Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 138,190	$ 123,128
Net income attributable to participating securities	(694)	(549)
Net income attributable to common shareholders	$ 137,496	$ 122,579