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Long-Term Debt (Schedule of Long-term Debt) (Details) $ in Thousands |  |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | ---
Jul. 12, 2022 | Apr. 29, 2015 USD ($) | Dec. 31, 2025 USD ($) Rate | Dec. 31, 2024 USD ($) Rate | Aug. 01, 2017 USD ($) | Aug. 04, 2014 USD ($)
Related Party Transaction [Line Items] |  |  |  |  |  |
Weighted average interest rate on all long-term debt | Rate |  |  | 5.80% | 6.40% |  |
Affiliated Entity | Westlake |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Long-term debt payable to Westlake |  |  | $ 399,674 | $ 399,674 |  |
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Long-term debt payable to Westlake |  |  | $ 22,619 | 22,619 |  |
Basis spread on variable rate, percent |  |  | 1.75% |  |  |
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent |  |  | 0.10% |  |  |
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Alternate Base Rate |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent |  |  | 1.00% |  |  |
OpCo Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  |  | $ 600,000
OpCo Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake | Line of Credit |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent | 2.00% |  |  |  |  |
MLP Revolver | Westlake |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Maximum borrowing capacity |  | $ 300,000 |  |  | $ 600,000 |
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Long-term debt payable to Westlake |  |  | $ 377,055 | $ 377,055 |  |
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Minimum |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent |  |  | 1.75% |  |  |
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Maximum |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent |  |  | 2.75% |  |  |
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent |  |  | 0.10% |  |  |
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Alternate Base Rate |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent | 1.00% |  | 1.00% |  |  |
MLP Revolver | Limited Partner | Westlake | Line of Credit |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Maximum consolidated leverage ratio during one year following acquisitions |  | 5.50 |  |  |  |
Leverage capital ratio required during other periods |  | 4.50 |  |  |  |
MLP Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake | Line of Credit |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |
Basis spread on variable rate, percent | 2.00% |  |  |  |  |

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