Income Statement [Abstract] Statement [Table] Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Product and Service, Other [Member] Product and Service, Other [Member] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Common units [Member] Common Units [Member] Common Units [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Publicly and Privately Held [Member] Unidentified Third Parties [Member] Unidentified Third Parties [Member] Westlake [Member] Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] Parent Company and Subsidiaries, Excluding Reporting Entity and Subsidiaries [Member] Statement [Line Items] Statement [Line Items] Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted Net sales—Westlake Revenue from Related Parties Total net sales Revenues Cost of sales Cost of Goods and Services Sold Gross profit Gross Profit Selling, general and administrative expenses Selling, General and Administrative Expense Income from operations Operating Income (Loss) Other income (expense) Nonoperating Income (Expense) [Abstract] Interest expense—Westlake Interest Expense, Related Party Other income, net Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax provision (benefit) Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Less: Net income attributable to noncontrolling interest in OpCo Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Westlake Chemical Partners LP Net Income (Loss) Attributable to Parent Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted) Earnings Per Share, Basic and Diluted [Abstract] Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Affiliated Entity [Member] Affiliated Entity [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Services received from Westlake and included in selling, general and administrative expenses Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party Organization, Consolidation and Presentation of Financial Statements [Abstract] Supplemental Information Additional Financial Information Disclosure [Text Block] Earnings Per Share [Abstract] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Managing Member or General Partner [Axis] Managing Member or General Partner [Axis] Incentive Distribution, Recipient [Domain] Incentive Distribution, Recipient [Domain] IDR Holders [Member] IDR Holders [Member] Incentive Distribution Rights Holders [Member] Common units [Member] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Distributions declared Distributed Earnings Subsequent distribution to IDR holders Incentive Distribution, Subsequent Distribution Amount Amount of incentive obligation earned in cash or stock during the period by the Partnership's incentive distribution rights holders and paid after the end of the accounting period. Distribution in excess of net income Undistributed Earnings, Basic Net income Weighted average units outsanding: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Net income per limited partner unit: Accounts Receivable, after Allowance for Credit Loss [Abstract] Schedule Of Accounts Receivable - Third Parties Schedule Of Accounts And Financing Receivables [Table Text Block] Tabular disclosure of the various categories of receivables, including trade and other receivables, and for each the gross carrying value, allowance (if appropriate), and net carrying value as of the balance sheet date. Accrued Liabilities [Abstract] Accrued Liabilities [Abstract] Accrued and other liabilities Accrued Liabilities, Current Derivative trading accrual Derivative trading accrual Derivative trading accrual Accrued interest Interest Payable, Current Accrued maintenance Accrued Maintenance Costs, Current Accrued Maintenance Costs, Current Accrued Income Taxes Accrued Income Taxes Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Increase (reduction) in capital expenditure accrual Increase (Decrease) in Capital Expenditure Accrual Increase (Decrease) in Capital Expenditure Accrual Statement of Financial Position [Abstract] Units issued Limited Partners' Capital Account, Units Issued Units outstanding Limited Partners' Capital Account, Units Outstanding Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Limited Partner [Member] Limited Partner [Member] General Partner [Member] General Partner [Member] ASSETS Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Receivable under the Investment Management Agreement—Westlake Chemical Corporation (Westlake) Receivables under Investment Management Agreements with Related Parties, Current Receivables under Investment Management Agreements with Related Parties, Current Accounts receivable, net—Westlake Accounts Receivable, Related Parties, Current Accounts receivable, net—third parties Receivables, Net, Current Inventories Inventory, Net Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property, plant and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Deferred charges and other assets, net Deferred Costs and Other Assets Total assets Assets LIABILITIES Liabilities and Equity [Abstract] Current liabilities Liabilities, Current [Abstract] Accounts payable—Westlake Accounts Payable, Related Parties, Current Accounts payable—third parties Accounts Payable, Current Total current liabilities Liabilities, Current Long-term debt payable to Westlake Due to Related Parties, Noncurrent Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Operating lease liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 13) Commitments and Contingencies EQUITY Stockholders' Equity Attributable to Parent [Abstract] Limited Partners' Capital Account Limited Partners' Capital Account General partner—Westlake General Partners' Capital Account Total Westlake Chemical Partners LP partners' capital Partners' Capital Noncontrolling interest in Westlake Chemical OpCo LP (OpCo) Noncontrolling Interest in Limited Partnerships Total equity Partners' Capital, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Other Assets, Noncurrent [Abstract] Deferred Charges and Other Assets Other Assets Disclosure [Text Block] Distribution Per Common Unit [Abstract] Distribution Per Common Unit [Abstract] Distribution Made to Limited Partner, Distributions Paid, Per Unit Distribution Made to Limited Partner, Distributions Paid, Per Unit Accounts Receivable - Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Accrued Liabilities [Member] Accrued Liabilities [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other income (expense) [Member] Other Nonoperating Income (Expense) [Member] Interest on related party debt payable Interest capitalized Interest Costs Capitalized Accrued interest on related party debt Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Inventory Disclosure [Abstract] Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Goods and services purchased from Westlake and capitalized as assets Related Party Transaction Purchases From Related Party Capitalized As Assets Related Party Transaction Purchases From Related Party Capitalized As Assets Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Limited Liability Company [Member] Limited Liability Company [Member] Majority-Owned Subsidiary, Unconsolidated [Member] Majority-Owned Subsidiary, Unconsolidated [Member] Number of units sold in public offering Partners' Capital Account, Units, Sold in Public Offering Net proceeds from private placement of common units Proceeds from Issuance or Sale of Equity Units sold in secondary offering price per unit (in dollars per share) Partners' Capital Account, Units, Sold in Public Offering, Price per Unit Partners' Capital Account, Units, Sold in Public Offering, Price per Unit Limited partner interest Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Limited partner interest, additional ownership Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Additional Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Additional Ownership Interest Amount paid to purchase additional limited partner interest Payments to Acquire Limited Partnership Interests Number of ethylene production facilities Number of Production Facilities Number of Production Facilities Westlake [Member] Operating Lease, Expense Operating Lease, Expense Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Interest earned related to the IMA Interest earned related to the IMA Interest earned related to the IMA Accounts receivable—Westlake, current and non-current Accounts Receivable, Related parties, Current and Noncurrent Accounts Receivable, Related parties, Current and Noncurrent Document Documentand Entity Information [Abstract] Document - Document and Entity Information [Abstract] Document Information [Table] Document Information [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Units, Units Outstanding Entity Common Stock, Shares Outstanding Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Property, Plant and Equipment [Abstract] Depreciation expense on property, plant and equipment Depreciation Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] OpCo Revolver [Member] OpCo Revolver [Member] OpCo Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term debt payable to Westlake, carrying value Long-term debt payable to Westlake, fair value Long-term Debt, Fair Value Schedule of Incentive Distribution Made to Managing Member or General Partner [Table] Schedule of Incentive Distribution Made to Managing Member or General Partner [Table] Distribution Type [Axis] Distribution Type [Axis] Distribution Type [Domain] Distribution Type [Domain] Cash Distribution [Member] Cash Distribution [Member] Incentive Distribution Made to Managing Member or General Partner [Line Items] Incentive Distribution Made to Managing Member or General Partner [Line Items] Net income attributable to the Partnership Distributions declared with respect to the incentive distribution rights Commitments and Contingencies Disclosure [Abstract]