Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Net income	$ 258,966	$ 221,393	$ 52,995
Depreciation and amortization	133,080	130,886	124,660
Deferred income taxes	14,114	14,153	31,207
Net changes in working capital and other	(43,864)	(83,148)	26,660
Net cash provided by operating activities	362,296	283,284	235,522
Additions to equity investments		(10,177)
Acquisition of business			(6,297)
Additions to property, plant and equipment	(176,843)	(81,269)	(99,769)
Proceeds from disposition of assets	2,880	914	3,255
Proceeds from insurance for involuntary conversion of assets			484
Proceeds from repayment of loan to affiliate	1,192	763
Purchase of securities and other investments	(30,265)
Settlements of derivative instruments	251	9,494	(859)
Net cash used for investing activities	(202,785)	(80,275)	(103,186)
Intercompany financing
Capitalized debt issuance costs	(2,697)	(3,331)	(2,203)
Dividends paid	(18,265)	(16,014)	(14,510)
Proceeds from exercise of stock options	5,344	3,745	879
Repurchase of common stock for treasury	(2,518)
Utilization of restricted cash	54,227	197,298	38,851
Net cash provided by financing activities	36,091	181,698	23,017
Net increase in cash and cash equivalents	195,602	384,707	155,353
Cash and cash equivalents at beginning of the year	630,299	245,592	90,239
Cash and cash equivalents at end of the year	825,901	630,299	245,592
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	258,966	221,393	52,995
Depreciation and amortization	1,683	2,154	1,461
Deferred income taxes	190	7,864	2,086
Net changes in working capital and other	(291,666)	(245,113)	(72,567)
Net cash provided by operating activities	(30,827)	(13,702)	(16,025)
Additions to equity investments
Acquisition of business
Additions to property, plant and equipment
Proceeds from disposition of assets
Proceeds from insurance for involuntary conversion of assets
Proceeds from repayment of loan to affiliate
Settlements of derivative instruments
Net cash used for investing activities
Intercompany financing	186,898	210,360	137,442
Capitalized debt issuance costs	(2,697)	(3,331)	(2,203)
Dividends paid	(18,265)	(16,014)	(14,510)
Proceeds from exercise of stock options	5,344	3,745	879
Repurchase of common stock for treasury	(2,518)
Utilization of restricted cash	54,227	197,298	38,851
Net cash provided by financing activities	222,989	392,058	160,459
Net increase in cash and cash equivalents	192,162	378,356	144,434
Cash and cash equivalents at beginning of the year	611,158	232,802	88,368
Cash and cash equivalents at end of the year	803,320	611,158	232,802
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	294,464	246,536	65,251
Depreciation and amortization	127,807	125,002	119,296
Deferred income taxes	14,225	6,048	27,113
Net changes in working capital and other	(45,667)	(87,299)	27,731
Net cash provided by operating activities	390,829	290,287	239,391
Additions to equity investments		(10,177)
Acquisition of business			(6,297)
Additions to property, plant and equipment	(175,706)	(79,928)	(98,555)
Proceeds from disposition of assets	2,877	914	3,255
Proceeds from insurance for involuntary conversion of assets			484
Proceeds from repayment of loan to affiliate
Purchase of securities and other investments	(30,265)
Settlements of derivative instruments	251	9,494	(859)
Net cash used for investing activities	(202,843)	(79,697)	(101,972)
Intercompany financing	(185,522)	(210,614)	(137,411)
Capitalized debt issuance costs
Dividends paid
Proceeds from exercise of stock options
Utilization of restricted cash
Net cash provided by financing activities	(185,522)	(210,614)	(137,411)
Net increase in cash and cash equivalents	2,464	(24)	8
Cash and cash equivalents at beginning of the year	53	77	69
Cash and cash equivalents at end of the year	2,517	53	77
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(2,869)	1,427	5,636
Depreciation and amortization	3,590	3,730	3,903
Deferred income taxes	(301)	241	2,008
Net changes in working capital and other	1,874	1,301	609
Net cash provided by operating activities	2,294	6,699	12,156
Additions to equity investments
Acquisition of business
Additions to property, plant and equipment	(1,137)	(1,341)	(1,214)
Proceeds from disposition of assets	3
Proceeds from insurance for involuntary conversion of assets
Proceeds from repayment of loan to affiliate	1,192	763
Settlements of derivative instruments
Net cash used for investing activities	58	(578)	(1,214)
Intercompany financing	(1,376)	254	(31)
Capitalized debt issuance costs
Dividends paid
Proceeds from exercise of stock options
Utilization of restricted cash
Net cash provided by financing activities	(1,376)	254	(31)
Net increase in cash and cash equivalents	976	6,375	10,911
Cash and cash equivalents at beginning of the year	19,088	12,713	1,802
Cash and cash equivalents at end of the year	20,064	19,088	12,713
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(291,595)	(247,963)	(70,887)
Depreciation and amortization
Deferred income taxes
Net changes in working capital and other	291,595	247,963	70,887
Net cash provided by operating activities
Additions to equity investments
Acquisition of business
Additions to property, plant and equipment
Proceeds from disposition of assets
Proceeds from insurance for involuntary conversion of assets
Proceeds from repayment of loan to affiliate
Settlements of derivative instruments
Net cash used for investing activities
Intercompany financing
Capitalized debt issuance costs
Dividends paid
Proceeds from exercise of stock options
Utilization of restricted cash
Net cash provided by financing activities
Net increase in cash and cash equivalents
Cash and cash equivalents at beginning of the year
Cash and cash equivalents at end of the year