SEGMENT INFORMATION (Details 1) - USD ($) $ in Millions	3 Months Ended				6 Months Ended		51 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020
Sales [Abstract]
Sales	$ 1,241.2		$ 1,592.9		$ 2,666.3	$ 3,146.3
Income (loss) before taxes:
Income (loss) before taxes	(160.1)		(24.9)		(266.0)	28.2
Corporate/Other:
Environmental expense	2.8		22.0		5.4	23.8
Restructuring charges	(1.7)	$ (1.7)	(3.8)	$ (4.0)	(3.4)	(7.8)	$ (243.7)
Other operating income	0.1		0.1		0.1	0.2
Interest expense	(69.4)		(57.9)		(132.5)	(115.3)
Interest income	0.2		0.3		0.3	0.5
Non-operating pension income	4.9		4.2		9.5	8.1
Other income	0.0		0.0		0.0	11.2
Recoveries for costs incurred and expensed	0.0		4.8		0.0	4.8
Chlor Alkali Products and Vinyls
Sales [Abstract]
Sales	651.2		909.2		1,411.1	1,781.4
Income (loss) before taxes:
Income (loss) before taxes	(57.0)		70.7		(91.3)	191.1
Epoxy
Sales [Abstract]
Sales	397.4		518.8		874.6	1,042.8
Income (loss) before taxes:
Income (loss) before taxes	(13.0)		3.9		(1.3)	14.4
Winchester
Sales [Abstract]
Sales	192.6		164.9		380.6	322.1
Income (loss) before taxes:
Income (loss) before taxes	16.0		10.1		26.5	19.2
Corporate/Other
Corporate/Other:
Environmental expense	2.8		17.2		5.4	19.0
Other corporate and unallocated costs	(37.4)		(35.3)		(68.5)	(74.4)
Restructuring charges	$ (1.7)		$ (3.8)		$ (3.4)	$ (7.8)