SEGMENT INFORMATION (Details 1) - USD ($) $ in Millions	3 Months Ended		60 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021
Sales [Abstract]
Sales	$ 1,918.8	$ 1,425.1
Income (loss) before taxes:
Income (loss) before taxes	306.1	(105.9)
Corporate/Other:
Environmental expense	2.5	2.6
Restructuring charges	(6.9)	(1.7)	$ (250.3)
Interest expense	(84.5)	(63.1)
Interest income	0.1	0.1
Non-operating pension income	9.3	4.6
Corporate/Other
Corporate/Other:
Environmental expense	0.3	2.6
Other corporate and unallocated costs	(33.0)	(31.1)
Restructuring charges	(6.9)	(1.7)
Chlor Alkali Products and Vinyls
Sales [Abstract]
Sales	867.0	759.9
Income (loss) before taxes:
Income (loss) before taxes	271.1	(34.3)
Epoxy
Sales [Abstract]
Sales	662.6	477.2
Income (loss) before taxes:
Income (loss) before taxes	65.2	11.7
Winchester
Sales [Abstract]
Sales	389.2	188.0
Income (loss) before taxes:
Income (loss) before taxes	$ 85.1	$ 10.5