Turnaround Costs, Net Turnaround Costs, Net Turnaround Costs, Net Document Type Document Type ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Related Party [Axis] Related Party [Axis] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Net effect of cash flow hedge Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax 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 Discounted cash flow projections period Discounted Cash Flow Methodology, Asset Impairment, Number Of Years Forecasted The number of forecast years utilized in developing discounted cash flow projections in determining asset impairment. Limited Partner [Member] Westlake [Member] Limited Partner [Member] 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. Statistical Measurement [Domain] Statistical Measurement [Domain] LIABILITIES Liabilities and Equity [Abstract] Line of Credit [Member] Line of Credit [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Quarterly distribution to noncontrolling interest retained in OpCo by Westlake Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Deferred Income Tax Liabilities, Net Deferred Income Tax Liabilities, Net Deferred Income Tax Liabilities, Net Interest earned related to the IMA Interest earned related to the IMA Interest earned related to the IMA Security Exchange Name Security Exchange Name Loss on Derivative Instruments, Pretax Loss on Derivative Instruments, Pretax Accounts receivable - third parties Increase (Decrease) in Accounts and Other Receivables Income from operations Income from operations Operating Income (Loss) Total current liabilities Liabilities, Current Impairment Of Long-Lived Assets and Intangible Assets Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current 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 Variable Rate [Domain] Variable Rate [Domain] Variable Rate [Axis] Variable Rate [Axis] Commitments and contingencies (Note 17) Commitments and Contingencies ASSETS Assets [Abstract] Investment, Name [Axis] Investment, Name [Axis] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] 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 Entity Address, State or Province Entity Address, State or Province Provision for federal income tax, at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Accounts payable—third parties Accounts Payable, Current Above $1.4063 up to $1.6875 Cash Distribution, Tranche Two [Domain] Cash Distribution, Tranche Two [Domain] Derivative Asset, Current Derivative Asset, Current Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Deferred Charges and Other Assets Other Assets Disclosure [Text Block] Property, plant and equipment Deferred Tax Liabilities, Property, Plant and Equipment Amortization period, maximum (in years) Plant And Equipment Planned Major Maintenance Activities Amortization Period Maximum The maximum amortization period of planned major maintenance activities. Income Taxes Paid Income Taxes Paid 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 Deferred charges and other assets, net Deferred charges and other assets, net Deferred Costs and Other Assets Proceeds from debt payable to Westlake Proceeds from Related Party Debt Schedule of Incentive Distributions Made to Managing Members or General Partners by Distribution Schedule of Incentive Distributions Made to Managing Members or General Partners by Distribution [Table Text Block] Westlake [Member] 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 State and local Current State and Local Tax Expense (Benefit) Partners' Equity (Equity Distribution Agreement) [Abstract] Partners' Equity (Equity Distribution Agreement) [Abstract] Partners' Equity (Equity Distribution Agreement) [Abstract] Income Taxes Income Tax, Policy [Policy Text Block] Accrued derivative liabilities, current Accrued derivative liabilities, current Accrued derivative liabilities, current 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 Other liabilities Other Liabilities, Noncurrent Plant and equipment Machinery and Equipment, Gross 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 Document Information [Table] Document Information [Table] Construction in progress Construction in Progress, Gross Inventories Inventories Inventory, Net Concentration Risk, Percentage Concentration Risk, Percentage 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 Limited Liability Company [Member] Limited Liability Company [Member] Statement [Line Items] Statement [Line Items] Class of Stock [Domain] Class of Stock [Domain] Weighted average interest rate on all long-term debt Long-term Debt, Weighted Average Interest Rate, at Point in Time Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering 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] Accrued interest on related party debt Accrued interest Interest Payable, Current Entity Voluntary Filers Entity Voluntary Filers Statement [Table] Statement [Table] Statistical Measurement [Axis] Statistical Measurement [Axis] 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 Nontrade Receivables, Current Nontrade Receivables, Current Income per limited partner unit (usd per unit) Basic and diluted earnings per common unit holder (usd per unit) Earnings Per Share, Basic and Diluted Distribution Type [Axis] Distribution Type [Axis] Entity Small Business Entity Small Business Distribution Type [Domain] Distribution Type [Domain] Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Feedstock, additives, and chemicals Inventory, Work in Process and Raw Materials Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Amendment Flag Amendment Flag Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Related Parties Amount in Cost of Sales Related Parties Amount in Cost of Sales Number of units authorized Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Total units available for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Repayment of debt payable to Westlake Repayments of Related Party Debt Purchase commitment, renewal term Long-term Purchase Commitment, Renewal Term Long-term Purchase Commitment, Renewal Term Net cash provided by operating 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 Exchange agreement amount of purchase agreement Purchase Commitment, Purchase Agreement, Mass Purchase Commitment, Purchase Agreement, Mass Allowance For Doubtful Accounts Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Schedule Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Other Assets [Abstract] Other Assets [Abstract] Statement of Partners' Capital [Abstract] Statement of Partners' Capital [Abstract] Derivative Instruments Derivatives, Policy [Policy Text Block] 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 Net income subsequent to the IPO in excess of distribution Distribution in excess of net income Undistributed Earnings, Basic Ethylene Production, Optional Ethylene Production, Optional Ethylene Production, Optional Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] 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] Property, Plant and Equipment by Type [Axis] Long-Lived Tangible Asset [Axis] Capitalized interest Interest capitalized Interest Costs Capitalized Income Statement Location [Axis] Income Statement Location [Axis] Allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Income Statement Location [Domain] Income Statement Location [Domain] 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 State and Local Jurisdiction [Member] State and Local Jurisdiction [Member] Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Selling, general and administrative expenses Services received from Westlake and included in selling, general and administrative expenses Selling, General and Administrative Expense Partnership's ownership interest (percent) Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Business Description and Accounting Policies Business Description and Accounting Policies [Text Block] Plan Name [Axis] Plan Name [Axis] Accounts receivable, net—third parties Receivables, Net, Current Total assets Assets Accrued Liabilities Accrued Liabilities [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Scenario [Axis] Scenario [Axis] Managing Member or General Partner [Axis] Managing Member or General Partner [Axis] Site Lease Agreement [Member] Site Lease Agreement [Member] Site Lease Agreement [Member] Incentive Distribution, Recipient [Domain] Incentive Distribution, Recipient [Domain] Derivative Liability, Current Derivative Liability, Current Description Of Business And Significant Accounting Policies Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Beginning balance Ending balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number 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 Underwriting Discounts, Structuring Fees and Offering Expenses on Issuance of Equity Underwriting Discounts, Structuring Fees and Offering Expenses on Issuance of Equity Underwriting Discounts, Structuring Fees and Offering Expenses on Issuance of Equity MLP Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Cost of Sales [Member] Cost of Sales [Member] Concentration Of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Plant And Equipment [Member] Plant And Equipment [Member] Plant And Equipment [Member] Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Depreciation and amortization Depreciation, Depletion and Amortization Schedule Of The Provision For (Benefit From) Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Product and Service [Axis] Product and Service [Axis] Total liabilities Liabilities Sales [Member] Sales [Member] 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 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 Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Balance sheet classifications Deferred Tax Assets, Net, Classification [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Feedstock Supply Agreement [Member] Feedstock Supply Agreement [Member] Feedstock Supply Agreement [Member] Amortization period, minimum (in years) Plant And Equipment Planned Major Maintenance Activities Amortization Period Minimum The minimum amortization period of planned major maintenance activities. Operating Lease, Expense Operating Lease, Expense Distribution declared Distribution Distributed Earnings Above $1.6875 Cash Distribution, Tranche Three [Domain] Cash Distribution, Tranche Three [Domain] Inventories Increase (Decrease) in Inventories IDR Holders [Member] IDR Holders [Member] Incentive Distribution Rights Holders [Member] Phantom Share Units (PSUs) [Member] Phantom Share Units (PSUs) [Member] Accounts payable Increase (Decrease) in Accounts Payable Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Other charges from Westlake and included in cost of sales Cost Of Goods Sold, Other Cost Of Goods Sold, Other Debt Instrument [Axis] Debt Instrument [Axis] Partner Type [Axis] Partner Type [Axis] Above $0.3163 up to $0.3438 Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] Westlake Chemical Partners LP [Member] Westlake Chemical Partners LP [Member] Westlake Chemical Partners LP Summary Of Quarterly Financial Information Quarterly Financial Information [Table Text Block] Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] Class of Stock [Line Items] Class of Stock [Line Items] Accrued and other liabilities Increase (Decrease) in Accrued Liabilities Accrual related to 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] Granted Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted Trade customers Accounts Receivable, before Allowance for Credit Loss, Current Total Westlake Chemical Partners LP partners' capital Partners' Capital Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] 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 State income tax provision, net of federal income tax effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Subsequent Event [Member] Subsequent Event [Member] Accrued taxes, current Accrued taxes, current Accrued taxes, current Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Ethylene Sales Agreement [Member] Ethylene Sales Agreement [Member] Ethylene Sales Agreement [Member] Limited partners' capital Limited Partners' Capital Account Partnership income not subject to entity-level tax Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Income Statement [Abstract] Income Statement [Abstract] Accumulated Other Comprehensive Income [Member] AOCI Attributable to Parent [Member] Quarterly distributions to unitholders Distribution Made to Limited Partner, Cash Distributions Paid Operating lease, rental amount Operating Leases, Rent Expense Use Of Estimates Use of Estimates, Policy [Policy Text Block] Current assets Assets, Current [Abstract] Income Tax Authority [Domain] Income Tax Authority [Domain] Amortization Amortization Long-term debt payable to Westlake Long-term debt Due to Related Parties, Noncurrent Derivative, Nonmonetary Notional Amount, Volume Derivative, Nonmonetary Notional Amount, Volume Goodwill, Gross Goodwill, Gross Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Related party transactions, term of agreements Related Party Transaction, Term Of Agreement Related Party Transaction, Term Of Agreement 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] Scenario [Domain] Scenario [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 Above $0.3438 up to $0.4125 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Reimbursement to Parent for State Tax [Member] Reimbursement to Parent for State Tax [Member] Reimbursement to Parent for State Tax [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Document Period End Date Document Period End Date Interest expense—Westlake Interest on related party debt payable Interest Expense, Related Party Director [Member] Director [Member] Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Accounts receivable, net—Westlake Accounts receivable, net—Westlake Accounts Receivable, Related Parties, Current Term of operating lease Lessee, Operating Lease, Term of Contract Accounts receivable, net—third parties Accounts and Other Receivables, Net, Current Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Information Disclosure [Abstract] Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Entity [Domain] Entity [Domain] Cover [Abstract] Cover [Abstract] Term of sales agreement Long-term Purchase Commitment, Period Quarterly Financial Information (Unaudited) Quarterly Financial Information [Text Block] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Property, plant and equipment, useful life (in years) Property, Plant and Equipment, Useful Life Property, Plant and Equipment, Net [Abstract] Property, Plant and Equipment, Net [Abstract] Other Noncurrent Assets, Other, Net Noncurrent Assets, Other, Net Affiliated Entity [Member] Affiliated Entity [Member] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Supplemental Information Other Income and Other Expense Disclosure [Text Block] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Cost of sales Cost of Goods and Services Sold Units issued for vested phantom units Net proceeds from private placement of common units Proceeds from Issuance or Sale of Equity Equity Components [Axis] Equity Components [Axis] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Minimum [Member] Minimum [Member] 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] 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 Unrecognized compensation cost Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Less: Net income attributable to noncontrolling interest in OpCo Net Income (Loss) Attributable to Noncontrolling Interest Entity Interactive Data Current Entity Interactive Data Current Fair Value Measurements Fair Value Disclosures [Text Block] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Other assets amortization period Finite-Lived Intangible Assets, Remaining Amortization Period Customer [Domain] Customer [Domain] Entity Registrant Name Entity Registrant Name Subsequent Event Type [Domain] Subsequent Event Type [Domain] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Derivative [Table] Derivative [Table] Excess Production Option [Member] Excess Production Option [Member] Excess Production Option [Member] Above $0.4125 Cash Distribution, Tranche Three [Member] Cash Distribution, Tranche Three [Member] 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]. 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] Ethylene Pipeline [Member] Ethylene Pipeline [Member] Ethylene Pipeline [Member] Westlake Chemical Partners LP Long-Term Incentive Plan [Member] Westlake Chemical Partners LP Long-Term Incentive Plan [Member] Westlake Chemical Partners LP Long-Term Incentive Plan [Member] Accrued Liabilities [Member] Accrued Liabilities [Member] Distributions per common unit [Abstract] Distributions per common unit [Abstract] Distributions per common unit [Abstract] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Purchase commitment, fixed margin on variable pricing Long-term Purchase Commitment, Exchange Fee, Fixed Margin Long-term Purchase Commitment, Exchange Fee, Fixed Margin Minimum Quarterly Distribution Per Unit Minimum Quarterly Distribution Per Unit Minimum Quarterly Distribution Per Unit Finished products Inventory, Finished Goods, Gross 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. Loss from disposition of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Entity Address, Postal Zip Code Entity Address, Postal Zip Code Turnaround Costs Property, Plant and Equipment, Planned Major Maintenance Activities, Policy [Policy Text Block] Weighted Average Number of Shares Outstanding, Basic and Diluted Basic and diluted (units) Weighted Average Number of Shares Outstanding, Basic and Diluted Gain on Derivative Instruments, Pretax Gain on Derivative Instruments, Pretax Goodwill Goodwill Services And Secondment Agreement [Member] Services And Secondment Agreement [Member] Services And Secondment Agreement [Member] Document Transition Report Document Transition Report Title of Individual [Axis] Title of Individual [Axis] General Partner [Member] General Partner [Member] 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. Other income (expense) Nonoperating Income (Expense) [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 Buildings And Improvements [Member] Building and Building Improvements [Member] Related Party Transactions (Related Party Leases) [Abstract] Related Party Transactions (Related Party Leases) [Abstract] Related Party Transactions (Related Party Leases) [Abstract] Equity [Abstract] Equity [Abstract] Ethylene Sales Agreement [Domain] Ethylene Sales Agreement [Domain] Ethylene Sales Agreement [Domain] Distributions [Line Items] Subsequent Event [Line Items] Customer Concentration Risk [Member] Customer Concentration Risk [Member] 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 Environmental Costs Environmental Costs, Policy [Policy Text Block] Accrued maintenance expense Accrued Maintenance Expense, Current Accrued Maintenance Expense, Current Entity File Number Entity File Number Debt Disclosure [Abstract] Debt Disclosure [Abstract] 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 Net cash used for financing activities Net Cash Provided by (Used in) Financing Activities Total compensation cost Share-based Payment Arrangement, Expense Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Weighted average limited partner units outstanding (basic and diluted) Weighted average units outsanding: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Counterparty Name [Axis] Counterparty Name [Axis] 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] Above $1.2938 up to $1.4063 Cash Distribution, Tranche One [Domain] Cash Distribution, Tranche One [Domain] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Document Fiscal Year Focus Document Fiscal Year Focus Document Annual Report Document Annual Report Majority-Owned Subsidiary, Unconsolidated [Member] Majority-Owned Subsidiary, Unconsolidated [Member] Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo") Noncontrolling Interest in Limited Partnerships Schedule Of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Entity Current Reporting Status Entity Current Reporting Status Related Party Transaction [Axis] Related Party Transaction [Axis] Distributions [Table] Subsequent Event [Table] Derivative Commodity Instruments Derivatives and Fair Value [Text Block] 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 Inventory, Net [Abstract] Inventory, Net [Abstract] 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 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 Basic and diluted earnings per common unitholder Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax Site lease agreement, number Site lease agreement, number Site lease agreement, number Deferred tax liabilities-total Deferred Tax Liabilities, Net 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 Concentration Risk Type [Domain] Concentration Risk Type [Domain] Amount paid to purchase additional limited partner interest Payments to Acquire Limited Partnership Interests Total liabilities and equity Liabilities and Equity Other Property, Plant and Equipment, Other, Gross Building and improvements Buildings and Improvements, Gross Income Taxes Income Tax Disclosure [Text Block] Entity Address, City or Town Entity Address, City or Town Organization, Consolidation, And Presentation Of Financial Statements [Table] Organization, Consolidation, And Presentation Of Financial Statements [Table] Organization, Consolidation, And Presentation Of Financial Statements [Table] Long-term Purchase Commitment, Option To Purchase Excess Production, Percentage Long-term Purchase Commitment, Option To Purchase Excess Production, Percentage Long-term Purchase Commitment, Option To Purchase Excess Production, Percentage Common units [Member] Limited Partners' Common Units [Member] Common Units [Member] Common Units [Member] Other Assets [Member] Other Assets [Member] Total equity Equity, beginning balance Equity, ending balance Partners' Capital, Including Portion Attributable to Noncontrolling Interest Equity Component [Domain] Equity Component [Domain] Agreements with Westlake and Related Parties Agreements with Westlake and Related Parties [Text Block] Agreements with Westlake and Related Parties [Text Block] 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 Gross Profit Property, plant and equipment, net Property, plant and equipment, net Property, Plant and Equipment, Net Entity Tax Identification Number Entity Tax Identification Number Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Unit-Based Compensation Share-based Payment Arrangement [Text Block] 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 attributable to Westlake Chemical Partners LP Net Income (Loss) Attributable to Parent 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 Investment, Name [Domain] Investment, Name [Domain] LIBOR [Member] London Interbank Offered Rate (LIBOR) [Member] Inventories Inventory Disclosure [Text Block] Accounts payable—Westlake Accounts Payable, Related Parties, Current Derivative, Nonmonetary Notional Amount, Mass Derivative, Nonmonetary Notional Amount, Mass 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 Goodwill, Deferred Charges and Other Assets Goodwill Disclosure [Text Block] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Schedule Of Deferred Tax Assets And Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] EQUITY Stockholders' Equity Attributable to Parent [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Long-term Purchase Commitment, Compliance Surcharge Amount Long-term Purchase Commitment, Compliance Surcharge Amount Long-term Purchase Commitment, Compliance Surcharge Cash Distribution [Member] Cash Distribution [Member] Schedule of Stockholders Equity [Table Text Block] Schedule of Stockholders Equity [Table Text Block] Entity Filer Category Entity Filer Category Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Product and Service [Domain] Product and Service [Domain] Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Schedule Of Property, Plant And Equipment Property, Plant and Equipment [Table Text Block] Increase (decrease) in capital expenditure accrual Increase (Decrease) in Capital Expenditure Accrual Increase (Decrease) in Capital Expenditure Accrual 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. Revenue Benchmark [Member] Revenue Benchmark [Member] Minimum percentage required to be purchased Long-term Purchase Commitment, Minimum Percentage Required Long-term Purchase Commitment, Minimum Percentage Required Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Product and Service, Other [Member] Product and Service, Other [Member] Units outstanding Limited Partners' Capital Account, Units Outstanding Related Party Transactions [Abstract] Related Party Transactions [Abstract] Net increase (decrease) 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) Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Public [Member] Unidentified Third Parties [Member] Unidentified Third Parties [Member] Distribution declared per unit (usd per share) Distribution Made to Limited Partner, Distributions Declared, Per Unit Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Ownership [Axis] Ownership [Axis] Document Information [Line Items] Document Information [Line Items] State and local Deferred State and Local Income Tax Expense (Benefit) Ownership [Domain] Ownership [Domain] Number of lease agreements Lessee Leasing Arrangements, Operating Leases, Number Lessee Leasing Arrangement, Operating Leases, Number Plan Name [Domain] Plan Name [Domain] Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Interest Paid, Excluding Capitalized Interest, Operating Activities Interest Paid, Excluding Capitalized Interest, Operating Activities Partners' Equity [Abstract] Partners' Equity [Abstract] Partners' Equity [Abstract] Unit Holders [Member] 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. Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Long-term debt, fair value Long-term Debt, Fair Value Cash And Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Total net sales Revenues Revenues Class of Stock [Axis] Class of Stock [Axis] Inventories Inventory, Policy [Policy Text Block] Provision for income taxes Total provision Income Tax Expense (Benefit) Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Schedule of Nonvested Restricted Stock Units Activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] 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 Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Title of Individual [Domain] Title of Individual [Domain] Accrued and other liabilities Accrued Liabilities, Current Local Phone Number Local Phone Number Subordinated units [Member] Limited Partners' Subordinated Units [Member] Subordinated Units [Member] Subordinated Units [Member] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] 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] Derivative [Line Items] Derivative [Line Items] Schedule Of Long-Term Debt Schedule of Long-term Debt Instruments [Table Text Block] Depreciation expense Depreciation Entity Address, Address Line One Entity Address, Address Line One Turnaround costs Deferred Tax Liabilities, Deferred Expense, Other Capitalized Costs Entity Address, Address Line Two Entity Address, Address Line Two Related Party Transaction [Domain] Related Party Transaction [Domain] Entity Emerging Growth Company Entity Emerging Growth Company Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Award Type [Axis] Award Type [Axis] Vested Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised 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 Maximum [Member] Maximum [Member] Limited Partners' Capital Account, Units Issued Limited Partners' Capital Account, Units Issued Site lease expense Site lease expense Site lease expense Noncontrolling Interest in OpCo [Member] Noncontrolling Interest [Member] Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Investee [Member] Investee [Member] Net cash used for investing activities Net Cash Provided by (Used in) Investing Activities Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Long-Term Debt Related Party Transactions, Long-term Debt [Text Block] Related Party Transactions, Long-term Debt [Text Block] Award Type [Domain] Award Type [Domain] 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 Schedule of Other Assets Schedule of Other Assets [Table Text Block] Trading Symbol Trading Symbol Net sales - Westlake Revenue from Related Parties OpCo Revolver [Member] OpCo Revolver [Member] OpCo Revolver [Member] Property, Plant And Equipment Property, Plant and Equipment Disclosure [Text Block] General partner—Westlake General Partners' Capital Account Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Net Income Per Limited Partner Unit Earnings Per Share [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Transportation and Freight Shipping and Handling Cost, Policy [Policy Text Block] Other [Member] Other Capitalized Property Plant and Equipment [Member] Current liabilities Liabilities, Current [Abstract] Entity Shell Company Entity Shell Company Accounts Receivable, after Allowance for Credit Loss [Abstract] Accounts Receivable, after Allowance for Credit Loss [Abstract] Westlake Chemical Corporation [Member] Westlake Chemical Corporation [Member] Westlake Chemical Corporation Segment Reporting Segment Reporting, Policy [Policy Text Block] Units issued for vested phantom units Stock Issued During Period, Value, Other Recent Accounting Pronouncements and Recently Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Entity Public Float Entity Public Float Statement of Financial Position [Abstract] Statement of Financial Position [Abstract]