Segment Reporting - Segment Data and Reconciliations of Segment Data to Consolidated Financial Statements and Non-GAAP Measures (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Net Sales		$ 594,689	$ 556,405	$ 1,187,944	$ 1,107,823
Cost of Sales		522,804	486,853	1,040,596	967,990
Operating Expenses		53,920	50,885	101,095	100,997
Operating Income		17,965	18,667	46,253	38,836
Consolidated Capital Expenditures		25,598	29,710	58,346	59,867
Depreciation and Amortization		31,289	28,010	60,559	55,614
Assets		2,416,130		2,416,130		$ 2,304,648
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		594,689	556,405	1,187,944	305,265
Cost of Sales	[1]	523,077	486,794	1,041,036	269,543
Operating Expenses	[2]	35,828	31,633	68,668	13,743
Operating Income		35,784	37,978	78,240	21,979
Segment Capital Expenditures		25,122	29,710	57,277	59,867
Depreciation and Amortization		30,961	27,552	59,941	54,738
Assets		2,287,842		2,287,842		2,172,779
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated Corporate Expenses	[3]	(17,819)	(19,311)	(31,987)	(37,872)
Unallocated Capital Expenditures	[4]	476		1,069
Unallocated Depreciation and Amortization	[5]	328	458	618	876
Unallocated Assets	[6]	128,288		128,288		131,869
Surfactants [Member]
Segment Reporting Information [Line Items]
Net Sales		411,456	379,795	841,793	770,615
Surfactants [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		411,456	379,795	841,793	770,615
Cost of Sales	[1]	370,660	338,908	747,326	679,286
Operating Expenses	[2]	27,429	23,825	52,170	48,187
Operating Income		13,367	17,062	42,297	43,142
Segment Capital Expenditures		19,675	26,036	43,679	52,620
Depreciation and Amortization		21,137	17,863	40,567	35,529
Assets		1,654,136		1,654,136		1,578,689
Polymers [Member]
Segment Reporting Information [Line Items]
Net Sales		162,751	159,757	308,867	305,265
Polymers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		162,751	159,757	308,867	1,107,823
Cost of Sales	[1]	138,124	139,111	269,020	967,625
Operating Expenses	[2]	7,468	7,049	14,670	63,490
Operating Income		17,159	13,597	25,177	76,708
Segment Capital Expenditures		4,581	2,616	11,652	5,121
Depreciation and Amortization		8,352	8,192	16,413	16,235
Assets		552,106		552,106		523,192
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net Sales		20,482	16,853	37,284	31,943
Specialty Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		20,482	16,853	37,284	31,943
Cost of Sales	[1]	14,293	8,775	24,690	18,796
Operating Expenses	[2]	931	759	1,828	1,560
Operating Income		5,258	7,319	10,766	11,587
Segment Capital Expenditures		866	1,058	1,946	2,126
Depreciation and Amortization		1,472	$ 1,497	2,961	$ 2,974
Assets		$ 81,600		$ 81,600		$ 70,898

[1] Cost of sales is comprised of raw material costs (including freight and shipping/handling expenses to deliver the raw materials), manufacturing plant labor expenses and other manufacturing overhead expenses, such as utilities, maintenance, depreciation, etc., that can be allocated to reportable segments.

[2] Operating expenses allocated to reportable segments are comprised of selling, administrative and research and development expenses. The CODM uses operating expenses in aggregate to analyze the performance of each reportable segment.

[3] Unallocated corporate expenses are primarily comprised of corporate administrative expenses (e.g., corporate finance, legal, human resources, information technology and environmental remediation expenses), deferred compensation and business restructuring and assets impairment expenses that are not included in segment operating income and not used to evaluate segment performance.

[4] Unallocated capital expenditures primarily include capital expenditures related to the Company’s Northfield, Illinois location.

[5] Unallocated depreciation and amortization primarily includes depreciation related to the Company’s Northfield, Illinois location.

[6] Unallocated assets primarily include assets in the Company’s Northfield, Illinois location.