GOODWILL AND INTANGIBLES (Details 1) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 2,119.0	$ 2,146.1	$ 2,118.0	$ 2,174.1
Acquisition activity		(28.8)
Foreign currency translation adjustment	1.0	0.8
Chlor Alkali Products and Vinyls Segment
Goodwill [Line Items]
Goodwill	1,832.1	1,854.8	1,831.3	1,877.5
Acquisition activity		(23.3)
Foreign currency translation adjustment	0.8	0.6
Epoxy Segment
Goodwill [Line Items]
Goodwill	286.9	291.3	$ 286.7	$ 296.6
Acquisition activity		(5.5)
Foreign currency translation adjustment	$ 0.2	$ 0.2