Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 372,591	$ 459,453	$ 614,976	$ 662,525
Accounts receivable, net	1,003,966	938,743
Inventories	821,708	801,100
Prepaid expenses and other current assets	43,695	48,493
Restricted cash	9,328	160,527
Total current assets	2,251,288	2,408,316
Property, plant and equipment, net	6,392,745	6,420,062
Goodwill	950,681	946,553
Customer relationships, net	596,641	611,615
Other intangible assets, net	172,697	175,839
Deferred charges and other assets, net	360,778	327,868
Total other assets, net	2,080,797	2,061,875
Total assets	10,724,830	10,890,253
Accounts payable	543,121	496,259
Accrued liabilities	400,310	537,483
Term loan	0	149,341
Total current liabilities	943,431	1,183,083
Long-term debt, net	3,601,642	3,678,654
Deferred income taxes	1,649,120	1,650,575
Pension and other liabilities	497,805	485,896
Total liabilities	6,691,998	6,998,208
Total Westlake Chemical Corporation stockholders' equity	3,659,196	3,523,629
Noncontrolling interests	373,636	368,416
Total equity	4,032,832	3,892,045	3,704,402	3,561,931
Total liabilities and equity	10,724,830	10,890,253
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	(5,294,258)	(4,832,599)
Inventories	0	0
Prepaid expenses and other current assets	(59,073)	(36,504)
Restricted cash	0	0
Total current assets	(5,353,331)	(4,869,103)
Property, plant and equipment, net	0	0
Goodwill	0	0
Customer relationships, net	0	0
Other intangible assets, net	0	(25,581)
Deferred charges and other assets, net	(10,951,977)	(10,832,054)
Total other assets, net	(10,951,977)	(10,857,635)
Total assets	(16,305,308)	(15,726,738)
Accounts payable	(5,198,283)	(4,807,780)
Accrued liabilities	(155,048)	(61,323)
Term loan		0
Total current liabilities	(5,353,331)	(4,869,103)
Long-term debt, net	(2,905,713)	(3,997,070)
Deferred income taxes	(23,385)	(22,494)
Pension and other liabilities	(1,115,437)	0
Total liabilities	(9,397,866)	(8,888,667)
Total Westlake Chemical Corporation stockholders' equity	(6,907,442)	(6,838,071)
Noncontrolling interests	0	0
Total equity	(6,907,442)	(6,838,071)
Total liabilities and equity	(16,305,308)	(15,726,738)
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	54,966	146,990	263,150	303,131
Accounts receivable, net	2,446,732	2,117,540
Inventories	0	0
Prepaid expenses and other current assets	53,239	30,748
Restricted cash	0	0
Total current assets	2,554,937	2,295,278
Property, plant and equipment, net	0	0
Goodwill	0	0
Customer relationships, net	0	0
Other intangible assets, net	0	0
Deferred charges and other assets, net	9,335,542	9,170,042
Total other assets, net	9,335,542	9,170,042
Total assets	11,890,479	11,465,320
Accounts payable	4,705,704	4,330,375
Accrued liabilities	17,449	26,367
Term loan		0
Total current liabilities	4,723,153	4,356,742
Long-term debt, net	3,508,130	3,584,949
Deferred income taxes	0	0
Pension and other liabilities	0	0
Total liabilities	8,231,283	7,941,691
Total Westlake Chemical Corporation stockholders' equity	3,659,196	3,523,629
Noncontrolling interests	0	0
Total equity	3,659,196	3,523,629
Total liabilities and equity	11,890,479	11,465,320
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	5,647	53,006	1,154	6,828
Accounts receivable, net	3,521,181	3,329,871
Inventories	605,775	597,819
Prepaid expenses and other current assets	38,066	41,755
Restricted cash	2,681	0
Total current assets	4,173,350	4,022,451
Property, plant and equipment, net	4,438,292	4,475,943
Goodwill	791,706	791,706
Customer relationships, net	453,985	468,645
Other intangible assets, net	102,339	130,243
Deferred charges and other assets, net	846,041	874,003
Total other assets, net	2,194,071	2,264,597
Total assets	10,805,713	10,762,991
Accounts payable	761,986	748,364
Accrued liabilities	357,968	389,216
Term loan		0
Total current liabilities	1,119,954	1,137,580
Long-term debt, net	2,999,225	4,090,775
Deferred income taxes	1,581,202	1,581,260
Pension and other liabilities	1,479,584	360,622
Total liabilities	7,179,965	7,170,237
Total Westlake Chemical Corporation stockholders' equity	3,625,748	3,592,754
Noncontrolling interests	0	0
Total equity	3,625,748	3,592,754
Total liabilities and equity	10,805,713	10,762,991
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	311,978	259,457	$ 350,672	$ 352,566
Accounts receivable, net	330,311	323,931
Inventories	215,933	203,281
Prepaid expenses and other current assets	11,463	12,494
Restricted cash	6,647	160,527
Total current assets	876,332	959,690
Property, plant and equipment, net	1,954,453	1,944,119
Goodwill	158,975	154,847
Customer relationships, net	142,656	142,970
Other intangible assets, net	70,358	71,177
Deferred charges and other assets, net	1,131,172	1,115,877
Total other assets, net	1,503,161	1,484,871
Total assets	4,333,946	4,388,680
Accounts payable	273,714	225,300
Accrued liabilities	179,941	183,223
Term loan		149,341
Total current liabilities	453,655	557,864
Long-term debt, net	0	0
Deferred income taxes	91,303	91,809
Pension and other liabilities	133,658	125,274
Total liabilities	678,616	774,947
Total Westlake Chemical Corporation stockholders' equity	3,281,694	3,245,317
Noncontrolling interests	373,636	368,416
Total equity	3,655,330	3,613,733
Total liabilities and equity	$ 4,333,946	$ 4,388,680