Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 152,827	$ 111,124	$ 291,017	$ 234,252
Net income attributable to participating securities	(819)	(504)	(1,513)	(1,054)
Net income attributable to common shareholders	$ 152,008	$ 110,620	$ 289,504	$ 233,198