Condensed Consolidating Financial Information Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 1,110,538	$ 825,901	$ 712,322	$ 630,299
Accounts receivable, net	418,000	407,372
Inventories	407,124	490,777
Prepaid expenses and other current assets	15,415	12,495
Deferred income taxes	19,693	19,611
Total current assets	1,970,770	1,756,156
Property, plant and equipment, net	1,309,752	1,232,066
Equity investments	44,815	46,741
Restricted cash	20,452	96,283
Other assets, net	96,149	135,575
Total assets	3,441,938	3,266,821
Accounts payable	208,309	227,034
Accrued liabilities	129,768	137,561
Total current liabilities	338,077	364,595
Long-term debt	764,604	764,563
Deferred income taxes	337,162	330,791
Other liabilities	49,784	50,560
Stockholders' equity	1,952,311	1,756,312
Total liabilities and stockholders' equity	3,441,938	3,266,821
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	1,083,192	803,320	693,400	611,158
Accounts receivable, net	27,934
Prepaid expenses and other current assets	193	363
Deferred income taxes	430	430
Total current assets	1,111,749	804,113
Equity investments	2,811,361	2,597,598
Restricted cash	20,452	96,283
Other assets, net	17,959	17,650
Total assets	3,961,521	3,515,644
Accounts payable	1,246,389	1,005,529
Accrued liabilities	9,053	76
Total current liabilities	1,255,442	1,005,605
Long-term debt	753,715	753,674
Other liabilities	53	53
Stockholders' equity	1,952,311	1,756,312
Total liabilities and stockholders' equity	3,961,521	3,515,644
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	4,691	2,517	810	53
Accounts receivable, net	1,652,181	1,384,705
Inventories	392,643	478,229
Prepaid expenses and other current assets	12,458	10,332
Deferred income taxes	19,049	19,049
Total current assets	2,081,022	1,894,832
Property, plant and equipment, net	1,301,589	1,223,073
Equity investments	53,800	53,912
Other assets, net	94,815	132,968
Total assets	3,531,226	3,304,785
Accounts payable	190,789	210,476
Accrued liabilities	146,419	120,656
Total current liabilities	337,208	331,132
Long-term debt	10,889	10,889
Deferred income taxes	343,299	336,165
Other liabilities	49,697	50,458
Stockholders' equity	2,790,133	2,576,141
Total liabilities and stockholders' equity	3,531,226	3,304,785
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	22,655	20,064	18,112	19,088
Accounts receivable, net	5,759	949
Inventories	14,481	12,548
Prepaid expenses and other current assets	2,764	1,800
Deferred income taxes	214	132
Total current assets	45,873	35,493
Property, plant and equipment, net	8,163	8,993
Equity investments	33,923	35,650
Other assets, net	1,896	2,467
Total assets	89,855	82,603
Accounts payable	12,744	3,748
Accrued liabilities	557	2,392
Total current liabilities	13,301	6,140
Long-term debt	11,500	11,500
Deferred income taxes	884	636
Other liabilities	34	49
Stockholders' equity	64,136	64,278
Total liabilities and stockholders' equity	89,855	82,603
Eliminations
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, net	(1,267,874)	(978,282)
Total current assets	(1,267,874)	(978,282)
Equity investments	(2,854,269)	(2,640,419)
Other assets, net	(18,521)	(17,510)
Total assets	(4,140,664)	(3,636,211)
Accounts payable	(1,241,613)	(992,719)
Accrued liabilities	(26,261)	14,437
Total current liabilities	(1,267,874)	(978,282)
Long-term debt	(11,500)	(11,500)
Deferred income taxes	(7,021)	(6,010)
Stockholders' equity	(2,854,269)	(2,640,419)
Total liabilities and stockholders' equity	$ (4,140,664)	$ (3,636,211)