Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 65,662	$ 183,604	$ 299,914	$ 535,041
Less: Net income attributable to participating securities	(294)	(195)	(1,347)	(653)
Net income attributable to common shareholders	$ 65,368	$ 183,409	$ 298,567	$ 534,388