XML 57 R44.htm IDEA: XBRL DOCUMENT
v3.25.4

Agreements with Westlake and Related Parties (Details) |  |  | 12 Months Ended |
--- | --- | --- | --- | ---
Oct. 28, 2025 | Aug. 04, 2014 USD ($) lease lb $ / lb | Dec. 31, 2025 USD ($) lb $ / lb | Dec. 31, 2024 USD ($)
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Term of Investment Management Agreement with Related Party, Maximum |  |  | 9 months |
IMA, Partnership earned amount added to market rate, basis points |  |  | five |
Receivables under Investment Management Agreements with Related Parties, Current | $ |  |  | $ 23,378,000 | $ 134,557,000
Westlake Chemical OpCo LP | Ethylene Sales Agreement | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Long-Term Purchase Commitment, Renewal Term | 12 months |  |  |
Westlake Chemical OpCo LP | Feedstock Supply Agreement | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Long-Term Purchase Commitment, Renewal Term | 12 months |  |  |
Westlake Chemical OpCo LP | Exchange Agreement |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Purchase commitment, fixed margin on variable pricing | $ / lb |  |  | 0.006 |
Exchange agreement amount of purchase agreement | lb |  |  | 200,000,000 |
Westlake Chemical OpCo LP | Westlake | Ethylene Sales Agreement | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Minimum percentage required to be purchased |  | 95.00% |  |
Maximum mass required to be purchased | lb |  | 3,800,000,000 |  |
Long-term Purchase Commitment, Excess Production Percentage |  | 95.00% |  |
Number of years used to calculate average expenses |  | 5 years |  |
Purchase commitment, fixed margin on variable pricing | $ / lb |  | 0.10 |  |
Long-term Purchase Commitment, Curtail Option Percentage |  | 5.00% |  |
Long-term Purchase Commitment, Compliance Surcharge Amount | $ |  | $ 500,000 |  |
Westlake Chemical OpCo LP | Westlake | Excess Production Option | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Purchase commitment, fixed margin on variable pricing | $ / lb |  | 0.10 |  |
Westlake Chemical OpCo LP | Westlake | Feedstock Supply Agreement | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Long-Term Purchase Commitment, Renewal Term |  |  | 12 months |
Westlake Chemical OpCo LP | Westlake | Services And Secondment Agreement | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Period of default in performance that can allow a party to terminate agreement |  | 30 days |  |
Westlake Chemical OpCo LP | Westlake | Site Lease Agreement | Investee |  |  |  |
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract] |  |  |  |
Number of lease agreements | lease |  | 2 |  |
Operating lease, rental amount | $ |  | $ 1 |  |
Term of operating lease |  | 50 years |  |

X
- Definition Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line. + References No definition available. + Details
Name: | us-gaap_LeaseAndRentalExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LongTermCommitmentExcludingUnconditionalPurchaseObligationAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition IMA, Partnership earned amount added to market rate, basis points + References No definition available. + Details
Name: | wlkp_IMAPartnershipEarnedAmountAddedToMarketRateBasisPoints
Namespace Prefix: | wlkp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessee Leasing Arrangement, Operating Leases, Number + References No definition available. + Details
Name: | wlkp_LesseeLeasingArrangementsOperatingLeasesNumber
Namespace Prefix: | wlkp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Long-term Purchase Commitment, Compliance Surcharge + References No definition available. + Details
Name: | wlkp_LongTermPurchaseCommitmentComplianceSurchargeAmount
Namespace Prefix: | wlkp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Curtail Option Percentage + References No definition available. + Details
Name: | wlkp_LongTermPurchaseCommitmentCurtailOptionPercentage
Namespace Prefix: | wlkp_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Excess Production Percentage + References No definition available. + Details
Name: | wlkp_LongTermPurchaseCommitmentExcessProductionPercentage
Namespace Prefix: | wlkp_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-Term Purchase Commitment, Renewal Term + References No definition available. + Details
Name: | wlkp_LongTermPurchaseCommitmentRenewalTerm
Namespace Prefix: | wlkp_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Exchange Fee, Fixed Margin + References No definition available. + Details
Name: | wlkp_LongtermPurchaseCommitmentExchangeFeeFixedMargin
Namespace Prefix: | wlkp_
Data Type: | srt-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Maximum Volume Required + References No definition available. + Details
Name: | wlkp_LongtermPurchaseCommitmentMaximumVolumeRequired
Namespace Prefix: | wlkp_
Data Type: | dtr-types:massItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Minimum Percentage Required + References No definition available. + Details
Name: | wlkp_LongtermPurchaseCommitmentMinimumPercentageRequired
Namespace Prefix: | wlkp_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Terms of Fee, Number Of Years Used To Calculate Average Expenses + References No definition available. + Details
Name: | wlkp_LongtermPurchaseCommitmentTermsofFeeNumberOfYearsUsedToCalculateAverageExpenses
Namespace Prefix: | wlkp_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Purchase Commitment, Purchase Agreement, Mass + References No definition available. + Details
Name: | wlkp_PurchaseCommitmentPurchaseAgreementMass
Namespace Prefix: | wlkp_
Data Type: | dtr-types:massItemType
Balance Type: | na
Period Type: | duration

X
- Definition Receivables under Investment Management Agreements with Related Parties, Current + References No definition available. + Details
Name: | wlkp_ReceivablesunderInvestmentManagementAgreementswithRelatedPartiesCurrent
Namespace Prefix: | wlkp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Related Party Transaction, Counterparty Default, Period Of Default, Allowing Termination Of Agreement + References No definition available. + Details
Name: | wlkp_RelatedPartyTransactionCounterpartyDefaultPeriodOfDefaultAllowingTerminationOfAgreement
Namespace Prefix: | wlkp_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Term of Investment Management Agreement with Related Party, Maximum + References No definition available. + Details
Name: | wlkp_TermofInvestmentManagementAgreementwithRelatedPartyMaximum
Namespace Prefix: | wlkp_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_CounterpartyNameAxis=wlkp_WestlakeChemicalOpCoLPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=wlkp_EthyleneSalesAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_InvesteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=wlkp_FeedstockSupplyAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=wlkp_ExchangeAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=wlkp_ParentCompanyAndSubsidiariesExcludingReportingEntityAndSubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=wlkp_ExcessProductionOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=wlkp_ServicesAndSecondmentAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=wlkp_SiteLeaseAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |