Turnaround costs, net Turnaround Costs, Net Turnaround Costs, Net Customer [Domain] Customer [Domain] State and local Current State and Local Tax Expense (Benefit) General partner—Westlake General Partners' Capital Account Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income Limited partners' interest in net income subsequent to IPO Net Income (Loss) Attributable to Parent Gain on Derivative Instruments, Pretax Gain on Derivative Instruments, Pretax Income Statement Location [Axis] Income Statement Location [Axis] Goodwill Goodwill Disclosure [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Balance sheet classifications Deferred Tax Assets, Net, Classification [Abstract] Net effect of cash flow hedge Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Segment Reporting Segment Reporting, Policy [Policy Text Block] Security Exchange Name Security Exchange Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Property, plant and equipment, net, before construction in progress Property, Plant and Equipment, Net Excluding Construction In-Progress Tangible assets that are held by an entity for use in the production or supply of goods and services, for rental to others, or for administrative purposes and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. Does not include construction in progress. Net income in excess of distribution (Distribution in excess of net income) Net income in excess of distribution (Distribution in excess of net income) Undistributed Earnings, Basic Interest earned related to the IMA Interest earned related to the IMA Interest earned related to the IMA Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Derivative Instruments Derivatives, Policy [Policy Text Block] Total units available for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Entity File Number Entity File Number Investee Investee [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Derivative, Nonmonetary Notional Amount, Mass Derivative, Nonmonetary Notional Amount, Mass Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Deferred Compensation Arrangement with Individual, Number of Directors That Retired in Period Deferred Compensation Arrangement with Individual, Number of Directors That Retired in Period Deferred Compensation Arrangement with Individual, Number of Directors That Retired in Period Turnaround Costs Property, Plant and Equipment, Planned Major Maintenance Activities, Policy [Policy Text Block] Net proceeds from private placement of common units Net proceeds from private placement of common units Proceeds from Issuance or Sale of Equity Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Weighted Average Grant Date Fair Value, Granted (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Amortization period, maximum (in years) Plant And Equipment Planned Major Maintenance Activities Amortization Period Maximum The maximum amortization period of planned major maintenance activities. Title of Individual [Domain] Title of Individual [Domain] 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 Receivables under Investment Management Agreements with Related Parties, Current Award Type [Domain] Award Type [Domain] Local Phone Number Local Phone Number ASSETS Assets [Abstract] Westlake Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] Parent Company and Subsidiaries, Excluding Reporting Entity and Subsidiaries [Member] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Prepaid expenses and other current assets Increase (Decrease) In Prepaid Expenses And Other Current Assets Increase (Decrease) In Prepaid Expenses And Other Current Assets Majority-Owned Subsidiary, Unconsolidated Majority-Owned Subsidiary, Unconsolidated [Member] Concentration Risk, Percentage Concentration Risk, Percentage Leverage capital ratio required during other periods Leverage Capital Ratio Required During Other Periods Represents the consolidated leverage ratio required per the debt agreement during periods other than than one-year period following certain types of acquisitions Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Quarterly distribution to noncontrolling interest retained in OpCo by Westlake Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Other gains, net Adjustments for Other Losses (Gains) to Reconcile Net Income to Cash Provided by (Used in) Operating Activities Adjustments for Other Losses (Gains) to Reconcile Net Income to Cash Provided by (Used in) Operating Activities Debt Instrument [Axis] Debt Instrument [Axis] Proceeds from debt payable to Westlake Proceeds from Related Party Debt Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Derivative Commodity Instruments Derivatives and Fair Value [Text Block] Related Party [Axis] Related Party [Axis] Number of years used to calculate average expenses Long-term Purchase Commitment, Terms of Fee, Number Of Years Used To Calculate Average Expenses Long-term Purchase Commitment, Terms of Fee, Number Of Years Used To Calculate Average Expenses Capital expenditures incurred but not yet paid Capital Expenditures Incurred but Not yet Paid Schedule Of Deferred Tax Assets And Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Vested Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Interest expense—Westlake Interest on related party debt payable Interest Expense, Related Party Distribution Type [Axis] Distribution Type [Axis] General Partner [Member] General Partner [Member] Deferred Charges and Other Assets Other Assets Disclosure [Text Block] Operating Lease, Expense Operating Lease, Expense Document Information [Line Items] Document Information [Line Items] Partnership income not subject to entity-level federal income tax Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Period of default in performance that can allow a party to terminate agreement Related Party Transaction, Counterparty Default, Period Of Default, Allowing Termination Of Agreement Related Party Transaction, Counterparty Default, Period Of Default, Allowing Termination Of Agreement Beginning balance Ending balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Quarterly distributions to unitholders Distribution Made to Limited Partner, Cash Distributions Paid Plant and equipment Machinery and Equipment, Gross Accounts receivable, net—third parties Accounts and Other Receivables, Net, Current Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Total deferred tax liabilities Deferred Tax Liabilities, Net Number of units authorized Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Property, plant and equipment Deferred Tax Liabilities, Property, Plant and Equipment Accounts receivable, net—third parties Receivables, Net, Current Entity Voluntary Filers Entity Voluntary Filers Purchase commitment, renewal term Long-term Purchase Commitment, Renewal Term Long-term Purchase Commitment, Renewal Term Plan Name [Axis] Plan Name [Axis] Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Weighted average limited partner units outstanding (basic and diluted) Weighted average units outsanding: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Exchange agreement amount of purchase agreement Purchase Commitment, Purchase Agreement, Mass Purchase Commitment, Purchase Agreement, Mass State income tax provision, net of federal income tax effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Entity Small Business Entity Small Business Total Westlake Chemical Partners LP partners' capital Partners' Capital Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Accrued Liabilities Accrued Liabilities [Abstract] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Total liabilities and equity Liabilities and Equity Long-term debt payable to Westlake Long-term debt Due to Related Parties, Noncurrent Accounts receivable - third parties Increase (Decrease) in Accounts and Other Receivables Limited partners' capital Limited Partners' Capital Account Other Assets [Abstract] Other Assets [Abstract] LIABILITIES Liabilities and Equity [Abstract] Accounts payable Increase (Decrease) in Accounts Payable Derivative [Line Items] Derivative [Line Items] Property, Plant and Equipment, Net [Abstract] Property, Plant and Equipment, Net [Abstract] Derivative Liability, Current Derivative Liability, Current Net Income Per Limited Partner Unit Earnings Per Share [Text Block] Entity Interactive Data Current Entity Interactive Data Current Additional ownership interest acquired Additional ownership interest 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 Minimum Minimum [Member] Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Affiliated Entity Affiliated Entity [Member] Gross profit Gross Profit Balance Sheet Location [Domain] Balance Sheet Location [Domain] Selling, general and administrative expenses Services received from Westlake and included in selling, general and administrative expenses Selling, General and Administrative Expense Income Tax Authority [Domain] Income Tax Authority [Domain] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Site Lease Agreement Site Lease Agreement [Member] Site Lease Agreement [Member] Derivative Asset, Current Derivative Asset, Current Entity Address, State or Province Entity Address, State or Province Environmental Costs Environmental Costs, Policy [Policy Text Block] MLP Revolver MLP Revolver [Member] MLP Revolver [Member] Units outstanding Limited Partners' Capital Account, Units Outstanding Current liabilities Liabilities, Current [Abstract] Plant and equipment Plant And Equipment [Member] Plant And Equipment [Member] Schedule Of The Provision For (Benefit From) Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Line of Credit Line of Credit [Member] Unit-Based Compensation Share-based Payment Arrangement [Text Block] Inventories Inventory Disclosure [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 Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Document Transition Report Document Transition Report Other income, net Nonoperating Income (Expense) Inventory, Net [Abstract] Inventory, Net [Abstract] Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Weighted Average Fair Value, beginning balance (usd per share) Weighted Average Fair Value, ending balance (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Customer Concentration Risk Customer Concentration Risk [Member] Limited Liability Company Limited Liability Company [Member] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Feedstock Supply Agreement Feedstock Supply Agreement [Member] Feedstock Supply Agreement [Member] Commitments and contingencies (Note 16) Commitments and Contingencies Amortization period, minimum (in years) Plant And Equipment Planned Major Maintenance Activities Amortization Period Minimum The minimum amortization period of planned major maintenance activities. Distributions [Table] Subsequent Event [Table] Schedule Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Entity Emerging Growth Company Entity Emerging Growth Company IDR Holders IDR Holders [Member] Incentive Distribution Rights Holders [Member] Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Westlake Chemical OpCo LP Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Statement of Partners' Capital [Abstract] Statement of Partners' Capital [Abstract] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Other charges from Westlake and included in cost of sales Cost Of Goods Sold, Other Cost Of Goods Sold, Other Ownership [Axis] Ownership [Axis] Above $1.2938 up to $1.4063 Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] Other receivables Nontrade Receivables, Current Westlake Chemical Partners LP Westlake Chemical Partners LP [Member] Westlake Chemical Partners LP Legal Entity [Axis] Legal Entity [Axis] Auditor Name Auditor Name Cover [Abstract] Cover [Abstract] Incentive Distribution, Recipient [Domain] Incentive Distribution, Recipient [Domain] Accrual related to capital expenditures Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Class of Stock [Axis] Class of Stock [Axis] Accrued turnaround costs Accrued Turnaround Costs, Current Accrued Turnaround Costs, Current Cash And Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Distribution Type [Domain] Distribution Type [Domain] Partners' Capital Account, Units, Sold in Public Offering, Price per Unit Partners' Capital Account, Units, Sold in Public Offering, Price per Unit Partners' Capital Account, Units, Sold in Public Offering, Price per Unit Income Tax Authority [Axis] Income Tax Authority [Axis] Accounts receivable, net—Westlake Accounts receivable, net—Westlake Accounts Receivable, Related Parties, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Net sales - Westlake Revenue from Related Parties Selling, General and Administrative Expenses Selling, General and Administrative Expenses [Member] Entity [Domain] Entity [Domain] Accrued and other liabilities Accrued Liabilities, Current Revenue from Contract with Customer, Excluding Assessed Tax Revenue from Contract with Customer, Excluding Assessed Tax Ethylene Sales Agreement Ethylene Sales Agreement [Member] Ethylene Sales Agreement [Member] Accounts Receivable—Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Document Information [Table] Document Information [Table] Equity [Abstract] Equity [Abstract] Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Variable Rate [Axis] Variable Rate [Axis] Income from operations Operating Income (Loss) Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Document Fiscal Year Focus Document Fiscal Year Focus Variable Rate [Domain] Variable Rate [Domain] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Depreciation expense Depreciation Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Accrued and other liabilities Increase (Decrease) in Accrued Liabilities Related party transactions, term of agreements Related Party Transaction, Term Of Agreement Related Party Transaction, Term Of Agreement Income taxes paid Income Taxes Paid Maximum mass required to be purchased Long-term Purchase Commitment, Maximum Volume Required Long-term Purchase Commitment, Maximum Volume Required Description Of Business Description Of Business [Policy Text Block] Description Of Business [Policy Text Block] Other Assets Other Assets [Member] Buyer deficiency fee Buyer deficiency fee Buyer deficiency fee Long-term debt, fair value Long-term Debt, Fair Value Above $1.4063 up to $1.6875 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Granted Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted Reimbursement to Parent for State Tax Reimbursement to Parent for State Tax [Member] Reimbursement to Parent for State Tax [Member] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment Maximum Maximum [Member] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Total liabilities Liabilities Award Type [Axis] Award Type [Axis] Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Turnaround costs Deferred Tax Liabilities, Deferred Expense, Other Capitalized Costs City Area Code City Area Code Managing Member or General Partner [Axis] Managing Member or General Partner [Axis] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Term of sales agreement Long-term Purchase Commitment, Period Entity Address, City or Town Entity Address, City or Town Capitalized interest Interest capitalized Interest Costs Capitalized Property, plant and equipment, useful life (in years) Property, Plant and Equipment, Useful Life EQUITY Stockholders' Equity Attributable to Parent [Abstract] Other Noncurrent Assets, Other, Net Noncurrent Assets, Other, Net Concentration Of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Accrued Liabilities Accrued Liabilities [Member] Westlake Chemical OpCo GP LLC Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Term of operating lease Lessee, Operating Lease, Term of Contract Entity Filer Category Entity Filer Category 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 Production Facilities Number of Production Facilities Number of Production Facilities Other Cash Provided by (Used in) Investing Activities, Other Cash Provided by (Used in) Investing Activities, Other Income Statement [Abstract] Income Statement [Abstract] Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Entity Registrant Name Entity Registrant Name Partner Type [Axis] Partner Type [Axis] Related Party Transaction [Axis] Related Party Transaction [Axis] Provision for income taxes Total provision Income Tax Expense (Benefit) Amendment Flag Amendment Flag Equity Components [Axis] Equity Components [Axis] Senior Unsecured Revolving Credit Facility Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Entity Tax Identification Number Entity Tax Identification Number Excess Production Option Excess Production Option [Member] Excess Production Option [Member] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Total current assets Assets, Current Above $1.6875 Cash Distribution, Tranche Three [Member] Cash Distribution, Tranche Three [Member] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Organization Consolidation And Presentation Of Financial Statements [Line Items] Organization Consolidation And Presentation Of Financial Statements [Line Items] Organization consolidation and presentation of financial statements [Line Items]. Inventories Inventories Inventory, Net Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Partners' Equity Schedule of Stockholders Equity [Table Text Block] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Ethylene pipeline Ethylene Pipeline [Member] Ethylene Pipeline [Member] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Westlake Chemical Partners LP Long-Term Incentive Plan Westlake Chemical Partners LP Long-Term Incentive Plan [Member] Westlake Chemical Partners LP Long-Term Incentive Plan [Member] Distributions per common unit [Abstract] Distributions per common unit [Abstract] Distributions per common unit [Abstract] Supplemental Information Other Income and Other Expense Disclosure [Text Block] Purchase commitment, fixed margin on variable pricing Long-term Purchase Commitment, Exchange Fee, Fixed Margin Long-term Purchase Commitment, Exchange Fee, Fixed Margin Entity Public Float Entity Public Float Unrecognized compensation cost Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Revenue Benchmark Revenue Benchmark [Member] Schedule Of Estimated Useful Lives Of Assets Schedule Of Estimated Useful Lives Of Assets [Table Text Block] Table of estimated useful lives of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Equity Component [Domain] Equity Component [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Statement [Line Items] Statement [Line Items] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Loss from disposition of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Services And Secondment Agreement Services And Secondment Agreement [Member] Services And Secondment Agreement [Member] Shortfall fees Shortfall fees Shortfall fees Rate used to discount future cash flows for goodwill impairment test Discounted Cash Flow Methodology, Goodwill Impairment, Discount Rate The discount rate percentage utilized when developing discounted cash flow projections in determining projected future cash flows as they relate to goodwill impairment. Counterparty Name [Domain] Counterparty Name [Domain] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Property, plant and equipment, gross Property, Plant and Equipment, Gross Excluding Construction In-Progress Gross amount, at the balance sheet date, of long-lived physical assets used in the normal conduct of business and not intended for resale. This can include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. Does not include construction in progress. Threshold period past due accounts receivable reviewed Threshold Period Past Due Accounts Receivable Reviewed Threshold Period Past Due Accounts Receivable Reviewed Related Party Transactions (Related Party Leases) [Abstract] Related Party Transactions (Related Party Leases) [Abstract] Related Party Transactions (Related Party Leases) [Abstract] Allowance For Doubtful Accounts Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Other Other Capitalized Property Plant and Equipment [Member] Property, Plant and Equipment by Type [Axis] Long-Lived Tangible Asset [Axis] Auditor Location Auditor Location Total equity Equity, beginning balance Equity, ending balance Partners' Capital, Including Portion Attributable to Noncontrolling Interest Accounts payable—Westlake Accounts Payable, Related Parties, Current Auditor [Abstract] Auditor [Abstract] Customer [Axis] Customer [Axis] Distribution declared per unit (usd per share) Distribution Made to Limited Partner, Distributions Declared, Per Unit Use Of Estimates Use of Estimates, Policy [Policy Text Block] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Feedstock purchased from Westlake and included in cost of sales Related Parties Amount In Cost Of Sales, Feedstock Purchased Related Parties Amount In Cost Of Sales, Feedstock Purchased Transportation and Freight Shipping and Handling Cost, Policy [Policy Text Block] Document Annual Report Document Annual Report Accrued maintenance expense Accrued Maintenance Expense, Current Accrued Maintenance Expense, Current Title of 12(b) Security Title of 12(b) Security Total assets Assets Amount paid to purchase additional limited partner interest Payments to Acquire Limited Partnership Interests Plan Name [Domain] Plan Name [Domain] Director Director [Member] Quarterly distributions to noncontrolling interest retained in OpCo by Westlake Payments to Noncontrolling Interests Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Quarterly distribution per unit threshold (usd per share) Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold Subordinated unit conversion Conversion of Units, Amount Conversion of Units, Amount Title of Individual [Axis] Title of Individual [Axis] Document Type Document Type Schedule of Nonvested Restricted Stock Units Activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Noncontrolling Interest in OpCo [Member] Noncontrolling Interest [Member] Total Related Parties Amount in Cost of Sales Schedule Of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Related Party Transactions (Major Customer and Credit Risk) [Abstract] Related Party Transactions (Major Customer and Credit Risk) [Abstract] Related Party Transactions (Major Customer and Credit Risk) [Abstract] Less: Net income attributable to noncontrolling interest in OpCo Net Income (Loss) Attributable to Noncontrolling Interest Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Distributions [Line Items] Subsequent Event [Line Items] Deferred charges and other assets, net Total deferred charges and other assets Deferred Costs and Other Assets Minimum quarterly distribution per unit (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 State and Local Jurisdiction State and Local Jurisdiction [Member] Weighted average interest rate on all long-term debt Long-term Debt, Weighted Average Interest Rate, at Point in Time Sales [Member] Sales [Member] Site lease agreement, number Site lease agreement, number Site lease agreement, number Term of Investment Management Agreement with Related Party, Maximum Term of Investment Management Agreement with Related Party, Maximum Term of Investment Management Agreement with Related Party, Maximum Net cash used for financing activities Net Cash Provided by (Used in) Financing Activities Deferred Income Tax Liabilities, Net Noncurrent deferred tax liability Deferred Income Tax Liabilities, Net Related Party Transaction [Line Items] Related Party Transaction [Line Items] Partnership's ownership interest (percent) Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Organization, Consolidation, And Presentation Of Financial Statements [Table] Organization, Consolidation, And Presentation Of Financial Statements [Table] Organization, Consolidation, And Presentation Of Financial Statements [Table] Other Property, Plant and Equipment, Other, Gross Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Common units Common Units [Member] Common Units [Member] Accounts payable—third parties Accounts Payable, Current Concentration Risk Type [Axis] Concentration Risk Type [Axis] Depreciation and amortization Depreciation, Depletion and Amortization Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] Inventories Increase (Decrease) in Inventories Agreements with Westlake and Related Parties Agreements with Westlake and Related Parties [Text Block] Agreements with Westlake and Related Parties [Text Block] Derivative [Table] Derivative [Table] 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 Cost of sales Cost of Goods and Services Sold Document Period End Date Document Period End Date Entity Central Index Key Entity Central Index Key Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] State and local Deferred State and Local Income Tax Expense (Benefit) Schedule Of Property, Plant And Equipment Property, Plant and Equipment [Table Text Block] Income Statement Location [Domain] Income Statement Location [Domain] Derivative, Nonmonetary Notional Amount, Volume Derivative, Nonmonetary Notional Amount, Volume Accounts Receivable, after Allowance for Credit Loss [Abstract] Accounts Receivable, after Allowance for Credit Loss [Abstract] Property, plant and equipment, net Property, plant and equipment, net Property, Plant and Equipment, Net Property, Plant And Equipment Property, Plant and Equipment Disclosure [Text Block] Other liabilities Other Liabilities, Noncurrent Schedule Of Long-Term Debt Schedule of Long-term Debt Instruments [Table Text Block] Trading Symbol Trading Symbol Earnings Per Share [Abstract] Earnings Per Share [Abstract] Repayment of debt payable to Westlake Repayments of Related Party Debt Long-term Purchase Commitment, Compliance Surcharge Amount Long-term Purchase Commitment, Compliance Surcharge Amount Long-term Purchase Commitment, Compliance Surcharge Related Party Transaction [Domain] Related Party Transaction [Domain] Total net sales Revenues Limited partners' distribution declared on common units Distribution Distributed Earnings Finished products Inventory, Finished Goods, Gross Impairment Of Long-Lived Assets and Intangible Assets Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block] Goodwill, Gross Goodwill, Gross Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Units issued for vested phantom units Stock Issued During Period, Value, Other Total compensation cost Share-based Payment Arrangement, Expense Entity Current Reporting Status Entity Current Reporting Status Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering per limited partner unit (basic and diluted) Earnings Per Share, Basic and Diluted [Abstract] Distributions declared with respect to the incentive distribution rights 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. Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Trade customers Accounts Receivable, before Allowance for Credit Loss, Current Counterparty Name [Axis] Counterparty Name [Axis] Minimum percentage required to be purchased Long-term Purchase Commitment, Minimum Percentage Required Long-term Purchase Commitment, Minimum Percentage Required Cash and cash equivalents at beginning of the year Cash and cash equivalents at end of the year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Current assets Assets, Current [Abstract] Income Taxes Income Tax, Policy [Policy Text Block] Units issued Limited Partners' Capital Account, Units Issued Publicly and Privately Held Unidentified Third Parties [Member] Unidentified Third Parties [Member] LIBOR London Interbank Offered Rate (LIBOR) [Member] Other assets amortization period Finite-Lived Intangible Assets, Remaining Amortization Period Entity Address, Postal Zip Code Entity Address, Postal Zip Code Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Net accounts receivable - Westlake Increase (Decrease) in Accounts Receivable, Related Parties Amortization Amortization Income Taxes Income Tax Disclosure [Text Block] Accrued interest on related party debt Interest Payable, Current Number of lease agreements Lessee Leasing Arrangements, Operating Leases, Number Lessee Leasing Arrangement, Operating Leases, Number Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Related Party [Domain] Related Party [Domain] Loss on Derivative Instruments, Pretax Loss on Derivative Instruments, Pretax Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Partners' Equity [Abstract] Partners' Equity [Abstract] Partners' Equity [Abstract] Unitholders Unit Holders [Member] Unit Holders [Member] Maximum consolidated leverage ratio during one year following acquisitions Maximum Consolidated Leverage Ratio During One Year Following Acquisitions Represents the consolidated leverage ratio required per the debt agreement during any one-year period following certain acquisitions. Number of units sold in public offering Partners' Capital Account, Units, Sold in Public Offering Weighted Average Number of Shares Outstanding, Basic and Diluted Basic and diluted (units) Weighted Average Number of Shares Outstanding, Basic and Diluted Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Other income (expense) Nonoperating Income (Expense) [Abstract] Auditor Firm ID Auditor Firm ID Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo") Noncontrolling Interest in Limited Partnerships Class of Stock [Line Items] Class of Stock [Line Items] Feedstock, additives and chemicals Inventory, Work in Process and Raw Materials Entity Address, Address Line One Entity Address, Address Line One Net cash used for investing activities Net Cash Provided by (Used in) Investing Activities Entity Address, Address Line Two Entity Address, Address Line Two Buildings and improvements Building and Building Improvements [Member] Changes in operating assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Subordinated units Subordinated Units [Member] Subordinated Units [Member] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Weighted Average Grant Date Fair Value, Vested (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Entity Shell Company Entity Shell Company Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Business Description and Accounting Policies Business Description and Accounting Policies [Text Block] Total current liabilities Liabilities, Current Class of Stock [Domain] Class of Stock [Domain] Limited Partner Westlake Limited Partner [Member] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Ownership [Domain] Ownership [Domain] Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Current Fiscal Year End Date Current Fiscal Year End Date Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Building and improvements Buildings and Improvements, Gross Cash Distribution Cash Distribution [Member] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Statement [Table] Statement [Table] Site lease expense Site lease expense Site lease expense Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Recent Accounting Pronouncements and Recently Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Statistical Measurement [Axis] Statistical Measurement [Axis] Long-Term Debt Related Party Transactions, Long-term Debt [Text Block] Related Party Transactions, Long-term Debt [Text Block] Provision for federal income tax, at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Subsequent Event Subsequent Event [Member] Common and Subordinated units Common And Subordinated Units [Member] Common And Subordinated Units [Member] Schedule of Other Assets Schedule of Other Assets [Table Text Block] Quarterly distribution to unitholders Limited Partners' Capital Account, Distribution Amount Goodwill Goodwill OpCo Revolver OpCo Revolver [Member] OpCo Revolver [Member] Cost of Sales [Member] Cost of Sales [Member] Construction in progress Construction in Progress, Gross Distributions per common unit Distribution Made to Limited Partner, Distributions Paid, Per Unit Inventories Inventory, Policy [Policy Text Block] Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM 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] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Phantom Share Units (PSUs) Phantom Share Units (PSUs) [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Related Party Transactions Related Party Transactions Disclosure [Text Block] Operating lease, rental amount Operating Leases, Rent Expense Westlake Chemical Corporation Westlake Chemical Corporation [Member] Westlake Chemical Corporation Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table]