Guarantor Disclosures (Condensed Consolidating Financial Information Statement Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 87,813	$ 83,544
Depreciation and amortization	35,794	33,016
Deferred income taxes	791	7,416
Net changes in working capital and other	(14,341)	(83,316)
Net cash provided by operating activities	110,057	40,660
Additions to property, plant and equipment	(64,902)	(28,808)
Proceeds from disposition of assets	3	630
Proceeds from repayment of loan to affiliate	167	167
Purchase of investments	(2,961)
Settlements of derivative instruments	511	(222)
Net cash used for investing activities	(67,182)	(28,233)
Intercompany financing
Dividends paid	(4,914)	(4,218)
Proceeds from exercise of stock options	480	4,820
Utilization of restricted cash	30,800	11,175
Net cash provided by financing activities	26,366	11,777
Net increase in cash and cash equivalents	69,241	24,204
Cash and cash equivalents at beginning of period	825,901	630,299
Cash and cash equivalents at end of period	895,142	654,503
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	87,813	83,544
Depreciation and amortization	400	438
Deferred income taxes	(48)	508
Net changes in working capital and other	(93,790)	(90,716)
Net cash provided by operating activities	(5,625)	(6,226)
Additions to property, plant and equipment
Proceeds from disposition of assets
Proceeds from repayment of loan to affiliate
Settlements of derivative instruments
Net cash used for investing activities
Intercompany financing	44,883	18,201
Dividends paid	(4,914)	(4,218)
Proceeds from exercise of stock options	480	4,820
Utilization of restricted cash	30,800	11,175
Net cash provided by financing activities	71,249	29,978
Net increase in cash and cash equivalents	65,624	23,752
Cash and cash equivalents at beginning of period	803,320	611,158
Cash and cash equivalents at end of period	868,944	634,910
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	94,652	91,090
Depreciation and amortization	34,593	31,727
Deferred income taxes	779	7,146
Net changes in working capital and other	(12,415)	(83,535)
Net cash provided by operating activities	117,609	46,428
Additions to property, plant and equipment	(64,871)	(28,748)
Proceeds from disposition of assets		630
Proceeds from repayment of loan to affiliate
Purchase of investments	(2,961)
Settlements of derivative instruments	511	(222)
Net cash used for investing activities	(67,321)	(28,340)
Intercompany financing	(49,242)	(18,076)
Dividends paid
Proceeds from exercise of stock options
Utilization of restricted cash
Net cash provided by financing activities	(49,242)	(18,076)
Net increase in cash and cash equivalents	1,046	12
Cash and cash equivalents at beginning of period	2,517	53
Cash and cash equivalents at end of period	3,563	65
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(870)	(339)
Depreciation and amortization	801	851
Deferred income taxes	60	(238)
Net changes in working capital and other	(1,918)	184
Net cash provided by operating activities	(1,927)	458
Additions to property, plant and equipment	(31)	(60)
Proceeds from disposition of assets	3
Proceeds from repayment of loan to affiliate	167	167
Settlements of derivative instruments
Net cash used for investing activities	139	107
Intercompany financing	4,359	(125)
Dividends paid
Proceeds from exercise of stock options
Utilization of restricted cash
Net cash provided by financing activities	4,359	(125)
Net increase in cash and cash equivalents	2,571	440
Cash and cash equivalents at beginning of period	20,064	19,088
Cash and cash equivalents at end of period	22,635	19,528
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(93,782)	(90,751)
Depreciation and amortization
Deferred income taxes
Net changes in working capital and other	93,782	90,751
Net cash provided by operating activities
Additions to property, plant and equipment
Proceeds from disposition of assets
Proceeds from repayment of loan to affiliate
Settlements of derivative instruments
Net cash used for investing activities
Intercompany financing
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 period
Cash and cash equivalents at end of period