Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

Portion of the carrying amount as of the balance sheet date of obligations due all related parties that is payable after one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.23)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

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- Definition

The cash inflow from a long-term borrowing made from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth. Alternate caption: Proceeds from Advances from Affiliates.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

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- 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.

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- Definition

Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Additional Ownership Interest

+ References

No definition available.

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Long-term Debt Payable to Westlake (Details) - USD ($) $ in Thousands				3 Months Ended		12 Months Ended
	Mar. 29, 2019	Sep. 29, 2017	Apr. 01, 2015	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Proceeds from debt payable to Westlake				$ 123,512	$ 3,648
Long-term debt payable to Westlake				$ 601,119		$ 477,608
Weighted average interest rate				4.80%		4.40%
Limited Partner [Member] \| OpCo Revolver [Member] \| Senior Unsecured Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake				$ 224,064		$ 224,064
Limited Partner [Member] \| OpCo Revolver [Member] \| Senior Unsecured Revolving Credit Facility [Member] \| LIBOR [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				2.00%		2.00%
Limited Partner [Member] \| MLP Revolver [Member] \| Senior Unsecured Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake				$ 377,055		$ 253,544
Limited Partner [Member] \| MLP Revolver [Member] \| Senior Unsecured Revolving Credit Facility [Member] \| LIBOR [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent				2.00%		2.00%
Westlake Chemical OpCo LP [Member] \| Affiliated Entity [Member]
Related Party Transaction [Line Items]
Proceeds from debt payable to Westlake	$ 123,512
Limited partner interest, additional ownership	4.50%	5.00%	2.70%