SEGMENT INFORMATION (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended			62 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Sales [Abstract]
Sales	$ 1,267.4	$ 533.6	$ 535.4	$ 518.0	$ 499.8	$ 593.6	$ 570.4	$ 577.4	$ 2,854.4	$ 2,241.2	$ 2,515.0
Income before taxes [Abstract]
Net (loss) income									6.7	162.7	250.0
Restructuring charge									(2.7)	(15.7)	(5.5)	$ (77.3)
Acquisition-related costs									(123.4)	(4.2)	0.0
Other operating income									45.7	1.5	0.7
Interest expense									(97.0)	(43.8)	(38.6)
Interest income									1.1	1.3	0.6
Other income (expense)									0.2	0.1	(1.3)
Earnings of non-consolidated affiliates [Abstract]
Total earnings of non-consolidated affiliates									1.7	1.7	2.8
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									228.9	139.1	135.3
Capital spending [Abstract]
Total capital spending									130.9	71.8	90.8
Assets
Total assets	9,321.8				2,698.1				9,321.8	2,698.1		9,321.8
Investments-Affiliated Companies (at equity) [Abstract]
Investments in non-consolidated affiliates	25.0				23.3				25.0	23.3		25.0
Chlor Alkali Products and Vinyls Segment
Sales [Abstract]
Sales									1,713.4	1,502.8	1,737.4
Income before taxes [Abstract]
Net (loss) income									115.5	130.1	213.5
Earnings of non-consolidated affiliates [Abstract]
Total earnings of non-consolidated affiliates									1.7	1.7	2.8
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									186.1	119.4	117.5
Capital spending [Abstract]
Total capital spending									94.5	49.6	68.0
Assets
Total assets	6,690.7				1,939.0				6,690.7	1,939.0		6,690.7
Investments-Affiliated Companies (at equity) [Abstract]
Investments in non-consolidated affiliates	25.0				23.3				25.0	23.3		25.0
Epoxy Segment
Sales [Abstract]
Sales									429.6	0.0	0.0
Income before taxes [Abstract]
Net (loss) income									(7.5)	0.0	0.0
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									20.9	0.0	0.0
Capital spending [Abstract]
Total capital spending									7.7	0.0	0.0
Assets
Total assets	1,591.2				0.0				1,591.2	0.0		1,591.2
Winchester Segment
Sales [Abstract]
Sales									711.4	738.4	777.6
Income before taxes [Abstract]
Net (loss) income									115.6	127.3	143.2
Restructuring charge									(0.7)	(1.9)	(1.8)	(24.7)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									17.4	16.3	14.9
Capital spending [Abstract]
Total capital spending									25.6	21.4	21.2
Assets
Total assets	411.9				361.0				411.9	361.0		411.9
Corporate/Other
Income before taxes [Abstract]
Net (loss) income									(40.8)	(33.9)	(62.6)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									4.5	3.4	2.9
Capital spending [Abstract]
Total capital spending									3.1	0.8	$ 1.6
Assets
Total assets	$ 628.0				$ 398.1				$ 628.0	$ 398.1		$ 628.0