GOODWILL AND INTANGIBLES (Details 1) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 2,119.4	$ 747.1	$ 2,174.1	$ 747.1
Acquisition activity	(55.0)	0.0
Foreign currency translation adjustment	0.3
Chlor Alkali Products and Vinyls Segment
Goodwill [Line Items]
Goodwill	1,832.4	747.1	1,877.5	747.1
Acquisition activity	(45.3)	0.0
Foreign currency translation adjustment	0.2
Epoxy Segment
Goodwill [Line Items]
Goodwill	287.0	0.0	$ 296.6	$ 0.0
Acquisition activity	(9.7)	$ 0.0
Foreign currency translation adjustment	$ 0.1