RESTRUCTURING CHARGES (Detail Textuals) $ in Millions	3 Months Ended	12 Months Ended			13 Months Ended	62 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 12, 2014 T	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 09, 2010 T
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 2.7	$ 15.7	$ 5.5		$ 77.3
Restructuring and Related Cost, Incurred Cost						37.3
Restructuring Reserve, Settled without Cash						32.5
Accrued Restructuring Costs	$ 15.7	6.7	15.7	10.2	$ 6.7	6.7		$ 13.9
Chlor Alkali Products Becancour
Restructuring Cost and Reserve [Line Items]
Tonnage reduction in chlor alkali manufacturing capacity (in tons) | T							185,000
Restructuring charges	$ 10.0	2.0			12.0
Additional restructuring and related expected cost		4.0			4.0	4.0
Chlor Alkali Products Mercury
Restructuring Cost and Reserve [Line Items]
Restructuring charges			3.8	3.7		40.6
Previous mercury cell capacity tonnage at Charleston, TN facility (in tons) | T										260,000
Membrane capacity tonnage capacity at Charleston, TN facility (in tons) | T										200,000
Winchester Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.7	$ 1.9	$ 1.8		24.7
Additional restructuring and related expected cost		1.0			1.0	1.0
Estimated Project Cost For Plant Relocation		110.0			110.0	110.0
Estimated Capital Spending For Facility Relocation		80.0			$ 80.0	$ 80.0
Government Grants for Facility Relocation Capital Spending									$ 31.0
Winchester Segment | Minimum
Restructuring Cost and Reserve [Line Items]
Forecast to reduce Winchester's annual operating costs		35.0
Winchester Segment | Maximum
Restructuring Cost and Reserve [Line Items]
Forecast to reduce Winchester's annual operating costs		$ 40.0