Related Party Transactions (Major Customer and Concentration Risk) (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Affiliated Entity \| Westlake \| Revenue Benchmark \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	83.30%	89.50%	83.20%	87.30%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
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-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 275
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 275
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
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-URI https://asc.fasb.org/1943274/2147478785/954-310-50-2

+ Details

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References + Details