Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 895,142	$ 825,901	$ 654,503	$ 630,299
Accounts receivable, net	444,609	407,372
Inventories	422,405	490,777
Prepaid expenses and other current assets	14,106	12,495
Deferred income taxes	19,614	19,611
Total current assets	1,795,876	1,756,156
Property, plant and equipment, net	1,263,556	1,232,066
Equity investments	46,039	46,741
Restricted cash	65,607	96,283
Other assets, net	158,969	135,575
Total assets	3,330,047	3,266,821
Accounts payable	197,449	227,034
Accrued liabilities	114,514	137,561
Total current liabilities	311,963	364,595
Long-term debt	764,583	764,563
Deferred income taxes	340,953	330,791
Other liabilities	49,518	50,560
Stockholders' equity	1,863,030	1,756,312
Total liabilities and stockholders' equity	3,330,047	3,266,821
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	868,944	803,320	634,910	611,158
Accounts receivable, net	21,593
Inventories
Prepaid expenses and other current assets	183	363
Deferred income taxes	430	430
Total current assets	891,150	804,113
Property, plant and equipment, net
Equity investments	2,708,670	2,597,598
Restricted cash	65,607	96,283
Other assets, net	17,299	17,650
Total assets	3,682,726	3,515,644
Accounts payable	1,045,333	1,005,529
Accrued liabilities	20,616	76
Total current liabilities	1,065,949	1,005,605
Long-term debt	753,694	753,674
Deferred income taxes
Other liabilities	53	53
Stockholders' equity	1,863,030	1,756,312
Total liabilities and stockholders' equity	3,682,726	3,515,644
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	3,563	2,517	65	53
Accounts receivable, net	1,475,952	1,384,705
Inventories	407,949	478,229
Prepaid expenses and other current assets	11,252	10,332
Deferred income taxes	19,050	19,049
Total current assets	1,917,766	1,894,832
Property, plant and equipment, net	1,255,117	1,223,073
Equity investments	53,978	53,912
Restricted cash
Other assets, net	156,943	132,968
Total assets	3,383,804	3,304,785
Accounts payable	182,086	210,476
Accrued liabilities	107,525	120,656
Total current liabilities	289,611	331,132
Long-term debt	10,889	10,889
Deferred income taxes	346,303	336,165
Other liabilities	49,431	50,458
Stockholders' equity	2,687,570	2,576,141
Total liabilities and stockholders' equity	3,383,804	3,304,785
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	22,635	20,064	19,528	19,088
Accounts receivable, net	4,718	949
Inventories	14,456	12,548
Prepaid expenses and other current assets	2,671	1,800
Deferred income taxes	134	132
Total current assets	44,614	35,493
Property, plant and equipment, net	8,439	8,993
Equity investments	34,968	35,650
Restricted cash
Other assets, net	2,285	2,467
Total assets	90,306	82,603
Accounts payable	12,312	3,748
Accrued liabilities	1,745	2,392
Total current liabilities	14,057	6,140
Long-term debt	11,500	11,500
Deferred income taxes	708	636
Other liabilities	34	49
Stockholders' equity	64,007	64,278
Total liabilities and stockholders' equity	90,306	82,603
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents
Accounts receivable, net	(1,057,654)	(978,282)
Inventories
Prepaid expenses and other current assets
Deferred income taxes
Total current assets	(1,057,654)	(978,282)
Property, plant and equipment, net
Equity investments	(2,751,577)	(2,640,419)
Restricted cash
Other assets, net	(17,558)	(17,510)
Total assets	(3,826,789)	(3,636,211)
Accounts payable	(1,042,282)	(992,719)
Accrued liabilities	(15,372)	14,437
Total current liabilities	(1,057,654)	(978,282)
Long-term debt	(11,500)	(11,500)
Deferred income taxes	(6,058)	(6,010)
Other liabilities
Stockholders' equity	(2,751,577)	(2,640,419)
Total liabilities and stockholders' equity	$ (3,826,789)	$ (3,636,211)