Business Segment Information - Segment Operating Performance (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Net sales	$ 383.2	$ 476.5	$ 1,208.1	$ 1,430.6
Cost of sales	333.4	360.7	1,012.7	1,124.8
Gross margin	49.8	115.8	195.4	305.8
Operating income (loss)	(5.0)	60.2	19.5	129.7
Securities earnings	6.5	6.9	19.9	20.3
Insurance recoveries	0.1	8.8	3.5	10.0
General expenses, net	(10.0)	(8.8)	(29.4)	(31.0)
Interest expense	(14.4)	(13.8)	(43.5)	(42.1)
Income (loss) before income taxes	(22.8)	53.3	(30.0)	86.9
Chemicals
Segment Reporting Information [Line Items]
Net sales	336.5	414.8	1,061.8	1,278.4
Cost of sales	293.7	319.7	896.1	1,010.2
Gross margin	42.8	95.1	165.7	268.2
Operating income (loss)	(1.3)	49.7	24.8	123.6
Component Products
Segment Reporting Information [Line Items]
Net sales	26.5	26.5	83.3	79.1
Cost of sales	18.4	18.3	57.5	54.6
Gross margin	8.1	8.2	25.8	24.5
Operating income (loss)	3.4	3.4	11.4	10.6
Waste Management
Segment Reporting Information [Line Items]
Net sales	9.9	24.5	34.9	43.4
Cost of sales	13.3	12.8	37.8	35.4
Gross margin	(3.4)	11.7	(2.9)	8.0
Operating income (loss)	(8.3)	6.9	(19.3)	(6.6)
Real Estate Management And Development
Segment Reporting Information [Line Items]
Net sales	10.3	10.7	28.1	29.7
Cost of sales	8.0	9.9	21.3	24.6
Gross margin	2.3	0.8	6.8	5.1
Operating income (loss)	$ 1.2	$ 0.2	$ 2.6	$ 2.1