Affiliated Entity Affiliated Entity [Member] Document Type Document Type Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Westlake Chemical OpCo GP LLC Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Related Party [Axis] Related Party [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Cost of sales Cost of Goods and Services Sold Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Net proceeds from private placement of common units Proceeds from Issuance or Sale of Equity Feedstock Purchased Feedstock Purchased [Member] Feedstock Purchased [Member] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Equity Components [Axis] Equity Components [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Minimum Minimum [Member] Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Balance Sheet Location [Domain] Balance Sheet Location [Domain] 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. IMA, Partnership earned amount added to market rate, basis points IMA, Partnership earned amount added to market rate, basis points IMA, Partnership earned amount added to market rate, basis points Number of ethylene production facilities Number of Production Facilities Number of Production Facilities Basis points above market rate for IMA Basis points above market rate for IMA Basis points above market rate for IMA Other Cash Provided by (Used in) Investing Activities, Other Cash Provided by (Used in) Investing Activities, Other Limited Partner Limited Partner [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] LIABILITIES Liabilities and Equity [Abstract] Less: Net income attributable to noncontrolling interest in OpCo Net Income (Loss) Attributable to Noncontrolling Interest Risks and Uncertainties [Abstract] Risks and Uncertainties [Abstract] Quarterly distribution to noncontrolling interest retained in OpCo by Westlake Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Deferred income taxes Deferred Income Tax Liabilities, Net Accrued taxes Accrued Income Taxes Entity Interactive Data Current Entity Interactive Data Current Interest earned related to the IMA Interest earned related to the IMA Interest earned related to the IMA Security Exchange Name Security Exchange Name Fair Value Measurements Fair Value Disclosures [Text Block] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Partners' Equity Stockholders' Equity Note Disclosure [Text Block] Accounts receivable—third parties Increase (Decrease) in Accounts and Other Receivables Income from operations Operating Income (Loss) Customer [Domain] Customer [Domain] Total current liabilities Liabilities, Current Entity Registrant Name Entity Registrant Name Senior Unsecured Revolving Credit Facility Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Concentration Risk [Line Items] Concentration Risk [Line Items] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Variable Rate [Domain] Variable Rate [Domain] Above $1.6875 Cash Distribution, Tranche Three [Member] Cash Distribution, Tranche Three [Member] Variable Rate [Axis] Variable Rate [Axis] Commitments and contingencies (Note 12) Commitments and Contingencies ASSETS Assets [Abstract] Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Entity Address, State or Province Entity Address, State or Province Accounts payable—third parties Accounts Payable, Current Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Incentive Distribution Made to Managing Member or General Partner [Line Items] Incentive Distribution Made to Managing Member or General Partner [Line Items] Accrued Liabilities Accrued Liabilities [Member] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Site lease agreements, term (in years) Site lease agreements, term (in years) Site lease agreements, term (in years) Deferred Charges and Other Assets Other Assets Disclosure [Text Block] Accounts receivable, net—third parties Accounts Receivable, after Allowance for Credit Loss, Current Finished products Inventory, Finished Goods, Gross Loss from disposition of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property 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 Deferred charges and other assets, net Deferred Costs and Other Assets Entity Address, Postal Zip Code Entity Address, Postal Zip Code Westlake Westlake Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] Parent Company and Subsidiaries, Excluding Reporting Entity and Subsidiaries [Member] Customer [Axis] Customer [Axis] Prepaid expenses and other current assets Increase (Decrease) In Prepaid Expenses And Other Current Assets Increase (Decrease) In Prepaid Expenses And Other Current Assets Goodwill Goodwill Document Transition Report Document Transition Report Other liabilities Other Liabilities, Noncurrent General Partner General Partner [Member] Other income (expense) Nonoperating Income (Expense) [Abstract] Document Information [Table] Document Information [Table] Document Quarterly Report Document Quarterly Report Inventories Inventories Inventory, Net 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 Equity [Abstract] Equity [Abstract] Concentration Risk, Percentage Concentration Risk, Percentage Supplemental Information Additional Financial Information Disclosure [Text Block] Limited Liability Company Limited Liability Company [Member] Customer Concentration Risk Customer Concentration Risk [Member] Statement [Line Items] Statement [Line Items] Class of Stock [Domain] Class of Stock [Domain] Weighted average interest rate Long-term Debt, Weighted Average Interest Rate, at Point in Time Net income per limited partner unit attributable to Westlake Chemical Partners LP per limited partner unit (basic and diluted) Net income per limited partner unit: Earnings Per Share, Basic and Diluted [Abstract] Accounts Receivable - Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Entity File Number Entity File Number Accrued interest on related party debt Interest Payable, Current Other service charges Other Service Charges [Member] Other Service Charges [Member] Statement [Table] Statement [Table] Statistical Measurement [Axis] Statistical Measurement [Axis] Schedule of Incentive Distributions Made to Managing Members or General Partners by Distribution Schedule of Distributions [Table Text Block] Schedule of Distributions [Table Text Block] Net cash used for financing activities Net Cash Provided by (Used in) Financing Activities Balance Sheet Location [Axis] Balance Sheet Location [Axis] Weighted average units outsanding: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Counterparty Name [Axis] Counterparty Name [Axis] Earnings Per Share, Basic and Diluted Earnings Per Share, Basic and Diluted Distribution Type [Axis] Distribution Type [Axis] Document Fiscal Year Focus Document Fiscal Year Focus Entity Small Business Entity Small Business Distribution Type [Domain] Distribution Type [Domain] Majority-Owned Subsidiary, Unconsolidated Majority-Owned Subsidiary, Unconsolidated [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo") Noncontrolling Interest in Limited Partnerships Entity Current Reporting Status Entity Current Reporting Status Common units (in usd per share) Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Feedstock, additives and chemicals Inventory, Work in Process and Raw Materials Related Party Transaction [Axis] Related Party Transaction [Axis] Amendment Flag Amendment Flag Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders (in usd per share) Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders Charges from related parties in cost of sales Related Parties Amount in Cost of Sales Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Other Assets [Line Items] Other Assets [Line Items] Other Assets [Line Items] Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Repayments of debt Repayments of Debt Site lease agreement, number Site lease agreement, number Site lease agreement, number Cash flows from investing activities Net Cash Provided by (Used in) Operating Activities Entity Central Index Key Entity Central Index Key Related Party [Domain] Related Party [Domain] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Number of units sold in public offering Partners' Capital Account, Units, Sold in Public Offering Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Amount paid to purchase additional limited partner interest Payments to Acquire Limited Partnership Interests Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Total liabilities and equity Liabilities and Equity Statement of Partners' Capital [Abstract] Statement of Partners' Capital [Abstract] Entity Address, City or Town Entity Address, City or Town Net income in excess of distribution (distribution in excess of net income) Undistributed Earnings, Basic Other Assets, Noncurrent [Abstract] Other Assets, Noncurrent [Abstract] Common units Common units Common Units [Member] Common Units [Member] Accounts receivable—Westlake, current and non-current Accounts Receivable, Related parties, Current and Noncurrent Accounts Receivable, Related parties, Current and Noncurrent Deferred Charges and Other Assets Other Assets [Member] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Total equity Total equity Total equity Partners' Capital, Including Portion Attributable to Noncontrolling Interest Buyer deficiency fee and shortfall Buyer Deficiency Fee and Shortfall Buyer Deficiency Fee and Shortfall Other gains, net Other Noncash Income (Expense) Accrued maintenance Accrued Maintenance Costs, Current Accrued Maintenance Costs, Current Equity Component [Domain] Equity Component [Domain] Income Statement Location [Axis] Income Statement Location [Axis] Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Entity Common Units, Units Outstanding Entity Common Stock, Shares Outstanding Income Statement Location [Domain] Income Statement Location [Domain] 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 Maturities of investments with Westlake under the Investment Management Agreement Maturities of investments with Westlake under the Investment Management Agreement Maturities of investments with Westlake under the Investment Management Agreement Gross profit Gross Profit Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Property, plant and equipment, net Property, Plant and Equipment, Net Selling, general and administrative expenses Selling, General and Administrative Expense Entity Tax Identification Number Entity Tax Identification Number Trade Customer Receivable Net Current Trade Customer Receivable Net Current Trade Customer Receivable Net Current Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income Net income attributable to the Partnership Net income Net Income (Loss) Attributable to Parent Limited partner interest Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Changes in operating assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Quarterly distributions to noncontrolling interest retained in OpCo by Westlake Payments to Noncontrolling Interests LIBOR [Member] London Interbank Offered Rate (LIBOR) [Member] Inventories Inventory Disclosure [Text Block] Accounts receivable, net—third parties Receivables, Net, Current Accounts payable—Westlake Accounts Payable, Related Parties, Current Concentration Risk [Table] Concentration Risk [Table] Total assets Assets Accrued Liabilities [Abstract] Accrued Liabilities [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Total current assets Assets, Current Current Fiscal Year End Date Current Fiscal Year End Date Managing Member or General Partner [Axis] Managing Member or General Partner [Axis] Incentive Distribution, Recipient [Domain] Incentive Distribution, Recipient [Domain] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Title of 12(b) Security Title of 12(b) Security Distribution Made to Limited Partner, Distributions Paid, Per Unit Distribution Made to Limited Partner, Distributions Paid, Per Unit Quarterly distribution to unitholders Limited Partners' Capital Account, Distribution Amount MLP Revolver MLP Revolver [Member] MLP Revolver [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] EQUITY Stockholders' Equity Attributable to Parent [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Depreciation and amortization Depreciation, Depletion and Amortization Product and Service [Axis] Product and Service [Axis] Total liabilities Liabilities Cash Distribution Cash Distribution [Member] Other receivables Other Receivables, Net, Current Weighted average limited partner units outstanding (basic and diluted) (in units) Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted 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 Entity Filer Category Entity Filer Category Product and Service [Domain] Product and Service [Domain] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Operating lease expense Operating Lease, Expense Distributions declared Distributed Earnings Inventories Increase (Decrease) in Inventories IDR Holders IDR Holders [Member] Incentive Distribution Rights Holders [Member] Increase (reduction) in capital expenditure accrual Increase (Decrease) in Capital Expenditure Accrual Increase (Decrease) in Capital Expenditure Accrual Accounts payable Increase (Decrease) in Accounts Payable Westlake Chemical OpCo LP Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Distributions declared with respect to the incentive distribution rights 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. Revenue Benchmark Revenue Benchmark [Member] Other income (expense) Other Nonoperating Income (Expense) [Member] Debt Instrument [Axis] Debt Instrument [Axis] Partner Type [Axis] Partner Type [Axis] Above $1.2938 up to $1.4063 Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] 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 Per Common Unit [Abstract] Distribution Per Common Unit [Abstract] Distribution Per Common Unit [Abstract] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Class of Stock [Line Items] Class of Stock [Line Items] Accrued and other liabilities Increase (Decrease) in Accrued Liabilities Accrued capital expenditures Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Adjustments to reconcile net income to net cash provided by operating activities Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Net co-product, ethylene and other sales—third parties Product and Service, Other [Member] Trade customers Accounts Receivable, before Allowance for Credit Loss, Current Total Westlake Chemical Partners LP partners' capital Partners' Capital Units outstanding Limited Partners' Capital Account, Units Outstanding Related Party Transactions [Abstract] Related Party Transactions [Abstract] Net increase in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Other income, net Nonoperating Income (Expense) 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 Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Publicly and Privately Held Unidentified Third Parties [Member] Unidentified Third Parties [Member] Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Distribution declared per unit (in usd per unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Distributions Made to Limited Partner, by Distribution [Table Text Block] Distributions Made to Limited Partner, by Distribution [Table Text Block] Ownership [Axis] Ownership [Axis] Document Information [Line Items] Document Information [Line Items] Subsequent Event Subsequent Event [Member] Ownership [Domain] Ownership [Domain] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Site lease agreements, OpCo annual obligation to WLK Site lease agreements, OpCo annual obligation to WLK Site lease agreements, OpCo annual obligation to WLK Limited Partners' Capital Account Limited Partners' Capital Account Unit Holders Unit Holders [Member] Unit Holders [Member] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Long-term debt payable to Westlake, fair value Long-term Debt, Fair Value Total net sales Revenues Class of Stock [Axis] Class of Stock [Axis] Income tax provision Income Tax Expense (Benefit) Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Income Statement [Abstract] Income Statement [Abstract] Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Quarterly distributions to unitholders Distribution Made to Limited Partner, Cash Distributions Paid Accrued and other liabilities Accrued Liabilities, Current Local Phone Number Local Phone Number Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Current assets Assets, Current [Abstract] Amortization expense Amortization Depreciation expense on property, plant and equipment Depreciation Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Long-term debt payable to Westlake Long-term debt payable to Westlake, carrying value Due to Related Parties, Noncurrent Related Party Transaction [Domain] Related Party Transaction [Domain] Entity Emerging Growth Company Entity Emerging Growth Company Alternate Base Rate [Domain] Alternate Base Rate [Domain] Alternate Base Rate [Domain] Legal Entity [Axis] Legal Entity [Axis] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment Counterparty Name [Domain] Counterparty Name [Domain] City Area Code City Area Code Buyer deficiency fee Buyer deficiency fee Buyer deficiency fee Maximum Maximum [Member] Above $1.4063 up to $1.6875 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Units issued Limited Partners' Capital Account, Units Issued Noncontrolling Interest in OpCo Noncontrolling Interest [Member] Document Period End Date Document Period End Date Interest expense—Westlake Interest on related party debt payable Interest Expense, Related Party Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Net cash used for investing activities Net Cash Provided by (Used in) Investing Activities Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Long-term Debt Payable to Westlake Related Party Transactions, Long-term Debt [Text Block] Related Party Transactions, Long-term Debt [Text Block] Accounts receivable, net—Westlake Accounts Receivable, Related Parties, Current Common And Subordinated Units [Member] Common And Subordinated Units [Member] Common And Subordinated Units [Member] Net accounts receivable—Westlake Increase (Decrease) in Accounts Receivable, Related Parties Trading Symbol Trading Symbol Related Party Transactions, Long-term Debt Related Party Transactions, Long-term Debt [Table Text Block] Related Party Transactions, Long-term Debt [Table Text Block] Net sales—Westlake Revenue from Related Parties Revenue from Related Parties OpCo Revolver OpCo Revolver [Member] OpCo Revolver [Member] Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] General partner—Westlake General Partners' Capital Account Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Entity [Domain] Entity [Domain] Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Distributions and Net Income Per Limited Partner Unit Earnings Per Share [Text Block] Cover [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Current liabilities Liabilities, Current [Abstract] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Entity Shell Company Entity Shell Company Accounts Receivable, after Allowance for Credit Loss [Abstract] Accounts Receivable, after Allowance for Credit Loss [Abstract] Stock Issued During Period, Value, Other Stock Issued During Period, Value, Other Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract]