Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 813,468	$ 461,301	$ 591,556	$ 790,078
Marketable Securities, Current	0	239,388
Accounts receivable, net	592,964	428,457
Inventories	500,552	471,879
Prepaid expenses and other current assets	18,884	13,888
Deferred income taxes	26,080	34,169
Total current assets	1,951,948	1,649,082
Property, plant and equipment, net	2,710,475	2,088,014
Equity investments	70,828	66,875
Other assets, net	393,032	256,938
Total assets	5,126,283	4,060,909
Accounts payable	263,365	249,613
Accrued liabilities	309,671	155,245
Total current liabilities	573,036	404,858
Long-term debt	763,968	763,879
Deferred income taxes	513,773	437,976
Other liabilities	153,158	35,593
Total liabilities	2,003,935	1,642,306
Total Westlake Chemical Corporation stockholders' equity	2,833,861	2,418,603
Noncontrolling interests	288,487	0
Total equity	3,122,348	2,418,603		1,872,256
Total liabilities and equity	5,126,283	4,060,909
Westlake Chemical Corporation
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	652,709	420,948	560,261	753,881
Marketable Securities, Current		239,388
Accounts receivable, net	15,064	3,879
Inventories	0	0
Prepaid expenses and other current assets	137	778
Deferred income taxes	342	441
Total current assets	668,252	665,434
Property, plant and equipment, net	0	0
Equity investments	3,878,703	2,815,752
Other assets, net	34,847	15,393
Total assets	4,581,802	3,496,579
Accounts payable	979,414	316,652
Accrued liabilities	15,448	8,334
Total current liabilities	994,862	324,986
Long-term debt	753,079	752,990
Deferred income taxes	0	0
Other liabilities	0	0
Total liabilities	1,747,941
Total Westlake Chemical Corporation stockholders' equity	2,833,861	2,418,603
Noncontrolling interests	0
Total equity	2,833,861
Total liabilities and equity	4,581,802	3,496,579
100% Owned Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	1,644	6,227	4,494	6,973
Marketable Securities, Current		0
Accounts receivable, net	1,377,250	666,344
Inventories	385,826	339,929
Prepaid expenses and other current assets	14,737	11,055
Deferred income taxes	25,446	28,974
Total current assets	1,804,903	1,052,529
Property, plant and equipment, net	1,451,807	1,318,119
Equity investments	1,207,569	636,461
Other assets, net	351,271	423,901
Total assets	4,815,550	3,431,010
Accounts payable	157,562	100,570
Accrued liabilities	238,225	134,452
Total current liabilities	395,787	235,022
Long-term debt	10,889	10,889
Deferred income taxes	473,343	260,171
Other liabilities	31,616	34,571
Total liabilities	911,635
Total Westlake Chemical Corporation stockholders' equity	3,903,915	2,890,357
Noncontrolling interests	0
Total equity	3,903,915
Total liabilities and equity	4,815,550	3,431,010
OpCo (Less Than 100% Owned Guarantor Subsidiary)
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	89,144	0	0	0
Marketable Securities, Current		0
Accounts receivable, net	58,106	71,812
Inventories	5,551	116,377
Prepaid expenses and other current assets	303	257
Deferred income taxes	0	4,448
Total current assets	153,104	192,894
Property, plant and equipment, net	806,648	762,972
Equity investments	0	10,411
Other assets, net	61,679	75,197
Total assets	1,021,431	1,041,474
Accounts payable	29,856	122,564
Accrued liabilities	3,412	26,688
Total current liabilities	33,268	149,252
Long-term debt	188,523	252,973
Deferred income taxes	1,507	182,855
Other liabilities	0	962
Total liabilities	223,298
Total Westlake Chemical Corporation stockholders' equity	798,133	455,432
Noncontrolling interests	0
Total equity	798,133
Total liabilities and equity	1,021,431	1,041,474
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	69,971	34,126	26,801	29,224
Marketable Securities, Current		0
Accounts receivable, net	170,833	2,755
Inventories	109,175	15,573
Prepaid expenses and other current assets	3,707	1,798
Deferred income taxes	292	306
Total current assets	353,978	54,558
Property, plant and equipment, net	452,020	6,923
Equity investments	356,286	31,518
Other assets, net	137,990	1,199
Total assets	1,300,274	94,198
Accounts payable	100,129	10,649
Accrued liabilities	77,279	1,282
Total current liabilities	177,408	11,931
Long-term debt	0	0
Deferred income taxes	43,155	729
Other liabilities	121,542	60
Total liabilities	342,105
Total Westlake Chemical Corporation stockholders' equity	669,682	81,478
Noncontrolling interests	288,487
Total equity	958,169
Total liabilities and equity	1,300,274	94,198
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Marketable Securities, Current		0
Accounts receivable, net	(1,028,289)	(316,333)
Inventories	0	0
Prepaid expenses and other current assets	0	0
Deferred income taxes	0	0
Total current assets	(1,028,289)	(316,333)
Property, plant and equipment, net	0	0
Equity investments	(5,371,730)	(3,427,267)
Other assets, net	(192,755)	(258,752)
Total assets	(6,592,774)	(4,002,352)
Accounts payable	(1,003,596)	(300,822)
Accrued liabilities	(24,693)	(15,511)
Total current liabilities	(1,028,289)	(316,333)
Long-term debt	(188,523)	(252,973)
Deferred income taxes	(4,232)	(5,779)
Other liabilities	0	0
Total liabilities	(1,221,044)
Total Westlake Chemical Corporation stockholders' equity	(5,371,730)	(3,427,267)
Noncontrolling interests	0
Total equity	(5,371,730)
Total liabilities and equity	$ (6,592,774)	$ (4,002,352)