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[Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Related Party Transaction [Line Items] Related Party Transaction [Line Items] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Feedstock Purchased Feedstock Purchased [Member] Feedstock Purchased [Member] All Individuals All Individuals [Member] All Award Types Award Type [Domain] Fair Value as of Grant Date Award Grant Date Fair Value Amortization expense Amortization Entity Filer Category Entity Filer Category Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Total Westlake Chemical Partners LP partners' capital Partners' Capital Statement [Table] Statement [Table] Current Fiscal Year End Date Current Fiscal Year 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Contingencies Insider Trading Policies and Procedures [Line Items] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Accounts Receivable, after Allowance for Credit Loss [Abstract] Accounts Receivable, after Allowance for Credit Loss [Abstract] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Partners' Equity Equity [Text Block] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities General Partner General Partner [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Senior Unsecured Revolving Credit Facility Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Ownership [Axis] Ownership 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Emerging Growth Company Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Company Selected Measure Name Company Selected Measure Name Accrued interest on related party debt Interest Payable, Current Shortfall Shortfall Fees Shortfall Fees Weighted average units outsanding: Earnings per Unit, Basic and Diluted, Other Disclosure [Abstract] Earnings per Unit, Basic and Diluted, Other Disclosure Finished products Inventory, Finished Goods, Gross LIABILITIES Liabilities and Equity [Abstract] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Westlake Parent Company [Member] EQUITY Equity, Attributable to Parent [Abstract] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Document Fiscal Period Focus Document Fiscal Period Focus Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings 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Disclosure [Text Block] Accrued and other liabilities Increase (Decrease) in Accrued Liabilities Cash Distribution Cash Distribution [Member] Document Fiscal Year Focus Document Fiscal Year Focus Distribution to noncontrolling interest retained in OpCo by Westlake Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Other service charges Other Service Charges [Member] Other Service Charges [Member] Number of common carrier pipelines Number of Common Carrier Pipelines Number of Common Carrier Pipelines Underlying Securities Award Underlying Securities Amount Entity Small Business Entity Small Business Diluted (in usd per share) Net Income (Loss), Net of Tax, Per Outstanding Limited Partnership Unit, Diluted Minimum Minimum [Member] Local Phone Number Local Phone Number Property, plant and equipment, net Property, Plant and Equipment, Net Recovery of Erroneously Awarded Compensation Disclosure [Line Items] 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] Total equity Total equity Total equity Partners' Capital, Including Portion Attributable to Noncontrolling Interest Receivables, Net, Current Accounts receivable, net—third parties Receivables, Net, Current Exercise Price Award Exercise Price Accounts Receivable Accounts Receivable [Member] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Long-term debt payable to Westlake Other Long-Term Debt, Noncurrent ASSETS Assets [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Nonrelated Party Nonrelated Party [Member] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Accrued Liabilities Accrued Liabilities [Member] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Depreciation expense on property, plant and equipment 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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 Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Other Assets [Line Items] Other Assets [Line Items] Other Assets [Line Items] Total net sales Revenues Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Other Assets, Noncurrent [Abstract] Other Assets, Noncurrent [Abstract] Distribution in excess of net income Undistributed Earnings, Basic Arrangement Duration Trading Arrangement Duration Other Performance Measure, Amount Other Performance Measure, Amount Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Inventories Increase (Decrease) in Inventories Entity Address, City or Town Entity Address, City or Town Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Site lease agreement, number Site lease agreement, number Site lease agreement, number Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Award Type Award Type [Axis] Amount paid to purchase additional limited partner interest Payments to Acquire Limited Partnership Interests Document Quarterly Report Document Quarterly Report Interest expense Interest expense Interest Expense Capital expenditures incurred but not yet paid Capital Expenditures Incurred but Not yet Paid Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Investments with Westlake under the Investment Management Agreement Supplemental Information Additional Financial Information Disclosure [Text Block] Document Transition Report Document Transition Report Award Timing Predetermined Award Timing Predetermined [Flag] Trading Arrangement: Trading Arrangement [Axis] Related Party Transactions Related Party Transactions Disclosure [Text Block] Termination Date Trading Arrangement Termination Date Managing Member or General Partner [Axis] Managing Member or General Partner [Axis] Accounts payable—third parties Increase (Decrease) in Accounts Payable PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Common units Common units Common Units [Member] Common Units [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Entity File Number Entity File Number Accrued Liabilities [Abstract] Accrued Liabilities [Abstract] Accrued maintenance Accrued Maintenance Costs, Current Accrued Maintenance Costs, Current Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Charges from related parties in cost of sales Related Parties Amount in Cost of Sales Entity Shell Company Entity Shell Company 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] Recently Issued Accounting Pronouncement and Recently Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Related Party Transactions [Abstract] Related Party Transactions [Abstract] All Trading Arrangements All Trading Arrangements [Member] Restatement Determination Date Restatement Determination Date 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 All Adjustments to Compensation All Adjustments to Compensation [Member] Award Timing Disclosures [Line Items] Counterparty Name [Domain] Counterparty Name [Domain] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] 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 Common unitholders Limited Partners' Capital Account Compensation Amount Outstanding Recovery Compensation Amount Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Gross profit Gross Profit Security Exchange Name Security Exchange Name Subsequent Event Type [Axis] Subsequent Event Type [Axis] Selling, general and administrative expenses Selling, General and Administrative Expense Selling, General and Administrative Expense Loss from disposition of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Common units (in usd per share) Basic (in usd per share) Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Employee Stock Option Employee Stock Option [Member] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current MLP Revolver MLP Revolver [Member] MLP Revolver [Member] Maximum Maximum [Member] Insider Trading Arrangements [Line Items] Document Type Document Type Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Related Party [Axis] Related Party, Type [Axis] Tabular List, Table Tabular List [Table Text Block] Shortfall fees recovered Shortfall fees recovered Shortfall fees recovered Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Registrant Name Entity Registrant Name Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Award Timing Method Award Timing Method [Text Block] Weighted average interest rate Long-Term Debt, Weighted Average Interest Rate, at Point in Time Adjustment to Compensation, Amount Adjustment to Compensation Amount Distribution declared per unit (in usd per unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit Distributions to unitholders Distribution Made to Limited Partner, Cash Distributions Paid 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 Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Proceeds from debt payable to Westlake Proceeds from Related Party Debt Other losses, net Other Noncash Income (Expense) Deferred charges and other assets, net Deferred Costs and Other Assets Document Period End Date Document Period End Date Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Adoption Date Trading Arrangement Adoption Date Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Accrued taxes Taxes Payable, Current Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Entity Central Index Key Entity Central Index Key Subsequent Event Subsequent Event [Member] Customer Concentration Risk Customer Concentration Risk [Member] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Variable Rate [Axis] Variable Rate [Axis] Provision for income taxes Income Tax Expense (Benefit) Income Statement [Abstract] Income Statement [Abstract] Accrued capital expenditures Accrued Capital Expenditures Accrued Capital Expenditures IDR Holders IDR Holders [Member] Incentive Distribution Rights Holders [Member] Units outstanding (in shares) Limited Partners' Capital Account, Units Outstanding Title of 12(b) Security Title of 12(b) Security Westlake Chemical OpCo LP Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Fair Value Measurements Fair Value Disclosures [Text Block] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Subsequent distribution to IDR holders Incentive Distribution, Subsequent Distribution Amount Amount of incentive obligation earned in cash or stock during the period by the Partnership's incentive distribution rights holders and paid after the end of the accounting period. Revenue Benchmark Revenue Benchmark [Member] Name Trading Arrangement, Individual Name Related Party [Domain] Related Party, Type [Domain] Payments of Ordinary Dividends, Noncontrolling Interest Payments of Ordinary Dividends, Noncontrolling Interest Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Distribution to unitholders Limited Partners' Capital Account, Distribution Amount Above $1.2938 up to $1.4063 Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] Equity [Abstract] Equity [Abstract] Inventories Inventory Disclosure [Text Block] Risks and Uncertainties [Abstract] Risks and Uncertainties [Abstract] Distribution Per Common Unit [Abstract] Distribution Per Common Unit [Abstract] Distribution Per Common Unit [Abstract] Other receivables Other Receivables, Net, Current Net co-products, ethylene and other sales—third parties Revenue from Contract with Customer, Excluding Assessed Tax Class of Stock [Line Items] Class of Stock [Line Items] Entity [Domain] Entity [Domain] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Amendment Flag Amendment Flag Distributions declared Distributed Earnings Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Legal Entity [Axis] Legal Entity [Axis] Schedule of Accounts, Notes, Loans and Financing Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Entity Tax Identification Number Entity Tax Identification Number 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 Inventories Inventories Inventory, Net Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Publicly and Privately Held Unidentified Third Parties [Member] Unidentified Third Parties [Member] Feedstock, additives and chemicals Inventory, Work in Process and Raw Materials Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Statistical Measurement [Axis] Statistical Measurement [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Entity Interactive Data Current Entity Interactive Data Current Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Site lease agreements, OpCo annual obligation to WLK Site lease agreements, OpCo annual obligation to WLK Site lease agreements, OpCo annual obligation to WLK Total Shareholder Return Amount Total Shareholder Return Amount Entity Common Units, Units Outstanding Entity Common Stock, Shares Outstanding Adjustment To PEO 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Distribution Type [Domain] Current assets Assets, Current [Abstract] Trade customers Accounts Receivable, before Allowance for Credit Loss, Current Balance Sheet Location [Axis] Balance Sheet Location [Axis] Total assets Assets Name Awards Close in Time to MNPI Disclosures, Individual Name Number of units sold in public offering (in shares) Partners' Capital Account, Units, Sold in Public Offering Entity Address, State or Province Entity Address, State or Province Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Partners' capital account, units, sold to related party (in shares) Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Counterparty Name [Axis] Counterparty Name [Axis] Cover [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] General partner—Westlake General Partners' Capital Account Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Accounts Receivable—Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Net income per limited partner unit: Earnings Per Share, Basic [Abstract] Other liabilities Other Liabilities, Noncurrent Non-NEOs Non-NEOs [Member] Accounts receivable—third parties Increase (Decrease) in Accounts and Other Receivables PEO PEO [Member] Other income (expense) Other Nonoperating Income (Expense) [Member] Units issued (in shares) Limited Partners' Capital Account, Units Issued Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Above $1.4063 up to $1.6875 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Non-PEO NEO Non-PEO NEO [Member] Distribution Type [Axis] Distribution Type [Axis] Equity Component [Domain] Equity Component [Domain] Adjustment to Compensation: Adjustment to Compensation [Axis] Net cash provided by (used for) investing activities Net Cash Provided by (Used in) Investing Activities Customer [Domain] Customer [Domain] Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Entity Current Reporting Status Entity Current Reporting Status Concentration Risk Type [Domain] Concentration Risk Type [Domain] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Long-term Debt Payable to Westlake Related Party Transactions, Long-term Debt [Text Block] Related Party Transactions, Long-term Debt [Text Block] Income from operations Operating Income (Loss) Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Total liabilities Liabilities Related Party Transactions, Long-term Debt Related Party Transactions, Long-term Debt [Table Text Block] Related Party Transactions, Long-term Debt [Table Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Long-term debt payable to Westlake OpCo Revolver [Member] OpCo Revolver [Member] Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Consolidated Entities [Domain] Consolidated Entities [Domain] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] All Executive Categories All Executive Categories [Member] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Related Party Transaction [Axis] Related Party Transaction [Axis] Partners units, maximum aggregate offering amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Statement of Partners' Capital [Abstract] Statement of Partners' Capital [Abstract] Statement [Line Items] Statement [Line Items] Concentration Risk [Table] Concentration Risk [Table] Related Party Transaction [Domain] Related Party Transaction [Domain] Distributions Made to Limited Partner, by Distribution Distributions Made to Limited Partner, by Distribution [Table Text Block] Partner Type [Axis] Partner Type [Axis] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Affiliated Entity Affiliated Entity [Member] Noncontrolling Interest in OpCo Noncontrolling Interest [Member] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract]