Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 790,078	$ 825,901	$ 630,299	$ 245,592
Marketable securities	124,873	0
Accounts receivable, net	400,159	407,372
Inventories	399,298	490,777
Prepaid expenses and other current assets	14,700	12,495
Deferred income taxes	22,305	19,611
Total current assets	1,751,413	1,756,156
Property, plant and equipment, net	1,510,048	1,232,066
Equity investments	43,736	46,741
Restricted cash	0	96,283
Other assets, net	106,999	135,575
Total assets	3,412,196	3,266,821
Accounts payable, current	217,050	227,034
Accrued liabilities	181,460	137,561
Total current liabilities	398,510	364,595
Long-term debt	763,761	764,563
Deferred income taxes	326,290	330,791
Other liabilities	51,379	50,560
Stockholders' equity	1,872,256	1,756,312	1,505,070	1,284,982
Total liabilities and stockholders' equity	3,412,196	3,266,821
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	753,881	803,320	611,158	232,802
Marketable securities	124,873
Accounts receivable, net	7,933	0
Inventories	0	0
Prepaid expenses and other current assets	389	363
Deferred income taxes	431	430
Total current assets	887,507	804,113
Property, plant and equipment, net	0	0
Equity investments	3,018,926	2,597,598
Restricted cash		96,283
Other assets, net	17,033	17,650
Total assets	3,923,466	3,515,644
Accounts payable, current	1,285,530	1,005,529
Accrued liabilities	12,808	76
Total current liabilities	1,298,338	1,005,605
Long-term debt	752,872	753,674
Deferred income taxes	0	0
Other liabilities	0	53
Stockholders' equity	1,872,256	1,756,312
Total liabilities and stockholders' equity	3,923,466	3,515,644
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	6,973	2,517	53	77
Marketable securities	0
Accounts receivable, net	1,675,274	1,384,705
Inventories	385,140	478,229
Prepaid expenses and other current assets	11,386	10,332
Deferred income taxes	21,581	19,049
Total current assets	2,100,354	1,894,832
Property, plant and equipment, net	1,502,902	1,223,073
Equity investments	65,448	53,912
Restricted cash		0
Other assets, net	94,678	132,968
Total assets	3,763,382	3,304,785
Accounts payable, current	192,443	210,476
Accrued liabilities	178,915	120,656
Total current liabilities	371,358	331,132
Long-term debt	10,889	10,889
Deferred income taxes	331,320	336,165
Other liabilities	51,312	50,458
Stockholders' equity	2,998,503	2,576,141
Total liabilities and stockholders' equity	3,763,382	3,304,785
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	29,224	20,064	19,088	12,713
Marketable securities	0
Accounts receivable, net	2,959	949
Inventories	14,158	12,548
Prepaid expenses and other current assets	2,925	1,800
Deferred income taxes	293	132
Total current assets	49,559	35,493
Property, plant and equipment, net	7,146	8,993
Equity investments	32,923	35,650
Restricted cash		0
Other assets, net	1,252	2,467
Total assets	90,880	82,603
Accounts payable, current	13,969	3,748
Accrued liabilities	852	2,392
Total current liabilities	14,821	6,140
Long-term debt	0	11,500
Deferred income taxes	934	636
Other liabilities	67	49
Stockholders' equity	75,058	64,278
Total liabilities and stockholders' equity	90,880	82,603
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Marketable securities	0
Accounts receivable, net	(1,286,007)	(978,282)
Inventories	0	0
Prepaid expenses and other current assets	0	0
Deferred income taxes	0	0
Total current assets	(1,286,007)	(978,282)
Property, plant and equipment, net	0	0
Equity investments	(3,073,561)	(2,640,419)
Restricted cash		0
Other assets, net	(5,964)	(17,510)
Total assets	(4,365,532)	(3,636,211)
Accounts payable, current	(1,274,892)	(992,719)
Accrued liabilities	(11,115)	14,437
Total current liabilities	(1,286,007)	(978,282)
Long-term debt	0	(11,500)
Deferred income taxes	(5,964)	(6,010)
Other liabilities	0	0
Stockholders' equity	(3,073,561)	(2,640,419)
Total liabilities and stockholders' equity	$ (4,365,532)	$ (3,636,211)