Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income to Westlake Chemical Corporation	$ 167,757	$ 170,290	$ 495,232	$ 439,453
Less: Net income attributable to participating securities	(353)	(587)	(1,099)	(1,691)
Net income attributable to common shareholders	$ 167,404	$ 169,703	$ 494,133	$ 437,762