Acquisitions (Pro Forma Information) (Details) (Vinnolit [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Vinnolit [Member]
Business Acquisition [Line Items]
Net sales	$ 5,152,806	$ 4,976,998
Net income	737,913	666,202
Net income attributable to noncontrolling interests	6,493	0
Net income attributable to Westlake Chemical Corporation	$ 731,420	$ 666,202
Earnings per common share attributable to Westlake Chemical Corporation:
Basic	$ 5.48	$ 4.98
Diluted	$ 5.46	$ 4.96

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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Business Acquisition, Pro Forma Net Income (Loss) Attributable to Noncontrolling Interest

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No definition available.

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Business Acquisition, Pro Forma Net Income (Loss) Attributable To Parent

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No definition available.

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