GOODWILL AND INTANGIBLE ASSETS (Details 1) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 1,420.2	$ 2,119.7	$ 1,420.2	$ 2,119.7
Foreign currency translation adjustment	0.0	0.0
Goodwill, Accumulated Impairment Loss	699.8
Chlor Alkali Products and Vinyls
Goodwill [Line Items]
Goodwill	1,275.3	1,832.7	1,275.3	1,832.7
Foreign currency translation adjustment	0.0	0.0
Goodwill, Accumulated Impairment Loss	557.6
Epoxy
Goodwill [Line Items]
Goodwill	144.9	287.0	$ 144.9	$ 287.0
Foreign currency translation adjustment	0.0	$ 0.0
Goodwill, Accumulated Impairment Loss	$ 142.2