The total amount of dividends declared in the period for each class of stock and the contractual amount of dividends (or interest on participating income bonds) that must be paid for the period (for example, unpaid cumulative dividends). Dividends declared in the current period do not include dividends declared in respect of prior-period unpaid cumulative dividends. Preferred dividends that are cumulative only if earned are deducted only to the extent that they are earned.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780133-109256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60A
-URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780132-109256

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e2740-109256

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 66
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e2814-109256

+ Details

Name:	us-gaap_DistributedEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Per unit of ownership amount of cash distributions declared to unit-holder of a limited partnership (LP).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DistributionMadeToLimitedPartnerLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of incentive obligation paid in cash or stock during the period to a limited liability corporation managing member or limited partnership general partner.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_IncentiveDistributionDistributionPerYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of limited partner units outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_NetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The earnings that is allocated to common stock and participating securities to the extent that each security may share in earnings as if all of the earnings for the period had been distributed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 65
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e2793-109256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60A
-URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780132-109256

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 66
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e2814-109256

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e2740-109256

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780133-109256

+ Details

Name:	us-gaap_UndistributedEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Incentive Distribution, Marginal Percentage Interest in Distributions

+ References

No definition available.

+ Details

Name:	wlkp_IncentiveDistributionMarginalPercentageInterestinDistributions
Namespace Prefix:	wlkp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Incentive Distribution, Quarterly Distribution Per Unit, Distribution Threshold

+ References

No definition available.

+ Details

Name:	wlkp_IncentiveDistributionQuarterlyDistributionPerUnitDistributionThreshold
Namespace Prefix:	wlkp_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders

+ References

No definition available.

+ Details

Name:	wlkp_IncentiveDistributionRightsTargetDistributionPerUnitRequiringMarginalPercentageDistributiontoIDRHolders
Namespace Prefix:	wlkp_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	wlkp_IncentiveDistributionSubsequentDistributionAmount
Namespace Prefix:	wlkp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Minimum Quarterly Distribution Per Unit

+ References

No definition available.

+ Details

Name:	wlkp_MinimumQuarterlyDistributionPerUnit
Namespace Prefix:	wlkp_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_IncentiveDistributionMadeToManagingMemberOrGeneralPartnerAxis=wlkp_IDRHoldersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LimitedPartnersCapitalAccountByClassAxis=wlkp_CommonUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=wlkp_ParentCompanyAndSubsidiariesExcludingReportingEntityAndSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LimitedPartnersCapitalAccountByClassAxis=wlkp_SubordinatedUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis=us-gaap_CashDistributionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LimitedPartnersCapitalAccountByClassAxis=wlkp_CommonAndSubordinatedUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis=wlkp_CashDistributionTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncentiveDistributionMadeToManagingMemberOrGeneralPartnerAxis=wlkp_UnitHoldersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis=wlkp_CashDistributionTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis=wlkp_CashDistributionTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Distributions and Net Income Per Limited Partner Unit (Distributions Declared) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Nov. 01, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Aug. 30, 2017	Dec. 31, 2016
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		$ 13,385	$ 8,661	$ 33,124	$ 30,089
Distributions declared		12,605	9,164	32,639	26,603
(Distribution in excess of net income) net income in excess of distribution		780	(503)	485	3,486
IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		498	91	1,052	139
Distribution declared with respect to the incentive distribution rights		498	91	1,052	139
(Distribution in excess of net income) net income in excess of distribution		0	0	0	0
Common units [Member]
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		12,887	4,552	23,078	15,909
Distributions declared		12,107	4,819	22,454	14,057
(Distribution in excess of net income) net income in excess of distribution		$ 780	(267)	$ 624	1,852
Common units [Member] \| Westlake [Member]
Distribution Made to Limited Partner [Line Items]
Units outstanding		14,122,230		14,122,230			1,436,115
Subordinated units [Member]
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		$ 0	4,018	$ 8,994	14,041
Distributions declared		0	4,254	9,133	12,407
(Distribution in excess of net income) net income in excess of distribution		$ 0	(236)	$ (139)	1,634
Subordinated units [Member] \| Westlake [Member]
Distribution Made to Limited Partner [Line Items]
Units outstanding		0		0		12,686,115	12,686,115
Cash Distribution [Member] \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Distribution declared with respect to the incentive distribution rights		$ 498	91	$ 1,052	139
Cash Distribution [Member] \| IDR Holders [Member] \| Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Distribution declared and paid to IDR holders	$ 498
Cash Distribution [Member] \| Common units [Member]
Distribution Made to Limited Partner [Line Items]
Minimum quarterly distribution per unit (in usd per unit)				$ 0.2750
Distributions declared		12,107	4,819	$ 22,454	14,057
Cash Distribution [Member] \| Subordinated units [Member]
Distribution Made to Limited Partner [Line Items]
Distributions declared		$ 0	$ 4,254	$ 9,133	$ 12,407
Cash Distribution [Member] \| Common And Subordinated Units [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)				$ 0.3163
Cash Distribution [Member] \| Common And Subordinated Units [Member] \| Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Distribution declared per unit (in usd per unit)	$ 0.3756
Above $0.3163 up to $0.3438 \| Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)				0.3163
Above $0.3163 up to $0.3438 \| Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)				$ 0.3438
Above $0.3163 up to $0.3438 \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions				15.00%
Above $0.3163 up to $0.3438 \| Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions				85.00%
Above $0.3438 up to $0.4125 \| Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)				$ 0.3438
Above $0.3438 up to $0.4125 \| Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Quarterly incentive distribution, per unit, distribution threshold				$ 0.4125
Above $0.3438 up to $0.4125 \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions				25.00%
Above $0.3438 up to $0.4125 \| Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions				75.00%
Above $0.4125 \| Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Quarterly incentive distribution, per unit, distribution threshold				$ 0.4125
Above $0.4125 \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions				50.00%
Above $0.4125 \| Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions				50.00%