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