Westlake Chemical Partners (WLKP) 10-Q4 May 222022 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2022	Apr. 27, 2022
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
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 partnership interests
Trading Symbol	WLKP
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Units, Units Outstanding		35,214,416
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001604665

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 19,234	$ 17,057
Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake")	111,224	106,243
Accounts receivable, net—Westlake	109,732	142,791
Accounts receivable, net—third parties	26,412	5,825
Inventories	7,887	8,898
Prepaid expenses and other current assets	238	396
Total current assets	274,727	281,210
Property, plant and equipment, net	1,030,571	1,043,539
Goodwill	5,814	5,814
Deferred charges and other assets, net	143,254	150,135
Total assets	1,454,366	1,480,698
Current liabilities
Accounts payable—Westlake	34,471	10,796
Accounts payable—third parties	21,082	35,105
Accrued and other liabilities	21,391	60,895
Debt payable to Westlake	377,055	0
Total current liabilities	453,999	106,796
Long-term debt payable to Westlake	22,619	399,674
Deferred income taxes	1,516	1,530
Total liabilities	478,134	508,000
Commitments and contingencies (Note 12)
EQUITY
Total Westlake Chemical Partners LP partners' capital	293,569	293,978
Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo")	682,663	678,720
Total equity	976,232	972,698
Total liabilities and equity	1,454,366	1,480,698
Limited Partner \| Common units \| Publicly and Privately Held
EQUITY
Limited Partners' Capital Account	481,550	481,796
Total equity	481,550	481,796
Limited Partner \| Common units \| Westlake
EQUITY
Limited Partners' Capital Account	54,591	54,754
Total equity	54,591	54,754
General Partner \| Westlake
EQUITY
General partner—Westlake	(242,572)	(242,572)
Total equity	$ (242,572)	$ (242,572)

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - Common units - shares	Mar. 31, 2022	Dec. 31, 2021
Publicly and Privately Held
Units issued	21,092,186	21,092,186
Westlake
Units issued	14,122,230	14,122,230

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Net sales—Westlake	$ 290,657	$ 219,803
Net co-product, ethylene and other sales—third parties	71,743	48,404
Total net sales	362,400	268,207
Cost of sales	270,961	180,508
Gross profit	91,439	87,699
Selling, general and administrative expenses	8,227	8,673
Income from operations	83,212	79,026
Other income (expense)
Interest expense—Westlake	(2,199)	(2,236)
Other income (expense), net	(25)	7
Income before income taxes	80,988	76,797
Income tax provision	163	175
Net income	80,825	76,622
Less: Net income attributable to noncontrolling interest in OpCo	64,631	61,476
Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income	$ 16,194	$ 15,146
Net income per limited partner unit attributable to Westlake Chemical Partners LP per limited partner unit (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in units)	35,214,416	35,198,903
Common units
Other income (expense)
Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income	$ 16,194	$ 15,146
Net income per limited partner unit attributable to Westlake Chemical Partners LP per limited partner unit (basic and diluted)
Common units (in usd per share)	$ 0.46	$ 0.43
Weighted average limited partner units outstanding (basic and diluted) (in units)	35,214,416	35,198,903
Common units \| Westlake
Net income per limited partner unit attributable to Westlake Chemical Partners LP per limited partner unit (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in units)	14,122,230	14,122,230
Common units \| Publicly and Privately Held
Net income per limited partner unit attributable to Westlake Chemical Partners LP per limited partner unit (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in units)	21,092,186	21,076,673

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Noncontrolling Interest in OpCo	WestlakeGeneral Partner	Common unitsPublicly and Privately HeldLimited Partner	Common unitsWestlakeLimited Partner
Total equity at Dec. 31, 2020	$ 915,137	$ 637,738	$ (242,572)	$ 471,701	$ 48,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	76,622	61,476		9,069	6,077
Quarterly distribution to unitholders	(16,593)			(9,936)	(6,657)
Quarterly distribution to noncontrolling interest retained in OpCo by Westlake	(62,058)	(62,058)
Total equity at Mar. 31, 2021			(242,572)
Total equity at Dec. 31, 2021	972,698	678,720	(242,572)	481,796	54,754
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	80,825	64,631		9,700	6,494
Quarterly distribution to unitholders	(16,603)			(9,946)	(6,657)
Quarterly distribution to noncontrolling interest retained in OpCo by Westlake	(60,688)	(60,688)
Total equity at Mar. 31, 2022	$ 976,232	$ 682,663	$ (242,572)	$ 481,550	$ 54,591

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021
Cash flows from operating activities
Net Income	$ 80,825	$ 913,108	$ 76,622
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	31,282		27,542
Loss from disposition of property, plant and equipment	2,970		1,359
Other loss, net	992		103
Changes in operating assets and liabilities
Accounts receivable—third parties	(21,593)		(8,744)
Net accounts receivable—Westlake	56,738		60,978
Inventories	1,011		303
Prepaid expenses and other current assets	158		175
Accounts payable	(11,634)		(625)
Accrued and other liabilities	(35,358)		(699)
Other, net	(581)		(1,606)
Cash flows from investing activities	104,810		155,408
Cash flows from investing activities
Additions to property, plant and equipment	(20,342)		(12,748)
Maturities of investments with Westlake under the Investment Management Agreement	50,000		0
Investments with Westlake under the Investment Management Agreement	(55,000)		(64,000)
Other	0		126
Net cash used for investing activities	(25,342)		(76,622)
Cash flows from financing activities
Quarterly distributions to noncontrolling interest retained in OpCo by Westlake	(60,688)		(62,058)
Quarterly distributions to unitholders	(16,603)		(16,593)
Net cash used for financing activities	(77,291)		(78,651)
Net increase in cash and cash equivalents	2,177		135
Cash and cash equivalents at beginning of period	17,057	$ 17,289	17,154
Cash and cash equivalents at end of period	$ 19,234		$ 17,289

Description of Business and Bas

Description of Business and Basis of Presentation	3 Months Ended
Description of Business and Basis of Presentation	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation 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. Basis of Presentation The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of the Partnership included in the annual report on Form 10-K for the fiscal year ended December 31, 2021 (the "2021 Form 10-K"), filed with the SEC on March 2, 2022. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Partnership for the fiscal year ended December 31, 2021. References to "Westlake" refer collectively to Westlake Corporation (formerly known as Westlake Chemical Corporation) and its subsidiaries, other than the Partnership, OpCo and OpCo GP. 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. In the opinion of the Partnership's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Partnership's financial position as of March 31, 2022, its results of operations for the three months ended March 31, 2022 and 2021 and the changes in its cash position for the three months ended March 31, 2022 and 2021. Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2022 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP 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 materially from those estimates.

Accounts Receivable - Third Par

Accounts Receivable - Third Parties	3 Months Ended
Accounts Receivable - Third Parties	Mar. 31, 2022
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts Receivable - Third Parties	Accounts Receivable—Third Parties Accounts receivable—third parties consist of the following: March 31, December 31, Trade customers $ 27,468 $ 5,875 Allowance for credit losses (1,056) (50) Accounts receivable, net—third parties $ 26,412 $ 5,825

Inventories

Inventories	3 Months Ended
Inventories	Mar. 31, 2022
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: March 31, December 31, Finished products $ 6,191 $ 5,458 Feedstock, additives and chemicals 1,696 3,440 Inventories $ 7,887 $ 8,898

Property, Plant and Equipment

Property, Plant and Equipment	3 Months Ended
Property, Plant and Equipment	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Depreciation expense on property, plant and equipment of $23,996 and $22,802 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2022 and 2021, respectively.

Deferred Charges and Other Asse

Deferred Charges and Other Assets	3 Months Ended
Deferred Charges and Other Assets	Mar. 31, 2022
Other Assets, Noncurrent [Abstract]
Deferred Charges and Other Assets	Deferred Charges and Other Assets Amortization expense on other assets of $7,286 and $4,740 is included in costs of sales in the consolidated statements of operations for the three months ended March 31, 2022 and 2021, respectively.

Distributions and Net Income Pe

Distributions and Net Income Per Limited Partner Unit	3 Months Ended
Distributions and Net Income Per Limited Partner Unit	Mar. 31, 2022
Earnings Per Share [Abstract]
Distributions and Net Income Per Limited Partner Unit	Distributions and Net Income Per Limited Partner Unit On May 2, 2022, the board of directors of Westlake Chemical Partners GP LLC ("Westlake GP"), the Partnership's general partner, declared a quarterly cash distribution for the three months ended March 31, 2022 of $0.4714 per unit. This distribution is payable on May 26, 2022 to unitholders of record as of May 12, 2022. 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. Three Months Ended March 31, 2022 2021 Net income attributable to the Partnership $ 16,194 $ 15,146 Less: Limited partners' distribution declared on common units 16,600 16,593 Distribution in excess of net income $ (406) $ (1,447) 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. Three Months Ended March 31, 2022 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 16,600 $ — $ 16,600 Distribution in excess of net income (406) — (406) Net income $ 16,194 $ — $ 16,194 Weighted average units outstanding: Basic and diluted 35,214,416 35,214,416 Net income per limited partner unit: Basic and diluted $ 0.46 Three Months Ended March 31, 2021 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 16,593 $ — $ 16,593 Distribution in excess of net income (1,447) — (1,447) Net income $ 15,146 $ — $ 15,146 Weighted average units outstanding: Basic and diluted 35,198,903 35,198,903 Net income per limited partner unit: Basic and diluted $ 0.43 The amended Partnership Agreement provides that the Partnership will distribute cash 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 the three months ended March 31, 2022 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 three months ended March 31, 2022 and 2021 were as follows: Three Months Ended March 31, 2022 2021 Distributions per common unit $ 0.4714 $ 0.4714

Partners' Equity

Partners' Equity	3 Months Ended
Partners' Equity	Mar. 31, 2022
Equity [Abstract]
Partners' Equity	7. 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 for utilization under this agreement. No common units were issued under this program as of March 31, 2022. 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	3 Months Ended
Related Party Transactions	Mar. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions	8. 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: Three Months Ended March 31, 2022 2021 Net sales—Westlake $ 290,657 $ 219,803 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: Three Months Ended March 31, 2022 2021 Feedstock purchased from Westlake and included in cost of sales $ 162,279 $ 82,116 Other charges from Westlake and included in cost of sales 39,467 31,842 Total $ 201,746 $ 113,958 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: Three Months Ended March 31, 2022 2021 Services received from Westlake and included in selling, general and administrative expenses $ 6,566 $ 7,912 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: Three Months Ended March 31, 2022 2021 Goods and services purchased from Westlake and capitalized as assets $ 750 $ 403 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 a term 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 $52 and $71 was included in the receivable under the Investment Management Agreement balance at March 31, 2022 and December 31, 2021, respectively. Total interest earned related to the Investment Management Agreement was $52 and $67 for the three months ended March 31, 2022 and 2021, respectively. The Partnership's receivable under the Investment Management Agreement was as follows: March 31, December 31, Receivable under the Investment Management Agreement $ 111,224 $ 106,243 Accounts Receivable from Related Parties The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake and the buyer deficiency fee and shortfall fee recognized under the Ethylene Sales Agreement. In 2021, OpCo declared force majeure events related to the flash fire at the Petro 2 facility, OpCo's Petro 1 facility outage, and the severe winter storm. As a result of these events, the Partnership recognized revenue for a buyer deficiency fee of $51,395 and shortfall fee of $58,906 during 2021. The buyer deficiency fee was collected from Westlake in January 2022 and the shortfall fee recognized in 2021 is recoverable during 2022 per the Ethylene Sales Agreement. The Partnership's accounts receivable from Westlake were as follows: March 31, December 31, Accounts receivable—Westlake $ 109,732 $ 142,791 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: March 31, December 31, Accounts payable—Westlake $ 34,471 $ 10,796 Related Party Leases OpCo is obligated to Westlake under various long-term and short-term noncancelable operating leases, primarily related to rail car leases and land. Operating lease rentals paid to Westlake for such leases were $686 for the three months ended March 31, 2022 and 2021, and 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. Debt Payable to Related Parties See Note 9 for a description of related party debt payable balances. Interest on related party debt payable balances for the three months ended March 31, 2022 and 2021 was $2,199 and $2,236, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. At March 31, 2022 and December 31, 2021, accrued interest on related party debt was $2,213 and $2,176, respectively, and is reflected as a component of accrued liabilities in the consolidated balance sheets. Debt payable to related parties was as follows: March 31, December 31, Total debt payable to Westlake $ 399,674 $ 399,674 Major Customer and Concentration of Credit Risk

Long-term Debt Payable to Westl

Long-term Debt Payable to Westlake	3 Months Ended
Long-term Debt Payable to Westlake	Mar. 31, 2022
Related Party Transactions [Abstract]
Long-term Debt Payable to Westlake	Long-Term Debt Payable to Westlake Long-term debt payable to Westlake consists of the following: March 31, December 31, OpCo Revolver (variable interest rate of London Interbank Offered Rate ("LIBOR") plus 2.0%, scheduled maturity of September 25, 2023) $ 22,619 $ 22,619 MLP Revolver (variable interest rate of LIBOR plus 2.0%, scheduled maturity of March 19, 2023) 377,055 377,055 Total debt $ 399,674 $ 399,674 Less current debt: MLP Revolver 377,055 — Long-term debt, net of current debt $ 22,619 $ 399,674 The weighted average interest rate on all debt was 2.2% and 2.1% at March 31, 2022 and December 31, 2021, respectively. As of March 31, 2022, the Partnership was in compliance with all of the covenants under the OpCo Revolver and the MLP Revolver.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2022
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 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 debt at March 31, 2022 and December 31, 2021 are summarized in the table below. The Partnership's debt includes the OpCo Revolver and the MLP Revolver at March 31, 2022. The fair value of 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 debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's debt include the selection of an appropriate discount rate. March 31, 2022 December 31, 2021 Carrying Fair Carrying Fair OpCo Revolver $ 22,619 $ 23,135 $ 22,619 $ 23,276 MLP Revolver 377,055 381,875 377,055 383,574

Supplemental Information

Supplemental Information	3 Months Ended
Supplemental Information	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental Information Accrued and Other Liabilities Accrued and other liabilities of $21,391 and $60,895 at March 31, 2022 and December 31, 2021, respectively, primarily comprised of accrued maintenance expense, accrued turnaround costs, accrued capital expenditures and accrued taxes, which were $4,152, $4,430, $4,606 and $3,137, respectively, at March 31, 2022 and $5,597, $40,250, $7,491 and $2,264, respectively, at December 31, 2021. Non-cash Investing Activity Capital expenditure related liabilities, included in accounts payable—third parties and accrued and other liabilities, were $8,056 and $6,272 at March 31, 2022 and 2021, respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2022
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 ("RCRA"), 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. Westlake will indemnify the Partnership for liabilities that occurred or existed prior to August 4, 2014. On September 27, 2021, shortly after the turnaround on Petro 2 commenced, there was a flash fire at the quench tower of the Petro 2 facility. Several contractors working on the quench tower were injured. There are lawsuits pending in connection with the flash fire. We expect insurance to cover most of the costs associated with these lawsuits. The Partnership is also involved in other legal proceedings incidental to the conduct of its business. 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.

Description of Business and B_2

Description of Business and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of the Partnership included in the annual report on Form 10-K for the fiscal year ended December 31, 2021 (the "2021 Form 10-K"), filed with the SEC on March 2, 2022. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Partnership for the fiscal year ended December 31, 2021. References to "Westlake" refer collectively to Westlake Corporation (formerly known as Westlake Chemical Corporation) and its subsidiaries, other than the Partnership, OpCo and OpCo GP. 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. In the opinion of the Partnership's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Partnership's financial position as of March 31, 2022, its results of operations for the three months ended March 31, 2022 and 2021 and the changes in its cash position for the three months ended March 31, 2022 and 2021. Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2022 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP 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 materially from those estimates.

Accounts Receivable - Third P_2

Accounts Receivable - Third Parties (Tables)	3 Months Ended
Accounts Receivable - Third Parties (Tables)	Mar. 31, 2022
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Schedule Of Accounts Receivable - Third Parties	Accounts receivable—third parties consist of the following: March 31, December 31, Trade customers $ 27,468 $ 5,875 Allowance for credit losses (1,056) (50) Accounts receivable, net—third parties $ 26,412 $ 5,825

Inventories (Tables)

Inventories (Tables)	3 Months Ended
Inventories (Tables)	Mar. 31, 2022
Inventory Disclosure [Abstract]
Schedule Of Inventory	Inventories consist of the following: March 31, December 31, Finished products $ 6,191 $ 5,458 Feedstock, additives and chemicals 1,696 3,440 Inventories $ 7,887 $ 8,898

Distributions and Net Income _2

Distributions and Net Income Per Limited Partner Unit (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Schedule of Incentive Distributions Made to Managing Members or General Partners by Distribution	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. Three Months Ended March 31, 2022 2021 Net income attributable to the Partnership $ 16,194 $ 15,146 Less: Limited partners' distribution declared on common units 16,600 16,593 Distribution in excess of net income $ (406) $ (1,447)
Schedule of Earnings Per Share, Basic and Diluted	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. Three Months Ended March 31, 2022 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 16,600 $ — $ 16,600 Distribution in excess of net income (406) — (406) Net income $ 16,194 $ — $ 16,194 Weighted average units outstanding: Basic and diluted 35,214,416 35,214,416 Net income per limited partner unit: Basic and diluted $ 0.46 Three Months Ended March 31, 2021 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 16,593 $ — $ 16,593 Distribution in excess of net income (1,447) — (1,447) Net income $ 15,146 $ — $ 15,146 Weighted average units outstanding: Basic and diluted 35,198,903 35,198,903 Net income per limited partner unit: Basic and diluted $ 0.43
Distributions Made to Limited Partner, by Distribution [Table Text Block]	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 the three months ended March 31, 2022 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 three months ended March 31, 2022 and 2021 were as follows: Three Months Ended March 31, 2022 2021 Distributions per common unit $ 0.4714 $ 0.4714

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
Related Party Transactions (Tables)	Mar. 31, 2022
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Sales to related parties were as follows: Three Months Ended March 31, 2022 2021 Net sales—Westlake $ 290,657 $ 219,803 Charges from related parties in cost of sales were as follows: Three Months Ended March 31, 2022 2021 Feedstock purchased from Westlake and included in cost of sales $ 162,279 $ 82,116 Other charges from Westlake and included in cost of sales 39,467 31,842 Total $ 201,746 $ 113,958 Charges from related parties included within selling, general and administrative expenses were as follows: Three Months Ended March 31, 2022 2021 Services received from Westlake and included in selling, general and administrative expenses $ 6,566 $ 7,912 Charges from related parties for goods and services capitalized as assets were as follows: Three Months Ended March 31, 2022 2021 Goods and services purchased from Westlake and capitalized as assets $ 750 $ 403 The Partnership's receivable under the Investment Management Agreement was as follows: March 31, December 31, Receivable under the Investment Management Agreement $ 111,224 $ 106,243 The Partnership's accounts receivable from Westlake were as follows: March 31, December 31, Accounts receivable—Westlake $ 109,732 $ 142,791 The Partnership's accounts payable to Westlake were as follows: March 31, December 31, Accounts payable—Westlake $ 34,471 $ 10,796 Debt payable to related parties was as follows: March 31, December 31, Total debt payable to Westlake $ 399,674 $ 399,674

Long-term Debt Payable to Wes_2

Long-term Debt Payable to Westlake (Tables)	3 Months Ended
Long-term Debt Payable to Westlake (Tables)	Mar. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions, Long-term Debt	Long-term debt payable to Westlake consists of the following: March 31, December 31, OpCo Revolver (variable interest rate of London Interbank Offered Rate ("LIBOR") plus 2.0%, scheduled maturity of September 25, 2023) $ 22,619 $ 22,619 MLP Revolver (variable interest rate of LIBOR plus 2.0%, scheduled maturity of March 19, 2023) 377,055 377,055 Total debt $ 399,674 $ 399,674 Less current debt: MLP Revolver 377,055 — Long-term debt, net of current debt $ 22,619 $ 399,674

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Summary Of Carrying And Fair Values Of Long-Term Debt	These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and 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 debt at March 31, 2022 and December 31, 2021 are summarized in the table below. The Partnership's debt includes the OpCo Revolver and the MLP Revolver at March 31, 2022. The fair value of 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 debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's debt include the selection of an appropriate discount rate. March 31, 2022 December 31, 2021 Carrying Fair Carrying Fair OpCo Revolver $ 22,619 $ 23,135 $ 22,619 $ 23,276 MLP Revolver 377,055 381,875 377,055 383,574

Description of Business and B_3

Description of Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 29, 2019	Aug. 04, 2014
Limited Partner
Limited Partners' Capital Account [Line Items]
Number of units sold in public offering	2,940,818	12,937,500
Units sold in secondary offering price per unit (in dollars per share)	$ 21.40
Westlake Chemical OpCo GP LLC \| Limited Liability Company
Limited Partners' Capital Account [Line Items]
Limited partner interest		100.00%
Westlake Chemical OpCo LP \| Affiliated Entity
Limited Partners' Capital Account [Line Items]
Limited partner interest	22.80%	10.60%
Limited partner interest, additional ownership	4.50%
Amount paid to purchase additional limited partner interest	$ 201,445
Westlake Chemical OpCo LP \| Westlake \| Majority-Owned Subsidiary, Unconsolidated
Limited Partners' Capital Account [Line Items]
Limited partner interest	77.20%

Accounts Receivable - Third P_3

Accounts Receivable - Third Parties Accounts Receivable—Third Parties (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Trade customers	$ 27,468	$ 5,875
Allowance for credit losses	(1,056)	(50)
Accounts receivable, net—third parties	$ 26,412	$ 5,825

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Finished products	$ 6,191	$ 5,458
Feedstock, additives and chemicals	1,696	3,440
Inventories	$ 7,887	$ 8,898

Property, Plant and Equipment (

Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense on property, plant and equipment	$ 23,996	$ 22,802

Deferred Charges and Other As_2

Deferred Charges and Other Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Deferred Charges and Other Assets
Other Assets [Line Items]
Amortization expense	$ 7,286	$ 4,740

Distributions and Net Income _3

Distributions and Net Income Per Limited Partner Unit (Distributions Declared) (Details) - USD ($) $ / shares in Units, $ in Thousands	May 02, 2022	Mar. 31, 2022	Mar. 31, 2021
Distribution Made to Limited Partner [Line Items]
Distribution in excess of net income		$ (406)	$ (1,447)
Net income attributable to the Partnership		$ 16,194	$ 15,146
Weighted average limited partner units outstanding (basic and diluted) (in units)		35,214,416	35,198,903
Distributions declared		$ 16,600	$ 16,593
IDR Holders
Distribution Made to Limited Partner [Line Items]
Distribution in excess of net income		0	0
Net income attributable to the Partnership		0	0
Distributions declared with respect to the incentive distribution rights		0	0
Common units
Distribution Made to Limited Partner [Line Items]
Distribution in excess of net income		(406)	(1,447)
Net income attributable to the Partnership		$ 16,194	$ 15,146
Weighted average limited partner units outstanding (basic and diluted) (in units)		35,214,416	35,198,903
Distributions declared		$ 16,600	$ 16,593
Common units (in usd per share)		$ 0.46	$ 0.43
Cash Distribution \| Common units
Distribution Made to Limited Partner [Line Items]
Distributions declared		$ 16,600	$ 16,593
Cash Distribution \| Common And Subordinated Units [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share)		$ 1.2938
Cash Distribution \| Common And Subordinated Units [Member] \| Subsequent Event
Distribution Made to Limited Partner [Line Items]
Distribution declared per unit (in usd per unit)	$ 0.4714
Above $1.2938 up to $1.4063 \| Minimum
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share)		1.2938
Above $1.2938 up to $1.4063 \| Maximum
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share)		$ 1.4063
Above $1.2938 up to $1.4063 \| Unit Holders
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions		85.00%
Above $1.2938 up to $1.4063 \| IDR Holders
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions		15.00%
Above $1.4063 up to $1.6875 \| Minimum
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share)		$ 1.4063
Above $1.4063 up to $1.6875 \| Maximum
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share)		$ 1.6875
Above $1.4063 up to $1.6875 \| Unit Holders
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions		75.00%
Above $1.4063 up to $1.6875 \| IDR Holders
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions		25.00%
Above $1.6875 \| Minimum
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share)		$ 1.6875
Above $1.6875 \| Unit Holders
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions		50.00%
Above $1.6875 \| IDR Holders
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions		50.00%

Distributions and Net Income _4

Distributions and Net Income Per Limited Partner Unit (Income In Excess Of Distribution) (Details) - USD ($) $ / shares in Units, $ in Thousands	May 02, 2022	Mar. 31, 2022	Mar. 31, 2021
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership		$ 16,194	$ 15,146
Distributions declared		16,600	16,593
Distribution in excess of net income		$ (406)	$ (1,447)
Distribution Made to Limited Partner, Distributions Paid, Per Unit		$ 0.4714	$ 0.4714
IDR Holders
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership		$ 0	$ 0
Distributions declared with respect to the incentive distribution rights		0	0
Distribution in excess of net income		0	0
Common units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership		16,194	15,146
Distributions declared		16,600	16,593
Distribution in excess of net income		(406)	(1,447)
Cash Distribution \| Common units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distributions declared		$ 16,600	$ 16,593
Cash Distribution \| Common And Subordinated Units [Member] \| Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution declared per unit (in usd per unit)	$ 0.4714

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	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Limited Partners' Capital Account [Line Items]
Distributions declared	$ 16,600	$ 16,593
Distribution in excess of net income	(406)	(1,447)
Net income	$ 16,194	$ 15,146
Weighted average limited partner units outstanding (basic and diluted) (in units)	35,214,416	35,198,903
Common units
Limited Partners' Capital Account [Line Items]
Distributions declared	$ 16,600	$ 16,593
Distribution in excess of net income	(406)	(1,447)
Net income	$ 16,194	$ 15,146
Weighted average limited partner units outstanding (basic and diluted) (in units)	35,214,416	35,198,903
Weighted average units outsanding:
Common units (in usd per share)	$ 0.46	$ 0.43
IDR Holders
Limited Partners' Capital Account [Line Items]
Subsequent distribution to IDR holders	$ 0	$ 0
Distribution in excess of net income	0	0
Net income	$ 0	$ 0

Distributions and Net Income _6

Distributions and Net Income Per Limited Partner Unit (Distribution Per Common Unit) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Distribution Per Common Unit [Abstract]
Distribution Made to Limited Partner, Distributions Paid, Per Unit	$ 0.4714	$ 0.4714

Partners' Equity (Details)

Partners' Equity (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
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 (in dollars per share)	$ 21.40
Affiliated Entity
Class of Stock [Line Items]
Partners' Capital Account, Units, Sold to Related Party	1,401,869

Related Party Transactions (Sal

Related Party Transactions (Sales to Related Parties) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Revenue from Related Parties	$ 290,657	$ 219,803
Buyer deficiency fee			$ 51,395

Related Party Transactions (Cos

Related Party Transactions (Cost of Sales from Related Parties) (Details) - Affiliated Entity - Westlake - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	$ 201,746	$ 113,958
Feedstock Purchased
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	162,279	82,116
Other service charges
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	$ 39,467	$ 31,842

Related Party Transactions (Ser

Related Party Transactions (Services from Related Parties Included in SG&A Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses	$ 6,566	$ 7,912

Related Party Transactions (Goo

Related Party Transactions (Goods and Services Purchased from Westlake and Capitalized as Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Related Party Transaction [Line Items]
IMA, Partnership earned amount added to market rate, basis points	five
Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Goods and services purchased from Westlake and capitalized as assets	$ 750	$ 403

Related Party Transactions (Acc

Related Party Transactions (Accounts Receivable from and Accounts Payable to Related Parties) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Buyer deficiency fee			$ 51,395
Shortfall			58,906
Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake")	$ 111,224		106,243
Accounts payable—Westlake	34,471		10,796
Accounts receivable, net—Westlake	109,732		$ 142,791
Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Interest earned related to the IMA	$ 52	$ 67

Related Party Transactions (Gen

Related Party Transactions (General) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Buyer deficiency fee			$ 51,395
IMA, Partnership earned amount added to market rate, basis points	five
Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Interest earned related to the IMA	$ 52	$ 67
Operating lease expense	686	$ 686
Accrued Liabilities \| Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Accrued interest included in receivable under IMA	$ 52		$ 71

Related Party Transactions (Deb

Related Party Transactions (Debt Payable to Related Parties) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Interest on related party debt payable	$ 2,199	$ 2,236
Long-term debt payable to Westlake	22,619		$ 399,674
Due to Related Parties	399,674
Other income (expense) \| Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Interest on related party debt payable	2,199	$ 2,236
Accrued Liabilities \| Affiliated Entity \| Westlake
Related Party Transaction [Line Items]
Accrued interest on related party debt	$ 2,213		$ 2,176

Related Party Transactions (Sit

Related Party Transactions (Site Lease Agreements) (Details)	3 Months Ended
	Mar. 31, 2022USD ($)
Related Party Transaction [Line Items]
Site lease agreement, number	2
Site lease agreements, term (in years)	50
Site lease agreements, OpCo annual obligation to WLK	$ 1

Related Party Transactions (Maj

Related Party Transactions (Major Customer and Concentration Risk) (Details)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Affiliated Entity \| Westlake \| Revenue Benchmark \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration Risk, Percentage	80.20%	82.00%

Long-term Debt Payable to Wes_3

Long-term Debt Payable to Westlake (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Long-term debt payable to Westlake	$ 22,619	$ 399,674
Debt, Long-term and Short-term, Combined Amount	$ 399,674
Weighted average interest rate	2.20%	2.10%
Debt payable to Westlake	$ 377,055	$ 0
Limited Partner \| OpCo Revolver \| Senior Unsecured Revolving Credit Facility
Related Party Transaction [Line Items]
Long-term debt payable to Westlake	$ 22,619	22,619
Limited Partner \| OpCo Revolver \| Senior Unsecured Revolving Credit Facility \| LIBOR [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	2.00%
Limited Partner \| MLP Revolver \| Senior Unsecured Revolving Credit Facility
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 377,055
Debt payable to Westlake	$ 377,055
Limited Partner \| MLP Revolver \| Senior Unsecured Revolving Credit Facility \| LIBOR [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	2.00%

Fair Value Measurements (Summar

Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, carrying value	$ 22,619	$ 399,674
OpCo Revolver \| Senior Unsecured Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, fair value	23,135	23,276
OpCo Revolver \| Senior Unsecured Revolving Credit Facility \| Limited Partner
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, carrying value	22,619	22,619
MLP Revolver \| Senior Unsecured Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, fair value	$ 381,875	383,574
MLP Revolver \| Senior Unsecured Revolving Credit Facility \| Limited Partner
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, carrying value		$ 377,055

Supplemental Information (Detai

Supplemental Information (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Accrued Liabilities [Abstract]
Accrued and other liabilities	$ 21,391	$ 60,895
Accrued taxes	3,137	2,264
Accrued maintenance	4,152	5,597
Accrued capital expenditures	4,606	7,491
Accrued Turnaround Costs	4,430	$ 40,250
Capital Expenditures Payable and Accrued	$ 8,056		$ 6,272

Uncategorized Items - wlkp-2022

Label	Element	Value
Noncontrolling Interest [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	$ 637,156,000
Unidentified Third Parties [Member] \| Common Units [Member] \| Limited Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	470,834,000
Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] \| Common Units [Member] \| Limited Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	$ 47,690,000