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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

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- Definition

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

+ References

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

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- Definition

The cash outflow for cost incurred directly with the issuance of an equity security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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- Definition

The cash inflow from the issuance of common limited partners units during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

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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

Limited Partnership Ownership Percentage Increase

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No definition available.

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- Definition

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

+ References

No definition available.

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Westlake Chemical Partners LP (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Sep. 29, 2017	Apr. 29, 2015	Aug. 04, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Partners' Capital Account, Units, Sold in Public Offering	5,175,000		12,937,500
Sale of Unit Price Per Unit	$ 22.00		$ 24.00
Net proceeds from WLKP LP common stock units	$ 111		$ 286	$ 111	$ 0	$ 0
Payments of Stock Issuance Costs	$ 3		$ 24
Westlake Chemical OpCo LP [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Partnership Ownership Percentage Increase	5.00%	2.70%
Subsidiary of Common Parent [Member] \| Westlake Chemical Partners LP [Member] \| IPO [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited partner interest (percent)			47.80%
Subsidiary of Common Parent [Member] \| Westlake Chemical OpCo LP [Member] \| IPO [Member] \| Limited Partner [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	18.30%		10.60%
Limited partner interest (percent)	81.70%		89.40%	81.70%