Westlake Chemical Partners (WLKP) 10-K 28 Feb 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Feb. 21, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36567
Entity Registrant Name	Westlake Chemical Partners LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	32-0436529
Entity Address, Address Line One	2801 Post Oak Boulevard
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77056
City Area Code	713
Local Phone Number	585-2900
Title of 12(b) Security	Common units representing limited partner interests
Trading Symbol	WLKP
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 420.2
Entity Common Stock, Shares Outstanding		35,228,134
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001604665

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Auditor [Abstract]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Houston, Texas
Auditor Firm ID	238

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 58,619	$ 64,782
Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake")	94,444	64,996
Accounts receivable, net—third parties	18,701	20,030
Inventories	4,432	4,715
Prepaid expenses and other current assets	442	305
Total current assets	226,203	245,793
Property, plant and equipment, net	943,843	990,213
Goodwill	5,814	5,814
Deferred charges and other assets, net	140,982	130,159
Total assets	1,316,842	1,371,979
Current liabilities
Accrued and other liabilities	24,980	17,537
Total current liabilities	56,335	66,941
Deferred income taxes	1,632	1,656
Other liabilities	2,951	0
Total liabilities	460,592	468,271
Commitments and contingencies (Note 16)
EQUITY
Total Westlake Chemical Partners LP partners' capital	279,934	291,930
Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo")	576,316	611,778
Total equity	856,250	903,708
Total liabilities and equity	1,316,842	1,371,979
Affiliated Entity
Current assets
Accounts receivable, net—Westlake	49,565	90,965
Current liabilities
Accounts payable—third parties	15,166	34,087
Nonrelated Party
Current assets
Accounts receivable, net—third parties	18,701	20,030
Current liabilities
Accounts payable—third parties	16,189	15,317
Westlake
EQUITY
General partner—Westlake	(242,572)	(242,572)
Westlake | Affiliated Entity
Current liabilities
Long-term debt payable to Westlake	399,674	399,674
Common units | Publicly and Privately Held
EQUITY
Limited partners' capital	$ 473,513	$ 480,643
Units issued	21,105,904	21,099,638
Common units | Westlake
EQUITY
Limited partners' capital	$ 48,993	$ 53,859
Units issued	14,122,230	14,122,230

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - Common units - shares	Dec. 31, 2023	Dec. 31, 2022
Publicly and Privately Held
Units issued	21,105,904	21,099,638
Units outstanding	21,105,904	21,099,638
Westlake
Units issued	14,122,230	14,122,230
Units outstanding	14,122,230	14,122,230

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Total net sales	$ 1,190,791	$ 1,593,147	$ 1,214,858
Cost of sales	803,332	1,215,782	773,152
Gross profit	387,459	377,365	441,706
Selling, general and administrative expenses	29,751	29,678	31,018
Income from operations	357,708	347,687	410,688
Other income (expense)
Other income, net	4,232	1,566	62
Income before income taxes	335,439	335,846	401,934
Provision for income taxes	813	1,017	549
Net income	334,626	334,829	401,385
Less: Net income attributable to noncontrolling interest in OpCo	280,343	270,656	318,838
Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income	$ 54,283	$ 64,173	$ 82,547
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted)	35,224,340	35,217,336	35,206,333
Affiliated Entity
Net co-products, ethylene and other sales—third parties	$ 1,026,655	$ 1,342,910	$ 1,026,586
Nonrelated Party
Net co-products, ethylene and other sales—third parties	164,136	250,237	188,272
Westlake | Affiliated Entity
Selling, general and administrative expenses	27,085	26,621	28,577
Other income (expense)
Interest expense—Westlake	(26,501)	(13,407)	(8,816)
Common units
Other income (expense)
Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income	$ 54,283	$ 64,173	$ 82,547
Diluted units	$ 1.54	$ 1.82	$ 2.34
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)
Common units	$ 1.54	$ 1.82	$ 2.34
Weighted average limited partner units outstanding (basic and diluted)	35,224,340	35,217,336	35,206,333
Common units | Publicly and Privately Held
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted)	21,102,110	21,095,106	21,084,103
Common units | Westlake
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted)	14,122,230	14,122,230	14,122,230

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Noncontrolling Interest in OpCo	Westlake General Partner	Common units Publicly and Privately Held Limited Partner	Common units Westlake Limited Partner
Equity, beginning balance at Dec. 31, 2020	$ 915,137	$ 637,738	$ (242,572)	$ 471,701	$ 48,270
Stockholders' Equity [Roll Forward]
Net income	401,385	318,838	0	49,435	33,112
Units issued for vested phantom units	411			411
Distribution to unitholders	(66,379)			(39,751)	(26,628)
Distribution to noncontrolling interest retained in OpCo by Westlake	(277,856)	(277,856)
Equity, ending balance at Dec. 31, 2021	972,698	678,720	(242,572)	481,796	54,754
Stockholders' Equity [Roll Forward]
Net income	334,829	270,656	0	38,439	25,734
Units issued for vested phantom units	190			190
Distribution to unitholders	(66,411)			(39,782)	(26,629)
Distribution to noncontrolling interest retained in OpCo by Westlake	(337,598)	(337,598)
Equity, ending balance at Dec. 31, 2022	903,708	611,778	(242,572)	480,643	53,859
Stockholders' Equity [Roll Forward]
Net income	334,626	280,343	0	32,519	21,764
Units issued for vested phantom units	141			141
Distribution to unitholders	(66,420)			(39,790)	(26,630)
Distribution to noncontrolling interest retained in OpCo by Westlake	(315,805)	(315,805)
Equity, ending balance at Dec. 31, 2023	$ 856,250	$ 576,316	$ (242,572)	$ 473,513	$ 48,993

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 334,626	$ 334,829	$ 401,385
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	110,203	121,074	108,814
Loss from disposition of property, plant and equipment	4,933	4,707	4,198
Other losses (gains), net	(27)	356	(276)
Changes in operating assets and liabilities
Accounts receivable - third parties	1,332	(14,435)	5,468
Net accounts receivable - Westlake	27,331	74,197	(31,756)
Inventories	283	4,183	(5,424)
Prepaid expenses and other current assets	(137)	91	(4)
Accounts payable—third parties	1,569	(17,001)	19,782
Accrued and other liabilities	4,026	(37,533)	37,574
Other, net	(32,140)	(6,732)	(131,322)
Net cash provided by operating activities	451,999	463,736	408,439
Cash flows from investing activities
Additions to property, plant and equipment	(46,821)	(54,118)	(81,171)
Investments with Westlake under the Investment Management Agreement	(174,116)	(319,884)	(276,000)
Maturities of investments with Westlake under the Investment Management Agreement	145,000	362,000	293,000
Other	0	0	(130)
Net cash used for investing activities	(75,937)	(12,002)	(64,301)
Cash flows from financing activities
Proceeds from debt payable to Westlake	209,250	32,000	0
Repayment of debt payable to Westlake	(209,250)	(32,000)	0
Distributions to unitholders	(66,420)	(66,411)	(66,379)
Net cash used for financing activities	(382,225)	(404,009)	(344,235)
Net increase (decrease) in cash and cash equivalents	(6,163)	47,725	(97)
Cash and cash equivalents at beginning of the year	64,782	17,057	17,154
Cash and cash equivalents at end of the year	58,619	64,782	17,057
Payments of Ordinary Dividends, Noncontrolling Interest	$ (315,805)	$ (337,598)	$ (277,856)

Description of Business and Sig

Description of Business and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Significant Accounting Policies	Description of Business and Significant Accounting Policies Description of Business Westlake Chemical Partners LP (the "Partnership") is a Delaware limited partnership formed in March 2014 to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, the Partnership completed its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests. In connection with the IPO, the Partnership acquired a 10.6% limited partner interest in Westlake Chemical OpCo LP ("OpCo") and a 100% interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), which is the general partner of OpCo. OpCo owns three ethylene production facilities and one common carrier ethylene pipeline (collectively, the "Contributed Assets"). Since the IPO, the Partnership has periodically purchased additional limited partner interest in OpCo. Most recently, on March 29, 2019, the Partnership purchased an additional 4.5% newly-issued limited partner interest in OpCo for approximately $201,445, resulting in an aggregate 22.8% limited partner interest in OpCo, effective January 1, 2019. The remaining 77.2% limited partner interest in OpCo is owned by Westlake Corporation. References to "Westlake" refer collectively to Westlake Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP. OpCo and Westlake entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which the Partnership generates a substantial majority of its revenue. For more information, see Note 2. The Partnership sells ethylene production in excess of volumes sold to Westlake, as well as all of the co-products resulting from the ethylene production, including propylene, crude butadiene, pyrolysis gasoline and hydrogen, directly to third parties on either a spot or contract basis. Co-products sold to third parties are transported by rail or truck. Net proceeds (after transportation and other costs) from the sales of ethylene co-products that result from the production of ethylene purchased by Westlake are netted against the ethylene price charged to Westlake under the Ethylene Sales Agreement, thereby reducing the Partnership's exposure to fluctuations in the market prices of these co-products. Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with the accounting principles generally accepted in the United States. The Partnership holds a 22.8% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 77.2% limited partner interest in OpCo is owned directly by Westlake, which has no rights to direct the activities that most significantly impact the economic performance of OpCo. As a result of the fact that substantially all of OpCo's activities are conducted on behalf of Westlake, and the fact that OpCo exhibits disproportionality of voting rights to economic interest, OpCo was deemed to be a variable interest entity. The Partnership, through its ownership of OpCo's general partner, has the power to direct the activities that most significantly impact the economic performance of OpCo, and it also has the obligation or right to absorb losses or receive benefits from OpCo that could potentially be significant to OpCo. As such, the Partnership was determined to be OpCo's primary beneficiary and therefore consolidates OpCo's results of operations and financial position. Westlake's retained interest of 77.2% is recorded as noncontrolling interest in the Partnership's consolidated financial statements. Cash and Cash Equivalents Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition. Allowance for Credit Losses The determination of the allowance for credit losses is based on estimation of the amount of accounts receivable that the Partnership believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Partnership's customers, the use of historical experience, the Partnership's accounts receivable aged trial balance, customer specific collectability analysis and an evaluation of economic conditions. The allowance for credit losses is reviewed quarterly. Past due balances over 90 days and high risk accounts, as determined by the analysis of financial strength of customers, are reviewed individually for collectability. Inventories Inventories primarily include product, material and supplies. Inventories are stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out ("FIFO") or average method. Property, Plant and Equipment Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects. Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Capitalized interest was $164, $80 and $0 for the years ended December 31, 2023, 2022 and 2021, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposal or retirement of property, plant and equipment are reflected in the statement of operations when the assets are sold or retired. The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract. The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. Settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period. Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows: Classification Years Buildings and improvements 40 Plant and equipment 25 Ethylene pipeline 35 Other 3-15 Impairment of Long-Lived Assets The accounting guidance for the impairment or disposal of long-lived assets requires that the Partnership assess long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Partnership when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the United States and world economies and uncertainties associated with governmental actions. Long-lived assets assessed for impairment are grouped by asset group, the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset group. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell. Impairment of Goodwill The accounting guidance requires that goodwill be tested for impairment at least annually, or when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below its carrying amount. The impairment test for the recorded goodwill was performed in the fourth quarter of 2023 and did not indicate impairment of the goodwill. As of December 31, 2023, the Partnership's recorded goodwill was $5,814. See Note 6 for more information on the Partnership's annual goodwill impairment test. Turnaround Costs The Partnership accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which typically ranges from five Concentration of Credit Risk Financial instruments which potentially subject the Partnership to concentration of risk consist principally of trade receivables from third-party customers who purchase ethylene and ethylene co-products. The Partnership performs periodic credit evaluations, as applicable, of the customers' financial condition and generally does not require collateral. The Partnership maintains allowances for potential losses, as applicable. Revenue Recognition Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement. The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales. The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (1) have an original expected duration of one year or less or (2) have only variable consideration that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations. The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement. The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. See Note 2 for a description of the terms of the Ethylene Sales Agreement. The Partnership's direct commodity price risk is limited to the sales to third parties. See the Partnership's consolidated statement of operations for the disaggregation of net sales to Westlake and net sales to third parties. Transportation and Freight Amounts billed to customers for freight and handling costs on outbound shipments are included in net sales in the consolidated statements of operations. Transportation and freight costs incurred by the Partnership on outbound shipments are included in cost of sales in the consolidated statements of operations. Environmental Costs Environmental costs relating to current operations are expensed or capitalized, as appropriate, depending on whether such costs provide future economic benefits. Remediation liabilities are recognized when the costs are considered probable and can be reasonably estimated. Measurement of liabilities is based on currently enacted laws and regulations, existing technology and undiscounted site-specific costs. Environmental liabilities in connection with properties that are sold or closed are realized upon such sale or closure, to the extent they are probable and estimable and not previously reserved. Recognition of any joint and several liabilities is based upon the Partnership's best estimate of its final pro rata share of the liability. Income Taxes The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances are recorded against deferred tax assets when it is considered more likely than not that the deferred tax assets will not be realized on a separate tax return basis. Segment Reporting The Partnership only operates one segment (ethylene production) and all of its operations are located in the United States. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. Other Comprehensive Income The Partnership has not reported consolidated statements of comprehensive income for the years ended December 31, 2023, 2022 and 2021 due to immateriality of the components of other comprehensive income. Recent Accounting Pronouncements Segment Reporting (ASU No. 2023-07) In November 2023, the Financial Accounting Standards Board ("FASB") issued an accounting standards update. The update requires public entities to disclose on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker ("CODM"), the title and position of the CODM and an explanation of how the CODM uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The update also requires that a public entity that has a single reportable segment provide all disclosures required by the update as well as all existing segment disclosures in Topic 280. The amendments in this update will be effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024 and are to be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Partnership is currently evaluating the impact of the update on the disclosures in the Partnership's financial statements. Income Taxes (ASU No. 2023-09) In December 2023, the FASB issued an accounting standards update to require additional tax disclosures under Topic 740 primarily related to the rate reconciliation and income taxes paid disclosures. The amendments in this update will be effective for fiscal years beginning after December 15, 2024 and are to be applied on a prospective basis. Retrospective application is also permitted. The update is not expected to have a material impact on the Partnership's disclosures.

Agreements with Westlake and Re

Agreements with Westlake and Related Parties	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Agreements with Westlake and Related Parties	Agreements with Westlake and Related Parties Ethylene Sales Agreement OpCo has entered into a 12-year ethylene sales agreement with Westlake (the "Ethylene Sales Agreement"). The Ethylene Sales Agreement requires Westlake to purchase a minimum volume of ethylene each year equal to 95% of OpCo's planned ethylene production per year (the "Minimum Commitment"), subject to certain exceptions and a maximum commitment of 3.8 billion pounds per year. So long as Westlake is not in default under the Ethylene Sales Agreement, if OpCo's actual production exceeds planned production, Westlake has the option to purchase up to 95% of the excess production (the "Excess Production Option"). The fee for each pound of ethylene purchased by Westlake from OpCo up to the Minimum Commitment in any calendar year will equal: • the actual price OpCo pays Westlake to purchase ethane (or other feedstock, such as propane, if applicable) to produce each pound of ethylene, subject to a specified cap and a floor on the amount of feedstock that should be needed to produce each pound of ethylene; plus • the actual price OpCo pays Westlake to purchase natural gas to produce each pound of ethylene, subject to a specified cap and a floor on the amount of natural gas that should be needed to produce each pound of ethylene; plus • OpCo's estimated operating costs (including selling, general and administrative expenses), divided by OpCo's planned ethylene production for the year (in pounds); plus • a five-year average of OpCo's expected future maintenance capital expenditures and other turnaround expenditures, divided by OpCo's planned ethylene production capacity for the year (in pounds); less • the proceeds (on a per pound of ethylene basis) received by OpCo from the sale of co-products (including, but not limited to, propylene, crude butadiene, pyrolysis gasoline and hydrogen) associated with producing the ethylene purchased by Westlake; plus • a $0.10 per pound margin. The fee for the Excess Production Option, if exercised, equals OpCo's estimated variable operating costs of producing the incremental ethylene, net of revenues from co-products sales plus a $0.10 per pound margin. The estimated operating costs and the expected future maintenance capital expenditures and other turnaround expenditures will be adjusted at the end of each year, to be applicable for the fee for the next calendar year, to reflect certain changes in forecasted costs. Under the Ethylene Sales Agreement OpCo has the option to curtail up to approximately 5% of its ethylene production annually in the event OpCo reasonably determines that its sales of such ethylene to third parties during the relevant period would be uneconomic. Certain of the pricing components that make up the price for ethylene sold under the Ethylene Sales Agreement are modified to reflect the portion of OpCo's production capacity that is used to process Westlake's purge gas instead of producing ethylene. Costs specific to the processing of Westlake's purge gas are recovered under the Services and Secondment Agreement (as described below), and not the Ethylene Sales Agreement. Pursuant to the Ethylene Sales Agreement, Westlake's obligation to pay for the annual minimum commitment (95% of OpCo's budgeted ethylene production), which is measured on an annual basis, is not reduced for a force majeure event lasting fewer than 45 consecutive days. In the event of a force majeure event, the Partnership recognizes buyer deficiency fees representing fixed margin and unavoided operating and maintenance capital expenditures and maintenance expenses per pound of volume committed by Westlake during the force majeure p eriod. In the event Westlake purchases less than its annual commitment, the Partnership recognizes buyer deficiency fees representing fixed margin and all expenses and expenditures incurred per pound of volume committed but not taken by Westlake. Payment for the buyer deficiency fee is scheduled to be received by the Partnership after the conclusion of the year in which the force majeure event occurred. The result of the fee structure is that OpCo should generally recover the portion of its total operating costs and maintenance capital expenditures and other turnaround expenditures corresponding to the portion of OpCo's aggregate production that is purchased by Westlake. Any shortfall in recovery of such costs is generally recognized during the period in which the related operating, maintenance or turnaround activities occur and is recoverable from Westlake in the subsequent year. Under the Ethylene Sales Agreement, if production costs billed to Westlake on an annual basis are less than 95% of the actual production costs incurred by OpCo during the contract year, OpCo is entitled to recover the shortfall in such production costs (proportionate to the volume sold to Westlake) in the subsequent year ("Shortfall"). The Ethylene Sales Agreement provides that, if compliance with any law adopted or modified following the IPO results in OpCo incurring additional costs in excess of $500 in any contract year, OpCo is entitled to charge Westlake a monthly surcharge following efforts to mitigate the effects of such matter. The Ethylene Sales Agreement has an initial term extending until December 31, 2026 and automatically renews thereafter for successive 12-month terms unless terminated. Feedstock Supply Agreement OpCo has entered into a feedstock supply agreement with Westlake, pursuant to which Westlake sells to OpCo ethane and other feedstock in amounts sufficient for OpCo to produce the ethylene to be sold under the Ethylene Sales Agreement (the "Feedstock Supply Agreement"). The Feedstock Supply Agreement provides that OpCo may obtain feedstock from Westlake based on Westlake's total cost of purchasing and delivering the feedstock, including applicable transportation, storage and other costs. Title and risk of loss for all feedstock purchased by OpCo through the Feedstock Supply Agreement passes to OpCo upon delivery to one of three delivery points described in the Feedstock Supply Agreement. The Feedstock Supply Agreement has an initial term extending until December 31, 2026 and automatically renews thereafter for successive 12-month terms unless terminated by either party; provided, however, that such agreement can only be renewed in the event the Ethylene Sales Agreement is renewed simultaneously. The Feedstock Supply Agreement may, in certain circumstances, terminate concurrently with the termination of the Ethylene Sales Agreement. Services and Secondment Agreement OpCo has entered into a Services and Secondment Agreement with Westlake, pursuant to which OpCo provides Westlake with certain services required for the operation of Westlake's facilities; and Westlake provides OpCo with comprehensive operating services for OpCo's facilities, ranging from services relating to the maintenance and operations of the common facilities necessary for the operation of OpCo's units, to making available certain shared utilities such as electricity and natural gas that are necessary for the operation of OpCo's units. Westlake also seconds employees to OpCo to allow OpCo to operate its facilities. Such seconded employees are under the control of OpCo while they work on OpCo's facilities. The Services and Secondment Agreement has an initial 12-year term. The Services and Secondment Agreement may be renewed thereafter upon agreement of the parties and shall automatically terminate if the Ethylene Sales Agreement terminates under certain circumstances. Westlake and OpCo each can terminate the Services and Secondment Agreement under certain circumstances, including if the other party materially defaults on the performance of its obligations and such default continues for a 30-day period. Site Lease Agreements OpCo has entered into two site lease agreements with Westlake pursuant to which Westlake leases to OpCo the real property underlying Lake Charles Olefins and Calvert City Olefins and grants OpCo rights to access and use certain other portions of Westlake's ethylene production facilities that are necessary to operate OpCo's production facilities. OpCo owes Westlake one dollar per site per year. The site lease agreements each have a term of 50 years. Each of the site lease agreements may be renewed if agreed by the parties. Omnibus Agreement The Partnership has entered into an Omnibus Agreement with Westlake that addresses (1) Westlake's indemnification of the Partnership for certain matters, including environmental and tax matters, (2) the provision by Westlake of certain management and other general and administrative services to the Partnership and its general partner and (3) the Partnership's reimbursement to Westlake for such services. The Omnibus Agreement also addresses Westlake's right of first refusal on any proposed transfer of the ethylene production facilities that serve Westlake's other facilities and Westlake's right of first refusal on any proposed transfer of the Partnership's equity interests in OpCo. Exchange Agreement OpCo and Westlake are parties to an exchange agreement, which continues on an annual basis, unless and until terminated by either party. Under the exchange agreement, OpCo may require Westlake to deliver up to 200 million pounds of ethylene for OpCo per year from the Site Leases to an ethylene hub in Mt. Belvieu, Texas, for which OpCo would be required to pay an exchange fee of $0.006 per pound. OpCo Partnership Agreement The Partnership, OpCo GP and Westlake are parties to an agreement of limited partnership for OpCo (the "OpCo LP Agreement"). The OpCo LP Agreement governs the ownership and management of OpCo and designates OpCo GP as the general partner of OpCo. OpCo GP generally has complete authority to manage OpCo's business and affairs. The Partnership controls OpCo GP, as its sole member, subject to certain approval rights held by Westlake. Investment Management Agreement The Partnership, OpCo and Westlake are parties to an Investment Management Agreement that authorizes Westlake to invest the Partnership and OpCo's excess cash with Westlake for durations of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. The Partnership had $94,444 of invested cash under the Investment Management Agreement at December 31, 2023.

Accounts Receivable_Third Parti

Accounts Receivable—Third Parties	12 Months Ended
	Dec. 31, 2023
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts Receivable—Third Parties	Accounts Receivable—Third Parties Accounts receivable—third parties consist of the following: December 31, 2023 2022 Trade customers $ 15,622 $ 18,813 Allowance for credit losses (278) (280) Other receivables 3,357 1,497 Accounts receivable, net—third parties $ 18,701 $ 20,030

Inventories

Inventories	12 Months Ended
	Dec. 31, 2023
Inventory, Net [Abstract]
Inventories	Inventories Inventories consist of the following: December 31, 2023 2022 Finished products $ 4,147 $ 4,093 Feedstock, additives and chemicals 285 622 Inventories $ 4,432 $ 4,715

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consist of the following: December 31, 2023 2022 Building and improvements $ 18,623 $ 18,551 Plant and equipment 1,936,295 1,937,439 Other 112,210 110,984 2,067,128 2,066,974 Less: Accumulated depreciation (1,161,032) (1,102,800) 906,096 964,174 Construction in progress 37,747 26,039 Property, plant and equipment, net $ 943,843 $ 990,213 Depreciation expense on property, plant and equipment of $84,511, $94,744 and $91,852 is included in cost of sales in the consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021, respectively.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2023
Other Assets [Abstract]
Goodwill	Goodwill The Partnership's goodwill balance was $5,814 at December 31, 2023 and 2022. The impairment assessment for the recorded goodwill was performed during the fourth quarter of 2023 and did not indicate impairment of the goodwill. The fair value of the reporting unit was calculated using both a discounted cash flow methodology and a market value methodology. The discounted cash flow projections were based on a long-term forecast to reflect the cyclicality of the Partnership's business. The forecast was based on projected market prices and spreads and estimates by management, including its strategic and operational plans. Other significant assumptions used in the discounted cash flow projection included sales volumes based on production capacities. The future cash flows were discounted to present value using a discount rate of 10.5%. The significant assumptions used in determining the fair value of the reporting unit using the market value methodology include the determination of appropriate market comparables and the estimated multiples of net income before interest expense, income taxes, depreciation and amortization (EBITDA) a willing buyer is likely to pay.

Deferred Charges and Other Asse

Deferred Charges and Other Assets	12 Months Ended
	Dec. 31, 2023
Other Assets [Abstract]
Deferred Charges and Other Assets	Deferred Charges and Other Assets Deferred charges and other assets, net consist of the following: December 31, 2023 2022 Turnaround costs, net $ 133,176 $ 127,647 Other 7,806 2,512 Deferred charges and other assets, net $ 140,982 $ 130,159 Amortization expense on deferred charges and other assets of $25,692, $26,330 and $16,962 is included in cost of sales in the consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021, respectively. Certain other assets are amortized over periods ranging from five

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt payable to Westlake consists of the following: December 31, 2023 2022 OpCo Revolver $ 22,619 $ 22,619 MLP Revolver 377,055 377,055 Long-term debt payable to Westlake $ 399,674 $ 399,674 On August 4, 2014, OpCo entered into a $600,000 senior unsecured revolving credit facility agreement with Westlake (as subsequently amended, the "OpCo Revolver"). On July 12, 2022, OpCo entered into the Second Amendment (the "OpCo Revolver Amendment") to the OpCo Revolver. Prior to the OpCo Revolver Amendment, the OpCo Revolver bore interest at the London Interbank Offered Rate ("LIBOR") plus 2.0%. The OpCo Revolver Amendment, among other things, extended the maturity date of the OpCo Revolver from September 25, 2023 to July 12, 2027 and provided for the replacement of LIBOR with the Secured Overnight Financing Rate, as administered by the Federal Reserve Bank of New York ("SOFR"). Borrowings under the OpCo Revolver now bear interest at a variable rate of either (a) SOFR plus the Applicable Margin plus a 0.10% credit spread adjustment or, if SOFR is no longer available, (b) the Alternate Base Rate plus the Applicable Margin minus 1.0%. The Applicable Margin under the OpCo Revolver is 1.75%. As of December 31, 2023, outstanding borrowings under the OpCo Revolver bore interest at SOFR plus the Applicable Margin and credit spread adjustment. On April 29, 2015, the Partnership entered into a $300,000 revolving credit facility agreement with an affiliate of Westlake (as subsequently amended, the "MLP Revolver") to fund the Partnership's purchase of an additional 2.7% newly-issued, limited partner interest in OpCo for $135,341. In 2017, the Partnership entered into an amendment to the MLP Revolver credit agreement, increasing borrowing capacity from $300,000 to $600,000. On March 29, 2019, the Partnership borrowed $123,511 under the MLP Revolver to partially fund the purchase of the additional 4.5% interest in OpCo. On July 12, 2022, the Partnership entered into the Fourth Amendment (the "MLP Revolver Amendment") to the MLP Revolver. Prior to the MLP Revolver Amendment, the MLP Revolver bore interest at a variable rate of either (a) LIBOR plus 2.0% or, if LIBOR were no longer available, (b) the Alternate Base Rate plus 1.0%. The MLP Revolver Amendment, among other things, extended the maturity date of the MLP Revolver from March 19, 2023 to July 12, 2027 and provided for the replacement of LIBOR with SOFR as the reference rate. Borrowings under the MLP Revolver now bear interest at a variable rate of either (a) SOFR plus the Applicable Margin plus a 0.10% credit spread adjustment or, if SOFR is no longer available, (b) the Alternate Base Rate plus the Applicable Margin minus 1.0%. The Applicable Margin under the MLP Revolver varies between 1.75% and 2.75%, depending on the Partnership's Consolidated Leverage Ratio. As of December 31, 2023, outstanding borrowings under the MLP Revolver bore interest at SOFR plus the Applicable Margin and credit spread adjustment. The MLP Revolver provides that the Partnership may pay all or a portion of the interest on any borrowings in kind, in which case any such amounts would be added to the principal amount of the loan. The MLP Revolver requires that the Partnership maintain a consolidated leverage ratio of either (1) during any one-year period following certain types of acquisitions (including acquisitions of additional interests in OpCo), 5.50:1.00 or less, or (2) during any other period, 4.50:1.00 or less. The MLP Revolver also contains certain other customary covenants. The repayment of borrowings under the MLP Revolver is subject to acceleration upon the occurrence of an event of default. As of December 31, 2023, the Partnership was in compliance with all of the covenants under the OpCo Revolver and the MLP Revolver. The weighted average interest rate on all long-term debt was 7.2% and 4.8% at December 31, 2023 and 2022, respectively. As of December 31, 2023, the Partnership had no scheduled maturities of long-term debt until 2027. The OpCo Revolver and the MLP Revolver are scheduled to mature on July 12, 2027.

Distributions and Net Income Pe

Distributions and Net Income Per Limited Partner Unit	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Distributions and Net Income Per Limited Partner Unit	Distributions and Net Income Per Limited Partner Unit On January 22, 2024, the board of directors of Westlake Chemical Partners GP LLC ("Westlake GP"), the Partnership's general partner, declared a quarterly cash distribution for the period from October 1, 2023 to December 31, 2023 of $0.4714 per common unit. This distribution was paid on February 20, 2024 to unitholders of record as of February 2, 2024. Distributions are declared subsequent to quarter end; therefore, the table below represents total cash distributions declared from earnings of the related periods pertaining to such distributions. Year Ended December 31, 2023 2022 2021 Net income attributable to the Partnership $ 54,283 $ 64,173 $ 82,547 Less: Limited partners' distribution declared on common units 66,421 66,403 66,388 Net income in excess of distribution (Distribution in excess of net income) $ (12,138) $ (2,230) $ 16,159 Net income per unit applicable to common limited partner units is computed by dividing the respective limited partners' interest in net income by the weighted-average number of common units outstanding for the period. Because the Partnership has more than one class of participating securities, it uses the two-class method when calculating the net income per unit applicable to limited partners. The classes of participating securities include common units and incentive distribution rights. Net income attributable to the Partnership is allocated to the unitholders in accordance with their respective ownership percentages in preparation of the consolidated statements of changes in equity. However, when distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions is first allocated to the general partner before the remaining net income is allocated to the unitholders based on their respective ownership percentages. Basic and diluted net income per unit is the same because the Partnership does not have any potentially dilutive units outstanding for the periods presented. Year Ended December 31, 2023 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 66,421 $ — $ 66,421 Distribution in excess of net income (12,138) — (12,138) Net income $ 54,283 $ — $ 54,283 Weighted average units outstanding: Basic and diluted 35,224,340 35,224,340 Net income per limited partner unit: Basic and diluted $ 1.54 Year Ended December 31, 2022 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 66,403 $ — $ 66,403 Distribution in excess of net income (2,230) — (2,230) Net income $ 64,173 $ — $ 64,173 Weighted average units outstanding: Basic and diluted 35,217,336 35,217,336 Net income per limited partner unit: Basic and diluted $ 1.82 Year Ended December 31, 2021 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 66,388 $ — $ 66,388 Net income in excess of distribution 16,159 — 16,159 Net income $ 82,547 $ — $ 82,547 Weighted average units outstanding: Basic and diluted 35,206,333 35,206,333 Net income per limited partner unit: Basic and diluted $ 2.34 The amended Partnership Agreement provides that the Partnership will distribute cash that is deemed to be operating surplus each quarter to all the unitholders, pro rata, until each unit has received a distribution of $1.2938. If cash distributions to the Partnership's unitholders exceed $1.2938 per common unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations: Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Above $1.2938 up to $1.4063 85.0 % 15.0 % Above $1.4063 up to $1.6875 75.0 % 25.0 % Above $1.6875 50.0 % 50.0 % The Partnership's distribution for each quarter in the year ended December 31, 2023 did not exceed the $1.2938 per unit threshold, and, as a result, no distribution was made with respect to the Partnership's incentive distribution rights to Westlake, as the holder of the Partnership's incentive distribution rights. Distribution Per Common Unit Distributions per common unit for the years ended December 31, 2023, 2022 and 2021 were as follows: Year Ended December 31, 2023 2022 2021 Distributions per common unit $ 1.8856 $ 1.8856 $ 1.8856

Partners' Equity

Partners' Equity	12 Months Ended
	Dec. 31, 2023
Partners' Equity [Abstract]
Partners' Equity	Partners' Equity On October 4, 2018, the Partnership and Westlake Chemical Partners GP LLC, the general partner of the Partnership, entered into an Equity Distribution Agreement with UBS Securities LLC, Barclays Capital Inc., Citigroup Global Markets Inc., Deutsche Bank Securities Inc., RBC Capital Markets, LLC, Merrill Lynch, Pierce, Fenner & Smith Incorporated and Wells Fargo Securities, LLC to offer and sell the Partnership's common units, from time to time, up to an aggregate offering amount of $50,000. The Equity Distribution Agreement was amended on February 28, 2020 to reference a new shelf registration and subsequent renewals thereof for utilization under this agreement. To date, no common units have been issued under this program. On March 29, 2019, the Partnership completed the issuance and sale of 2,940,818 common units at a price of $21.40 per unit through a private placement. TTWF LP, Westlake's principal stockholder and a related party, acquired 1,401,869 common units out of 2,940,818 common units issued in the private placement.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Partnership and OpCo regularly enter into related party transactions with Westlake. See below for a description of transactions with related parties. Sales to Related Parties OpCo sells ethylene to Westlake under the Ethylene Sales Agreement. Additionally, the Partnership and OpCo from time to time provide other services or products for which it charges Westlake a fee. Sales to related parties were as follows: Year Ended December 31, 2023 2022 2021 Net sales—Westlake $ 1,026,655 $ 1,342,910 $ 1,026,586 Based on OpCo's 2022 production, the Partnership recognized buyer deficiency fees of $23,835 during the year ended December 31, 2022. The buyer deficiency fee is measured periodically based upon the lower of the actual production deficiency at period end or the estimated annual production deficiency based upon OpCo's annual anticipated production. These periodic estimates are updated at the end of the year based on actual annual production. The buyer deficiency fees are classified as a component of net sales—Westlake. The buyer deficiency fee was received by the Partnership in January 2023. OpCo declared force majeure events in 2021 related to the flash fire at OpCo's Petro 2 facility, OpCo's Petro 1 facility outage, and due to the severe winter storm. As a result of these force majeure events in 2021, the Partnership recognized revenue for a buyer deficiency fee and Shortfall in 2021 of $51,395 and of $58,906, respectively. The buyer deficiency fee is measured periodically based upon the lower of the actual production deficiency at period end or the estimated annual production deficiency based upon OpCo's annual anticipated production. These periodic estimates are updated at the end of the year based on actual annual production. The buyer deficiency fees and Shortfall are classified as a component of net sales—Westlake. The buyer deficiency fee recognized in 2021 was received by the Partnership in January 2022 and out of the total Shortfall of $58,906 recognized in 2021, $51,713 was received by the Partnership in 2022 and $7,004 was received in 2023 pursuant to the terms of the Ethylene Sales Agreement. Cost of Sales from Related Parties Charges for goods and services purchased by the Partnership and OpCo from Westlake and included in cost of sales relate primarily to feedstock purchased under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement. Charges from related parties in cost of sales were as follows: Year Ended December 31, 2023 2022 2021 Feedstock purchased from Westlake and included in cost of sales $ 398,700 $ 764,123 $ 404,359 Other charges from Westlake and included in cost of sales 123,039 172,761 130,541 Total $ 521,739 $ 936,884 $ 534,900 Services from Related Parties Included in Selling, General and Administrative Expenses Charges for services purchased by the Partnership from Westlake and included in selling, general and administrative expenses primarily relate to services Westlake performs on behalf of the Partnership under the Omnibus Agreement, including the Partnership's finance, legal, information technology, human resources, communication, ethics and compliance and other administrative functions. Charges from related parties included within selling, general and administrative expenses were as follows: Year Ended December 31, 2023 2022 2021 Services received from Westlake and included in selling, general and $ 27,085 $ 26,621 $ 28,577 Goods and Services from Related Parties Capitalized as Assets Charges for goods and services purchased by the Partnership and OpCo from Westlake which were capitalized as assets relate primarily to the services of Westlake employees under the Services and Secondment Agreement. Charges from related parties for goods and services capitalized as assets were as follows: Year Ended December 31, 2023 2022 2021 Goods and services purchased from Westlake and capitalized as assets $ 3,660 $ 2,852 $ 16,318 Receivable under the Investment Management Agreement On August 1, 2017, the Partnership, OpCo and Westlake executed an investment management agreement (the "Investment Management Agreement") that authorized Westlake to invest the Partnership's and OpCo's excess cash with Westlake for durations of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. Accrued interest of $1,272 and $940 was included in the receivable under the Investment Management Agreement balance at December 31, 2023 and 2022, respectively. Total interest earned related to the Investment Management Agreement was $4,424, $1,875 and $296 for the years ended December 31, 2023, 2022 and 2021, respectively. The Partnership's receivable under the Investment Management Agreement was as follows: December 31, 2023 2022 Receivable under the Investment Management Agreement $ 94,444 $ 64,996 Accounts Receivable from Related Parties The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake and any buyer deficiency fee and Shortfall recognized under the Ethylene Sales Agreement. As discussed above under "Sales to Related Parties", the buyer deficiency fee for the year ended December 31, 2022 was received by the Partnership in January 2023. Further, out of the total Shortfall recognized in 2021, $7,193 remained to be collected by the Partnership as of December 31, 2022. Of this amount, $7,004 was received during the year ended December 31, 2023 pursuant to the terms of the Ethylene Sales Agreement. The Partnership's accounts receivable from Westlake were as follows: December 31, 2023 2022 Accounts receivable—Westlake $ 49,565 $ 90,965 Accounts Payable to Related Parties The Partnership's accounts payable to Westlake result primarily from feedstock purchases under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement and the Omnibus Agreement. The Partnership's accounts payable to Westlake were as follows: December 31, 2023 2022 Accounts payable—Westlake $ 15,166 $ 34,087 Debt Payable to Related Parties See Note 8 for a description of related party debt payable balances. Interest on related party debt payable balances, net of capitalized interest, for the years ended December 31, 2023, 2022 and 2021 was $26,501, $13,407 and $8,816, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. At December 31, 2023 and 2022, accrued interest on related party debt was $6,675 and $4,733, respectively, and is reflected as a component of accrued and other liabilities in the consolidated balance sheets. Debt payable to related parties was as follows: December 31, 2023 2022 Long-term debt payable to Westlake $ 399,674 $ 399,674 Related Party Leases OpCo is obligated to Westlake under various long-term and short-term noncancelable operating leases, primarily related to rail cars and land. Operating lease rentals paid to Westlake for such leases were $1,869, $2,624 and $3,037 for the years ended December 31, 2023, 2022 and 2021, respectively, and are reflected in other charges from Westlake that are included in cost of sales. OpCo has two site lease agreements with Westlake, each of which has a term of 50 years. Pursuant to the site lease agreements, OpCo pays Westlake one dollar per site per year. Major Customer and Concentration of Credit Risk During the years ended December 31, 2023, 2022 and 2021, Westlake accounted for approximately 86.2%, 84.3% and 84.5%, respectively, of the Partnership's net sales. General During the years ended December 31, 2023, 2022 and 2021, the Partnership reimbursed $347, $243 and $186, respectively, to Westlake for certain state tax payments. Other See Note 10 above for an additional related party transaction.

Unit-based Compensation

Unit-based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Unit-based Compensation	Unit-based Compensation The Westlake Chemical Partners LP Long-Term Incentive Plan (the "Plan") was adopted on July 15, 2014 and provides for grants of unit options, restricted units, phantom units, unit awards, distribution equivalent rights ("DERs") and other unit-based awards. The purpose of the Plan is to attract and retain the services of individuals who are essential for the growth and profitability of the Partnership and to encourage such individuals to devote their best efforts to advancing the business of the Partnership and its affiliates. Awards under the Plan are determined by the board of directors of the Partnership's general partner or a committee thereof (the "Committee"). Under the Plan, DERs may be granted, which represent a contingent right to receive an amount in cash, units, restricted units and/or phantom units, as determined by the Committee at its sole discretion, equal in value to the cash distributions made by the Partnership with respect to a common unit during the period such award is outstanding. The terms and conditions of each award are determined by the Committee. The maximum number of common units of the Partnership that may be delivered with respect to awards under the Plan is 1,270,000. The phantom units along with a corresponding number of DERs were granted to certain non-employee directors of the general partner of the Partnership during the years ended December 31, 2023, 2022 and 2021. These phantom units vest on the first anniversary of the grant date. There were no forfeitures under the Plan during 2023, 2022 and 2021. The total fair value of phantom units that vested during the year ended December 31, 2023 was $278. Non-vested phantom unit awards as of December 31, 2023 and 2022 and changes during the respective periods were as follows: Number of Weighted Non-vested balance at December 31, 2021 11,178 $ 22.90 Granted 12,531 25.30 Vested (11,178) 25.42 Non-vested balance at December 31, 2022 12,531 23.50 Granted 18,564 22.65 Vested (12,531) 22.18 Non-vested balance at December 31, 2023 18,564 21.65 Each phantom unit represents the right to receive, upon vesting, either a cash payment equal to the fair market value of one Partnership common unit or a Partnership common unit. Each DER has distribution rights only so long as the phantom units to which it relates to has not vested or been settled. The awards, which are classified as liability awards for financial accounting purposes, are re-measured at each reporting date until they vest. The total units available for grant at December 31, 2023 were 1,198,853. The total compensation cost recognized during the years ended December 31, 2023, 2022 and 2021 was $349, $282 and $436, respectively, and is included in selling, general and administrative expenses and the related liability is classified as accrued and other liabilities in the consolidated financial statements of the Partnership. The unrecognized compensation cost associated with all grants under the Plan at December 31, 2023 was $214 and the weighted average remaining term of the units at December 31, 2023 was 0.6 years.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Partnership reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels: Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that are not corroborated by market data. The Partnership has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and long-term debt payable to Westlake, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Partnership's long-term debt at December 31, 2023 and December 31, 2022 are summarized in the table below. The fair value of long-term debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate. December 31, 2023 December 31, 2022 Carrying Fair Carrying Fair Long-term debt payable to Westlake $ 399,674 $ 408,110 $ 399,674 $ 405,879

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes. The components of income tax of the Partnership are as follows: Year Ended December 31, 2023 2022 2021 Current State and local $ 837 $ 891 $ 561 Deferred State and local (24) 126 (12) Total provision $ 813 $ 1,017 $ 549 The reconciliation of income tax expense at the U.S. statutory rate to the income tax expense is as follows: Year Ended December 31, 2023 2022 2021 Provision for federal income tax, at statutory rate $ 70,442 $ 70,528 $ 84,406 State income tax provision, net of federal income tax effect 813 1,017 549 Partnership income not subject to entity-level federal income tax (70,442) (70,528) (84,406) Total provision $ 813 $ 1,017 $ 549 The tax effects of the principal temporary differences between financial reporting and income tax reporting are as follows: December 31, 2023 2022 Property, plant and equipment $ (1,402) $ (1,438) Turnaround costs (230) (218) Total deferred tax liabilities $ (1,632) $ (1,656) Balance sheet classifications Noncurrent deferred tax liability $ (1,632) $ (1,656) Total deferred tax liabilities $ (1,632) $ (1,656)

Supplemental Information

Supplemental Information	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental Information Accrued and Other Liabilities Accrued and other liabilities were $24,980 and $17,537 at December 31, 2023 and 2022, respectively. Accrued maintenance expense, accrued capital expenditures, accrued interest on related party debt and accrued taxes, which are components of accrued and other liabilities, were $5,170, $4,627, $6,675 and $3,033 at December 31, 2023, respectively, and were $3,752, $2,442, $4,733 and $2,652 at December 31, 2022, respectively. No other component of accrued and other liabilities was more than five percent of total current liabilities. Cash Flow Information Non-cash Investing Activity Capital expenditure related liabilities, included in accounts payable—third parties and accrued and other liabilities, were $7,809, $6,372, and $14,415 at December 31, 2023, 2022, and 2021, respectively. Interest and Income Taxes Interest paid by the Partnership, net of interest capitalized, was $24,537, $10,850 and $8,976 for the years ended December 31, 2023, 2022 and 2021, respectively. Income tax paid by the Partnership was $827, $683 and $676 for the years ended December 31, 2023, 2022 and 2021, respectively, of which $480, $440 and $490 was paid directly to the tax authorities for the years ended December 31, 2023, 2022 and 2021, and $347, $243 and $186 was paid to Westlake as reimbursements for the years ended December 31, 2023, 2022 and 2021. Operating Leases Right-of-use assets obtained in exchange for operating lease obligations were $5,079, $0 and $0 for the years ended December 31, 2023, 2022 and 2021, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Partnership is subject to environmental laws and regulations that can impose civil and criminal sanctions and that may require the Partnership to mitigate the effects of contamination caused by the release or disposal of hazardous substances into the environment. These laws include the federal Clean Air Act, the federal Water Pollution Control Act, the Resource Conservation and Recovery Act, the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), the Toxic Substances Control Act and various other federal, state and local laws and regulations. Under CERCLA, an owner or operator of property may be held strictly liable for remediating contamination without regard to whether that person caused the contamination, and without regard to whether the practices that resulted in the contamination were legal at the time they occurred. Because the Partnership's production sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on the Partnership. Pursuant to the Omnibus Agreement, certain subsidiaries of Westlake will indemnify the Partnership for liabilities that occurred or existed prior to August 4, 2014. In September 2021, shortly after the turnaround on OpCo's Petro 2 facility commenced, there was a flash fire at the quench tower of the Petro 2 facility. Contractors and employees working on and near the quench tower were injured and multiple lawsuits were filed against Westlake and OpCo. Final settlements were reached with all of the plaintiffs to fully resolve the lawsuits by Westlake, but payment by the insurance carriers has not yet been completed. Westlake is responsible for indemnifying the Partnership in connection to any loss OpCo may have incurred as a result of the fire. The Partnership is also involved in other legal proceedings incidental to the conduct of its business. After considering all relevant facts and circumstances, including applicable insurance and indemnification by Westlake, the Partnership does not believe that any of these legal proceedings will have a material adverse effect on its financial condition, results of operations or cash flows. Other Commitments The Partnership has various purchase commitments for its capital projects and for materials, supplies and services incident to the ordinary conduct of business.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss) Attributable to Parent	$ 54,283	$ 64,173	$ 82,547

Insider Trading Arrangements

Insider Trading Arrangements	12 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Description of Business and S_2

Description of Business and Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description Of Business	Description of Business Westlake Chemical Partners LP (the "Partnership") is a Delaware limited partnership formed in March 2014 to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, the Partnership completed its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests. In connection with the IPO, the Partnership acquired a 10.6% limited partner interest in Westlake Chemical OpCo LP ("OpCo") and a 100% interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), which is the general partner of OpCo. OpCo owns three ethylene production facilities and one common carrier ethylene pipeline (collectively, the "Contributed Assets"). Since the IPO, the Partnership has periodically purchased additional limited partner interest in OpCo. Most recently, on March 29, 2019, the Partnership purchased an additional 4.5% newly-issued limited partner interest in OpCo for approximately $201,445, resulting in an aggregate 22.8% limited partner interest in OpCo, effective January 1, 2019. The remaining 77.2% limited partner interest in OpCo is owned by Westlake Corporation. References to "Westlake" refer collectively to Westlake Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP. OpCo and Westlake entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which the Partnership generates a substantial majority of its revenue. For more information, see Note 2.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with the accounting principles generally accepted in the United States. The Partnership holds a 22.8% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 77.2% limited partner interest in OpCo is owned directly by Westlake, which has no rights to direct the activities that most significantly impact the economic performance of OpCo. As a result of the fact that substantially all of OpCo's activities are conducted on behalf of Westlake, and the fact that OpCo exhibits disproportionality of voting rights to economic interest, OpCo was deemed to be a variable interest entity. The Partnership, through its ownership of OpCo's general partner, has the power to direct the activities that most significantly impact the economic performance of OpCo, and it also has the obligation or right to absorb losses or receive benefits from OpCo that could potentially be significant to OpCo. As such, the Partnership was determined to be OpCo's primary beneficiary and therefore consolidates OpCo's results of operations and financial position. Westlake's retained interest of 77.2% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.
Cash And Cash Equivalents	Cash and Cash Equivalents Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.
Allowance For Doubtful Accounts	Allowance for Credit Losses The determination of the allowance for credit losses is based on estimation of the amount of accounts receivable that the Partnership believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Partnership's customers, the use of historical experience, the Partnership's accounts receivable aged trial balance, customer specific collectability analysis and an evaluation of economic conditions. The allowance for credit losses is reviewed quarterly. Past due balances over 90 days and high risk accounts, as determined by the analysis of financial strength of customers, are reviewed individually for collectability.
Inventories	Inventories Inventories primarily include product, material and supplies. Inventories are stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out ("FIFO") or average method.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects. Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Capitalized interest was $164, $80 and $0 for the years ended December 31, 2023, 2022 and 2021, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposal or retirement of property, plant and equipment are reflected in the statement of operations when the assets are sold or retired. The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract. The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. Settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period.
Impairment Of Long-Lived Assets and Intangible Assets	Impairment of Long-Lived Assets The accounting guidance for the impairment or disposal of long-lived assets requires that the Partnership assess long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Partnership when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the United States and world economies and uncertainties associated with governmental actions. Long-lived assets assessed for impairment are grouped by asset group, the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset group. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell. Impairment of Goodwill The accounting guidance requires that goodwill be tested for impairment at least annually, or when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below its carrying amount. The impairment test for the recorded goodwill was performed in the fourth quarter of 2023 and did not indicate impairment of the goodwill. As of December 31, 2023, the Partnership's recorded goodwill was $5,814. See Note 6 for more information on the Partnership's annual goodwill impairment test.
Turnaround Costs	Turnaround Costs The Partnership accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which typically ranges from five
Concentration Of Credit Risk	Concentration of Credit Risk
Revenue Recognition	Revenue Recognition Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement. The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales. The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (1) have an original expected duration of one year or less or (2) have only variable consideration that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations. The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement. The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. See Note 2 for a description of the terms of the Ethylene Sales Agreement. The Partnership's direct commodity price risk is limited to the sales to third parties. See the Partnership's consolidated statement of operations for the disaggregation of net sales to Westlake and net sales to third parties.
Transportation and Freight	Transportation and Freight Amounts billed to customers for freight and handling costs on outbound shipments are included in net sales in the consolidated statements of operations. Transportation and freight costs incurred by the Partnership on outbound shipments are included in cost of sales in the consolidated statements of operations.
Environmental Costs	Environmental Costs
Income Taxes	Income Taxes The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances are recorded against deferred tax assets when it is considered more likely than not that the deferred tax assets will not be realized on a separate tax return basis.
Segment Reporting	Segment Reporting The Partnership only operates one segment (ethylene production) and all of its operations are located in the United States.
Use Of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Comprehensive Income	Other Comprehensive Income The Partnership has not reported consolidated statements of comprehensive income for the years ended December 31, 2023, 2022 and 2021 due to immateriality of the components of other comprehensive income.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Segment Reporting (ASU No. 2023-07) In November 2023, the Financial Accounting Standards Board ("FASB") issued an accounting standards update. The update requires public entities to disclose on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker ("CODM"), the title and position of the CODM and an explanation of how the CODM uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The update also requires that a public entity that has a single reportable segment provide all disclosures required by the update as well as all existing segment disclosures in Topic 280. The amendments in this update will be effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024 and are to be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Partnership is currently evaluating the impact of the update on the disclosures in the Partnership's financial statements. Income Taxes (ASU No. 2023-09) In December 2023, the FASB issued an accounting standards update to require additional tax disclosures under Topic 740 primarily related to the rate reconciliation and income taxes paid disclosures. The amendments in this update will be effective for fiscal years beginning after December 15, 2024 and are to be applied on a prospective basis. Retrospective application is also permitted. The update is not expected to have a material impact on the Partnership's disclosures.

Description of Business and S_3

Description of Business and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects. Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Capitalized interest was $164, $80 and $0 for the years ended December 31, 2023, 2022 and 2021, respectively. Repair and maintenance costs are charged to operations as incurred. Gains and losses on the disposal or retirement of property, plant and equipment are reflected in the statement of operations when the assets are sold or retired. The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract. The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. Settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period.
Schedule Of Estimated Useful Lives Of Assets	Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows: Classification Years Buildings and improvements 40 Plant and equipment 25 Ethylene pipeline 35 Other 3-15

Accounts Receivable_Third Par_2

Accounts Receivable—Third Parties (Tables)	12 Months Ended
	Dec. 31, 2023
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Schedule Of Accounts Receivable	Accounts receivable—third parties consist of the following: December 31, 2023 2022 Trade customers $ 15,622 $ 18,813 Allowance for credit losses (278) (280) Other receivables 3,357 1,497 Accounts receivable, net—third parties $ 18,701 $ 20,030

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2023
Inventory, Net [Abstract]
Schedule Of Inventory	Inventories consist of the following: December 31, 2023 2022 Finished products $ 4,147 $ 4,093 Feedstock, additives and chemicals 285 622 Inventories $ 4,432 $ 4,715

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment, Net [Abstract]
Schedule Of Property, Plant And Equipment	Property, plant and equipment consist of the following: December 31, 2023 2022 Building and improvements $ 18,623 $ 18,551 Plant and equipment 1,936,295 1,937,439 Other 112,210 110,984 2,067,128 2,066,974 Less: Accumulated depreciation (1,161,032) (1,102,800) 906,096 964,174 Construction in progress 37,747 26,039 Property, plant and equipment, net $ 943,843 $ 990,213

Deferred Charges and Other As_2

Deferred Charges and Other Assets (Tables)	12 Months Ended
	Dec. 31, 2023
Other Assets [Abstract]
Schedule of Other Assets	Deferred charges and other assets, net consist of the following: December 31, 2023 2022 Turnaround costs, net $ 133,176 $ 127,647 Other 7,806 2,512 Deferred charges and other assets, net $ 140,982 $ 130,159

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	Long-term debt payable to Westlake consists of the following: December 31, 2023 2022 OpCo Revolver $ 22,619 $ 22,619 MLP Revolver 377,055 377,055 Long-term debt payable to Westlake $ 399,674 $ 399,674

Distributions and Net Income _2

Distributions and Net Income Per Limited Partner Unit (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Year Ended December 31, 2023 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 66,421 $ — $ 66,421 Distribution in excess of net income (12,138) — (12,138) Net income $ 54,283 $ — $ 54,283 Weighted average units outstanding: Basic and diluted 35,224,340 35,224,340 Net income per limited partner unit: Basic and diluted $ 1.54 Year Ended December 31, 2022 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 66,403 $ — $ 66,403 Distribution in excess of net income (2,230) — (2,230) Net income $ 64,173 $ — $ 64,173 Weighted average units outstanding: Basic and diluted 35,217,336 35,217,336 Net income per limited partner unit: Basic and diluted $ 1.82 Year Ended December 31, 2021 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 66,388 $ — $ 66,388 Net income in excess of distribution 16,159 — 16,159 Net income $ 82,547 $ — $ 82,547 Weighted average units outstanding: Basic and diluted 35,206,333 35,206,333 Net income per limited partner unit: Basic and diluted $ 2.34
Distributions Made to Limited Partner, by Distribution	The amended Partnership Agreement provides that the Partnership will distribute cash that is deemed to be operating surplus each quarter to all the unitholders, pro rata, until each unit has received a distribution of $1.2938. If cash distributions to the Partnership's unitholders exceed $1.2938 per common unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations: Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Above $1.2938 up to $1.4063 85.0 % 15.0 % Above $1.4063 up to $1.6875 75.0 % 25.0 % Above $1.6875 50.0 % 50.0 % The Partnership's distribution for each quarter in the year ended December 31, 2023 did not exceed the $1.2938 per unit threshold, and, as a result, no distribution was made with respect to the Partnership's incentive distribution rights to Westlake, as the holder of the Partnership's incentive distribution rights. Distribution Per Common Unit Distributions per common unit for the years ended December 31, 2023, 2022 and 2021 were as follows: Year Ended December 31, 2023 2022 2021 Distributions per common unit $ 1.8856 $ 1.8856 $ 1.8856
Schedule of Distributions	Distributions are declared subsequent to quarter end; therefore, the table below represents total cash distributions declared from earnings of the related periods pertaining to such distributions. Year Ended December 31, 2023 2022 2021 Net income attributable to the Partnership $ 54,283 $ 64,173 $ 82,547 Less: Limited partners' distribution declared on common units 66,421 66,403 66,388 Net income in excess of distribution (Distribution in excess of net income) $ (12,138) $ (2,230) $ 16,159

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Sales to related parties were as follows: Year Ended December 31, 2023 2022 2021 Net sales—Westlake $ 1,026,655 $ 1,342,910 $ 1,026,586 Charges from related parties in cost of sales were as follows: Year Ended December 31, 2023 2022 2021 Feedstock purchased from Westlake and included in cost of sales $ 398,700 $ 764,123 $ 404,359 Other charges from Westlake and included in cost of sales 123,039 172,761 130,541 Total $ 521,739 $ 936,884 $ 534,900 Charges from related parties included within selling, general and administrative expenses were as follows: Year Ended December 31, 2023 2022 2021 Services received from Westlake and included in selling, general and $ 27,085 $ 26,621 $ 28,577 Charges from related parties for goods and services capitalized as assets were as follows: Year Ended December 31, 2023 2022 2021 Goods and services purchased from Westlake and capitalized as assets $ 3,660 $ 2,852 $ 16,318 The Partnership's receivable under the Investment Management Agreement was as follows: December 31, 2023 2022 Receivable under the Investment Management Agreement $ 94,444 $ 64,996 The Partnership's accounts receivable from Westlake were as follows: December 31, 2023 2022 Accounts receivable—Westlake $ 49,565 $ 90,965 December 31, 2023 2022 Accounts payable—Westlake $ 15,166 $ 34,087 Debt payable to related parties was as follows: December 31, 2023 2022 Long-term debt payable to Westlake $ 399,674 $ 399,674

Unit-based Compensation (Tables

Unit-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Nonvested Restricted Stock Units Activity	Non-vested phantom unit awards as of December 31, 2023 and 2022 and changes during the respective periods were as follows: Number of Weighted Non-vested balance at December 31, 2021 11,178 $ 22.90 Granted 12,531 25.30 Vested (11,178) 25.42 Non-vested balance at December 31, 2022 12,531 23.50 Granted 18,564 22.65 Vested (12,531) 22.18 Non-vested balance at December 31, 2023 18,564 21.65

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule Of Carrying And Fair Values Of Long-Term Debt	The carrying and fair values of the Partnership's long-term debt at December 31, 2023 and December 31, 2022 are summarized in the table below. The fair value of long-term debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate. December 31, 2023 December 31, 2022 Carrying Fair Carrying Fair Long-term debt payable to Westlake $ 399,674 $ 408,110 $ 399,674 $ 405,879

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule Of The Provision For (Benefit From) Income Taxes	The components of income tax of the Partnership are as follows: Year Ended December 31, 2023 2022 2021 Current State and local $ 837 $ 891 $ 561 Deferred State and local (24) 126 (12) Total provision $ 813 $ 1,017 $ 549
Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense	The reconciliation of income tax expense at the U.S. statutory rate to the income tax expense is as follows: Year Ended December 31, 2023 2022 2021 Provision for federal income tax, at statutory rate $ 70,442 $ 70,528 $ 84,406 State income tax provision, net of federal income tax effect 813 1,017 549 Partnership income not subject to entity-level federal income tax (70,442) (70,528) (84,406) Total provision $ 813 $ 1,017 $ 549
Schedule Of Deferred Tax Assets And Liabilities	The tax effects of the principal temporary differences between financial reporting and income tax reporting are as follows: December 31, 2023 2022 Property, plant and equipment $ (1,402) $ (1,438) Turnaround costs (230) (218) Total deferred tax liabilities $ (1,632) $ (1,656) Balance sheet classifications Noncurrent deferred tax liability $ (1,632) $ (1,656) Total deferred tax liabilities $ (1,632) $ (1,656)

Description of Business and S_4

Description of Business and Significant Accounting Policies (Narrative) (Details) $ in Thousands				12 Months Ended
	Mar. 29, 2019 USD ($) shares	Apr. 29, 2015 USD ($)	Aug. 04, 2014 shares	Dec. 31, 2023 USD ($) Segment production_facility	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Threshold period past due accounts receivable reviewed				90 days
Capitalized interest				$ 164	$ 80	$ 0
Goodwill				$ 5,814	$ 5,814
Amortization period, minimum (in years)				5 years
Amortization period, maximum (in years)				6 years
Number of operating segments | Segment				1
Limited Liability Company | Westlake Chemical OpCo GP LLC | Westlake Chemical Partners LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest (percent)			100%
Affiliated Entity | Westlake Chemical OpCo LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Amount paid to purchase additional limited partner interest	$ 201,445
Affiliated Entity | Westlake Chemical OpCo LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Additional ownership interest acquired	4.50%	2.70%
Amount paid to purchase additional limited partner interest		$ 135,341
Affiliated Entity | Westlake Chemical OpCo LP | Westlake Chemical Partners LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest (percent)	22.80%		10.60%
Westlake | Majority-Owned Subsidiary, Unconsolidated | Westlake Chemical OpCo LP | Westlake Chemical Corporation
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest (percent)	77.20%
Westlake Chemical OpCo LP
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of Production Facilities | production_facility				3
Limited Partner
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of units sold in public offering | shares	2,940,818		12,937,500

Description of Business and S_5

Description of Business and Significant Accounting Policies (Schedule Of Estimated Useful Lives Of Assets) (Details)	Dec. 31, 2023
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	40 years
Plant and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	25 years
Ethylene pipeline
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	35 years
Minimum | Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	3 years
Maximum | Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	15 years

Agreements with Westlake and _2

Agreements with Westlake and Related Parties (Details)		12 Months Ended
	Aug. 04, 2014 USD ($) lease lb $ / lb	Dec. 31, 2023 USD ($) lb $ / lb	Dec. 31, 2022 USD ($)
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Term of Investment Management Agreement with Related Party, Maximum		9 months
IMA, Partnership earned amount added to market rate, basis points		five
Receivables under Investment Management Agreements with Related Parties, Current | $		$ 94,444,000	$ 64,996,000
Westlake Chemical OpCo LP | Exchange Agreement
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Purchase commitment, fixed margin on variable pricing | $ / lb		0.006
Exchange agreement amount of purchase agreement | lb		200,000,000
Westlake Chemical OpCo LP | Westlake | Services And Secondment Agreement | Investee
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Related party transactions, term of agreements	12 years
Period of default in performance that can allow a party to terminate agreement	30 days
Westlake Chemical OpCo LP | Westlake | Site Lease Agreement | Investee
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Number of lease agreements | lease	2
Operating lease, rental amount | $	$ 1
Term of operating lease	50 years
Westlake Chemical OpCo LP | Westlake | Ethylene Sales Agreement | Investee
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Term of sales agreement	12 years
Minimum percentage required to be purchased	95%
Maximum mass required to be purchased | lb	3,800,000,000
Number of years used to calculate average expenses	5 years
Purchase commitment, fixed margin on variable pricing | $ / lb	0.10
Long-term Purchase Commitment, Compliance Surcharge Amount | $	$ 500,000
Purchase commitment, renewal term	12 months
Westlake Chemical OpCo LP | Westlake | Feedstock Supply Agreement | Investee
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Related party transactions, term of agreements	12 months
Westlake Chemical OpCo LP | Westlake | Excess Production Option | Investee
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Purchase commitment, fixed margin on variable pricing | $ / lb	0.10

Accounts Receivable_Third Par_3

Accounts Receivable—Third Parties (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Trade customers	$ 15,622	$ 18,813
Allowance for credit losses	(278)	(280)
Other receivables	3,357	1,497
Accounts receivable, net—third parties	$ 18,701	$ 20,030

Inventories (Schedule Of Invent

Inventories (Schedule Of Inventory) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Inventory, Net [Abstract]
Finished products	$ 4,147	$ 4,093
Feedstock, additives and chemicals	285	622
Inventories	$ 4,432	$ 4,715

Property, Plant and Equipment_2

Property, Plant and Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment, Net [Abstract]
Building and improvements	$ 18,623	$ 18,551
Plant and equipment	1,936,295	1,937,439
Other	112,210	110,984
Property, plant and equipment, gross	2,067,128	2,066,974
Less: Accumulated depreciation	(1,161,032)	(1,102,800)
Property, plant and equipment, net, before construction in progress	906,096	964,174
Construction in progress	37,747	26,039
Property, plant and equipment, net	943,843	990,213
Depreciation expense	$ 84,511	$ 94,744	$ 91,852

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Gross	$ 5,814	$ 5,814
Rate used to discount future cash flows for goodwill impairment test	10.50%

Deferred Charges and Other As_3

Deferred Charges and Other Assets (Schedule Of Intangible and Other Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Assets [Abstract]
Turnaround costs, net	$ 133,176	$ 127,647
Other	7,806	2,512
Deferred charges and other assets, net	$ 140,982	130,159
Minimum
Deferred Charges and Other Assets [Line Items]
Other assets amortization period	5 years
Maximum
Deferred Charges and Other Assets [Line Items]
Other assets amortization period	20 years
Other Assets
Deferred Charges and Other Assets [Line Items]
Amortization	$ 25,692	$ 26,330	$ 16,962

Long-Term Debt (Schedule of Lon

Long-Term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands				12 Months Ended
	Jul. 12, 2022	Mar. 29, 2019	Apr. 29, 2015	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Aug. 01, 2017	Aug. 04, 2014
Related Party Transaction [Line Items]
Proceeds from debt payable to Westlake				$ 209,250	$ 32,000	$ 0
Weighted average interest rate on all long-term debt				7.20%	4.80%
Limited Partner | Senior Unsecured Revolving Credit Facility
Related Party Transaction [Line Items]
Long-term debt payable to Westlake				$ 399,674	$ 399,674
Affiliated Entity | Westlake
Related Party Transaction [Line Items]
Long-term debt payable to Westlake				399,674	399,674
Affiliated Entity | Westlake Chemical OpCo LP
Related Party Transaction [Line Items]
Additional ownership interest		4.50%	2.70%
Amount paid to purchase additional limited partner interest			$ 135,341
Proceeds from debt payable to Westlake		$ 123,511
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility
Related Party Transaction [Line Items]
Long-term debt payable to Westlake				$ 22,619	22,619
Basis spread on variable rate, percent				1.75%
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				0.10%
OpCo Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Alternate Base Rate
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				1%
OpCo Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake
Related Party Transaction [Line Items]
Maximum borrowing capacity								$ 600,000
OpCo Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake | Line of Credit
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	2%
MLP Revolver | Westlake
Related Party Transaction [Line Items]
Maximum borrowing capacity			$ 300,000				$ 600,000
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility
Related Party Transaction [Line Items]
Long-term debt payable to Westlake				$ 377,055	$ 377,055
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Minimum
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				1.75%
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Maximum
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				2.75%
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				0.10%
MLP Revolver | Limited Partner | Senior Unsecured Revolving Credit Facility | Alternate Base Rate
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	1%			1%
MLP Revolver | Limited Partner | Westlake | Line of Credit
Related Party Transaction [Line Items]
Maximum consolidated leverage ratio during one year following acquisitions			5.50
Leverage capital ratio required during other periods			4.50
MLP Revolver | Limited Partner | Westlake Chemical OpCo LP | Westlake | Line of Credit
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	2%

Distributions and Net Income _3

Distributions and Net Income Per Limited Partner Unit (Narrative) (Details) - $ / shares		12 Months Ended
	Jan. 22, 2024	Dec. 31, 2023
Above $1.2938 up to $1.4063 | Minimum
Distributions [Line Items]
Quarterly distribution per unit threshold (usd per share)		$ 1.2938
Common and Subordinated units | Cash Distribution
Distributions [Line Items]
Minimum quarterly distribution per unit (usd per share)		$ 1.2938
Common and Subordinated units | Cash Distribution | Subsequent Event
Distributions [Line Items]
Distribution declared per unit (usd per share)	$ 0.4714

Distributions and Net Income _4

Distributions and Net Income Per Limited Partner Unit (Income In Excess Of Distribution) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Limited partners' interest in net income subsequent to IPO	$ 54,283	$ 64,173	$ 82,547
Limited partners' distribution declared on common units	66,421	66,403	66,388
Net income in excess of distribution (Distribution in excess of net income)	(12,138)	(2,230)	16,159
Common units
Limited partners' interest in net income subsequent to IPO	54,283	64,173	82,547
Limited partners' distribution declared on common units	66,421	66,403	66,388
Net income in excess of distribution (Distribution in excess of net income)	$ (12,138)	$ (2,230)	$ 16,159

Distributions and Net Income _5

Distributions and Net Income Per Limited Partner Unit (Basic and Diluted Income Per Limited Partner Unit) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Limited Partners' Capital Account [Line Items]
Distribution	$ 66,421	$ 66,403	$ 66,388
Net income in excess of distribution (Distribution in excess of net income)	(12,138)	(2,230)	16,159
Limited partners' interest in net income subsequent to IPO	$ 54,283	$ 64,173	$ 82,547
Weighted average limited partner units outstanding (basic and diluted)	35,224,340	35,217,336	35,206,333
IDR Holders
Limited Partners' Capital Account [Line Items]
Distributions declared with respect to the incentive distribution rights	$ 0	$ 0	$ 0
Net income in excess of distribution (Distribution in excess of net income)	0	0	0
Limited partners' interest in net income subsequent to IPO	0	0	0
Common units
Limited Partners' Capital Account [Line Items]
Distribution	66,421	66,403	66,388
Net income in excess of distribution (Distribution in excess of net income)	(12,138)	(2,230)	16,159
Limited partners' interest in net income subsequent to IPO	$ 54,283	$ 64,173	$ 82,547
Weighted average limited partner units outstanding (basic and diluted)	35,224,340	35,217,336	35,206,333
Common units	$ 1.54	$ 1.82	$ 2.34
Diluted units	$ 1.54	$ 1.82	$ 2.34

Distributions and Net Income _6

Distributions and Net Income Per Limited Partner Unit (Incentive Distribution Rights) (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares
Above $1.2938 up to $1.4063 | Unitholders
Distribution Made to Limited Partner [Line Items]
Marginal Percentage Interest in Distributions	85%
Above $1.2938 up to $1.4063 | IDR Holders
Distribution Made to Limited Partner [Line Items]
Marginal Percentage Interest in Distributions	15%
Above $1.4063 up to $1.6875 | Unitholders
Distribution Made to Limited Partner [Line Items]
Marginal Percentage Interest in Distributions	75%
Above $1.4063 up to $1.6875 | IDR Holders
Distribution Made to Limited Partner [Line Items]
Marginal Percentage Interest in Distributions	25%
Above $1.6875 | Unitholders
Distribution Made to Limited Partner [Line Items]
Marginal Percentage Interest in Distributions	50%
Above $1.6875 | IDR Holders
Distribution Made to Limited Partner [Line Items]
Marginal Percentage Interest in Distributions	50%
Minimum | Above $1.2938 up to $1.4063
Distribution Made to Limited Partner [Line Items]
Quarterly distribution per unit threshold (usd per share)	$ 1.2938
Minimum | Above $1.4063 up to $1.6875
Distribution Made to Limited Partner [Line Items]
Quarterly distribution per unit threshold (usd per share)	1.4063
Minimum | Above $1.6875
Distribution Made to Limited Partner [Line Items]
Quarterly distribution per unit threshold (usd per share)	1.6875
Maximum | Above $1.2938 up to $1.4063
Distribution Made to Limited Partner [Line Items]
Quarterly distribution per unit threshold (usd per share)	1.4063
Maximum | Above $1.4063 up to $1.6875
Distribution Made to Limited Partner [Line Items]
Quarterly distribution per unit threshold (usd per share)	$ 1.6875

Distributions and Net Income _7

Distributions and Net Income Per Limited Partner Unit (Distributions per common unit) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Distributions per common unit [Abstract]
Distributions per common unit	$ 1.8856	$ 1.8856	$ 1.8856

Partners' Equity (Incentive Dis

Partners' Equity (Incentive Distribution Rights) (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 29, 2019	Oct. 04, 2018	Aug. 04, 2014
Class of Stock [Line Items]
Partners units, maximum aggregate offering amount, ATM		$ 50,000
Affiliated Entity
Class of Stock [Line Items]
Partners' capital account, units, sold to related party	1,401,869
Limited Partner
Class of Stock [Line Items]
Number of units sold in public offering	2,940,818		12,937,500
Units sold in secondary offering price per unit	$ 21.40

Related Party Transactions (Sal

Related Party Transactions (Sales to Related Parties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Buyer deficiency fee		$ 23,835	$ 51,395
Shortfall fees			58,906
Shortfall fees recovered	$ 7,004	51,713
Affiliated Entity
Related Party Transaction [Line Items]
Net sales	$ 1,026,655	$ 1,342,910	$ 1,026,586

Related Party Transactions (Cos

Related Party Transactions (Cost of Sales from Related Parties) (Details) - Affiliated Entity - Westlake - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Total	$ 521,739	$ 936,884	$ 534,900
Feedstock Purchased
Related Party Transaction [Line Items]
Total	398,700	764,123	404,359
Other Service Charges
Related Party Transaction [Line Items]
Total	$ 123,039	$ 172,761	$ 130,541

Related Party Transactions (Ser

Related Party Transactions (Services from Related Parties Included in SG&A Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses	$ 29,751	$ 29,678	$ 31,018
Affiliated Entity | Westlake
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses	$ 27,085	$ 26,621	$ 28,577

Related Party Transactions (Goo

Related Party Transactions (Goods and Services from Related Parties that have been Capitalized) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Affiliated Entity | Westlake
Related Party Transaction [Line Items]
Goods and services purchased from Westlake and capitalized as assets	$ 3,660	$ 2,852	$ 16,318

Related Party Transactions (Rec

Related Party Transactions (Receivable under the Investment Management Agreement) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
IMA, Partnership earned amount added to market rate, basis points	five
Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake")	$ 94,444	$ 64,996
Westlake | Affiliated Entity
Related Party Transaction [Line Items]
Interest earned related to the IMA	4,424	1,875	$ 296
Westlake | Affiliated Entity | Accounts Receivable
Related Party Transaction [Line Items]
Accrued interest included in receivable under IMA	$ 1,272	$ 940

Related Party Transactions (Acc

Related Party Transactions (Accounts Receivable from and Accounts Payable to Related Parties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Shortfall fees not yet recovered		$ 7,193
Shortfall fees recovered	$ 7,004	51,713
Affiliated Entity
Related Party Transaction [Line Items]
Accounts receivable, net—Westlake	49,565	90,965
Accounts payable—third parties	$ 15,166	$ 34,087

Related Party Transactions (Deb

Related Party Transactions (Debt Payable to Related Parties) (Details) - Affiliated Entity - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Accrued interest on related party debt	$ 6,675	$ 4,733
Westlake
Related Party Transaction [Line Items]
Interest Expense	(26,501)	(13,407)	$ (8,816)
Long-term debt payable to Westlake	399,674	399,674
Westlake | Accrued Liabilities
Related Party Transaction [Line Items]
Accrued interest on related party debt	$ 6,675	$ 4,733

Related Party Transactions (Rel

Related Party Transactions (Related Party Leases) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Aug. 04, 2014
Westlake Chemical OpCo LP | Westlake | Investee | Site Lease Agreement
Related Party Transaction [Line Items]
Site lease agreement, number	2
Term of operating lease				50 years
Site lease expense	$ 1
Westlake | Affiliated Entity
Related Party Transaction [Line Items]
Operating lease expense	$ 1,869,000	$ 2,624,000	$ 3,037,000

Related Party Transactions Rela

Related Party Transactions Related Party Transactions (Major Customer and Credit Risk) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue Benchmark | Westlake | Customer Concentration Risk | Affiliated Entity
Related Party Transaction [Line Items]
Concentration Risk, Percentage	86.20%	84.30%	84.50%

Related Party Transactions (Gen

Related Party Transactions (General) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Income taxes paid	$ 827	$ 683	$ 676
Affiliated Entity | Reimbursement to Parent for State Tax | Westlake
Related Party Transaction [Line Items]
Income taxes paid	$ 347	$ 243	$ 186

Unit-based Compensation (Detail

Unit-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jul. 15, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unrecognized compensation weighted average remaining term	7 months 6 days
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of phantom units vested	$ 278
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Beginning balance	12,531	11,178
Granted	18,564	12,531
Vested	(12,531)	(11,178)
Ending balance	18,564	12,531	11,178
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Fair Value, beginning balance (usd per share)	$ 23.50	$ 22.90
Weighted Average Grant Date Fair Value, Granted (usd per share)	22.65	25.30
Weighted Average Grant Date Fair Value, Vested (usd per share)	22.18	25.42
Weighted Average Fair Value, ending balance (usd per share)	$ 21.65	$ 23.50	$ 22.90
Westlake Chemical Partners LP Long-Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units authorized				1,270,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Total units available for grant	1,198,853
Unrecognized compensation cost	$ 214
Westlake Chemical Partners LP Long-Term Incentive Plan | Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Total compensation cost	$ 349	$ 282	$ 436

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Carrying And Fair Values Of Long-Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, fair value	$ 408,110	$ 405,879
Westlake | Affiliated Entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake	$ 399,674	$ 399,674

Income Taxes (Schedule Of The P

Income Taxes (Schedule Of The Provision For (Benefit From) Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current
State and local	$ 837	$ 891	$ 561
Deferred
State and local	(24)	126	(12)
Total provision	$ 813	$ 1,017	$ 549

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Provision for federal income tax, at statutory rate	$ 70,442	$ 70,528	$ 84,406
State income tax provision, net of federal income tax effect	813	1,017	549
Partnership income not subject to entity-level federal income tax	(70,442)	(70,528)	(84,406)
Total provision	$ 813	$ 1,017	$ 549

Income Taxes (Schedule Of Defer

Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Property, plant and equipment	$ (1,402)	$ (1,438)
Turnaround costs	(230)	(218)
Total deferred tax liabilities	(1,632)	(1,656)
Noncurrent deferred tax liability	$ (1,632)	$ (1,656)

Supplemental Information (Accru

Supplemental Information (Accrued Liabilities and Other Income, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued Liabilities
Accrued and other liabilities	$ 24,980	$ 17,537
Accrued maintenance expense	5,170	3,752
Accrual related to capital expenditures	4,627	2,442
Accrued Taxes	$ 3,033	$ 2,652

Supplemental Information (Cash

Supplemental Information (Cash Flow Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Capital expenditures incurred but not yet paid	$ 7,809	$ 6,372	$ 14,415
Interest paid	24,537	10,850	8,976
Income taxes paid	827	683	676
Right-of-use assets obtained in exchange for operating lease obligations	5,079	0	0
Reimbursement to Parent for State Tax | Westlake | Affiliated Entity
Related Party Transaction [Line Items]
Income taxes paid	347	243	186
State and Local Jurisdiction
Related Party Transaction [Line Items]
Income taxes paid	$ 480	$ 440	$ 490