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Westlake Chemical Partners LP (Details) - USD ($) $ / shares in Units, $ in Millions |  |  |  | 12 Months Ended
--- | --- | --- | --- | ---
Mar. 29, 2019 | Oct. 04, 2018 | Aug. 04, 2014 | Dec. 31, 2020
Related Party Transaction [Line Items] |  |  |  |
Partners' Capital Account, Units, Sold in Public Offering |  |  | 12,937,500 |
Partners' Capital Account, Units, Sold in Private Placement | 2,940,818 |  |  |
Sale of Unit Price Per Unit (in usd per share) | $ 21.40 |  |  |
Proceeds from Issuance of Private Placement | $ 63 |  |  |
Partners' Units, Maximum Aggregate Offering Amount, ATM |  | $ 50 |  |
Westlake Chemical OpCo LP [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Payments to Acquire Limited Partnership Interests | $ 201 |  |  |
Limited Partner [Member] | Westlake Chemical OpCo LP [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Limited Partnership Ownership Percentage Increase | 4.50% |  |  |
Principal Owner [Member] | TTWF LP [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Partners' Capital Account, Units, Acquisitions | 1,401,869 |  |  |
Subsidiary of Common Parent [Member] | Limited Partner [Member] | Westlake Chemical Partners LP [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Partners' Capital Account, Units |  |  |  | 14,122,230
Subsidiary of Common Parent [Member] | IPO [Member] | Limited Partner [Member] | Westlake Chemical OpCo LP [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest |  |  |  | 22.80%
Limited partner interest (percent) |  |  |  | 77.20%
Subsidiary of Common Parent [Member] | IPO [Member] | Limited Partner [Member] | Westlake Chemical Partners LP [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Limited partner interest (percent) |  |  |  | 40.10%

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