Earnings Per Share (Schedule Of Net Income Attributable To Common Stockholders) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 183,291	$ 167,757	$ 169,443	$ 158,032	$ 170,972	$ 170,290	$ 145,816	$ 123,347	$ 678,523	$ 610,425	$ 385,555
Less: Net income attributable to participating securities									(1,502)	(2,562)	(2,160)
Net income attributable to common shareholders									$ 677,021	$ 607,863	$ 383,395