Organization, Consolidation and Presentation of Financial Statements [Abstract] Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Notes [Member] Senior Notes [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Westlake [Member] Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] Parent Company and Subsidiaries, Excluding Reporting Entity and Subsidiaries [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] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Accrued Liabilities [Member] Accrued Liabilities [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other income (expense) Other Nonoperating Income (Expense) [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] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Interest on related party debt payable Interest Expense, Related Party Interest capitalized Interest Costs Capitalized Accrued interest on related party debt Interest Payable, Current Long-term debt payable to Westlake Due to Related Parties, Noncurrent Earnings Per Share [Abstract] 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 Above $0.3438 up to $0.4125 Cash Distribution, Tranche Two [Member] Cash Distribution, Tranche Two [Member] Above $0.4125 Cash Distribution, Tranche Three [Member] Cash Distribution, Tranche Three [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] Subordinated units [Member] Subordinated Units [Member] Subordinated Units [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] 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] Distribution declared per unit (in usd per unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit Distribution declared and paid to IDR holders Incentive Distribution, Distribution Minimum quarterly distribution per unit (in usd per unit) Minimum Quarterly Distribution Per Unit Minimum Quarterly Distribution 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 Net Income (Loss) Attributable to Parent Distributions declared Distributed Earnings Distribution declared with respect to the incentive distribution rights Incentive Distribution, Subsequent Distribution Amount Amount of incentive obligation earned in cash or stock during the period by the Partnership's incentive distribution rights holders and paid after the end of the accounting period. (Distribution in excess of net income) net income in excess of distribution Undistributed Earnings, Basic Quarterly incentive distribution, per unit, distribution threshold Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold Fair Value Disclosures [Abstract] Fair Value, Liabilities Measured on Recurring Basis Fair Value, Liabilities Measured on Recurring Basis [Table Text Block] Summary Of Carrying And Fair Values Of Long-Term Debt Fair Value, by Balance Sheet Grouping [Table 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 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 Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Property, Plant and Equipment [Abstract] Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Inventory Disclosure [Abstract] Finished products Inventory, Finished Goods, Gross Feedstock, additives and chemicals Inventory, Work in Process and Raw Materials Inventories Inventory, Net Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Fair Values of Derivatives Instruments in Consolidated Balance Sheet Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Derivative Instruments, Gain (Loss) Derivative Instruments, Gain (Loss) [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Net sales—Westlake Revenue from Related Parties Statement of Partners' Capital [Abstract] Statement [Table] Statement [Table] Public [Member] Unidentified Third Parties [Member] Unidentified Third Parties [Member] Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Limited Partner [Member] Limited Partner [Member] General Partner [Member] General Partner [Member] 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] Statement [Line Items] Statement [Line Items] Equity, beginning balance Partners' Capital, Including Portion Attributable to Noncontrolling Interest 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 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 Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Pending Litigation [Member] Pending Litigation [Member] Settled Litigation [Member] Settled Litigation [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Unfavorable Regulatory Action [Member] Unfavorable Regulatory Action [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Possible amount of claims in settlement for compliance violations Loss Contingency, Estimate of Possible Loss Number of claims settled Loss Contingency, Claims Settled, Number Amount of settlement for compliance violations Litigation Settlement, Amount Income Statement [Abstract] Net co-product, ethylene and other sales—third parties Other Revenue, Net Total net sales Revenue, Net Cost of sales Cost of Goods 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 Provision for income taxes 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) Earnings Per Share, Basic and Diluted [Abstract] Income per limited partner unit (usd per share) Earnings Per Share, Basic and Diluted Weighted average limited partner units outstanding (basic and diluted) Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Weighted average limited partner units outstanding (basic and diluted) (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Distributions per common unit (usd per share) Distribution Made to Limited Partner, Distributions Paid, Per Unit Ineffective portion of a derivative instrument Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net 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] August 2013 Promissory Note [Member] Promissory Notes, 2013 [Member] Promissory Notes, 2013 [Member] OpCo Revolver [Member] OpCo Revolver [Member] OpCo Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] MLP Revolver [Member] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Senior Unsecured Revolving Credit Facility [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Asset - Interest rate contract Interest Rate Derivative Assets, at Fair Value Long-term debt payable to Westlake, carrying value Long-term debt payable to Westlake, fair value Long-term Debt, Fair Value Statement of Financial Position [Abstract] Units issued Limited Partners' Capital Account, Units Issued Units outstanding Limited Partners' Capital Account, Units Outstanding ASSETS Assets [Abstract] Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable—Westlake Chemical Corporation (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 other assets, net Other Assets, Noncurrent 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 15) 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 Total liabilities and equity Liabilities and Equity Schedule Of Inventory Schedule of Inventory, Current [Table Text Block] Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Inventories Inventory Disclosure [Text Block] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [Member] Westlake Chemical OpCo LP [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] Number of site lease agreements Lessee Leasing Arrangements, Operating Leases, Number Lessee Leasing Arrangement, Operating Leases, Number Lease term Lessee Leasing Arrangements, Operating Leases, Term of Contract Operating lease rent expense Operating Leases, Rent Expense Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Accounts receivable—Westlake, current and non-current Accounts Receivable, Related parties, Current and Noncurrent Accounts Receivable, Related parties, Current and Noncurrent Accounts payable—Westlake Schedule of Limited Partners' Capital Account by Class [Table] Schedule of Limited Partners' Capital Account by Class [Table] Common units [Member] Subordinated units [Member] Limited Partners' Capital Account [Line Items] Limited Partners' Capital Account [Line Items] Subsequent distribution to IDR holders Net income Weighted average units outsanding: Basic and diluted (shares) Net income per limited partner unit: Long-term Debt Payable to Westlake Related Party Transactions, Long-term Debt [Text Block] Related Party Transactions, Long-term Debt [Text Block] Derivative [Table] Derivative [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Contract [Member] Interest Rate Contract [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Interest Expense [Member] Interest Expense [Member] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash Flow Hedging [Member] Cash Flow Hedging [Member] Deferred charges and other assets, net [Member] Other Assets [Member] Derivative [Line Items] Derivative [Line Items] Loss recognized in statement of operations Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion Change in value recognized in other comprehensive loss Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Financial Instruments [Abstract] Financial Instruments [Abstract] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] 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] Statement of Comprehensive Income [Abstract] Change in fair value of cash flow hedge Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Reclassification of loss to net income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interest in OpCo Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to Westlake Chemical Partners LP Comprehensive Income (Loss), Net of Tax, Attributable to Parent Supplemental Information Additional Financial Information Disclosure [Text Block] 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 Cash and Cash Equivalents [Table] Schedule of Cash and Cash Equivalents [Table] Investments by Category [Axis] Investments by Category [Axis] Marketable Securities and Investments Held at Cost [Domain] Marketable Securities and Investments Held at Cost [Domain] Held-to-maturity Securities [Member] Held-to-maturity Securities [Member] Cash and Cash Equivalents [Line Items] Cash and Cash Equivalents [Line Items] Cash Equivalents, at Carrying Value Cash Equivalents, at Carrying Value 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] Subsequent Event [Table] Subsequent Event [Table] Subsequent Event [Line Items] Subsequent Event [Line Items] Distribution declared and paid to IDR holders Westlake [Member] Shortfall percentage threshold Shortfall percentage threshold Shortfall percentage threshold Buyer deficiency fee Buyer deficiency fee Buyer deficiency fee Equity [Abstract] Accumulated Other Comprehensive (Loss) Income Comprehensive Income (Loss) Note [Text Block] Other Assets, Noncurrent [Abstract] Other Assets Other Assets Disclosure [Text Block] Related Party Transactions Related Party Transactions Disclosure [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Interest rate contract transfers between Level 1 and Level 2 fair value, amount Interest rate contract transfers between Level 1 and Level 2 fair value, amount Interest rate contract transfers between Level 1 and Level 2 fair value, amount 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. Risks and Uncertainties [Abstract] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Net sales [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] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Concentration Risk [Line Items] Concentration Risk [Line Items] Concentration risk percentage of net sales Concentration Risk, Percentage 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 Limited partner interest Limited Liability Company (LLC) or Limited Partnership (LP), 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 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 Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Derivative Instruments Derivatives, Policy [Policy Text Block] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Balance at beginning of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Interest rate contract - Other comprehensive loss before reclassification Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Interest rate contract - Amounts reclassified to net income Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Balance at end of period Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Schedule Of Other Assets [Table] Other Assets [Member] Other Assets [Line Items] Other Assets [Line Items] Other Assets [Line Items] Amortization expense Amortization Major Customer and Concentration of Credit Risk Concentration Risk Disclosure [Text Block] Schedule of Accumulated Other Comprehensive (Loss) Income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate [Member] Prime Rate [Member] LIBOR [Member] London Interbank Offered Rate (LIBOR) [Member] Weighted average interest rate Long-term Debt, Weighted Average Interest Rate Basis spread on variable rate, percent Debt Instrument, Basis Spread on Variable Rate Accrued Liabilities [Abstract] Accrued Liabilities [Abstract] Accrued capital expenditures Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Accrued interest Accrued taxes Accrued Income Taxes, Current Accrued Turnaround Costs, Current Accrued Turnaround Costs, Current Accrued Turnaround Costs, 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 Proceeds from involuntary conversion of assets Insurance Proceeds for Involuntary Conversion Insurance Proceeds for Involuntary Conversion Financial Instruments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] 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 Provision for doubtful accounts Provision for Doubtful Accounts (Gain)/loss from disposition of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Gain on involuntary conversion of assets (Gain) Loss on Involuntary Conversion of Assets (Gain) Loss on Involuntary Conversion of Assets Deferred income taxes Deferred Income Tax Expense (Benefit) 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 Proceeds from disposition of assets Proceeds from Sale of Property, Plant, and Equipment 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 increase (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 Accounts Receivable - Third Parties Loans, Notes, Trade and Other Receivables Disclosure [Text Block] 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 Distributions and Net Income Per Limited Partner Unit Earnings Per Share [Text Block] 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 Depreciation expense on property, plant and equipment Depreciation