Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Operations) (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
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,135,871	$ 1,253,227	$ 998,576	$ 1,027,676	$ 951,625	$ 1,004,165	$ 939,047	$ 864,647	$ 4,415,350	[1]	$ 3,759,484	[1]	$ 3,571,041	[1]
Cost of sales									3,098,000		2,658,046		2,834,081
Gross profit	362,849	361,520	305,971	287,010	295,671	304,471	273,487	227,809	1,317,350		1,101,438		736,960
Selling, general and administrative expenses									193,359		147,974		121,609
Income from operations	302,387	306,761	266,788	248,055	257,580	266,602	235,227	194,055	1,123,991		953,464		615,351
Interest expense									(37,352)		(18,082)		(43,049)
Debt retirement costs									0		0		(7,082)
Gain from sales of equity securities									0		0		16,429
Other income, (expense), net									(2,721)		6,790		3,520
Income before income taxes									1,083,918		942,172		585,169
(Benefit from) provision for income taxes									398,902		331,747		199,614
Equity in net income of subsidiaries									0		0		0
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
Net income									685,016		610,425		385,555
Net income attributable to noncontrolling interests									6,493		0		0
Comprehensive income									601,706		618,649		383,785
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									2,082		2,128		2,004
Income from operations									(2,082)		(2,128)		(2,004)
Interest expense									(39,763)		(18,030)		(42,989)
Debt retirement costs													(7,082)
Gain from sales of equity securities													1
Other income, (expense), net									21,001		11,798		28,171
Income before income taxes									(20,844)		(8,360)		(23,903)
(Benefit from) provision for income taxes									248		(2,031)		1,825
Equity in net income of subsidiaries									699,615		616,754		411,283
Net income attributable to Westlake Chemical Corporation									678,523		610,425		385,555
Net income									678,523		610,425		385,555
Net income attributable to noncontrolling interests									0
Comprehensive income									601,706		618,649		383,785
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									3,727,361		3,195,406		2,788,088
Cost of sales									3,162,246		2,971,258		2,693,592
Gross profit									565,115		224,148		94,496
Selling, general and administrative expenses									144,987		114,211		89,030
Income from operations									420,128		109,937		5,466
Interest expense									(10)		(52)		(60)
Debt retirement costs													0
Gain from sales of equity securities													16,428
Other income, (expense), net									(4,921)		(2,438)		(16,633)
Income before income taxes									415,197		107,447		5,201
(Benefit from) provision for income taxes									202,501		34,340		(11,821)
Equity in net income of subsidiaries									496,244		546,546		395,920
Net income attributable to Westlake Chemical Corporation									708,940		619,653		412,942
Net income									708,940		619,653		412,942
Net income attributable to noncontrolling interests									0
Comprehensive income									703,148		629,308		410,549
Westlake Chemical OpCo LP [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									1,749,700		2,127,747		2,249,098
Cost of sales									1,003,888		1,255,140		1,613,446
Gross profit									745,812		872,607		635,652
Selling, general and administrative expenses									26,870		25,451		24,103
Income from operations									718,942		847,156		611,549
Interest expense									(10,499)		(8,032)		(8,937)
Debt retirement costs													0
Gain from sales of equity securities													0
Other income, (expense), net									3,151		7,701		4,186
Income before income taxes									711,594		846,825		606,798
(Benefit from) provision for income taxes									199,388		300,279		210,878
Equity in net income of subsidiaries									0		0		0
Net income attributable to Westlake Chemical Corporation									512,206		546,546		395,920
Net income									512,206		546,546		395,920
Net income attributable to noncontrolling interests									0
Comprehensive income									512,206		546,546		395,920
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									475,401		48,016		48,205
Cost of sales									447,676		43,333		41,393
Gross profit									27,725		4,683		6,812
Selling, general and administrative expenses									40,722		6,184		6,472
Income from operations									(12,997)		(1,501)		340
Interest expense									(492)		0		0
Debt retirement costs													0
Gain from sales of equity securities													0
Other income, (expense), net									(8,540)		(2,239)		(3,267)
Income before income taxes									(22,029)		(3,740)		(2,927)
(Benefit from) provision for income taxes									(3,235)		(841)		(1,268)
Equity in net income of subsidiaries									15,962		0		0
Net income attributable to Westlake Chemical Corporation									(9,325)		(2,899)		(1,659)
Net income									(2,832)		(2,899)		(1,659)
Net income attributable to noncontrolling interests									6,493
Comprehensive income									(80,407)		(4,506)		(1,036)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales									(1,537,112)		(1,611,685)		(1,514,350)
Cost of sales									(1,515,810)		(1,611,685)		(1,514,350)
Gross profit									(21,302)		0		0
Selling, general and administrative expenses									(21,302)		0		0
Income from operations									0		0		0
Interest expense									13,412		8,032		8,937
Debt retirement costs													0
Gain from sales of equity securities													0
Other income, (expense), net									(13,412)		(8,032)		(8,937)
Income before income taxes									0		0		0
(Benefit from) provision for income taxes									0		0		0
Equity in net income of subsidiaries									(1,211,821)		(1,163,300)		(807,203)
Net income attributable to Westlake Chemical Corporation									(1,211,821)		(1,163,300)		(807,203)
Net income									(1,211,821)		(1,163,300)		(807,203)
Net income attributable to noncontrolling interests									0
Comprehensive income									$ (1,134,947)		$ (1,171,348)		$ (805,433)

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