Consolidated Statements of Changes in Stockholders' Equity Statement (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Benefits Liability Net Of Tax [Member]	Cumulative Foreign Currency Exchange [Member]	Unrealized Holding Losses On Investments Net Of Tax [Member]	Noncontrolling Interest [Member]
Amount, beginning balance at Dec. 31, 2012	$ 1,872,256	$ 1,345	$ (13,302)	$ 495,581	$ 1,399,472	$ (16,351)	$ 5,511	$ 0	$ 0
Number of Shares, beginning balance at Dec. 31, 2012		134,374,448	568,986
Net income	610,425				610,425				0
Other comprehensive (loss) income	8,224					9,655	(1,607)	176	0
Common stock repurchased, shares			683,936
Common stock repurchased	(32,918)		(32,918)						0
Shares issued - stock- based compensation, shares	3,437	1		3,436
Shares issued - stock- based compensation		225,924
Stock-based compensation, net of tax on stock options exercised, shares		(20,164)
Stock-based compensation, net of tax on stock options exercised	12,415			12,415
Dividends paid	(55,236)				(55,236)
Amount, ending balance at Dec. 31, 2013	2,418,603	1,346	(46,220)	511,432	1,954,661	(6,696)	3,904	176	0
Number of Shares, ending balance at Dec. 31, 2013		134,580,208	1,252,922
Net income	497,631				495,232				2,399
Net income	495,232
Other comprehensive (loss) income	(33,817)					383	(37,882)	3,682	0
Common stock repurchased, shares			104,163
Common stock repurchased	(9,495)		(9,495)						0
Shares issued - stock- based compensation, shares	5,502	1	2,467	3,034
Shares issued - stock- based compensation		124,566	(136,541)
Stock-based compensation, net of tax on stock options exercised, shares		(24,610)
Stock-based compensation, net of tax on stock options exercised	13,526			13,526
Dividends paid	(55,690)				(55,690)
Issuance of Westlake Chemical Partners LP common units	286,088								286,088
Amount, ending balance at Sep. 30, 2014	$ 3,122,348	$ 1,347	$ (53,248)	$ 527,992	$ 2,394,203	$ (6,313)	$ (33,978)	$ 3,858	$ 288,487
Number of Shares, ending balance at Sep. 30, 2014		134,680,164	1,220,544