Consolidated and Combined Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net sales - Westlake	$ 973,081	$ 853,719	$ 834,918
Net co-products, ethylene and feedstock sales—third parties	199,900	133,017	172,303
Net sales	1,172,981	986,736	1,007,221
Cost of sales	769,314	595,405	624,339
Gross profit	403,667	391,331	382,882
Selling, general and administrative expenses	29,260	24,887	23,550
Income from operations	374,407	366,444	359,332
Other income (expense)
Interest expense—Westlake	(21,861)	(12,607)	(4,967)
Other income, net	1,792	601	160
Income before income taxes	354,338	354,438	354,525
Provision for income taxes	1,280	1,035	672
Net income	353,058	353,403	353,853
Less: Net income attributable to noncontrolling interest in OpCo	304,388	312,463	314,022
Limited partners' interest in net income subsequent to IPO	$ 48,670	$ 40,940	$ 39,831
Weighted average limited partner units outstanding (basic and diluted)
Weighted Average Number of Shares Outstanding, Basic and Diluted	28,392,470	27,059,730	27,059,730
Distributions per common unit (usd per unit)	$ 1.44	$ 1.29	$ 1.15
Common units [Member]
Other income (expense)
Limited partners' interest in net income subsequent to IPO	$ 38,010	$ 21,597	$ 21,158
Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering per limited partner unit (basic and diluted)
Income per limited partner unit (usd per unit)	$ 1.72	$ 1.50	$ 1.47
Weighted average limited partner units outstanding (basic and diluted)
Weighted Average Number of Shares Outstanding, Basic and Diluted	22,101,547	14,373,615	14,373,615
Subordinated units [Member]
Other income (expense)
Limited partners' interest in net income subsequent to IPO	$ 8,994	$ 19,062	$ 18,673
Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering per limited partner unit (basic and diluted)
Income per limited partner unit (usd per unit)	$ 1.43	$ 1.50	$ 1.47
Weighted average limited partner units outstanding (basic and diluted)
Weighted Average Number of Shares Outstanding, Basic and Diluted	6,290,923	12,686,115	12,686,115
Public [Member] | Common units [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted Average Number of Shares Outstanding, Basic and Diluted	14,270,240	12,937,500	12,937,500
Westlake [Member] | Common units [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted Average Number of Shares Outstanding, Basic and Diluted	7,831,307	1,436,115	1,436,115
Westlake [Member] | Subordinated units [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted Average Number of Shares Outstanding, Basic and Diluted	6,290,923	12,686,115	12,686,115