Business Segment Information - Segment Operating Performance (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 426.9	$ 353.5
Cost of sales	308.0	311.5
Gross margin	118.9	42.0
Operating income (loss)	60.7	(10.3)
Securities earnings	7.0	6.8
Insurance recoveries	0.1	0.1
General expenses, net	(12.4)	(11.5)
Interest expense	(15.6)	(15.7)
Income (loss) before income taxes	39.8	(30.6)
Chemicals
Segment Reporting Information [Line Items]
Net sales	369.8	318.5
Cost of sales	266.8	278.5
Gross margin	103.0	40.0
Operating income (loss)	55.0	3.0
Component Products
Segment Reporting Information [Line Items]
Net sales	29.9	27.1
Cost of sales	20.3	18.9
Gross margin	9.6	8.2
Operating income (loss)	4.5	3.4
Waste Management
Segment Reporting Information [Line Items]
Net sales	21.5	5.2
Cost of sales	16.7	11.7
Gross margin	4.8	(6.5)
Operating income (loss)	0.6	(10.8)
Real Estate Management And Development
Segment Reporting Information [Line Items]
Net sales	5.7	2.7
Cost of sales	4.2	2.4
Gross margin	1.5	0.3
Operating income (loss)	$ 0.6	$ (5.9)