Segment Reporting - Segment Data and Reconciliations of Segment Data to Consolidated Financial Statements and Non-GAAP Measures (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Net Sales		$ 593,255	$ 551,418
Cost of Sales		517,792	481,137
Operating Expenses		47,175	50,112
Operating Income		28,288	20,169
Consolidated Capital Expenditures		32,748	30,157
Depreciation and Amortization		29,270	27,604
Assets		2,389,683		$ 2,304,648
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		593,255	551,418
Cost of Sales	[1]	517,959	480,831
Operating Expenses	[2]	32,840	31,858
Operating Income		42,456	38,729
Segment Capital Expenditures		32,155	30,157
Depreciation and Amortization		28,980	27,186
Assets		2,261,959		2,172,779
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated Corporate Expenses	[3]	(14,168)	(18,560)
Unallocated Capital Expenditures	[4]	593
Unallocated Depreciation and Amortization	[5]	290	418
Unallocated Assets	[6]	127,724		131,869
Surfactants [Member]
Segment Reporting Information [Line Items]
Net Sales		430,337	390,820
Surfactants [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		430,337	390,820
Cost of Sales	[1]	376,666	340,378
Operating Expenses	[2]	24,741	24,363
Operating Income		28,930	26,079
Segment Capital Expenditures		24,004	26,584
Depreciation and Amortization		19,430	17,666
Assets		1,643,031		1,578,689
Polymers [Member]
Segment Reporting Information [Line Items]
Net Sales		146,116	145,508
Polymers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		146,116	145,508
Cost of Sales	[1]	130,896	130,432
Operating Expenses	[2]	7,202	6,694
Operating Income		8,018	8,382
Segment Capital Expenditures		7,071	2,505
Depreciation and Amortization		8,061	8,043
Assets		543,296		523,192
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net Sales		16,802	15,090
Specialty Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		16,802	15,090
Cost of Sales	[1]	10,397	10,021
Operating Expenses	[2]	897	801
Operating Income		5,508	4,268
Segment Capital Expenditures		1,080	1,068
Depreciation and Amortization		1,489	$ 1,477
Assets		$ 75,632		$ 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.