Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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The number of each class of partnership units outstanding at the balance sheet date. Units represent shares of ownership of the general, limited, and preferred partners.

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Change in the number of units for each class of partners' capital accounts during the year due to acquisitions. Partners include general, limited and preferred partners.

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The number of units sold in a private placement of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

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The number of units sold in a public offering of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

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Cash outflow related to the acquisition or continued holding of limited partnership interests held for investment purposes.

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The cash inflow associated with the amount received from entity's raising of capital via private rather than public placement.

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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.

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Limited Partnership Ownership Percentage Increase

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Partners' Units, Maximum Aggregate Offering Amount, ATM

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Per unit amount received by subsidiary or equity investee for each unit issued or sold in the unit transaction.

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Westlake Chemical Partners LP (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended	12 Months Ended
	Mar. 29, 2019	Oct. 04, 2018	Mar. 31, 2020	Dec. 31, 2014
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	$ 21.40
Proceeds from Issuance of Private Placement	$ 63
Partners' Units, Maximum Aggregate Offering Amount, ATM		$ 50
Principal Stockholder [Member] \| TTWF LP [Member]
Related Party Transaction [Line Items]
Partners' Capital Account, Units, Acquisitions	1,401,869
Westlake Chemical OpCo LP [Member]
Related Party Transaction [Line Items]
Proceeds from issuance of Westlake Chemical Partners LP common units	$ 201
Westlake Chemical OpCo LP [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Partnership Ownership Percentage Increase	4.50%
Westlake Chemical OpCo LP [Member] \| Subsidiary of Common Parent [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest			22.80%
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest			77.20%
Westlake Chemical Partners LP [Member] \| Subsidiary of Common Parent [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest			40.10%
Ownership interest (in units)			14,122,230