Acquisitions (Pro Forma Information) (Details) (Vinnolit [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013
Vinnolit [Member]
Pro Forma Information:
Net sales	$ 4,016,935	$ 3,747,619
Net income	550,667	480,964
Net income attributable to noncontrolling interests	2,399	0
Net income attributable to Westlake Chemical Corporation	$ 548,268	$ 480,964
Earnings per common share attributable to Westlake Chemical Corporation:
Basic, in dollars per share	$ 4.11	$ 3.59
Diluted, in dollars per share	$ 4.09	$ 3.58

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.

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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