Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 665,045	$ 685,016	$ 610,425
Depreciation and amortization	247,761	210,159	159,267
Deferred income taxes	39,784	58,967	93,732
Net changes in working capital and other	126,246	78,234	(110,695)
Net cash provided by operating activities	1,078,836	1,032,376	752,729
Acquisition of business, net of cash acquired	15,782	(611,087)	(178,309)
Additions to property, plant and equipment	(491,426)	(431,104)	(679,222)
Construction of assets pending sale-leaseback	0	0	(136)
Additions to equity investments	0	0	(23,338)
Proceeds from disposition of assets	49	181	151
Proceeds from sale of equity method investments	27,865	0	0
Proceeds from repayment of loan acquired	0	45,923	0
Proceeds from repayment of loan to affiliate	0	0	167
Proceeds from sales and maturities of securities	48,900	342,045	252,519
Purchase of securities	(605,098)	(117,332)	(367,150)
Settlements of derivative instruments	(2,248)	(1,831)	(6,920)
Net cash used for investing activities	(1,006,176)	(773,205)	(1,002,238)
Intercompany financing	0	0	0
Proceeds from (Repayments of) Intercompany Financing, Subsidiary	0
Net distributions prior to WLKP initial public offering			0
Capitalized debt issuance costs	0	(1,186)	0
Dividends paid	(91,551)	(77,656)	(55,236)
Distribution Made to Limited Partner, Cash Distributions Paid	(14,856)	(2,204)
Net proceeds from issuance of Westlake Chemical Partners LP common units	0	286,088	0
Payments to Acquire Limited Partnership Interests	0	0
Proceeds from exercise of stock options	1,063	5,524	3,437
Proceeds from issuance of notes payable	52,960	0	0
Repayment of notes payable	(73,615)	0	0
Repurchase of common stock for treasury	(162,459)	(52,630)	(32,918)
Windfall tax benefits from share-based payment arrangements	1,646	6,704	5,449
Net cash (used for) provided by financing activities	(286,812)	164,640	(79,268)
Effect of exchange rate changes on cash and cash equivalents	(3,924)	(4,511)	0
Net (decrease) increase in cash and cash equivalents	(218,076)	419,300	(328,777)
Cash and cash equivalents at beginning of the year	880,601	461,301	790,078
Cash and cash equivalents at end of the year	662,525	880,601	461,301
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	646,010	678,523	610,425
Depreciation and amortization	2,004	1,673	1,459
Deferred income taxes	(285)	(288)	74
Net changes in working capital and other	(660,777)	(706,043)	(622,194)
Net cash provided by operating activities	(13,048)	(26,135)	(10,236)
Acquisition of business, net of cash acquired	0	0	0
Additions to property, plant and equipment	0	0	0
Construction of assets pending sale-leaseback			0
Additions to equity investments			0
Proceeds from disposition of assets	0	0	0
Proceeds from sale of equity method investments	0
Proceeds from repayment of loan acquired		0
Proceeds from repayment of loan to affiliate			0
Proceeds from sales and maturities of securities	48,900	342,045	252,519
Purchase of securities	(556,211)	(117,332)	(367,150)
Settlements of derivative instruments	0	0	0
Net cash used for investing activities	(507,311)	224,713	(114,631)
Intercompany financing	418,844	155,665	(128,798)
Proceeds from (Repayments of) Intercompany Financing, Subsidiary	0
Net distributions prior to WLKP initial public offering		0	0
Capitalized debt issuance costs		(1,186)
Dividends paid	(91,551)	(77,656)	(55,236)
Distribution Made to Limited Partner, Cash Distributions Paid	0	0
Net proceeds from issuance of Westlake Chemical Partners LP common units		0
Payments to Acquire Limited Partnership Interests	0	0
Proceeds from exercise of stock options	1,063	5,524	3,437
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	(162,459)	(52,630)	(32,918)
Windfall tax benefits from share-based payment arrangements	1,646	6,704	5,449
Net cash (used for) provided by financing activities	167,543	36,421	(208,066)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	(352,816)	234,999	(332,933)
Cash and cash equivalents at beginning of the year	655,947	420,948	753,881
Cash and cash equivalents at end of the year	303,131	655,947	420,948
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	575,262	708,940	619,653
Depreciation and amortization	124,897	111,389	81,897
Deferred income taxes	33,369	55,344	56,787
Net changes in working capital and other	(368,494)	(1,077,982)	(607,033)
Net cash provided by operating activities	365,034	(202,309)	151,304
Acquisition of business, net of cash acquired	0	0	(178,309)
Additions to property, plant and equipment	(215,405)	(209,111)	(453,538)
Construction of assets pending sale-leaseback			(136)
Additions to equity investments			(23,338)
Proceeds from disposition of assets	18	180	75
Proceeds from sale of equity method investments	27,865
Proceeds from repayment of loan acquired		0
Proceeds from repayment of loan to affiliate			0
Proceeds from sales and maturities of securities	0	0	0
Purchase of securities	(48,887)	0	0
Settlements of derivative instruments	(2,248)	(1,698)	0
Net cash used for investing activities	(238,657)	(210,629)	(655,246)
Intercompany financing	(585,007)	(244,122)	(100,330)
Proceeds from (Repayments of) Intercompany Financing, Subsidiary	135,341
Net distributions prior to WLKP initial public offering		448,101	603,526
Capitalized debt issuance costs		0
Dividends paid	0	151,729	0
Distribution Made to Limited Partner, Cash Distributions Paid	327,060	54,060
Net proceeds from issuance of Westlake Chemical Partners LP common units		0
Payments to Acquire Limited Partnership Interests	0	0
Proceeds from exercise of stock options	0	0	0
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	0	0	0
Windfall tax benefits from share-based payment arrangements	0	0	0
Net cash (used for) provided by financing activities	(122,606)	409,768	503,196
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	3,771	(3,170)	(746)
Cash and cash equivalents at beginning of the year	3,057	6,227	6,973
Cash and cash equivalents at end of the year	6,828	3,057	6,227
Westlake Chemical OpCo LP [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	359,318	512,206	546,546
Depreciation and amortization	81,210	77,611	73,463
Deferred income taxes	(456)	8,608	37,054
Net changes in working capital and other	19,175	4,879	(54,554)
Net cash provided by operating activities	459,247	603,304	602,509
Acquisition of business, net of cash acquired	0	0	0
Additions to property, plant and equipment	(231,185)	(202,823)	(223,130)
Construction of assets pending sale-leaseback			0
Additions to equity investments			0
Proceeds from disposition of assets	0	0	0
Proceeds from sale of equity method investments	0
Proceeds from repayment of loan acquired		0
Proceeds from repayment of loan to affiliate			0
Proceeds from sales and maturities of securities	0	0	0
Purchase of securities	0	0	0
Settlements of derivative instruments	0	(133)	(6,920)
Net cash used for investing activities	(231,185)	(202,956)	(230,050)
Intercompany financing	156,368	102,702	231,067
Proceeds from (Repayments of) Intercompany Financing, Subsidiary	(135,341)
Net distributions prior to WLKP initial public offering		(448,101)	(603,526)
Capitalized debt issuance costs		0
Dividends paid	0	(151,729)	0
Distribution Made to Limited Partner, Cash Distributions Paid	(352,545)	(57,763)
Net proceeds from issuance of Westlake Chemical Partners LP common units		0
Payments to Acquire Limited Partnership Interests	135,341	286,088
Proceeds from exercise of stock options	0	0	0
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	0	0	0
Windfall tax benefits from share-based payment arrangements	0	0	0
Net cash (used for) provided by financing activities	(196,177)	(268,803)	(372,459)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	31,885	131,545	0
Cash and cash equivalents at beginning of the year	131,545	0	0
Cash and cash equivalents at end of the year	163,430	131,545	0
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	107,607	(2,832)	(2,899)
Depreciation and amortization	39,650	19,486	2,448
Deferred income taxes	7,156	(4,697)	(183)
Net changes in working capital and other	113,190	645,559	9,786
Net cash provided by operating activities	267,603	657,516	9,152
Acquisition of business, net of cash acquired	15,782	(611,087)	0
Additions to property, plant and equipment	(44,836)	(19,170)	(2,554)
Construction of assets pending sale-leaseback			0
Additions to equity investments			0
Proceeds from disposition of assets	31	1	76
Proceeds from sale of equity method investments	0
Proceeds from repayment of loan acquired		45,923
Proceeds from repayment of loan to affiliate			167
Proceeds from sales and maturities of securities	0	0	0
Purchase of securities	0	0	0
Settlements of derivative instruments	0	0	0
Net cash used for investing activities	(29,023)	(584,333)	(2,311)
Intercompany financing	9,795	(14,245)	(1,939)
Proceeds from (Repayments of) Intercompany Financing, Subsidiary	0
Net distributions prior to WLKP initial public offering		0	0
Capitalized debt issuance costs		0
Dividends paid	0	0	0
Distribution Made to Limited Partner, Cash Distributions Paid	10,629	1,499
Net proceeds from issuance of Westlake Chemical Partners LP common units		286,088
Payments to Acquire Limited Partnership Interests	(135,341)	(286,088)
Proceeds from exercise of stock options	0	0	0
Proceeds from issuance of notes payable	52,960
Repayment of notes payable	(73,615)
Repurchase of common stock for treasury	0	0	0
Windfall tax benefits from share-based payment arrangements	0	0	0
Net cash (used for) provided by financing activities	(135,572)	(12,746)	(1,939)
Effect of exchange rate changes on cash and cash equivalents	(3,924)	(4,511)
Net (decrease) increase in cash and cash equivalents	99,084	55,926	4,902
Cash and cash equivalents at beginning of the year	90,052	34,126	29,224
Cash and cash equivalents at end of the year	189,136	90,052	34,126
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(1,023,152)	(1,211,821)	(1,163,300)
Depreciation and amortization	0	0	0
Deferred income taxes	0	0	0
Net changes in working capital and other	1,023,152	1,211,821	1,163,300
Net cash provided by operating activities	0	0	0
Acquisition of business, net of cash acquired	0	0	0
Additions to property, plant and equipment	0	0	0
Construction of assets pending sale-leaseback			0
Additions to equity investments			0
Proceeds from disposition of assets	0	0	0
Proceeds from sale of equity method investments	0
Proceeds from repayment of loan acquired		0
Proceeds from repayment of loan to affiliate			0
Proceeds from sales and maturities of securities	0	0	0
Purchase of securities	0	0	0
Settlements of derivative instruments	0	0	0
Net cash used for investing activities	0	0	0
Intercompany financing			0
Net distributions prior to WLKP initial public offering		0	0
Capitalized debt issuance costs		0
Dividends paid	0	0	0
Distribution Made to Limited Partner, Cash Distributions Paid	0	0
Net proceeds from issuance of Westlake Chemical Partners LP common units		0
Payments to Acquire Limited Partnership Interests	0	0
Proceeds from exercise of stock options	0	0	0
Proceeds from issuance of notes payable	0
Repayment of notes payable	0
Repurchase of common stock for treasury	0	0	0
Windfall tax benefits from share-based payment arrangements	0	0	0
Net cash (used for) provided by financing activities	0	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net (decrease) increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of the year	0	0	0
Cash and cash equivalents at end of the year	$ 0	$ 0	$ 0