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] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] 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] Related Party Transaction [Line Items] Related Party Transaction [Line Items] 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 Inventory Disclosure [Abstract] Finished products Inventory, Finished Goods, Gross Feedstock, additives and chemicals Inventory, Work in Process and Raw Materials Inventories Inventory, Net Organization, Consolidation and Presentation of Financial Statements [Abstract] Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Accrued Liabilities [Member] Accrued Liabilities [Member] Distribution Type [Axis] Distribution Type [Axis] Distribution Type [Domain] Distribution Type [Domain] Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] Cash Distribution, Tranche One [Member] 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] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Site Lease Agreement [Member] Site Lease Agreement [Member] Site Lease Agreement [Member] Westlake [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Reimbursed income tax payments Reimbursed income tax payments Reimbursed income tax payments 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 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 Earnings Per Share [Abstract] 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] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Number of site lease agreements Lessee Leasing Arrangements, Operating Leases, Number Lessee Leasing Arrangement, Operating Leases, Number Lease term Lessee, Operating Lease, Term of Contract Operating lease rent expense Operating Leases, Rent Expense Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR [Member] London Interbank Offered Rate (LIBOR) [Member] Long-term debt payable to Westlake Weighted average interest rate Long-term Debt, Weighted Average Interest Rate, at Point in Time Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Equity [Abstract] Equity Stockholders' Equity Note Disclosure [Text Block] Accounts Receivable, Net [Abstract] 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. Accounts Receivable - Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Subsequent Events [Abstract] Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] 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] Subordinated units [Member] Subordinated Units [Member] Subordinated 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. Net income in excess of distribution (Distribution in excess of net income) Undistributed Earnings, Basic Net income Net Income (Loss) Attributable to Parent Weighted average units outsanding: Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Basic and diluted (shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Net income per limited partner unit: Earnings Per Share, Basic and Diluted [Abstract] Income per limited partner unit (usd per share) Earnings Per Share, Basic and Diluted 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 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] Common units [Member] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Units, Units Outstanding Entity Common Stock, Shares Outstanding Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other income (expense) Other Nonoperating Income (Expense) [Member] Interest on related party debt payable Interest Expense, Related Party Interest capitalized Interest Costs Capitalized Accrued interest on related party debt Interest Payable, Current Other Assets, Noncurrent [Abstract] Other Assets Other Assets 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] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] 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] Subordinated units [Member] Public [Member] Unidentified Third Parties [Member] Unidentified Third Parties [Member] Statement [Line Items] Statement [Line Items] ASSETS Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value 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 Accounts receivable, net—Westlake Accounts Receivable, Related Parties, Current Accounts receivable, net—third parties Receivables, Net, Current Inventories 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 Other assets, net Other Assets [Abstract] 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—Westlake Accounts Payable, Related Parties, Current Accounts payable—third parties Accounts Payable, Current Accrued liabilities Accrued Liabilities, Current Total current liabilities Liabilities, Current Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Other liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 12) 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 Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax 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 Trade customers Accounts Receivable, Gross, Current Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Trade Customer Receivable Net Current Trade Customer Receivable Net Current Trade Customer Receivable Net Current Other Other Receivables, Net, Current Accounts receivable, net—third parties Statement of Partners' Capital [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Noncontrolling Interest in OpCo [Member] Noncontrolling Interest [Member] Equity, beginning balance Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net effect of cash flow hedge Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Net proceeds from equity offering Proceeds from Issuance or Sale of Equity Conversion of Units, Amount Conversion of Units, Amount Conversion of Units, Amount Units issued for vested phantom units Stock Issued During Period, Value, Share-based Compensation, Gross Quarterly distributions 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 Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Subsequent Events [Text Block] Subsequent Events [Text Block] Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Partners Units, Maximum Aggregate Offering Amount, ATM Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] 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 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] Sales Revenue, Net [Member] Sales Revenue, Net [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 Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Supplemental Information Additional Financial Information Disclosure [Text Block] Property, Plant and Equipment [Abstract] Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] 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] 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 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 Limited partner interest Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest 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 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 Depreciation expense on property, plant and equipment Depreciation Accrued Liabilities [Abstract] Accrued Liabilities [Abstract] Accrued interest Accrued taxes Accrued Income Taxes, Current Accrued maintenance Accrued Maintenance Costs, Current Accrued Maintenance Costs, Current Increase (reduction) in capital expenditure accrual Increase (Decrease) in Capital Expenditure Accrual Increase (Decrease) in Capital Expenditure Accrual Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Cash Distribution [Member] Cash Distribution [Member] Above $0.3163 up to $0.3438 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Three [Member] 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] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Distribution declared per unit (in usd per unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit Marginal percentage interest in distributions Incentive Distribution, Marginal Percentage Interest in Distributions Incentive Distribution, Marginal Percentage Interest in Distributions Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd 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 Net income attributable to the Partnership Distributions declared with respect to the incentive distribution rights Quarterly incentive distribution, per unit, distribution threshold Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold Weighted average limited partner units outstanding (basic and diluted) (in shares) Fair Value Measurements Fair Value Disclosures [Text Block] Accounts receivable—Westlake, current and non-current Accounts Receivable, Related parties, Current and Noncurrent Accounts Receivable, Related parties, Current and Noncurrent Related Party Transactions Related Party Transactions Disclosure [Text Block] Distributions and Net Income Per Limited Partner Unit Earnings Per Share [Text Block] Inventories Inventory Disclosure [Text Block] 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] Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Units issued Limited Partners' Capital Account, Units Issued Units outstanding Limited Partners' Capital Account, Units Outstanding 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 Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Income Statement [Abstract] 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] Net sales - Westlake Revenue from Related Parties Total net sales Revenues Cost of Goods and Services Sold 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 Other income, net Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax provision (benefit) 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 Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted) Weighted average limited partner units outstanding (basic and diluted) Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Other Assets [Member] Other Assets [Member] Other Assets [Line Items] Other Assets [Line Items] Other Assets [Line Items] Amortization expense Amortization Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Line Items] Class of Stock [Line Items] Statement of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income 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] 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 decrease in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period