Business and Geographic Segments - Segment Operating Performance (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 495.9	$ 496.5	$ 481.7	$ 405.3	$ 390.5	$ 393.1	$ 387.5	$ 348.3	$ 1,879.4	$ 1,519.4	$ 1,487.9
Cost of sales									1,277.4	1,219.2	1,259.5
Gross margin	185.3	161.5	141.2	114.0	101.4	85.7	64.7	48.4	602.0	300.2	228.4
Operating income	$ 125.4	98.6	$ 78.8	$ 60.1	$ 55.2	$ 34.8	$ 16.9	$ 0.5	362.9	107.4	21.1
Securities earnings									29.5	27.2	26.4
Insurance recoveries									0.4	0.4	3.7
General expenses, net									(35.0)	(37.3)	(39.5)
Loss on prepayment of debt		$ (7.1)							(7.1)
Interest expense									(58.9)	(58.1)	(53.6)
Income (loss) from continuing operations before income taxes									291.8	39.6	(41.9)
Depreciation and amortization									59.0	67.5	69.9
Capital expenditures									71.3	58.9	54.6
Chemicals
Segment Reporting Information [Line Items]
Net sales									1,729.0	1,364.3	1,348.8
Cost of sales									1,172.1	1,109.2	1,158.5
Gross margin									556.9	255.1	190.3
Operating income									341.1	91.0	7.1
Chemicals | Operating Segment
Segment Reporting Information [Line Items]
Depreciation and amortization									43.4	42.6	44.3
Capital expenditures									64.3	53.0	47.5
Component Products
Segment Reporting Information [Line Items]
Net sales									112.0	108.9	109.0
Cost of sales									77.2	73.8	75.6
Gross margin									34.8	35.1	33.4
Operating income									15.2	15.6	14.0
Component Products | Operating Segment
Segment Reporting Information [Line Items]
Depreciation and amortization									3.7	3.7	3.5
Capital expenditures									2.8	3.2	4.2
Real Estate Management And Development
Segment Reporting Information [Line Items]
Net sales									38.4	46.2	30.1
Cost of sales									28.1	36.2	25.4
Gross margin									10.3	10.0	4.7
Operating income									6.6	0.8
Real Estate Management And Development | Operating Segment
Segment Reporting Information [Line Items]
Depreciation and amortization									3.0	2.9	2.8
Capital expenditures									3.3	2.0	1.2
Waste Management | Operating Segment
Segment Reporting Information [Line Items]
Depreciation and amortization									8.9	18.3	19.3
Capital expenditures									$ 0.9	$ 0.7	$ 1.7