Segment Information - Schedule of Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Net sales	$ 776.1	$ 869.2	$ 1,475.3	$ 1,653.8
Operating income (loss)	(37.6)	43.1	(72.8)	65.2
Interest expense, net	(18.0)	(18.3)	(35.0)	(35.9)
Debt refinancing costs				3.2
Foreign exchange loss	(0.1)	(0.1)	(1.0)	(0.8)
Income (loss) from continuing operations before income taxes	(55.7)	24.7	(108.8)	25.3
Chlorovinyls [Member]
Segment Reporting Information [Line Items]
Net sales	578.4	666.1	1,134.5	1,314.5
Operating income (loss)	(37.1)	37.8	(46.7)	81.6
Building Products [Member]
Segment Reporting Information [Line Items]
Net sales	197.7	203.1	340.8	339.3
Operating income (loss)	26.7	23.3	30.8	19.8
Intersegment Elimination [Member] | Chlorovinyls [Member]
Segment Reporting Information [Line Items]
Net sales	38.0	61.1	93.3	117.2
Intersegment Elimination [Member] | Building Products [Member]
Segment Reporting Information [Line Items]
Net sales			0.1
Intersegment Eliminations Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Net sales	(38.0)	(61.1)	(93.4)	(117.2)
Operating income (loss)	(27.2)	(18.0)	(56.9)	(36.2)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	776.1	869.2	1,475.3	1,653.8
Operating income (loss)	(37.6)	43.1	(72.8)	65.2
Operating Segments [Member] | Chlorovinyls [Member]
Segment Reporting Information [Line Items]
Net sales	616.4	727.2	1,227.8	1,431.7
Operating Segments [Member] | Building Products [Member]
Segment Reporting Information [Line Items]
Net sales	$ 197.7	$ 203.1	$ 340.9	$ 339.3