SEGMENT INFORMATION (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Sales	$ 1,553.4	$ 1,710.3
United States
Disaggregation of Revenue [Line Items]
Sales	909.4	947.1
Europe [Member]
Disaggregation of Revenue [Line Items]
Sales	276.8	325.3
Other foreign [Member]
Disaggregation of Revenue [Line Items]
Sales	367.2	437.9
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	872.2	936.1
Chlor Alkali Products and Vinyls | United States
Disaggregation of Revenue [Line Items]
Sales	604.0	608.1
Chlor Alkali Products and Vinyls | Europe [Member]
Disaggregation of Revenue [Line Items]
Sales	38.6	45.8
Chlor Alkali Products and Vinyls | Other foreign [Member]
Disaggregation of Revenue [Line Items]
Sales	229.6	282.2
Epoxy
Disaggregation of Revenue [Line Items]
Sales	524.0	603.3
Epoxy | United States
Disaggregation of Revenue [Line Items]
Sales	164.1	180.4
Epoxy | Europe [Member]
Disaggregation of Revenue [Line Items]
Sales	235.4	278.5
Epoxy | Other foreign [Member]
Disaggregation of Revenue [Line Items]
Sales	124.5	144.4
Winchester
Disaggregation of Revenue [Line Items]
Sales	157.2	170.9
Winchester | United States
Disaggregation of Revenue [Line Items]
Sales	141.3	158.6
Winchester | Europe [Member]
Disaggregation of Revenue [Line Items]
Sales	2.8	1.0
Winchester | Other foreign [Member]
Disaggregation of Revenue [Line Items]
Sales	$ 13.1	$ 11.3