue [Line Items]
Sales	195.8	229.6
Epoxy
Disaggregation of Revenue [Line Items]
Sales	477.2	524.0
Epoxy | United States
Disaggregation of Revenue [Line Items]
Sales	158.8	164.1
Epoxy | Europe
Disaggregation of Revenue [Line Items]
Sales	194.4	235.4
Epoxy | Other foreign
Disaggregation of Revenue [Line Items]
Sales	124.0	124.5
Winchester
Disaggregation of Revenue [Line Items]
Sales	188.0	157.2
Winchester | United States
Disaggregation of Revenue [Line Items]
Sales	174.1	141.3
Winchester | Europe
Disaggregation of Revenue [Line Items]
Sales	2.5	2.8
Winchester | Other foreign
Disaggregation of Revenue [Line Items]
Sales	$ 11.4	$ 13.1