Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income	$ 144,710	$ 128,936
Depreciation and amortization	150,269	65,714
Deferred income taxes	(6,273)	58,637
Net changes in working capital and other	(131,312)	(124,352)
Net cash provided by (used for) operating activities	(157,394)	(128,935)
Additions to property, plant and equipment	(134,285)	(136,328)
Additions to cost method investment	(15,000)	0
Proceeds from disposition of assets	66	104
Proceeds from involuntary conversion of assets	1,555	0
Proceeds from sales and maturities of securities	0	26,859
Purchase of securities	0	(36,637)
Settlements of derivative instruments	(355)	(1,219)
Net cash used for investing activities	(148,019)	(147,221)
Intercompany financing	0	0
Debt issuance costs	(319)	0
Dividends paid	(24,656)	(23,700)
Distributions to noncontrolling interests	(4,463)	(3,985)
Proceeds from issuance of notes payable	1,874	2,050
Proceeds from drawdown of revolver	50,000	0
Restricted cash associated with term loan	154,000	0
Repayment of term loan	(150,000)	0
Repayment of notes payable	(2,469)	(7,095)
Repayment of revolver	(125,000)	0
Other	1,354	288
Repurchase of common stock for treasury	0	(679)
Net cash provided by (used for) financing activities	99,679	33,121
Effect of exchange rate changes on cash and cash equivalents	3,442	3,858
Net increase (decrease) in cash and cash equivalents	86,862	47,549
Cash and cash equivalents at beginning of period	459,453	662,525
Cash and cash equivalents at end of period	372,591	614,976
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	(134,529)	(129,112)
Depreciation and amortization	0	0
Deferred income taxes	0	0
Net changes in working capital and other	134,529	129,112
Net cash provided by (used for) operating activities	0	0
Additions to property, plant and equipment	0	0
Additions to cost method investment	0
Proceeds from disposition of assets	0	0
Proceeds from involuntary conversion of assets	0
Proceeds from sales and maturities of securities		0
Purchase of securities		0
Settlements of derivative instruments	0	0
Net cash used for investing activities	0	0
Intercompany financing	0	0
Debt issuance costs	0
Dividends paid	0	0
Distributions to noncontrolling interests	0	0
Proceeds from issuance of notes payable	0	0
Proceeds from drawdown of revolver	0
Restricted cash associated with term loan	0
Repayment of term loan	0
Repayment of notes payable	0	0
Repayment of revolver	0
Other	0	0
Repurchase of common stock for treasury		0
Net cash provided by (used for) financing activities	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	138,190	123,128
Depreciation and amortization	0	0
Deferred income taxes	(585)	(2,724)
Net changes in working capital and other	(213,242)	(120,345)
Net cash provided by (used for) operating activities	75,637	(59)
Additions to property, plant and equipment	0	0
Additions to cost method investment	0
Proceeds from disposition of assets	0	0
Proceeds from involuntary conversion of assets	0
Proceeds from sales and maturities of securities		26,859
Purchase of securities		(29,045)
Settlements of derivative instruments	0	0
Net cash used for investing activities	0	(2,186)
Intercompany financing	78,234	(13,763)
Debt issuance costs	(319)
Dividends paid	(24,656)	(23,700)
Distributions to noncontrolling interests	0	0
Proceeds from issuance of notes payable	0	0
Proceeds from drawdown of revolver	50,000
Restricted cash associated with term loan	154,000
Repayment of term loan	(150,000)
Repayment of notes payable	0	0
Repayment of revolver	(125,000)
Other	1,354	288
Repurchase of common stock for treasury		(679)
Net cash provided by (used for) financing activities	16,387	37,854
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	92,024	39,981
Cash and cash equivalents at beginning of period	146,990	303,131
Cash and cash equivalents at end of period	54,966	263,150
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	20,754	14,135
Depreciation and amortization	98,578	32,687
Deferred income taxes	(2,905)	55,473
Net changes in working capital and other	(28,009)	(94,115)
Net cash provided by (used for) operating activities	(88,418)	(8,180)
Additions to property, plant and equipment	(120,719)	(50,568)
Additions to cost method investment	(15,000)
Proceeds from disposition of assets	66	6
Proceeds from involuntary conversion of assets	1,555
Proceeds from sales and maturities of securities		0
Purchase of securities		0
Settlements of derivative instruments	(355)	(1,219)
Net cash used for investing activities	(134,453)	(51,781)
Intercompany financing	(95,698)	(42,072)
Debt issuance costs	0
Dividends paid	0	0
Distributions to noncontrolling interests	94,631	79,999
Proceeds from issuance of notes payable	0	0
Proceeds from drawdown of revolver	0
Restricted cash associated with term loan	0
Repayment of term loan	0
Repayment of notes payable	(257)	0
Repayment of revolver	0
Other	0	0
Repurchase of common stock for treasury		0
Net cash provided by (used for) financing activities	1,324	(37,927)
Effect of exchange rate changes on cash and cash equivalents	0	0
Net increase (decrease) in cash and cash equivalents	47,359	5,674
Cash and cash equivalents at beginning of period	53,006	6,828
Cash and cash equivalents at end of period	5,647	1,154
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	120,295	120,785
Depreciation and amortization	51,691	33,027
Deferred income taxes	(2,783)	5,888
Net changes in working capital and other	(24,590)	(39,004)
Net cash provided by (used for) operating activities	(144,613)	(120,696)
Additions to property, plant and equipment	(13,566)	(85,760)
Additions to cost method investment	0
Proceeds from disposition of assets	0	98
Proceeds from involuntary conversion of assets	0
Proceeds from sales and maturities of securities		0
Purchase of securities		(7,592)
Settlements of derivative instruments	0	0
Net cash used for investing activities	(13,566)	(93,254)
Intercompany financing	17,464	55,835
Debt issuance costs	0
Dividends paid	0	0
Distributions to noncontrolling interests	(99,094)	(83,984)
Proceeds from issuance of notes payable	1,874	2,050
Proceeds from drawdown of revolver	0
Restricted cash associated with term loan	0
Repayment of term loan	0
Repayment of notes payable	(2,212)	(7,095)
Repayment of revolver	0
Other	0	0
Repurchase of common stock for treasury		0
Net cash provided by (used for) financing activities	81,968	33,194
Effect of exchange rate changes on cash and cash equivalents	3,442	3,858
Net increase (decrease) in cash and cash equivalents	(52,521)	1,894
Cash and cash equivalents at beginning of period	259,457	352,566
Cash and cash equivalents at end of period	$ 311,978	$ 350,672