Business Segment Information - Segment Operating Performance (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net sales	$ 408.8	$ 491.7	$ 824.9	$ 954.1
Cost of sales	352.5	387.5	679.3	764.1
Gross margin	56.3	104.2	145.6	190.0
Operating income (loss)	(10.1)	46.7	24.5	69.5
Securities earnings	6.7	6.6	13.4	13.4
Insurance recoveries	0.3	0.4	3.4	1.2
General expenses, net	(11.2)	(13.9)	(19.4)	(22.2)
Interest expense	(14.5)	(14.6)	(29.1)	(28.3)
Income (loss) before income taxes	(28.8)	25.2	(7.2)	33.6
Chemicals
Segment Reporting Information [Line Items]
Net sales	360.2	443.5	725.3	863.6
Cost of sales	314.2	350.3	602.4	690.5
Gross margin	46.0	93.2	122.9	173.1
Operating income (loss)	(7.9)	46.3	26.1	73.9
Component Products
Segment Reporting Information [Line Items]
Net sales	28.9	26.8	56.8	52.6
Cost of sales	19.8	18.3	39.1	36.3
Gross margin	9.1	8.5	17.7	16.3
Operating income (loss)	4.3	3.9	8.0	7.2
Waste Management
Segment Reporting Information [Line Items]
Net sales	10.0	11.9	25.0	18.9
Cost of sales	12.4	11.9	24.5	22.6
Gross margin	(2.4)		0.5	(3.7)
Operating income (loss)	(8.1)	(5.0)	(11.0)	(13.5)
Real Estate Management And Development
Segment Reporting Information [Line Items]
Net sales	9.7	9.5	17.8	19.0
Cost of sales	6.1	7.0	13.3	14.7
Gross margin	3.6	2.5	4.5	4.3
Operating income (loss)	$ 1.6	$ 1.5	$ 1.4	$ 1.9