SEGMENT INFORMATION (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Sales [Abstract]
Sales	$ 445.8	$ 550.2	$ 529.1	$ 436.0	$ 385.4	$ 432.8	$ 405.7	$ 362.0	$ 1,961.1	$ 1,585.9	$ 1,531.5
Income before taxes [Abstract]
Income before taxes by segment									379.4	76.9	209.9
Restructuring charge									(10.7)	(34.2)	0
Other operating income									8.8	2.5	9.1
Interest expense									(30.4)	(25.4)	(11.6)
Interest income									1.2	1.0	1.1
Other income									175.1	1.5	0.1
Earnings of non-consolidated affiliates [Abstract]
Total earnings of non-consolidated affiliates									9.6	29.9	37.7
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									99.3	86.9	71.7
Capital spending [Abstract]
Total capital spending									200.9	85.3	137.9
Assets [Abstract]
Total assets	2,449.6				2,048.7				2,449.6	2,048.7
Investments-Affiliated Companies (at equity) [Abstract]
Total investments-affiliated companies	27.6				25.9				27.6	25.9
Sales By Geographic Area [Abstract]
Segment reporting information revenue	445.8	550.2	529.1	436.0	385.4	432.8	405.7	362.0	1,961.1	1,585.9	1,531.5
Total assets	2,449.6				2,048.7				2,449.6	2,048.7
Export sales from the United States to unaffiliated customers									22.0	22.1	20.9
United States [Member]
Sales [Abstract]
Sales									1,774.0	1,425.7	1,375.9
Assets [Abstract]
Total assets	2,208.8				1,774.5				2,208.8	1,774.5
Sales By Geographic Area [Abstract]
Segment reporting information revenue									1,774.0	1,425.7	1,375.9
Transfers between areas									50.0	39.4	29.6
Total assets	2,208.8				1,774.5				2,208.8	1,774.5
Foreign [Member]
Sales [Abstract]
Sales									187.1	160.2	155.6
Assets [Abstract]
Total assets	240.8				274.2				240.8	274.2
Sales By Geographic Area [Abstract]
Segment reporting information revenue									187.1	160.2	155.6
Transfers between areas									95.3	66.1	73.3
Total assets	240.8				274.2				240.8	274.2
Intersegment Elimination [Member]
Sales By Geographic Area [Abstract]
Transfers between areas									(145.3)	(105.5)	(102.9)
Chlor Alkali Products Segment [Member]
Sales [Abstract]
Sales									1,389.1	1,036.6	963.8
Income before taxes [Abstract]
Income before taxes by segment									245.0	117.2	125.4
Restructuring charge									(2.8)	(28.0)
Earnings of non-consolidated affiliates [Abstract]
Total earnings of non-consolidated affiliates									9.6	29.9	37.7
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									85.6	74.8	59.8
Capital spending [Abstract]
Total capital spending									134.2	67.6	123.8
Assets [Abstract]
Total assets	1,652.3				1,130.8				1,652.3	1,130.8
Investments-Affiliated Companies (at equity) [Abstract]
Total investments-affiliated companies	27.6				25.9				27.6	25.9
Sales By Geographic Area [Abstract]
Segment reporting information revenue									1,389.1	1,036.6	963.8
Total assets	1,652.3				1,130.8				1,652.3	1,130.8
Winchester Segment [Member]
Sales [Abstract]
Sales									572.0	549.3	567.7
Income before taxes [Abstract]
Income before taxes by segment									37.9	63.0	68.6
Restructuring charge									(7.0)	(6.2)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									10.9	10.1	9.8
Capital spending [Abstract]
Total capital spending									63.9	15.2	12.4
Assets [Abstract]
Total assets	328.6				268.5				328.6	268.5
Sales By Geographic Area [Abstract]
Segment reporting information revenue									572.0	549.3	567.7
Total assets	328.6				268.5				328.6	268.5
Corporate/Other [Member]
Income before taxes [Abstract]
Income before taxes by segment									(47.5)	(48.7)	17.2
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									2.8	2.0	2.1
Capital spending [Abstract]
Total capital spending									2.8	2.5	1.7
Assets [Abstract]
Total assets	468.7				649.4				468.7	649.4
Sales By Geographic Area [Abstract]
Total assets	$ 468.7				$ 649.4				$ 468.7	$ 649.4