Segment Reporting - Segment Data and Reconciliations of Segment Data to Consolidated Financial Statements and Non-GAAP Measures (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net Sales	[1]	$ 2,332,114	$ 2,180,274	$ 2,325,768
Cost of Sales		2,062,226	1,908,060	2,048,170
Operating Expenses		200,989	201,734	204,979
Operating income		78,549	70,480	58,613
Assets		2,357,702	2,304,648	2,363,354
Consolidated Capital Expenditures		122,514	122,776	260,335
Depreciation and Amortization		126,041	112,197	105,338
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		2,332,114	2,180,274	2,325,768
Cost of Sales	[2]	2,062,851	1,908,143	2,050,495
Operating Expenses	[3]	133,000	124,982	130,628
Operating income		136,263	147,149	144,645
Assets		2,249,599	2,172,779	2,193,849
Segment Capital Expenditures		124,718	120,585	260,622
Depreciation and Amortization		124,660	110,394	102,592
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated Corporate Expenses	[4]	(57,714)	(76,669)	(86,032)
Unallocated Assets	[5]	108,103	131,869	169,505
Unallocated Capital Expenditures	[6]	(2,204)	2,191	(287)
Unallocated Depreciation and Amortization	[7]	1,381	1,803	2,746
Surfactants [Member]
Segment Reporting Information [Line Items]
Net Sales		1,665,983	1,532,115	1,602,819
Surfactants [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		1,665,983	1,532,115	1,602,819
Cost of Sales	[2]	1,497,333	1,352,022	1,431,462
Operating Expenses	[3]	101,292	94,475	98,958
Operating income		67,358	85,618	72,399
Assets		1,630,551	1,578,689	1,586,148
Segment Capital Expenditures		88,676	90,766	231,341
Depreciation and Amortization		85,655	72,028	64,377
Polymers [Member]
Segment Reporting Information [Line Items]
Net Sales		584,477	584,905	642,471
Polymers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		584,477	584,905	642,471
Cost of Sales	[2]	512,872	516,902	553,590
Operating Expenses	[3]	28,340	27,380	28,111
Operating income		43,265	40,623	60,770
Assets		536,748	523,192	537,193
Segment Capital Expenditures		30,528	25,827	19,971
Depreciation and Amortization		33,103	32,417	32,426
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net Sales		81,654	63,254	80,478
Specialty Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales		81,654	63,254	80,478
Cost of Sales	[2]	52,646	39,219	65,443
Operating Expenses	[3]	3,368	3,127	3,559
Operating income		25,640	20,908	11,476
Assets		82,300	70,898	70,508
Segment Capital Expenditures		5,514	3,992	9,310
Depreciation and Amortization		$ 5,902	$ 5,949	$ 5,789

[1] Net sales are attributed to countries based on the location of the Company legal entity making the sale.

[2] Cost of sales is comprised of raw material costs (including freight and handling expenses to deliver the raw materials), manufacturing plant labor expenses and various manufacturing overhead expenses, such as utilities, maintenance, operating supplies, amortization and manufacturing asset depreciation expenses, warehouse and rail car expenses that can be allocated to reportable segments. For more details about items included in Cost of sales line item on the Consolidated Statements of Income, see Note 1, Summary of Significant Accounting Policies, of the notes to the Company’s consolidated financial statements included in Item 8 of this Form 10-K).

[3] Operating expenses allocated to reportable segments are comprised of selling, administrative and research and development expenses. The CODM uses operating expenses balances in their aggregate to analyze the performance of each reportable segment. For more details about items included in Operating expenses line items on the Consolidated Statements of Income, see Note 1, Summary of Significant Accounting Policies, of the notes to the Company’s consolidated financial statements included in Item 8 of this Form 10-K).

[4] Unallocated corporate expenses are primarily comprised of corporate administrative expenses (e.g., corporate finance, legal, human resources and information technology), environmental remediation expenses, deferred compensation, business restructuring, assets and goodwill impairment expenses and gain on sales of assets that are not included in segment operating income and not used to evaluate segment performance. For more details about items included in unallocated corporate expenses, see Note 22, Business Restructuring and Assets Impairment and Note 20, Sales of Assets of the notes to the Company’s consolidated financial statements included in Item 8 of this Form 10-K).

[5] Unallocated assets primarily include assets at the Company’s headquarters.

[6] Unallocated capital expenditures primarily include capital expenditures related to the Company’s headquarters.

[7] Unallocated depreciation and amortization primarily includes depreciation related to the Company’s headquarters.