Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 111,124	$ 205,095	$ 234,252	$ 351,437
Less: Net income attributable to participating securities	(504)	(253)	(1,054)	(457)
Net income attributable to common shareholders	$ 110,620	$ 204,842	$ 233,198	$ 350,980