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

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-Publisher FASB
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-Topic 272
-SubTopic 10
-Section 50
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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
-Section S99
-Paragraph 1
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-Publisher FASB
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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=109223946&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
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

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- Definition

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

+ References

No definition available.

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- Definition

Number of Production Facilities

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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) $ / shares in Units, $ in Thousands						3 Months Ended
	Mar. 29, 2019 USD ($) $ / shares shares	Sep. 29, 2017 USD ($) $ / shares shares	Apr. 29, 2015 USD ($)	Apr. 01, 2015	Aug. 04, 2014 shares	Mar. 31, 2019 USD ($) production_facility	Mar. 31, 2018 USD ($)
Limited Partners' Capital Account [Line Items]
Proceeds from private placement of common units	$ 62,934					$ 62,934	$ 0
Westlake Chemical OpCo LP [Member] \| Affiliated Entity [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest	22.80%	18.30%		13.30%	10.60%
Limited partner interest, additional ownership	4.50%	5.00%		2.70%
Amount paid to purchase additional limited partner interest	$ 201,445	$ 229,207	$ 135,341
Westlake Chemical OpCo GP LLC [Member] \| Limited Liability Company [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest					100.00%
Westlake [Member] \| Westlake Chemical OpCo LP [Member] \| Majority-Owned Subsidiary, Unconsolidated [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest	77.20%
Westlake Chemical OpCo LP [Member]
Limited Partners' Capital Account [Line Items]
Number of ethylene production facilities \| production_facility						3
Limited Partner [Member]
Limited Partners' Capital Account [Line Items]
Number of units sold in public offering \| shares	2,940,818	5,175,000			12,937,500
Units sold in secondary offering price per unit (in dollars per share) \| $ / shares	$ 21.40	$ 22.00