Related Party Transactions [Abstract] Long-term Debt Payable to Westlake Related Party Transactions, Long-term Debt [Text Block] Related Party Transactions, Long-term Debt [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Accounts Receivable, after Allowance for Credit Loss [Abstract] Accounts Receivable - Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Accrued Liabilities [Member] Accrued Liabilities [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Affiliated Entity [Member] Affiliated Entity [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Westlake [Member] Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] Parent Company and Subsidiaries, Excluding Reporting Entity and Subsidiaries [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Operating Lease, Expense Operating Lease, Expense Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Accrued interest included in receivable under IMA Interest earned related to the IMA Interest earned related to the IMA Interest earned related to the IMA Property, Plant and Equipment [Abstract] Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 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] Depreciation and amortization Depreciation, Depletion and Amortization Loss from disposition of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Other gains, net Other Noncash Income (Expense) Changes in operating assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Accounts receivable—third parties Increase (Decrease) in Accounts and Other Receivables Net accounts receivable—Westlake Increase (Decrease) in Accounts Receivable, Related Parties Inventories Increase (Decrease) in Inventories Prepaid expenses and other current assets Increase (Decrease) In Prepaid Expenses And Other Current Assets Increase (Decrease) In Prepaid Expenses And Other Current Assets Accounts payable Increase (Decrease) in Accounts Payable Accrued and other liabilities Increase (Decrease) in Accrued Liabilities Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Cash flows from investing activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to property, plant and equipment Payments to Acquire Property, Plant, and Equipment 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 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 Cash Provided by (Used in) Investing Activities, Other Cash Provided by (Used in) Investing Activities, Other Net cash used for investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Net proceeds from private placement of common units Proceeds from Issuance or Sale of Equity Proceeds from debt payable to Westlake Proceeds from Related Party Debt Repayment of debt payable to Westlake Repayments of Related Party Debt Quarterly distributions to noncontrolling interest retained in OpCo by Westlake Payments to Noncontrolling Interests Quarterly distributions to unitholders Distribution Made to Limited Partner, Cash Distributions Paid Net cash used for financing activities Net Cash Provided by (Used in) Financing Activities 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 and cash equivalents at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents at end of period 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. Income Statement [Abstract] Statement [Table] Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Product and Service, Other [Member] Product and Service, Other [Member] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Common units [Member] Common Units [Member] Common Units [Member] Publicly and Privately Held [Member] Unidentified Third Parties [Member] Unidentified Third Parties [Member] Westlake [Member] Statement [Line Items] Statement [Line Items] Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted Net sales—Westlake Revenue from Related Parties Total net sales Revenues Cost of sales Cost of Goods and Services Sold Gross profit Gross Profit Selling, general and administrative expenses Selling, General and Administrative Expense Income from operations Operating Income (Loss) Other income (expense) Nonoperating Income (Expense) [Abstract] Interest expense—Westlake Interest Expense, Related Party Other income, net Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax provision Income Tax Expense (Benefit) Net income Less: Net income attributable to noncontrolling interest in OpCo Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income Net Income (Loss) Attributable to Parent Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax Net income per limited partner unit attributable to Westlake Chemical Partners LP per limited partner unit (basic and diluted) Earnings Per Share, Basic and Diluted [Abstract] Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] OpCo Revolver [Member] OpCo Revolver [Member] OpCo Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Limited Partner [Member] Limited Partner [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term debt payable to Westlake, carrying value Due to Related Parties, Noncurrent Long-term debt payable to Westlake, fair value Long-term Debt, Fair Value Depreciation expense on property, plant and equipment Depreciation Earnings Per Share [Abstract] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Managing Member or General Partner [Axis] Managing Member or General Partner [Axis] Incentive Distribution, Recipient [Domain] Incentive Distribution, Recipient [Domain] IDR Holders [Member] IDR Holders [Member] Incentive Distribution Rights Holders [Member] Common units [Member] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Distributions declared Distributed Earnings 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. Distribution in excess of net income Undistributed Earnings, Basic Net income Weighted average units outsanding: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Net income per limited partner unit: Earnings Per Share, Basic and Diluted Earnings Per Share, Basic and Diluted Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] 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 Accounts receivable—Westlake, current and non-current Accounts Receivable, Related parties, Current and Noncurrent Accounts Receivable, Related parties, Current and Noncurrent Accounts payable—Westlake Accounts Payable, Related Parties, Current Statement of Financial Position [Abstract] Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] General Partner [Member] General Partner [Member] ASSETS Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable, net—Westlake Accounts Receivable, Related Parties, Current Accounts receivable, net—third parties Accounts Receivable, after Allowance for Credit Loss, Current Inventories Inventory, Net Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property, plant and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Deferred charges and other assets, net Deferred Costs and Other Assets Total assets Assets LIABILITIES Liabilities and Equity [Abstract] Current liabilities Liabilities, Current [Abstract] Accounts payable—third parties Accounts Payable, Current Accrued and other liabilities Accrued Liabilities, Current Total current liabilities Liabilities, Current Long-term debt payable to Westlake Deferred income taxes Deferred Income Tax Liabilities, Net Other liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 13) Commitments and Contingencies EQUITY Stockholders' Equity Attributable to Parent [Abstract] Limited Partners' Capital Account Limited Partners' Capital Account General partner—Westlake General Partners' Capital Account Total Westlake Chemical Partners LP partners' capital Partners' Capital Noncontrolling interest in Westlake Chemical OpCo LP (OpCo) Noncontrolling Interest in Limited Partnerships Total equity Partners' Capital, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Inventory Disclosure [Abstract] Inventories Inventory Disclosure [Text Block] Other Assets, Noncurrent [Abstract] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Deferred Charges and Other Assets [Member] Other Assets [Member] Other Assets [Line Items] Other Assets [Line Items] Other Assets [Line Items] Amortization expense Amortization 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 Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Commodity Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Related Party Transactions, Long-term Debt Related Party Transactions, Long-term Debt [Table Text Block] Related Party Transactions, Long-term Debt [Table Text Block] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other income (expense) [Member] Other Nonoperating Income (Expense) [Member] Interest on related party debt payable Interest capitalized Interest Costs Capitalized Accrued interest on related party debt Interest Payable, Current Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Line Items] Class of Stock [Line Items] Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Number of units sold in public offering Partners' Capital Account, Units, Sold in Public Offering 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 Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Partners' Capital Account, Units, Sold to Related Party Revenue from Related Parties 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 Units issued Limited Partners' Capital Account, Units Issued Units outstanding Limited Partners' Capital Account, Units Outstanding Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR [Member] London Interbank Offered Rate (LIBOR) [Member] Alternate Base Rate [Domain] Alternate Base Rate [Domain] Alternate Base Rate [Domain] Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Repayments of debt Repayments of Debt 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 Weighted average interest rate Long-term Debt, Weighted Average Interest Rate, at Point in Time Risks and Uncertainties [Abstract] Concentration Risk [Table] Concentration Risk [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Revenue Benchmark [Member] Revenue Benchmark [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Customer Concentration Risk [Member] Customer Concentration Risk [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration Risk, Percentage Concentration Risk, Percentage Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Westlake Chemical OpCo GP LLC [Member] Limited Liability Company [Member] Limited Liability Company [Member] Majority-Owned Subsidiary, Unconsolidated [Member] Majority-Owned Subsidiary, Unconsolidated [Member] Limited partner interest Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Amount paid to purchase additional limited partner interest Payments to Acquire Limited Partnership Interests Number of ethylene production facilities Number of Production Facilities Number of Production Facilities Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Deferred Charges and Other Assets Other Assets Disclosure [Text Block] Site lease agreement, number Site lease agreement, number Site lease agreement, number Site lease agreements, term (in years) Site lease agreements, term (in years) Site lease agreements, term (in years) Site lease agreements, OpCo annual obligation to WLK Site lease agreements, OpCo annual obligation to WLK Site lease agreements, OpCo annual obligation to WLK Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Feedstock purchased [Member] Feedstock Purchased [Member] Feedstock Purchased [Member] Other service charges [Member] Other Service Charges [Member] Other Service Charges [Member] Charges from related parties in cost of sales Related Parties Amount in Cost of Sales Distributions and Net Income Per Limited Partner Unit Earnings Per Share [Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Accrued Liabilities [Abstract] Accrued Liabilities [Abstract] Accrued interest Accrued taxes Accrued Income Taxes Accrued maintenance Accrued Maintenance Costs, Current Accrued Maintenance Costs, Current Other accrued accounts payable Other accrued accounts payable Other accrued accounts payable Derivative trading accrual Derivative trading accrual Derivative trading accrual Accrued capital expenditures Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Increase (reduction) in capital expenditure accrual Increase (Decrease) in Capital Expenditure Accrual Increase (Decrease) in Capital Expenditure Accrual Distribution Per Common Unit [Abstract] Distribution Per Common Unit [Abstract] Distribution Made to Limited Partner, Distributions Paid, Per Unit Distribution Made to Limited Partner, Distributions Paid, Per Unit Statement of Partners' Capital [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Noncontrolling Interest in OpCo [Member] Noncontrolling Interest [Member] Equity, beginning balance Net proceeds from private placement of common units Quarterly distribution to unitholders Limited Partners' Capital Account, Distribution Amount Quarterly distribution to noncontrolling interest retained in OpCo by Westlake Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Equity, ending balance Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Partners' Equity Stockholders' Equity Note Disclosure [Text Block] Document Documentand Entity Information [Abstract] Document - Document and Entity Information [Abstract] Document Information [Table] Document Information [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Document Quarterly Report Document Quarterly Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Units, Units Outstanding Entity Common Stock, Shares Outstanding Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date 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] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Distributions Made to Limited Partner, by Distribution [Table Text Block] Distributions Made to Limited Partner, by Distribution [Table Text Block] Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Distribution Type [Axis] Distribution Type [Axis] Distribution Type [Domain] Distribution Type [Domain] Cash Distribution [Member] Cash Distribution [Member] Above $1.2938 up to $1.4063 Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] Above $1.4063 up to $1.6875 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Above $1.6875 Cash Distribution, Tranche Three [Member] Cash Distribution, Tranche Three [Member] Common And Subordinated Units [Member] Common And Subordinated Units [Member] Common And Subordinated Units [Member] Unit Holders [Member] Unit Holders [Member] Unit Holders [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Distribution declared per unit (in usd per unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit 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 Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders Net income attributable to the Partnership Distributions declared with respect to the incentive distribution rights Trade customers Accounts Receivable, before Allowance for Credit Loss, Current Allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Trade Customer Receivable Net Current Trade Customer Receivable Net Current Trade Customer Receivable Net Current Other receivables Other Receivables, Net, Current Accounts receivable, net—third parties Receivables, Net, Current Finished products Inventory, Finished Goods, Gross Feedstock, additives and chemicals Inventory, Work in Process and Raw Materials Inventories Schedule of Incentive Distribution Made to Managing Member or General Partner [Table] Schedule of Incentive Distribution Made to Managing Member or General Partner [Table] Incentive Distribution Made to Managing Member or General Partner [Line Items] Incentive Distribution Made to Managing Member or General Partner [Line Items] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Related Party Transactions Related Party Transactions Disclosure [Text Block] Derivative Commodity Instruments [Abstract] Derivative Commodity Instruments [Abstract] Derivative [Table] Derivative [Table] Sales [Member] Sales [Member] Cost of Sales [Member] Cost of Sales [Member] Derivative [Line Items] Derivative [Line Items] Derivative, Nonmonetary Notional Amount, Volume Derivative, Nonmonetary Notional Amount, Volume Derivative, Nonmonetary Notional Amount, Mass Derivative, Nonmonetary Notional Amount, Mass Derivative Liability, Current Derivative Liability, Current Gain on derivative instruments Gain on Derivative Instruments, Pretax Loss on derivative instruments Loss on Derivative Instruments, Pretax Derivative Asset, Current Derivative Asset, Current Supplemental Information Additional Financial Information Disclosure [Text Block]