RESTRUCTURING CHARGE (Detail Textuals) (USD $) In Millions, unless otherwise specified	12 Months Ended			26 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012	Dec. 09, 2010 T
Restructuring and Related Activities [Abstract]
Previous mercury cell capacity tonnage at Charleston, TN facility (in tons)					260,000
Membrane capacity tonnage capacity at Charleston, TN facility (in tons)					200,000
Percentage reduction of electricity usage per ECU produced (in hundredths)	25.00%			25.00%
Tonnage reduction in chlor alkali manufacturing capacity (in tons)					160,000
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 8.5	$ 10.7	$ 34.2	$ 53.4
Accrued Restructuring Costs	13.9	12.1	7.0	13.9
Cash expenditures incurred				11.2
Restructuring Reserve, Settled without Cash				28.3
Chlor Alkali Products Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.3	2.8	28.0	33.1
Additional restructuring and related expected cost	6
Winchester Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6.2	7.0	6.2	20.3
Additional restructuring and related expected cost	10
Forecast to reduce Winchester's annual operating costs	30
Estimated five-year project cost for Winchester relocation	110			110
Estimated capital spending for Winchester relocation	$ 80			$ 80
Percentage of capital spending offset provided by State of Mississippi tax incentives (in hundredths)	40.00%			40.00%