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

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-Topic 272
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- Definition

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.

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 1
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

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- Definition

The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
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- Definition

Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Additional Ownership Interest

+ References

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- Definition

Partners' Capital Account, Units, Sold in Public Offering, Price per Unit

+ References

No definition available.

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Description of Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended			9 Months Ended
	Mar. 29, 2019	Aug. 04, 2014	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Limited Partners' Capital Account [Line Items]
Net proceeds from private placement of common units	$ 62,934		$ (255)	$ (18)	$ 62,934	$ 0	$ 62,661
Limited Partner [Member]
Limited Partners' Capital Account [Line Items]
Number of units sold in public offering	2,940,818	12,937,500
Units sold in secondary offering price per unit (in dollars per share)	$ 21.40
Westlake Chemical OpCo GP LLC [Member] \| Limited Liability Company [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest		100.00%
Westlake Chemical OpCo LP [Member] \| Affiliated Entity [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest	22.80%	10.60%
Limited partner interest, additional ownership	4.50%
Amount paid to purchase additional limited partner interest	$ 201,445
Westlake Chemical OpCo LP [Member] \| Westlake [Member] \| Majority-Owned Subsidiary, Unconsolidated [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest	77.20%