Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 986,766	$ 1,188,037	$ 1,185,002	$ 1,103,531	$ 1,135,871	$ 1,253,227	$ 998,576	$ 1,027,676	$ 4,463,336	[1]	$ 4,415,350	[1]	$ 3,759,484	[1]
Cost of sales									3,278,145		3,098,000		2,658,046
Gross profit	236,188	311,276	353,181	284,546	362,849	361,520	305,971	287,010	1,185,191		1,317,350		1,101,438
Selling, general and administrative expenses									225,364		193,359		147,974
Income from operations	181,145	254,028	295,374	229,280	302,387	306,761	266,788	248,055	959,827		1,123,991		953,464
Interest expense									(34,656)		(37,352)		(18,082)
Other income, (expense), net									38,270		(2,721)		6,790
(Loss) income before income taxes									963,441		1,083,918		942,172
(Benefit from) provision for income taxes									298,396		398,902		331,747
Equity in net income of subsidiaries									0		0		0
Net income									665,045		685,016		610,425
Net income attributable to noncontrolling interests									19,035		6,493		0
Net income attributable to Westlake Chemical Corporation	$ 110,969	$ 183,604	$ 205,095	$ 146,342	$ 183,291	$ 167,757	$ 169,443	$ 158,032	646,010		678,523		610,425
Comprehensive income									596,151		601,706		618,649
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									0		0		0
Cost of sales									0		0		0
Gross profit									0		0		0
Selling, general and administrative expenses									2,478		2,082		2,128
Income from operations									(2,478)		(2,082)		(2,128)
Interest expense									(42,197)		(39,763)		(18,030)
Other income, (expense), net									19,614		21,001		11,798
(Loss) income before income taxes									(25,061)		(20,844)		(8,360)
(Benefit from) provision for income taxes									(7,237)		248		(2,031)
Equity in net income of subsidiaries									663,834		699,615		616,754
Net income									646,010		678,523		610,425
Net income attributable to noncontrolling interests									0		0
Net income attributable to Westlake Chemical Corporation									646,010		678,523		610,425
Comprehensive income									596,151		601,706		618,649
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									3,660,393		3,727,361		3,195,406
Cost of sales									2,944,420		3,162,246		2,971,258
Gross profit									715,973		565,115		224,148
Selling, general and administrative expenses									167,431		144,987		114,211
Income from operations									548,542		420,128		109,937
Interest expense									(10)		(10)		(52)
Other income, (expense), net									1,033		(4,921)		(2,438)
(Loss) income before income taxes									549,565		415,197		107,447
(Benefit from) provision for income taxes									288,329		202,501		34,340
Equity in net income of subsidiaries									314,026		496,244		546,546
Net income									575,262		708,940		619,653
Net income attributable to noncontrolling interests									0		0
Net income attributable to Westlake Chemical Corporation									575,262		708,940		619,653
Comprehensive income									572,731		703,148		629,308
Westlake Chemical OpCo LP [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									1,007,221		1,749,700		2,127,747
Cost of sales									624,339		1,003,888		1,255,140
Gross profit									382,882		745,812		872,607
Selling, general and administrative expenses									20,138		26,870		25,451
Income from operations									362,744		718,942		847,156
Interest expense									(2,691)		(10,499)		(8,032)
Other income, (expense), net									(63)		3,151		7,701
(Loss) income before income taxes									359,990		711,594		846,825
(Benefit from) provision for income taxes									672		199,388		300,279
Equity in net income of subsidiaries									0		0		0
Net income									359,318		512,206		546,546
Net income attributable to noncontrolling interests									0		0
Net income attributable to Westlake Chemical Corporation									359,318		512,206		546,546
Comprehensive income									359,318		512,206		546,546
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									1,039,165		475,401		48,016
Cost of sales									933,007		447,676		43,333
Gross profit									106,158		27,725		4,683
Selling, general and administrative expenses									55,139		40,722		6,184
Income from operations									51,019		(12,997)		(1,501)
Interest expense									(521)		(492)		0
Other income, (expense), net									28,449		(8,540)		(2,239)
(Loss) income before income taxes									78,947		(22,029)		(3,740)
(Benefit from) provision for income taxes									16,632		(3,235)		(841)
Equity in net income of subsidiaries									45,292		15,962		0
Net income									107,607		(2,832)		(2,899)
Net income attributable to noncontrolling interests									19,035		6,493
Net income attributable to Westlake Chemical Corporation									88,572		(9,325)		(2,899)
Comprehensive income									42,143		(80,407)		(4,506)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									(1,243,443)		(1,537,112)		(1,611,685)
Cost of sales									(1,223,621)		(1,515,810)		(1,611,685)
Gross profit									(19,822)		(21,302)		0
Selling, general and administrative expenses									(19,822)		(21,302)		0
Income from operations									0		0		0
Interest expense									10,763		13,412		8,032
Other income, (expense), net									(10,763)		(13,412)		(8,032)
(Loss) income before income taxes									0		0		0
(Benefit from) provision for income taxes									0		0		0
Equity in net income of subsidiaries									(1,023,152)		(1,211,821)		(1,163,300)
Net income									(1,023,152)		(1,211,821)		(1,163,300)
Net income attributable to noncontrolling interests									0		0
Net income attributable to Westlake Chemical Corporation									(1,023,152)		(1,211,821)		(1,163,300)
Comprehensive income									$ (974,192)		$ (1,134,947)		$ (1,171,348)

[1] Revenues are attributed to countries based on location of customer.