Segment Information - Summary of Results of Segment Operations (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenues from external customers
Net sales	$ 459.3	$ 407.5
Depreciation and amortization expense	14.2	16.1
Items excluded from the determination of segment profit:
Impairment, restructuring and plant closure costs	(0.1)	(3.3)
Gain on sale of assets	2.5	7.5
LIFO expense	(1.7)	(1.0)
Mark-to-market commodity hedging (losses) gains	(0.3)	2.6
Interest expense	(9.8)	(10.1)
Depreciation and amortization	(14.2)	(16.1)
Income tax provision	(9.7)	(8.5)
Discontinued operations	(0.5)	(0.4)
Net income	18.8	25.8
Railroad and Utility Products and Services [Member]
Revenues from external customers
Net sales	183.4	191.9
Performance Chemicals [Member]
Revenues from external customers
Net sales	136.4	123.6
Carbon Materials and Chemicals [Member]
Revenues from external customers
Net sales	139.5	92.0
Operating Segments [Member] | Railroad and Utility Products and Services [Member]
Revenues from external customers
Net sales	183.4	191.9
Depreciation and amortization expense	5.4	6.3
Adjusted EBITDA:
Adjusted EBITDA	11.6	16.4
Items excluded from the determination of segment profit:
Depreciation and amortization	(5.4)	(6.3)
Operating Segments [Member] | Performance Chemicals [Member]
Revenues from external customers
Net sales	136.4	123.6
Depreciation and amortization expense	3.9	4.8
Adjusted EBITDA:
Adjusted EBITDA	20.9	27.8
Items excluded from the determination of segment profit:
Depreciation and amortization	(3.9)	(4.8)
Operating Segments [Member] | Carbon Materials and Chemicals [Member]
Revenues from external customers
Net sales	139.5	92.0
Depreciation and amortization expense	4.9	5.0
Adjusted EBITDA:
Adjusted EBITDA	20.1	10.4
Items excluded from the determination of segment profit:
Depreciation and amortization	(4.9)	(5.0)
Intersegment [Member]
Revenues from external customers
Net sales	22.6	21.3
Intersegment [Member] | Performance Chemicals [Member]
Revenues from external customers
Net sales	4.0	3.5
Intersegment [Member] | Carbon Materials and Chemicals [Member]
Revenues from external customers
Net sales	18.6	17.8
Corporate, Non-Segment [Member]
Items excluded from the determination of segment profit:
Corporate unallocated	$ 0.0	$ 0.5