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Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2014	Mar. 02, 2015	Jun. 30, 2014
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Entity Registrant Name	WESTLAKE CHEMICAL PARTNERS LP
Entity Central Index Key	0001604665
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0
Common units [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		14,373,615
Subordinated units [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		12,686,115

Combined and Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 133,750	$ 0
Accounts receivable, net—Westlake Chemical Corporation (Westlake)	18,529
Accounts receivable, net—third parties	37,520
Inventories	6,634
Prepaid expenses and other current assets	212
Deferred income taxes	0
Total current assets	196,645
Property, plant and equipment, net	842,057
Equity investment	0
Other assets, net
Goodwill and intangible assets, net	5,814
Deferred charges and other assets	51,919
Total other assets, net	57,733
Total assets	1,096,435
Current liabilities
Accounts payable—Westlake	7,470
Accounts payable—third parties	12,614
Accrued liabilities	11,900
Total current liabilities	31,984
Long-term debt payable to Westlake	227,638
Deferred income taxes	1,848
Other liabilities	15
Total liabilities	261,485
Commitments and contingencies (Notes 9 and 19)
NET INVESTMENT
Net investment	0
Total Westlake Chemical Partners LP partners' capital	87,524
Noncontrolling interest in Westlake Chemical OpCo LP (OpCo)	747,426
Total equity	834,950	455,432
Total liabilities and equity	1,096,435
Predecessor [Member]
Current assets
Cash and cash equivalents		0
Accounts receivable, net—Westlake Chemical Corporation (Westlake)		0
Accounts receivable, net—third parties		71,812
Inventories		116,377
Prepaid expenses and other current assets		257
Deferred income taxes		4,448
Total current assets		192,894
Property, plant and equipment, net		762,972
Equity investment		10,411
Other assets, net
Goodwill and intangible assets, net		5,873
Deferred charges and other assets		69,324
Total other assets, net		75,197
Total assets		1,041,474
Current liabilities
Accounts payable—Westlake		0
Accounts payable—third parties		122,564
Accrued liabilities		26,688
Total current liabilities		149,252
Long-term debt payable to Westlake		252,973
Deferred income taxes		182,855
Other liabilities		962
Total liabilities		586,042
Commitments and contingencies (Notes 9 and 19)
NET INVESTMENT
Net investment		455,432
Total Westlake Chemical Partners LP partners' capital		455,432
Noncontrolling interest in Westlake Chemical OpCo LP (OpCo)		0
Total equity	0	455,432
Total liabilities and equity		1,041,474
Limited Partner [Member] \| Common units [Member] \| Public [Member]
NET INVESTMENT
Limited partners' capital	290,377
Total equity	290,377
Limited Partner [Member] \| Common units [Member] \| Public [Member] \| Predecessor [Member]
NET INVESTMENT
Limited partners' capital		0
Limited Partner [Member] \| Common units [Member] \| Westlake [Member]
NET INVESTMENT
Limited partners' capital	4,038
Total equity	4,038
Limited Partner [Member] \| Common units [Member] \| Westlake [Member] \| Predecessor [Member]
NET INVESTMENT
Limited partners' capital		0
Limited Partner [Member] \| Subordinated units [Member] \| Westlake [Member]
NET INVESTMENT
Limited partners' capital	35,681
Total equity	35,681
Limited Partner [Member] \| Subordinated units [Member] \| Westlake [Member] \| Predecessor [Member]
NET INVESTMENT
Limited partners' capital		0
General Partner [Member] \| Westlake [Member]
NET INVESTMENT
General partner—Westlake	(242,572)
Total equity	$ (242,572)
General Partner [Member] \| Westlake [Member] \| Predecessor [Member]
NET INVESTMENT
General partner—Westlake		$ 0

Consolidated Balance Sheets (Parenthetical) - shares	Dec. 31, 2014	Dec. 31, 2013
Common units [Member] \| Westlake [Member]
Units issued	1,436,115	0
Units outstanding	1,436,115	0
Common units [Member] \| Public [Member]
Units issued	12,937,500	0
Units outstanding	12,937,500	0
Subordinated units [Member] \| Westlake [Member]
Units issued	12,686,115	0
Units outstanding	12,686,115	0

Combined and Consolidated Statements of Operations - USD ($) $ in Thousands	5 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net sales - Westlake		$ 1,292,089
Net co-products, ethylene and feedstock sales—third parties		457,611
Net sales		1,749,700
Cost of sales		1,003,888
Gross profit		745,812
Selling, general and administrative expenses		29,256
Income from operations		716,556
Other income (expense)
Interest expense—Westlake		(10,499)
Other income, net		3,151
Income before income taxes		709,208
Provision for income taxes	$ 1,065	199,388
Net income	148,486	$ 509,820	$ 546,546	$ 395,920
Less: Net income attributable to noncontrolling interest in OpCo	134,909
Limited partners' interest in net income subsequent to IPO	$ 13,577
Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering per limited partner unit (basic and diluted)
Income per limited partner unit (usd per unit)	$ 0.50
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (units)	27,059,730
Common units [Member]
Other income (expense)
Limited partners' interest in net income subsequent to IPO	$ 7,213
Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering per limited partner unit (basic and diluted)
Income per limited partner unit (usd per unit)	$ 0.50
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (units)	14,373,615
Subordinated units [Member]
Other income (expense)
Limited partners' interest in net income subsequent to IPO	$ 6,364
Net income attributable to Westlake Chemical Partners LP subsequent to initial public offering per limited partner unit (basic and diluted)
Income per limited partner unit (usd per unit)	$ 0.50
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (units)	12,686,115
Public [Member] \| Common units [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (units)	12,937,500
Westlake [Member] \| Common units [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (units)	1,436,115
Westlake [Member] \| Subordinated units [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (units)	12,686,115
Predecessor [Member]
Net sales - Westlake			1,603,043	1,507,501
Net co-products, ethylene and feedstock sales—third parties			524,704	741,597
Net sales			2,127,747	2,249,098
Cost of sales			1,255,140	1,613,446
Gross profit			872,607	635,652
Selling, general and administrative expenses			25,451	24,103
Income from operations			847,156	611,549
Other income (expense)
Interest expense—Westlake			(8,032)	(8,937)
Other income, net			7,701	4,186
Income before income taxes			846,825	606,798
Provision for income taxes			300,279	210,878
Net income			$ 546,546	$ 395,920

Combined and Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Noncontrolling Interest in OpCo [Member]	Westlake [Member] General Partner [Member]	Common units [Member] Public [Member] Limited Partner [Member]	Common units [Member] Westlake [Member] Limited Partner [Member]	Subordinated units [Member] Westlake [Member] Limited Partner [Member]
Equity, beginning balance (Predecessor [Member]) at Dec. 31, 2011	$ 216,705
Equity, beginning balance at Dec. 31, 2011	216,705
Net income \| Predecessor [Member]	395,920
Net income	395,920
Net distributions to Westlake \| Predecessor [Member]	(338,813)
Net distributions to Westlake	(338,813)
Equity, ending balance (Predecessor [Member]) at Dec. 31, 2012	273,812
Equity, ending balance at Dec. 31, 2012	273,812
Net income \| Predecessor [Member]	546,546
Net income	546,546
Net distributions to Westlake \| Predecessor [Member]	(603,526)
Net distributions to Westlake	(603,526)
Contribution of debt payable to Westlake into net investment \| Predecessor [Member]	238,600
Contribution of debt payable to Westlake into net investment	238,600
Equity, ending balance (Predecessor [Member]) at Dec. 31, 2013	455,432
Equity, ending balance at Dec. 31, 2013	455,432
Net income	509,820
Equity, ending balance (Predecessor [Member]) at Dec. 31, 2014	0
Equity, ending balance at Dec. 31, 2014	$ 834,950	$ 747,426	$ (242,572)	$ 290,377	$ 4,038	$ 35,681

Combined and Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net income	$ 509,820	$ 546,546	$ 395,920
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	77,611
Provision for doubtful accounts	65
Loss from disposition of fixed assets	1,544
Deferred income taxes	8,608
Income from equity method investment, net of dividends	1,073
Changes in operating assets and liabilities
Accounts receivable - third parties	(31,551)
Net accounts receivable - Westlake	(11,059)
Inventories	24,686
Prepaid expenses and other current assets	(624)
Accounts payable	(4,915)
Accrued and other liabilities	20,166
Other, net	8,588
Net cash provided by operating activities	604,012
Cash flows from investing activities
Additions to property, plant and equipment	(202,823)
Settlements of derivative instruments	(133)
Net cash used for investing activities	(202,956)
Cash flows from financing activities
Net distributions to Westlake prior to initial public offering	(448,101)
Repayment of debt payable to Westlake with proceeds from the initial public offering	(78,940)
Net proceeds from issuance of common units	286,088
Proceeds from initial public offering distributed to Westlake	(151,729)
Proceeds from debt payable to Westlake	181,642
Quarterly distribution for the period from August 4, 2014 to September 30, 2014 to noncontrolling interest retained in OpCo by Westlake	(51,655)
Quarterly distributions to unitholders	(4,611)
Net cash used for financing activities	(267,306)
Net increase in cash and cash equivalents	133,750
Cash and cash equivalents at beginning of period	0
Cash and cash equivalents at end of period	133,750	0
Predecessor [Member]
Cash flows from operating activities
Net income		546,546	395,920
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		73,463	64,257
Provision for doubtful accounts		40	82
Loss from disposition of fixed assets		1,905	2,834
Deferred income taxes		37,054	(8,096)
Income from equity method investment, net of dividends		402	277
Changes in operating assets and liabilities
Accounts receivable - third parties		14,352	13,612
Net accounts receivable - Westlake		0
Inventories		(6,057)	53,061
Prepaid expenses and other current assets		(150)	164
Accounts payable		7,362	(34,937)
Accrued and other liabilities		(20,852)	17,717
Other, net		(51,556)	(8,070)
Net cash provided by operating activities		602,509	496,821
Cash flows from investing activities
Additions to property, plant and equipment		(223,130)	(158,440)
Settlements of derivative instruments		(6,920)	432
Net cash used for investing activities		(230,050)	(158,008)
Cash flows from financing activities
Net distributions to Westlake prior to initial public offering		(603,526)	(338,813)
Repayment of debt payable to Westlake with proceeds from the initial public offering		0	0
Net proceeds from issuance of common units		0	0
Proceeds from initial public offering distributed to Westlake		0	0
Proceeds from debt payable to Westlake		231,067	0
Quarterly distribution for the period from August 4, 2014 to September 30, 2014 to noncontrolling interest retained in OpCo by Westlake		0	0
Quarterly distributions to unitholders		0	0
Net cash used for financing activities		(372,459)	(338,813)
Net increase in cash and cash equivalents		0	0
Cash and cash equivalents at beginning of period	$ 0	0	0
Cash and cash equivalents at end of period		$ 0	$ 0

Description Of Business And Significant Accounting Policies

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description Of Business And Significant Accounting Policies

Description of Business and Significant Accounting Policies

Description of Business, Formation of Partnership and Initial Public Offering

Westlake Chemical Partners LP ("Westlake Chemical Partners LP" or the "Partnership") is a Delaware limited partnership formed in March 2014 to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, the Partnership completed an initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests. In connection with the IPO, the Partnership acquired a 10.6% interest in Westlake Chemical OpCo LP ("OpCo") and a 100% interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), which is the general partner of OpCo. OpCo owns three ethylene production facilities and a common carrier ethylene pipeline (collectively, the "Contributed Assets").

Unless the context otherwise requires, references in these financial statements to the "Predecessor" refer to Westlake Chemical Partners LP Predecessor, the Partnership's predecessor for accounting purposes and refer to the time periods prior to the IPO. References in these financial statements to the Partnership, OpCo and OpCo GP used in the present tense or prospectively refer to the period subsequent to the IPO. References to "Westlake" refer collectively to Westlake Chemical Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.

Prior to the IPO, the Predecessor generated revenue predominantly by selling ethylene and ethylene co-products to Westlake and external customers. The Predecessor typically shipped ethylene, propylene and hydrogen via pipeline systems that connected its ethylene plants to Westlake and numerous third-party customers. The Predecessor transported its butadiene and pyrolysis gasoline by rail or truck.

In connection with the IPO, OpCo and Westlake entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which the Partnership generates a substantial majority of its revenue. The Ethylene Sales Agreement has a 12-year initial term and a minimum commitment provision under which Westlake has agreed to purchase 95% of OpCo's planned ethylene production each year, subject to a maximum of 3.8 billion pounds per year. This agreement represents a long-term, minimum-purchase commitment by Westlake with variable pricing equal to OpCo's actual feedstock and natural gas costs and estimated other costs of producing ethylene, plus a fixed margin of $0.10 per pound, less revenue from associated co-products sales. Currently, the Partnership expects to sell 95% of its ethylene production to Westlake. For more information, see Note 2 to the combined and consolidated financial statements.

The Partnership sells ethylene production in excess of volumes sold to Westlake, as well as all of the co-products resulting from the ethylene production, including propylene, crude butadiene, pyrolysis gasoline and hydrogen, directly to third parties on either a spot or contract basis. Co-products sold to third parties continue to be transported by rail or truck. Net proceeds (after transportation and other costs) from the sales of ethylene co-products that result from the production of ethylene purchased by Westlake are netted against the ethylene price charged to Westlake under the Ethylene Sales Agreement, thereby reducing the Partnership's exposure to fluctuations in the market prices of these co-products. The Partnership's operations consist of one reportable segment: ethylene production.

The Predecessor's operations consisted of the entire ethylene business of Westlake, including the activities of the Contributed Assets, as well as activities which were retained by Westlake. Ethylene business activities retained by Westlake include, but are not limited to, procuring feedstock, managing inventory and commodity risk and transporting ethylene from manufacturing facilities. The Partnership's operations consist of activities relating solely to the Contributed Assets.

Basis of Presentation

The accompanying combined and consolidated financial statements have been prepared in conformity with the accounting principles generally accepted in the United States.

Financial information presented for the periods prior to the IPO consists of the Predecessor's combined financial position as of December 31, 2013, its results of operations, changes in equity and cash flows for the years ended December 31, 2013 and 2012. Financial information of the Predecessor is derived from the financial statements and accounting records of Westlake. Subsequent to the IPO, the Partnership's financial position, results of operations and cash flows consist of the consolidated activities and balances of the Partnership. The Partnership's consolidated financial statements include the accounts of the Partnership and its consolidated subsidiaries, including OpCo.

For the year ended December 31, 2014, the results of operations, changes in equity and cash flows include the Partnership's consolidated results subsequent to the IPO and the Predecessor's combined results prior to the IPO. For these periods, the results of operations and cash flows are referred to as the Partnership's consolidated results and cash flows.

The Partnership holds a 10.6% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 89.4% limited partner interest in OpCo is owned directly by Westlake, which has no rights to direct the activities that most significantly impact the economic performance of OpCo. As a result of the fact that substantially all of OpCo's activities are conducted on behalf of Westlake, and the fact that OpCo exhibits disproportionality of voting rights to economic interest, OpCo was deemed to be a variable interest entity. The Partnership, through its ownership of OpCo's general partner, has the power to direct the activities that most significantly impact the economic performance of OpCo, and it also has the obligation or right to absorb losses or receive benefits from OpCo that could potentially be significant to OpCo. As such, the Partnership was determined to be OpCo's primary beneficiary and therefore consolidates OpCo's results of operations and financial position. Westlake's retained interest of 89.4% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.

All financial information presented for the periods after the IPO represents the consolidated results of operations, financial position and cash flows of the Partnership. Financial information for the periods prior to the IPO represents the combined results of operations, financial position and cash flows of the Predecessor. The combined and consolidated financial statements were prepared as follows:


•	The consolidated statement of operations for the year ended December 31, 2014 consists of the consolidated results of the Partnership for the period from August 4, 2014 through December 31, 2014 and the combined results of the Predecessor for the period from January 1, 2014 through August 3, 2014 and for the years ended December 31, 2013 and 2012.


•	The consolidated balance sheet as of December 31, 2014 consists of the consolidated balances of the Partnership, while the combined balance sheet as of December 31, 2013 consists of the combined balances of the Predecessor.


•	The consolidated statement of cash flows for the year ended December 31, 2014 consists of the consolidated results of the Partnership for the period from August 4, 2014 through December 31, 2014 and the combined results of the Predecessor for the period from January 1, 2014 through August 3, 2014 and for the years ended December 31, 2013 and 2012.

•

The consolidated statement of changes in equity for the year ended December 31, 2014 consists of the combined activity for the Predecessor prior to August 4, 2014, and the consolidated activity for the Partnership at and subsequent to the IPO on August 4, 2014 through December 31, 2014. The combined statements of changes in equity for the years ended December 31, 2013 and 2012 consist entirely of the combined activity of the Predecessor.

The combined statements of operations for the periods before August 4, 2014 include expense allocations for certain functions historically performed by Westlake and allocated to the ethylene business, including allocations of general corporate expenses related to finance, legal, information technology, human resources, communications, ethics and compliance, shared services, employee benefits and incentives and stock-based compensation. These allocations were based primarily on direct usage, when identifiable, with the remainder allocated on the basis of fixed assets, headcount or other measures. Management believes the assumptions underlying the combined financial statements, including the assumptions regarding the allocation of expenses from Westlake, are reasonable and reflect all costs related to the operations of the Predecessor, including those incurred by Westlake on behalf of the Predecessor. Nevertheless, the combined financial statements may not include all of the expenses that would have been incurred had the Predecessor been a stand-alone company during the periods presented and may not reflect its results of operations, financial position and cash flows had the Predecessor been a stand-alone company during the periods presented.

With respect to the Predecessor, Westlake used a centralized approach to the cash management and financing of its operations. The cash generated by the Predecessor's operations was transferred to Westlake daily, and Westlake funded the Predecessor's operating and investing activities as needed. Accordingly, the cash and cash equivalents generated by the Predecessor's operations that were held by Westlake were not presented in its combined financial statements for any of the periods presented. The Predecessor reflected transfers of cash to and from Westlake's cash management system as a component of Net investment on its combined balance sheet, and as part of Net distributions to Westlake prior to the initial public offering on its combined statements of cash flows.

Cash and Cash Equivalents

Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.

Allowance for Doubtful Accounts

The determination of the allowance for doubtful accounts is based on estimation of the amount of accounts receivable that the Partnership believes are unlikely to be collected. Estimating this amount requires analysis of the financial strength of the Partnership's customers, the use of historical experience, the Partnership's accounts receivable aged trial balance and specific collectibility analysis. The allowance for doubtful accounts is reviewed quarterly. Past due balances over 90 days and high risk accounts, as determined by the analysis of financial strength of customers, are reviewed individually for collectibility.

Inventories

Inventories primarily include product, material and supplies. Inventories are stated at the lower of cost or market. Cost is determined using the first-in, first-out ("FIFO") or average method.

Property, Plant and Equipment

Property, plant and equipment are carried at cost, net of accumulated depreciation. Cost includes expenditures for improvements and betterments that extend the useful lives of the assets and interest capitalized on significant capital projects. Historical costs include expenditures for improvements and betterments that extend the useful lives of the assets.

Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Capitalized interest was $2,638 for the period from August 4, 2014 to December 31, 2014. Repair and maintenance costs are charged to operations as incurred.

The accounting guidance for asset retirement obligations requires the recording of liabilities equal to the fair value of asset retirement obligations and corresponding additional asset costs, when there is a legal asset retirement obligation as a result of existing or enacted law, statute or contract. The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. Settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period.

Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:



Classification		Years

Buildings and improvements		25
Plant and equipment		25
Ethylene pipeline		35
Other		3-10

Impairment of Long-Lived Assets

The accounting guidance for the impairment or disposal of long-lived assets requires that the Partnership assess long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, including when negative conditions such as significant current or projected operating losses exist. Other factors considered by the Partnership when determining if an impairment assessment is necessary include, but are not limited to, significant changes or projected changes in supply and demand fundamentals (which would have a negative impact on operating rates or margins), new technological developments, new competitors with significant raw material or other cost advantages, adverse changes associated with the United States and world economies and uncertainties associated with governmental actions. Long-lived assets assessed for impairment are grouped at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future net undiscounted cash flows expected to be generated by the asset. Assets are considered to be impaired if the carrying amount of an asset exceeds the future undiscounted cash flows. The impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed of are reported at the lower of the carrying amount or estimated fair value less costs to sell.

Impairment of Intangible Assets

The accounting guidance for goodwill and intangible assets requires that goodwill and indefinite-lived intangible assets are tested for impairment at least annually. Other intangible assets with finite lives are amortized over their estimated useful life and reviewed for impairment in accordance with the provisions of the accounting guidance. As of December 31, 2014, the Partnership's recorded goodwill was $5,814. See Note 8 for more information on the Partnership's annual goodwill impairment test.

Turnaround Costs

The Partnership accounts for turnaround costs under the deferral method. Turnarounds are the scheduled and required shutdowns of specific operating units in order to perform planned major maintenance activities. The costs related to the significant overhaul and refurbishment activities include maintenance materials, parts and direct labor costs. The costs of the turnaround are deferred when incurred at the time of the turnaround and amortized (within depreciation and amortization) on a straight-line basis until the next planned turnaround, which ranges from three to six years. Deferred turnaround costs are presented as a component of other assets, net. The cash outflows related to these costs are included in operating activities in the consolidated statement of cash flows.

Exchanges

The Partnership enters into inventory exchange transactions with respect to ethylene. These exchanges are settled in like-kind quantities and are valued at lower of cost or market. The Predecessor entered into inventory exchange transactions with third parties, which involve fungible commodities. These exchanges are settled in like-kind quantities and are valued at lower of cost or market. Cost is determined using the FIFO method.

Concentration of Credit Risk

Financial instruments which potentially subject the Partnership to concentration of risk consist principally of trade receivables from third-party customers who purchase ethylene and ethylene co-products. The Partnership performs periodic credit evaluations, as applicable, of the customers' financial condition and generally does not require collateral. The Partnership maintains allowances for potential losses, as applicable.

Revenue Recognition

Revenue is recognized when persuasive evidence of an arrangement exists, products are delivered to the customer, the sales price is fixed or determinable, and collectibility is reasonably assured. Title and risk of loss passes to the customer upon delivery under executed customer purchase orders or contracts. Provisions for discounts, rebates and returns are provided for in the same period as the related sales are recorded.

Net Income per Unit

The accounting guidance for earnings per unit requires the Partnership to present basic earnings per unit and diluted earnings per unit. Net income per unit applicable to common limited partner units and to subordinated limited partner units is computed by dividing the respective limited partners' interest in net income by the weighted average number of common units, subordinated units and incentive distribution rights outstanding. Because the Partnership has more than one class of participating securities, it uses the two-class method when calculating the net income per unit applicable to limited partners. The classes of participating securities include common units and subordinated units. Diluted net income per limited partner unit is the same as basic net income per limited partner unit, as there were no potentially dilutive common or subordinated units outstanding as of December 31, 2014. During the periods presented prior to the IPO, the Predecessor was wholly owned by Westlake. Accordingly, the Predecessor has not presented net income per unit.

Price Risk Management

The accounting guidance for derivative instruments and hedging activities requires that the Partnership and the Predecessor recognize all derivative instruments on the balance sheet at fair value, and changes in the derivative's fair value must be currently recognized in earnings or comprehensive income, depending on the designation of the derivative. If the derivative is designated as a fair value hedge, the changes in the fair value of the derivative and of the hedged item attributable to the hedged risk are recognized in earnings. If the derivative is designated as a cash flow hedge, the effective portion of the change in the fair value of the derivative is recorded in comprehensive income and is recognized in the statement of operations when the hedged item affects earnings. Ineffective portions of changes in the fair value of cash flow hedges are recognized in earnings currently. During the years presented, neither the Partnership nor the Predecessor had cash flow hedges.

The Predecessor utilized commodity derivative instruments to reduce price risks by purchasing or selling futures on established exchanges. The Predecessor took both fixed and variable positions, depending upon anticipated future physical purchases and sales of these commodities. The fair value of derivative financial instruments was estimated using quoted market prices in active markets and observable market-based inputs or unobservable inputs that were corroborated by market data when active markets were not available. The Predecessor assessed both counterparty as well as its own nonperformance risk when measuring the fair value of derivative liabilities. The Predecessor did not consider its nonperformance risk to be significant. See Note 15 for a summary of the fair value of derivative instruments. The Partnership did not enter into such instruments since the date of the IPO on August 4, 2014.

Environmental Costs

Environmental costs relating to current operations are expensed or capitalized, as appropriate, depending on whether such costs provide future economic benefits. Remediation liabilities are recognized when the costs are considered probable and can be reasonably estimated. Measurement of liabilities is based on currently enacted laws and regulations, existing technology and undiscounted site-specific costs. Environmental liabilities in connection with properties that are sold or closed are realized upon such sale or closure, to the extent they are probable and estimable and not previously reserved. Recognition of any joint and several liabilities is based upon the Partnership's best estimate of its final pro rata share of the liability.

Fair Value of Financial Instruments

The amounts reported in the combined and consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The fair value of the Partnership's senior unsecured revolving credit facility and OpCo's promissory notes payable to Westlake, which were assumed by OpCo in connection with the IPO (the "August 2013 Promissory Notes"), at December 31, 2014, approximates the fair value due to the variable nature of the interest rate. The fair value of financial instruments is estimated using quoted market prices in active markets and observable market-based inputs or unobservable inputs that are corroborated by market data when active markets are not available. See Note 15 for more information on the fair value of financial instruments.

Income Taxes

The Partnership is a limited partnership and is treated as a partnership for U.S. federal income tax purposes and, therefore, is not liable for entity-level federal income taxes. The Partnership is, however, subject to state and local income taxes. The Predecessor's operating results were included in Westlake's consolidated U.S. federal and state income tax returns. Amounts presented in the combined financial statements prior to the IPO relate to income taxes that have been determined on a separate tax return basis, and the Predecessor's contribution to Westlake Chemical Corporation's net operating losses and tax credits have been included in the Predecessor's financial statements. The Predecessor utilized the liability method of accounting for deferred income taxes. Under the liability method, deferred tax assets or liabilities are recorded based upon temporary differences between the tax basis of assets and liabilities and their carrying values for financial reporting purposes. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities during the period. Valuation allowances were recorded against deferred tax assets when it was considered more likely than not that the deferred tax assets will not be realized on a separate tax return basis.

Employee Benefit Plans

The employees supporting the Predecessor's operations were employees of Westlake and its affiliates. Their payroll costs and employee benefit plan costs were charged to the Predecessor by Westlake. Westlake sponsors various employee pension and postretirement health and life insurance plans. The Predecessor was considered to have participated in multiemployer benefit plans of Westlake. As a participant in multiemployer benefit plans, the Predecessor recognized as expense in each period an allocation from Westlake, and the Predecessor did not recognize any employee benefit plan assets or liabilities except for accruals for contributions due.

Segment Reporting

The Partnership accounts for segment reporting in accordance with the Financial Accounting Standards Board guidance, which establishes standards for entities to report information about the operating segments and geographic areas in which they operate. The Partnership only operates one segment (ethylene production) and all of its operations are located in the United States.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Net Investment

In the combined balance sheets, Net investment represents Westlake's historical investment in the Predecessor, its accumulated net earnings after taxes, and the net effect of transactions with, and allocations from, Westlake.

Other Assets

Certain other assets (see Note 8) are amortized over periods ranging from five to 20 years using the straight-line method.

Comprehensive Income

The Partnership has reported no comprehensive income due to the absence of items of other comprehensive income in the years presented.

Initial Public Offering

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Initial Public Offering

Contributed Assets

In connection with the IPO, the Partnership acquired a 10.6% interest in OpCo and a 100% interest in OpCo GP. OpCo owns the Contributed Assets.

Other assets contributed to OpCo in conjunction with the IPO include the deferred turnaround costs associated with Lake Charles Olefins and Calvert City Olefins, co-products inventories, goodwill and other assets. Additionally, OpCo assumed the August 2013 Promissory Notes in the amount of $246,056.

The Predecessor's combined financial statements reflect certain assets, liabilities and business activities that were retained by Westlake and, therefore, are not reflected in the Partnership's consolidated financial statements. Assets and liabilities which are reflected in the Predecessor's combined financial statements but which were retained by Westlake include working capital accounts, ethylene and other inventories, an equity interest in a pipeline joint venture, deferred federal income taxes, certain long-term debt payable to Westlake and other long-term liabilities. Ethylene business activities retained by Westlake include, but are not limited to, procuring feedstock, managing inventory and commodity risk and transporting ethylene from manufacturing facilities. See Note 17 for details of the Predecessor's net liabilities retained by Westlake.

Initial Public Offering

On July 30, 2014, the Partnership's common units began trading on the New York Stock Exchange under the ticker symbol "WLKP." On August 4, 2014, the Partnership completed the IPO of 12,937,500 common units at a price to the public of $24.00 per unit ($22.53 per unit net of underwriting discount), including 1,687,500 common units that were issued pursuant to the exercise in full of the underwriters' over-allotment option.

In connection with the IPO, in exchange for Westlake's contribution of a 5.8% limited partner interest in OpCo and OpCo's general partner interest to the Partnership, Westlake received:


•	1,436,115 common units and 12,686,115 subordinated units; and


•	the Partnership's general partner interest and its incentive distribution rights.

The Partnership received net proceeds of $286,088 from the IPO, net of underwriting discounts, structuring fees and offering expenses of approximately $24,412. The Partnership used the net proceeds from the IPO to purchase an additional 4.8% limited partner interest in OpCo, resulting in the Partnership owning a 10.6% limited partner interest in OpCo. The Partnership recorded the incremental 4.8% limited partner interest in OpCo at its historical carrying value of $43,516 and the excess cash paid over historical carrying value of $242,572 as a decrease to the General partner—Westlake capital account. Accordingly, the Partnership's consolidated financial statements reflect the 89.4% limited partner interest in OpCo that was retained by Westlake as a noncontrolling interest.

From the period beginning August 4, 2012 to July 31, 2013, Westlake incurred approximately $151,729 in capital expenditures (the "Pre-August 2013 Capex") with respect to the assets contributed to OpCo. The portion of these capital expenditures incurred before January 1, 2013 was accounted for as an adjustment to Net investment, as it was funded through equity. The portion of the capital expenditures incurred from January 1, 2013 through July 31, 2013 was accounted for as a liability and is reflected as such on the Predecessor's combined financial statements, and the associated liability was retained by Westlake in connection with the IPO. During the period from August 1, 2013 through August 3, 2014, Westlake funded capital expenditures of $246,056 related to the Contributed Assets under the terms of the August 2013 Promissory Notes. At the close of the IPO, the outstanding balance of the August 2013 Promissory Notes was $246,056.

OpCo used the $286,088 it received from the Partnership in exchange for a 4.8% limited partner interest in OpCo to (1) establish a $55,419 turnaround reserve, (2) reimburse Westlake $151,729 for the Pre-August 2013 Capex, and (3) repay $78,940 of the August 2013 Promissory Notes assumed by OpCo. Immediately after the repayment, the outstanding indebtedness payable to Westlake under the August 2013 Promissory Notes was $167,116.

Agreements with Westlake and Related Parties

The agreements described below became effective on August 4, 2014, concurrent with the closing of the IPO.

Ethylene Sales Agreement

OpCo entered into a 12-year ethylene sales agreement with Westlake (the "Ethylene Sales Agreement"). The Ethylene Sales Agreement requires Westlake to purchase a minimum volume of ethylene each year equal to 95% of OpCo's planned ethylene production per year (the "Minimum Commitment"), subject to certain exceptions and a maximum commitment of 3.8 billion pounds per year. So long as Westlake is not in default under the Ethylene Sales Agreement, if OpCo's actual production exceeds planned production, Westlake has the option to purchase up to 95% of the excess production (the "Excess Production Option").

The fee for each pound of ethylene purchased by Westlake from OpCo up to the Minimum Commitment in any calendar year will equal:


•	the actual price OpCo pays Westlake to purchase ethane (or other feedstock, such as propane, if applicable) to produce each pound of ethylene, subject to a specified cap and a floor on the amount of feedstock that should be needed to produce each pound of ethylene; plus


•	the actual price OpCo pays Westlake to purchase natural gas to produce each pound of ethylene, subject to a specified cap and a floor on the amount of natural gas that should be needed to produce each pound of ethylene; plus


•	OpCo's estimated operating costs (including selling, general and administrative expenses), divided by OpCo's planned ethylene production for the year (in pounds); plus


•	a five-year average of OpCo's expected future maintenance capital expenditures and other turnaround expenditures, divided by OpCo's planned ethylene production capacity for the year (in pounds); less


•	the proceeds (on a per pound of ethylene basis) received by OpCo from the sale of co-products (including, but not limited to, propylene, crude butadiene, pyrolysis gasoline and hydrogen) associated with producing the ethylene purchased by Westlake; plus


•	a $0.10 per pound margin.

The fee for the Excess Production Option, if exercised, equals OpCo's estimated variable operating costs of producing the incremental ethylene, net of revenues from co-products sales plus a $0.10 per pound margin.

The estimated operating costs and the expected future maintenance capital expenditures and other turnaround expenditures will be adjusted at the end of each year, to be applicable for the fee for the next calendar year, to reflect certain changes in forecasted costs.

The result of the fee structure is that OpCo should recover the portion of its total operating costs and maintenance capital expenditures and other turnaround expenditures corresponding to the portion of OpCo's aggregate production that is purchased by Westlake. The Ethylene Sales Agreement has an initial term extending until December 31, 2026 and automatically renews thereafter for successive 12-month terms unless terminated.

Feedstock Supply Agreement

OpCo entered into a feedstock supply agreement with Westlake, pursuant to which Westlake agreed to sell to OpCo ethane and other feedstock in amounts sufficient for OpCo to produce the ethylene to be sold under the Ethylene Sales Agreement (the "Feedstock Supply Agreement"). The Feedstock Supply Agreement provides that OpCo may obtain feedstock from Westlake based on Westlake's total cost of purchasing and delivering the feedstock, including applicable transportation, storage and other costs. Title and risk of loss for all feedstock purchased by OpCo through the Feedstock Supply Agreement passes to OpCo upon delivery to one of three delivery points described in the Feedstock Supply Agreement.

The Feedstock Supply Agreement has an initial term extending until December 31, 2026 and automatically renews thereafter for successive 12-month terms unless terminated by either party; provided, however, that such agreement can only be renewed in the event the Ethylene Sales Agreement is renewed simultaneously. The Feedstock Supply Agreement may, in certain circumstances, terminate concurrently with the termination of the Ethylene Sales Agreement.

Services and Secondment Agreement

OpCo entered into a services and secondment agreement with Westlake, pursuant to which OpCo provides Westlake with certain services required for the operation of Westlake's facilities; and Westlake provides OpCo with comprehensive operating services for OpCo's facilities, ranging from services relating to the maintenance and operations of the common facilities necessary for the operation of OpCo's units, to making available certain shared utilities such as electricity and natural gas that are necessary for the operation of OpCo's units. Westlake also seconds employees to OpCo to allow OpCo to operate its facilities. Such seconded employees will be under the control of OpCo while they work on OpCo's facilities.

The services and secondment agreement has an initial 12-year term. The services and secondment agreement may be renewed thereafter upon agreement of the parties and shall automatically terminate if the Ethylene Sales Agreement terminates under certain circumstances. Westlake and OpCo each can terminate the services and secondment agreement under certain circumstances, including if the other party materially defaults on the performance of its obligations and such default continues for a 30-day period.

Site Lease Agreements

OpCo entered into two site lease agreements with Westlake pursuant to which Westlake leases to OpCo the real property underlying Lake Charles Olefins and Calvert City Olefins, respectively, and grants OpCo rights to access and use certain other portions of Westlake's ethylene production facilities that are necessary to operate OpCo's production facilities. OpCo owes Westlake one dollar per site per year. The site lease agreements each have a term of 50 years. Each of the site lease agreements may be renewed if agreed by the parties.

Omnibus Agreement

The Partnership entered into an omnibus agreement with Westlake that addresses (1) Westlake's indemnification of the Partnership for certain matters, including environmental and tax matters, (2) the provision by Westlake of certain management and other general and administrative services to the Partnership and its general partner and (3) the Partnership's reimbursement to Westlake for such services. The omnibus agreement also addresses Westlake's right of first refusal on any proposed transfer of the ethylene production facilities that serve Westlake's other facilities and Westlake's right of first refusal on any proposed transfer of the Partnership's equity interests in OpCo.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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-Number 210
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-Article 4

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-Number 210
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+ Details

Recent Accounting Pronouncements	12 Months Ended
Recent Accounting Pronouncements	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that will supersede the existing revenue recognition guidance. The new accounting guidance creates a framework by which an entity will allocate the transaction price to separate performance obligations and recognize revenue when each performance obligation is satisfied. Under the new standard, entities will be required to use judgment and make estimates, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price, allocating the transaction price to each separate performance obligation and determining when an entity satisfies its performance obligations. The standard allows for either "full retrospective" adoption, meaning that the standard is applied to all of the periods presented with a cumulative catch-up as of the earliest period presented, or "modified retrospective" adoption, meaning the standard is applied only to the most current period presented in the financial statements with a cumulative catch-up as of the current period. The accounting standard will be effective for reporting periods beginning after December 15, 2016. The Partnership is in the process of evaluating the impact that the new accounting guidance will have on its consolidated financial position, results of operations and cash flows. Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern In August 2014, the FASB issued an accounting standards update on management's responsibility to evaluate whether there is substantial doubt about an entity's ability to continue as a going concern. The new accounting guidance requires management to perform interim and annual assessments of an entity's ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if "conditions or events raise substantial doubt about the entity's ability to continue as a going concern." The accounting standard will be effective for reporting periods ending after December 15, 2016 and is not expected to have an impact on the Partnership's consolidated financial position, results of operations and cash flows.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Number 210
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+ Details

Financial Instruments	12 Months Ended
Financial Instruments	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Financial Instruments	Financial Instruments Cash Equivalents The Partnership had $40,003 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at December 31, 2014. The Partnership's investments in held-to-maturity securities are held at amortized cost, which approximates fair value.

Accounts Receivable—Third Parties

12 Months Ended

Dec. 31, 2014

Accounts Receivable, Net [Abstract]

Accounts Receivable—Third Parties

Accounts receivable—third parties consist of the following:



	December 31,
	2014		2013
			Predecessor
Trade customers	$	37,514	$	73,594
Allowance for doubtful accounts	—		(2,105		)
	37,514		71,489
Other	6		323
Accounts receivable, net—third parties	$	37,520	$	71,812

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventories

12 Months Ended

Dec. 31, 2014

Inventory, Net [Abstract]

Inventories

Inventories consist of the following:



	December 31,
	2014		2013
			Predecessor
Finished products	$	6,257	$	21,330
Feedstock, additives and chemicals	377		80,407
Materials and supplies	—		14,640
Inventories	$	6,634	$	116,377

Property, Plant And Equipment

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment, Net [Abstract]

Property, Plant And Equipment

Property, Plant and Equipment

Property, plant and equipment consist of the following:



	December 31,
	2014			2013
				Predecessor
Land	$	—		$	4,126
Building and improvements	14,961			32,941
Plant and equipment	1,151,091			1,058,304
Other	61,533			55,478
	1,227,585			1,150,849
Less: Accumulated depreciation	(550,568		)	(561,301		)
	677,017			589,548
Construction in progress	165,040			173,424
Property, plant and equipment, net	$	842,057		$	762,972

Depreciation expense on property, plant and equipment of $60,004, $57,299 and $53,125 is included in cost of sales in the combined and consolidated statements of operations for the years ended December 31, 2014, 2013 and 2012, respectively.

Other Assets

12 Months Ended

Dec. 31, 2014

Other Assets [Abstract]

Other Assets

Other assets consist of the following:



	December 31, 2014							December 31, 2013							Weighted Average Life
								Predecessor
	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
Intangible assets:
Technology	$	—	$	—		$	—	$	9,618	$	(9,618	)	$	—
Goodwill	5,814		—			5,814		5,814		—			5,814
Other	—		—			—		59		—			59
Total intangible assets	5,814		—			5,814		15,491		(9,618		)	5,873
Turnaround costs	96,835		(51,536		)	45,299		96,678		(34,537		)	62,141		5
Other	8,662		(2,042		)	6,620		8,662		(1,479		)	7,183		15
Total deferred charges and other assets	105,497		(53,578		)	51,919		105,340		(36,016		)	69,324
Other assets, net	$	111,311	$	(53,578	)	$	57,733	$	120,831	$	(45,634	)	$	75,197

Amortization expense on other assets of $17,607, $16,164 and $11,132 is included in the combined and consolidated statements of operations for the years ended December 31, 2014, 2013 and 2012, respectively.

At December 31, 2014, there were no scheduled amortizations of intangible assets in the next five years.

Goodwill

There was no change in the carrying amount of goodwill during 2014.

The impairment test for the recorded goodwill was performed in October 2014 and did not indicate impairment of the goodwill. The fair value of the goodwill was calculated using both a discounted cash flow methodology and a market value methodology. The discounted cash flow projections were based on a nine-year forecast, from 2015 to 2023, to reflect the cyclicality of the Partnership's business. The forecast was based on (1) prices and spreads projected by IHS Chemical, a chemical industry organization offering market and business advisory services for the chemical market, for the same period, and (2) estimates by management, including their strategic and operational plans. Other significant assumptions used in the discounted cash flow projection included sales volumes based on current capacities. The future cash flows were discounted to present value using a discount rate of 8.8%. The significant assumptions used in determining the fair value of the reporting unit using the market value methodology include the determination of appropriate market comparables and the estimated multiples of EBITDA a willing buyer is likely to pay. Under the discounted cash flow methodology, even if the fair value of OpCo decreased by 10%, the carrying value of OpCo would not exceed its fair value.

Long-Term Debt

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Long-Term Debt

Long-term debt consists of the following:



	December 31,
	2014		2013
			Predecessor
2006 Pipeline Note (variable interest rate of prime plus 0.25%, original scheduled maturity of November 30, 2016)	$	—	$	14,400
August 2013 Promissory Notes (variable interest rate of prime plus 1.5%, original scheduled maturity of August 1, 2023)	167,116		238,573
Senior unsecured revolving credit facility (variable interest rate of LIBOR plus 3.0%, original scheduled maturity of August 4, 2019)	60,522		—
Long-term debt payable to Westlake	$	227,638	$	252,973

In 2013, the August 2013 Promissory Notes were issued for capital expenditures incurred by Westlake on behalf of the Predecessor's operations. Proceeds drawn under the August 2013 Promissory Notes during 2014 were used to fund capital expenditures at the Predecessor's ethylene plants. In connection with the IPO, OpCo assumed the August 2013 Promissory Notes and used proceeds from the IPO to repay a portion of the balance it assumed. See Note 2 for a description of the August 2013 Promissory Notes and proceeds used to repay balances of such promissory notes assumed in connection with the IPO.

In connection with the IPO on August 4, 2014, OpCo entered into a senior unsecured revolving credit facility with Westlake. The credit facility accrues interest quarterly at a rate of LIBOR plus 3.0%, which may be paid-in-kind as an addition to the principal at OpCo's option.

As of December 31, 2014, the Partnership was in compliance with all of the covenants with respect to the August 2013 Promissory Notes and the revolving credit facility.

The weighted average interest rate on all long-term debt was 4.35% and 4.69% at December 31, 2014 and 2013, respectively.

As of December 31, 2014, the Partnership had no maturities of long-term debt until 2019. The Partnership's revolving credit facility matures on August 4, 2019, and the August 2013 Promissory Notes mature on August 1, 2023.

Net Income Per Limited Partner Unit

12 Months Ended

Dec. 31, 2014

Earnings Per Share [Abstract]

Net Income Per Limited Partner Unit

Net income per unit applicable to common limited partner units and to subordinated limited partner units is computed by dividing the respective limited partners' interest in net income for the period subsequent to the IPO by the weighted-average number of common units and subordinated units outstanding for the period. Because the Partnership has more than one class of participating securities, Partnership uses the two-class method when calculating the net income per unit applicable to limited partners. The classes of participating securities include common units, subordinated units and incentive distribution rights. Basic and diluted net income per unit is the same because the Partnership does not have any potentially dilutive units outstanding for the periods presented.

On October 28, 2014, the Board of Directors of Westlake Chemical Partners GP LLC, the Partnership's general partner, declared an initial prorated quarterly cash distribution for the period from August 4, 2014 through September 30, 2014 of $0.1704 per unit, or $4,611 in total. This distribution was paid on November 25, 2014 to unitholders of record as of November 10, 2014.

On January 30, 2015, the Board of Directors of Westlake Chemical Partners GP LLC declared a quarterly cash distribution for the period from October 1, 2014 to December 31, 2014 of $0.2750 per unit, or $7,441 in total. This distribution was paid on February 24, 2015 to unitholders of record as of February 9, 2015.



	Year Ended December 31, 2014
Net income attributable to the Partnership subsequent to the IPO	$	13,577
Less:
Limited partners' distribution declared on common units	6,403
Limited partners' distribution declared on subordinated units	5,649
Net income subsequent to the IPO in excess of distribution	$	1,525



	December 31, 2014
	Limited Partners' Common Units		Limited Partners' Subordinated Units		Incentive Distribution Rights		Total
Net income attributable to the Partnership subsequent to the IPO:
Distribution	$	6,403	$	5,649	$	—	$	12,052
Net income subsequent to the IPO in excess of distribution	810		715		—		1,525
Net income subsequent to the IPO	$	7,213	$	6,364	$	—	$	13,577
Weighted average units outstanding:
Basic and diluted	14,373,615		12,686,115				27,059,730
Net income per limited partner unit:
Basic and diluted	$	0.50	$	0.50			$	0.50

Related Party Transactions

12 Months Ended

Dec. 31, 2014

Related Party Transactions

The Partnership and OpCo regularly enter into related party transactions with Westlake. See below for a description of transactions with related parties.

Sales to Related Parties

OpCo sells ethylene to Westlake under the Ethylene Sales Agreement. Additionally, the Partnership and OpCo from time to time provide other services or products for which it charges Westlake a fee. Prior to the IPO, the Predecessor sold the majority of its ethylene to Westlake for use in Westlake's downstream operations.

Sales to related parties were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Net sales—Westlake	$	1,292,089	$	1,603,043	$	1,507,501

Cost of Sales from Related Parties

Charges for goods and services purchased by the Partnership and OpCo from Westlake and included in cost of sales relate primarily to feedstock purchased under the Feedstock Supply Agreement and services provided under the services and secondment agreement. Prior to the IPO, services provided by Westlake and included in cost of sales related primarily to services provided by employees of Westlake Management Services, Inc., a subsidiary of Westlake. The cost of services provided by employees of Westlake Management Services, Inc. was allocated to the Predecessor's operations primarily on the basis of direct usage.

Charges from related parties in cost of sales were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Feedstock purchased from Westlake and included in cost of sales	$	155,232	$	—	$	—
Other charges from Westlake and included in cost of sales	60,264		61,770		57,454
Total	$	215,496	$	61,770	$	57,454

Services from Related Parties Included in Selling, General and Administrative Expenses

Charges for services purchased by the Partnership from Westlake and included in selling, general and administrative expenses primarily relate to services Westlake performs on behalf of the Partnership under the Omnibus Agreement, including the Partnership's finance, legal, information technology, human resources, communication, ethics and compliance and other administrative functions. Prior to the IPO, the Predecessor was allocated costs incurred by Westlake on its behalf for similar functions. These allocations were based primarily on the basis of direct usage when identifiable, with the remainder allocated on the basis of fixed assets, headcount or other measure.

Charges from related parties included within selling, general and administrative expenses were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Services received from Westlake and included in selling, general and administrative expenses	$	21,302	$	24,054	$	22,485

Goods and Services from Related Parties Capitalized as Assets

Charges for goods and services purchased by the Partnership and OpCo from Westlake which were capitalized as assets relate primarily to the services of Westlake employees under the Services and Secondment Agreement. Prior to the IPO, salaries and benefits of Westlake Management Services, Inc. were allocated to the Predecessor primarily on the basis of direct usage.

Charges from related parties for goods and services capitalized as assets were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Goods and services purchased from Westlake and capitalized as assets	$	5,823	$	20,222	$	8,902

Accounts Receivable from and Accounts Payable to Related Parties

The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake under the Ethylene Sales Agreement. The Partnership's accounts payable to Westlake result primarily from feedstock purchases under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement and the omnibus agreement. Prior to the IPO, ethylene sales and other transactions between the Predecessor and Westlake were settled immediately through net investment and, therefore, the Predecessor did not have related party accounts receivable or related party accounts payable balances.

The related party accounts receivable and accounts payable balances were as follows:



	December 31,
	2014		2013
			Predecessor
Accounts receivable, net—Westlake	$	18,529	$	—
Accounts payable—Westlake	7,470		—

Debt Payable to Related Parties

OpCo assumed the August 2013 Promissory Notes and entered into a senior unsecured revolving credit facility with Westlake in connection with the IPO. Prior to the IPO, the Predecessor funded certain capital expenditures through the August 2013 Promissory Notes payable to Westlake which were assumed by the Partnership in connection with the IPO. See Note 9 for a description of related party debt payable balances. Interest capitalized as a component of property, plant and equipment on related party debt was $2,638 for the period from August 4, 2014 to December 31, 2014. At December 31, 2014 and 2013, accrued interest on related party debt was $2,403 and $504, respectively, and is reflected as a component accrued liabilities. Additionally, at December 31, 2013, accrued interest of $7,506 was included as a component of the outstanding debt payable to Westlake.

Debt payable to related parties was as follows:



	December 31,
	2014		2013
			Predecessor
Long-term debt payable to Westlake	$	227,638	$	252,973

General

OpCo, together with other subsidiaries of Westlake not included in these combined and consolidated financial statements, are guarantors under Westlake's revolving credit facility and the indentures governing its senior notes. As of December 31, 2014, Westlake had outstanding letters of credit totaling $31,392 under its revolving credit facility and $754,000 principal amount outstanding under its senior notes (less the unamortized discount of $892).

The indentures governing Westlake's senior notes prevent OpCo from making distributions to the Partnership if any default or event of default (as defined in the indentures) exists. However, Westlake's credit facility does not prevent OpCo from making distributions to the Partnership.

Westlake uses a centralized cash management system to finance its operations. Interest paid, net of capitalized interest, and income taxes have been paid directly by Westlake and charged to the Predecessor through related party accounts receivable, net. Related party accounts receivable, net were settled immediately through net investment, and therefore, the Predecessor did not pay cash for interest expense or income tax expense during the years ended December 31, 2013 or 2012.

OpCo has entered into two site lease agreements with Westlake in connection with the IPO, and each has a term of 50 years. Pursuant to the site lease agreements, OpCo pays Westlake one dollar per site per year.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Partners' Equity

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Partners' Equity

Common Unit

As described below, the common unitholders have preference over subordinated unitholders on receipt of distributions, including, in certain circumstances, cash distributions upon liquidation, as set out in the Partnership's agreement of limited partnership (the "Partnership Agreement"). The common unitholders have limited rights on matters affecting Partnership's business, limited voting rights and are not entitled to elect the general partner or its directors.

Subordinated Unit

The subordinated unitholders have similar rights as the common unitholders. However, during the subordination period, the subordinated unitholders are not entitled to receive quarterly distributions from operating surplus until the common unitholders have received the minimum quarterly distribution from operating surplus and, among other things, in certain circumstances, are subordinated in the receipt of cash distributions upon liquidation. The subordination period will end on the first business day after the Partnership has earned and paid an aggregate amount of at least the minimum quarterly distribution multiplied by the total number of outstanding common and subordinated units for each of three consecutive, non-overlapping four-quarter periods ending on or after June 30, 2017 and there are no outstanding arrearages on the Partnership's common units. Notwithstanding the foregoing, the subordination period will end on the first business day after the Partnership has paid an aggregate amount of at least 150.0% of the minimum quarterly distribution on an annualized basis multiplied by the total number of outstanding common and subordinated units and have earned that amount plus the related distribution on the incentive distribution rights, for any four-quarter period ending on or after June 30, 2015 and there are no outstanding arrearages on Partnership's common units.

Incentive Distribution Rights

The Partnership Agreement generally provides that the Partnership will distribute cash each quarter during the subordination period in the following manner: first, to the holders of common units, until each common unit has received the minimum quarterly distribution of $0.2750, plus any arrearages from prior quarters; second, to the holders of subordinated units, until each subordinated unit has received the minimum quarterly distribution of $0.2750; and third, to the holders of common and subordinated units, pro rata, until each unit has received a distribution of $0.3163. If cash distributions to the Partnership's unitholders exceed $0.3163 per common unit and subordinated unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations:



	Marginal Percentage Interest in Distributions
Total Quarterly Distribution Per Unit	Unitholders		IDR Holders
Above $0.3163 up to $0.3438	85.0	%	15.0	%
Above $0.3438 up to $0.4125	75.0	%	25.0	%
Above $0.4125	50.0	%	50.0	%

Unit-Based Compensation	12 Months Ended
Unit-Based Compensation	Dec. 31, 2014
Share-based Compensation [Abstract]
Unit-Based Compensation	Unit-based Compensation The Westlake Chemical Partners LP Long-Term Incentive Plan (the "Plan") was adopted on July 15, 2014 and provides for grants of unit options, restricted units, phantom units, unit awards, distribution equivalent rights ("DERs") and other unit-based awards. The purpose of the Plan is to attract and retain the services of individuals who are essential for the growth and profitability of the Partnership and to encourage such individuals to devote their best efforts to advancing the business of the Partnership and its affiliates. Awards under the Plan are determined by the board of directors of the Partnership's general partner or a committee thereof (the "Committee"). Under the Plan, DERs may be granted, which represent a contingent right to receive an amount in cash, units, restricted units and/or phantom units, as determined by the Committee at its sole discretion, equal in value to the cash distributions made by the Partnership with respect to a common unit during the period such award is outstanding. The terms and conditions of each award are determined by the Committee. The maximum number of common units of the Partnership that may be delivered with respect to awards under the Plan is 1,270,000. For the period from August 4, 2014 through December 31, 2014, 4,404 phantom units along with a corresponding number of DERs were granted to certain non-employee directors of the general partner of the Partnership, which awards will vest on the third anniversary of the grant date. Each phantom unit represents the right to receive, upon vesting, a cash payment equal to the fair market value of one Partnership common unit. Each DER has distribution rights only so long as the phantom units to which it relates to has not vested or been settled. The awards, which are classified as liability awards for financial accounting purposes, are re-measured (based on the closing price of the Partnership's common units on the New York Stock Exchange) at each reporting date until they vest. There were no forfeitures under the Plan through December 31, 2014. The total units available for grant at December 31, 2014 was 1,265,596. The total compensation cost recognized from August 4, 2014 through December 31, 2014 was $15, and is included in selling, general and administrative expenses and classified as a liability in the consolidated 2014 financial statements of the Partnership. The unrecognized compensation cost associated with all grants under the Plan during the year ended December 31, 2014 was $111.

Derivative Commodity Instruments

12 Months Ended

Dec. 31, 2014

Derivative Instruments and Hedges, Assets [Abstract]

Derivative Commodity Instruments

Commodity Risk Management

The Predecessor used derivative instruments to reduce price volatility risk on raw materials and products, as a substantial portion of its raw materials and products were commodities whose prices fluctuate as market supply and demand fundamentals change. The Predecessor employed strategies to protect against such instability, including ethylene product feedstock flexibility. The Predecessor did not use derivative instruments to engage in speculative activities. The Contributed Assets do not include the entity engaged in commodity risk management activities or any of its open derivative positions. The Partnership has not engaged in any hedging activity and did not use derivative instruments in the period subsequent to the IPO through December 31, 2014. Therefore, there are no derivative assets or liabilities reflected in the consolidated balance sheet of the Partnership as of December 3l, 2014.

For derivative instruments that are designated and qualify as fair value hedges, the gains or losses on the derivative instruments, as well as the offsetting losses or gains on the hedged items attributable to the hedged risk, were included in cost of sales in the combined and consolidated statements of operations for the years ended December 31, 2014, 2013 and 2012. The Partnership had no derivative instruments that were designated as fair value hedges subsequent to the IPO through December 31, 2014.

Gains and losses from changes in the fair value of derivative instruments that are not designated as hedging instruments were included in gross profit in the combined and consolidated statements of operations for the years ended December 31, 2014, 2013 and 2012. The Partnership had no derivative instruments that were not designated as hedging instruments subsequent to the IPO through December 31, 2014.

The exposure on commodity derivatives used for price risk management includes the risk that the counterparty will not pay if the market declines below the established fixed price. In such case, the derivative holder would lose the benefit of the derivative differential on the volume of the commodities covered. In any event, the derivative holders would continue to receive the market price on the actual volume hedged. Derivative holders also bear the risk of losing the benefit of market improvements over the fixed derivative price for the term and volume of the derivative instruments (as such improvements would accrue to the benefit of the counterparty).

Disclosures related to the Predecessor's derivative assets and derivative liabilities subject to enforceable master netting arrangements have not been presented as they were not material to the Predecessor's combined balance sheet at December 31, 2013. There was no open derivative position at December 31, 2014.

The fair values of derivative instruments in the combined and consolidated balance sheets were as follows:



	Asset Derivatives
	Balance Sheet Location	Fair Value as of December 31,
	Balance Sheet Location	2014		2013
				Predecessor
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	—	$	296
Total asset derivatives		$	—	$	296

	Liability Derivatives
	Balance Sheet Location	Fair Value as of December 31,
	Balance Sheet Location	2014		2013
				Predecessor
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	—	$	176
Total liability derivatives		$	—	$	176

The following tables reflect the impact of derivative instruments designated as fair value hedges and the related hedged item on the combined and consolidated statements of operations. There was no material ineffectiveness with regard to the Predecessor's qualifying hedges in 2013 and 2012.



Derivatives in Fair Value Hedging Relationships	Location of Gain (Loss) Recognized in Income on Derivative	Year Ended December 31,
Derivatives in Fair Value Hedging Relationships	Location of Gain (Loss) Recognized in Income on Derivative	2014		2013			2012
				Predecessor			Predecessor
Commodity forward contracts	Cost of sales	$	—	$	(303	)	$	17,163



Hedged Items in Fair Value Hedging Relationships	Location of Gain (Loss) Recognized in Income on Hedged Items	Year Ended December 31,
Hedged Items in Fair Value Hedging Relationships		2014		2013		2012
				Predecessor		Predecessor
Firm commitment designated as the hedged item	Cost of sales	$	—	$	143	$	(18,394	)

The impact of derivative instruments that have not been designated as hedges in the combined and consolidated statements of operations were as follows:



Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized in Income on Derivative	Year Ended December 31,
Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized in Income on Derivative	2014			2013		2012
					Predecessor		Predecessor
Commodity forward contracts	Gross profit	$	(9,244	)	$	5,438	$	(11,961	)

See Note 15 for the fair value of derivative instruments.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Partnership reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels:

Level 1: Quoted market prices in active markets for identical assets or liabilities.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data.

Level 3: Unobservable inputs that are not corroborated by market data.

There were no assets or liabilities accounted for at fair value on a recurring basis as of December 31, 2014. The following table summarizes, by level within the fair value hierarchy, the Predecessor's assets and liabilities that were accounted for at fair value on a recurring basis at December 31, 2013:



	December 31, 2013
	Level 1		Level 2			Total

	Predecessor
Derivative instruments
Risk management assets - Commodity forward contracts	$	48	$	248		$	296
Risk management liabilities - Commodity forward contracts	—		(176		)	(176		)

The Level 2 measurements for the Predecessor's commodity contracts are derived using forward curves supplied by industry recognized and unrelated third-party services. There were no transfers in and out of Levels 1 and 2 of the fair value hierarchy during 2014 and 2013.

The Partnership has other financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and long-term debt, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Partnership's and the Predecessor's long-term debt at December 31, 2014 and 2013 are summarized in the table below. The Partnership's long-term debt includes the August 2013 Promissory Notes and the senior unsecured revolving credit facility. The fair value of debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate.



	December 31, 2014				December 31, 2013
	Carrying Value		Fair Value		Carrying Value		Fair Value

					Predecessor
2006 Pipeline Note	$	—	$	—	$	14,400	$	13,922
August 2013 Promissory Notes	167,116		167,116		238,573		238,573
Senior unsecured revolving credit facility	60,522		60,522		—		—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Income Taxes

The components of income tax disaggregated between the Partnership and the Predecessor are as follows:



	Partnership		Predecessor
	Period from August 4, 2014 to December 31, 2014		Period from January 1, 2014 to August 3, 2014		Year Ended December 31,
	Period from August 4, 2014 to December 31, 2014		Period from January 1, 2014 to August 3, 2014			2013		2012
Current
Federal	$	—	$	168,773		$	233,014	$	196,467
State and local	800		21,207			30,211		22,507
	800		189,980			263,225		218,974
Deferred
Federal	—		6,890			32,675		(8,137		)
State and local	265		1,453			4,379		41
	265		8,343			37,054		(8,096		)
Total provision	$	1,065	$	198,323		$	300,279	$	210,878

The reconciliation of income tax expense at the U.S. statutory rate to the income tax expense disaggregated between the Partnership and the Predecessor is as follows:



	Partnership			Predecessor
	Period from August 4, 2014 to December 31, 2014			Period from January 1, 2014 to August 3, 2014			Year Ended December 31,
	Period from August 4, 2014 to December 31, 2014			Period from January 1, 2014 to August 3, 2014				2013			2012
Provision for federal income tax, at statutory rate	$	52,343		$	195,880			$	296,389		$	212,379
State income tax provision, net of federal income tax effect	1,065			14,729				22,484			14,656
Partnership income not subject to entity-level tax	(52,343		)	—				—			—
Manufacturing deduction	—			(12,214		)		(18,270		)	(16,065		)
Other, net	—			(72		)		(324		)	(92		)
	$	1,065		$	198,323			$	300,279		$	210,878

The tax effects of the principal temporary differences between financial reporting and income tax reporting are as follows:



	December 31,
	2014			2013
				Predecessor
Credit carryforward	$	—		$	25
Accruals	—			3,570
Allowance for doubtful accounts	—			(136		)
Inventories	—			1,313
Other	—			(373		)
Deferred taxes assets—total	—			4,399
Property, plant and equipment	(1,650		)	(159,033		)
Turnaround costs	(198		)	(23,773		)
Deferred tax liabilities—total	(1,848		)	(182,806		)
Total net deferred tax liabilities	$	(1,848	)	$	(178,407	)

Balance sheet classifications
Current deferred tax asset	$	—		$	4,448
Noncurrent deferred tax liability	(1,848		)	(182,855		)
Total net deferred tax liabilities	$	(1,848	)	$	(178,407	)

Supplemental Information

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Information

Net Liabilities Retained by Westlake

Net liabilities of the Predecessor that were retained by Westlake and not assumed by OpCo in connection with the IPO are composed of the following:



Net liabilities retained by Westlake
Accounts receivable, net—third parties	$	64,650
Inventories	85,057
Prepaid expenses and other current assets	669
Deferred income taxes	4,448
Property, plant and equipment, net	62,886
Equity investments	9,338
Accounts payable—third parties	(101,671		)
Accrued liabilities	(37,451		)
Deferred income taxes	(189,615		)
Long-term debt	(137,103		)
Other liabilities	(914		)
Total	$	(239,706	)

Accrued Liabilities

Accrued liabilities were $11,900 and $26,688 at December 31, 2014 and 2013, respectively. Accrued taxes, interest accrued on long-term debt and accrual related to capital expenditures, which are components of accrued liabilities, were $1,622, $2,403 and $5,026 at December 31, 2014, respectively. Accrued employee payroll and benefits, which is a component of accrued liabilities, was $10,598 at December 31, 2013. No other component of accrued liabilities was more than five percent of total current liabilities.

Other Income, Net



	Year Ended December 31,
	2014			2013			2012
				Predecessor			Predecessor
Income from equity method investment	$	2,973		$	4,711		$	4,172
Claims recovery	—			3,158			—
Franchise taxes	(11		)	(172		)	(144		)
Other	189			4			158
Other income, net	$	3,151		$	7,701		$	4,186

Cash Flow Information

Non-cash Operating Activity

The Predecessor settled $9,315 and $7,506 of its total interest expense incurred on long-term debt payable to Westlake as an addition to principal on debt outstanding in 2014 and 2013, respectively.

Non-cash Investing Activity

The change in capital expenditure accrual reducing additions to property, plant and equipment was $418, $7,937 and $1,333 for the years ended December 31, 2014, 2013 and 2012, respectively.

Non-cash Financing Activity

Related party notes payable to Westlake of $238,600 were deemed settled through net investment in 2013. The non-cash settlement was recorded as an increase in Westlake's net investment in the Predecessor. No cash was transferred in connection with the deemed settlement of these notes.

Interest and Income Taxes

Westlake uses a centralized cash management system to finance its operations. Interest paid, net of interest capitalized, and income taxes have been paid directly by Westlake and charged to the Predecessor through related party accounts receivable, net. Related party accounts receivable, net were settled immediately through net investment, and therefore, the Predecessor did not pay cash for interest expense or income tax expense during the years ended December 31, 2013 or 2012. Interest paid, net of interest capitalized was $1,366 for the year ended December 31, 2014.

Major Customer and Concentration Risk	12 Months Ended
Major Customer and Concentration Risk	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Major Customer and Concentration of Credit Risk	Major Customer and Concentration of Credit Risk During the years ended December 31, 2014, 2013 and 2012, Westlake accounted for approximately 73.8%, 75.3% and 67.0%, respectively, of the Partnership's and the Predecessor's net sales.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2014

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

The Partnership is subject to environmental laws and regulations that can impose civil and criminal sanctions and that may require the Partnership to mitigate the effects of contamination caused by the release or disposal of hazardous substances into the environment. These laws include the federal Clean Air Act, the federal Water Pollution Control Act, the Resource Conservation and Recovery Act ("RCRA"), the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), the Toxic Substances Control Act and various other federal, state and local laws and regulations. Under CERCLA, an owner or operator of property may be held strictly liable for remediating contamination without regard to whether that person caused the contamination, and without regard to whether the practices that resulted in the contamination were legal at the time they occurred. Because the Partnership's production sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on the Partnership. Westlake will indemnify the Partnership for liabilities that occurred or existed prior to August 4, 2014.

Contract Disputes with Goodrich and PolyOne. In connection with the 1990 and 1997 acquisitions of the Goodrich Corporation ("Goodrich") chemical manufacturing facility in Calvert City, Kentucky, which is a portion of the B.F. Goodrich superfund site, Goodrich agreed to indemnify Westlake for any liabilities related to preexisting contamination at the site. Westlake agreed to indemnify Goodrich for post-closing contamination caused by Westlake's operations. The soil and groundwater at the site had been extensively contaminated under Goodrich's operations. In 1993, Goodrich spun off the predecessor of PolyOne Corporation ("PolyOne"), and that predecessor assumed Goodrich's indemnification obligations relating to preexisting contamination.

In 2003, litigation arose among Westlake, Goodrich and PolyOne with respect to the allocation of the cost of remediating contamination at the site. The parties settled this litigation in December 2007, and the case was dismissed. In the settlement the parties agreed that, among other things: (1) PolyOne would pay 100% of the costs (with specified exceptions), net of recoveries or credits from third parties, incurred with respect to environmental issues at the Calvert City site from August 1, 2007 forward; (2) either Westlake or PolyOne might, from time to time in the future (but not more than once every five years), institute an arbitration proceeding to adjust that percentage; and (3) Westlake and PolyOne would negotiate a new environmental remediation utilities and services and secondment agreement to cover Westlake's provision to or on behalf of PolyOne of certain environmental remediation services at the site. The current environmental remediation activities at the Calvert City site do not have a specified termination date but are expected to last for the foreseeable future. The costs incurred by Westlake that have been invoiced to PolyOne to provide the environmental remediation services were $2,805 and $3,284 in 2014 and 2013, respectively. By letter dated March 16, 2010, PolyOne notified Westlake that it was initiating an arbitration proceeding under the settlement agreement. In this proceeding, PolyOne seeks to readjust the percentage allocation of costs and to recover approximately $1,400 from Westlake in reimbursement of previously paid remediation costs. The arbitration is currently stayed pending the outcome of discussions between other parties and their insurance carriers.

State Administrative Proceedings. There are several administrative proceedings in Kentucky involving Westlake, Goodrich and PolyOne related to the same manufacturing site in Calvert City, which includes OpCo's ethylene production facility in Calvert City. In 2003, the Kentucky Environmental and Public Protection Cabinet (the "Cabinet") re-issued Goodrich's RCRA permit which requires Goodrich to remediate contamination at the Calvert City manufacturing site. Both Goodrich and PolyOne challenged various terms of the permit in an attempt to shift Goodrich's clean-up obligations under the permit to Westlake. Westlake intervened in the proceedings. The Cabinet has suspended all corrective action under the RCRA permit in deference to a remedial investigation and feasibility study ("RIFS") being conducted, under the auspices of the U.S. Environmental Protection Agency ("EPA") pursuant to an Administrative Settlement Agreement ("AOC"), which became effective on December 9, 2009. See "Federal Administrative Proceedings" below. Periodic status conferences will be held to evaluate whether additional proceedings will be required.

Federal Administrative Proceedings. In May 2009, the Cabinet sent a letter to the EPA requesting the EPA's assistance in addressing contamination at the Calvert City site under CERCLA. In its response to the Cabinet, the EPA stated that it concurred with the Cabinet's request and would incorporate work previously conducted under the Cabinet's RCRA authority into the EPA's cleanup efforts under CERCLA. Since 1983, the EPA has been addressing contamination at an abandoned landfill adjacent to the Partnership's plant which had been operated by Goodrich and which was being remediated pursuant to CERCLA. The EPA has directed Goodrich and PolyOne to conduct additional investigation activities at the landfill and at the Calvert City site. In June 2009, the EPA notified Westlake that Westlake may have potential liability under section 107(a) of CERCLA at its plant site. Liability under section 107(a) of CERCLA is strict and joint and several. The EPA also identified Goodrich and PolyOne, among others, as potentially responsible parties at the plant site. Westlake negotiated, in conjunction with the other potentially responsible parties, an AOC and an order to conduct an RIFS. Due to the Partnership's ownership and current operation of the property, the Partnership may be subject to additional requirements and liabilities under CERCLA.

Potential Flare Modifications. For several years, the EPA has been conducting an enforcement initiative against petroleum refineries and petrochemical plants with respect to emissions from flares. A number of companies have entered into consent agreements with the EPA requiring both modifications to reduce flare emissions and the installation of additional equipment to better track flare operations and emissions. On April 21, 2014, Westlake received a Clean Air Act Section 114 Information Request from the EPA which sought information regarding flares at the Calvert City and Lake Charles facilities. Westlake submitted information pursuant to such request, including information regarding three flares that the Partnership owns. The EPA has informed Westlake that the information provided leads the EPA to believe that some of the flares are out of compliance with applicable standards. The EPA has demanded that Westlake conduct additional flare sampling and provide supplemental information. Westlake is currently in negotiations with the EPA regarding these demands, some of which are applicable to the Partnership's flares. The EPA has indicated that it is seeking a consent decree with that would obligate Westlake to take corrective actions relating to the alleged noncompliance. Westlake has not agreed that any flares are out of compliance or that any corrective actions are warranted. Depending on the outcome of Westlake's negotiations with the EPA, additional controls on emissions from the Partnership's flares may be required and these could result in increased capital and operating costs.

Louisiana Notice of Violations. The Louisiana Department of Environmental Quality ("LDEQ") has issued notices of violations ("NOVs") regarding the Partnership's assets, and those of Westlake, for various air compliance issues. The Partnership and Westlake are working with LDEQ to settle these claims, and a global settlement of all claims is being discussed. While settlement may result in a total civil penalty in excess of $100, such a settlement will likely cover assets owned by the Partnership and Westlake, and to the extent it covers the Partnership's assets, Westlake will indemnify the Partnership for liabilities to the extent such liabilities occurred or existed prior to August 4, 2014.

In addition to the matters described above, the Partnership is involved in various legal proceedings incidental to the conduct of its business. The Partnership does not believe that any of these legal proceedings will have a material adverse effect on its financial condition, results of operations or cash flows.

Other Commitments

The Partnership is obligated under various long-term and short-term noncancelable operating leases, primarily related to rail car leases and land. Several of the leases provide for renewal terms. At December 31, 2014, future minimum lease commitments were as follows:



2015	$	1,041
2016	604
2017	443
2018	127
2019	59
Thereafter	98
	$	2,372

Rental expense was approximately $3,558, $3,933 and $2,999 for the years ended December 31, 2014, 2013 and 2012, respectively.

The Partnership has various purchase commitments for its capital projects and for materials, supplies and services incident to the ordinary conduct of business. Such commitments are at prices not in excess of market prices.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Distribution On January 30, 2015, the Board of Directors of the Partnership's general partner declared a quarterly distribution of $0.2750 per unit, or $7,441 in total, which was paid on February 24, 2015 to unitholders of record as of February 9, 2015. General The financial statements of the Partnership are substantially comprised of the financial statements of OpCo, which issued its annual financial statements on February 25, 2015. Accordingly, the Partnership has evaluated transactions for consideration as recognized subsequent events in the annual financial statements through the date of February 25, 2015. Additionally, the Partnership has evaluated transactions that occurred as of the issuance of these financial statements, on March 9, 2015, for purposes of disclosure of unrecognized subsequent events.

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (Unaudited)



	Three Months Ended
	March 31, 2014		June 30, 2014		September 30, 2014		December 31, 2014
	Predecessor		Predecessor
Net sales	$	560,014	$	524,135	$	392,008	$	273,543
Gross profit	232,314		246,546		164,993		101,959
Income from operations	224,536		240,381		156,133		95,506
Net income	143,874		153,844		118,173		93,929
Net income attributable to Westlake Chemical Partners LP subsequent to the IPO and limited partners' interest in net income
Basic and diluted earnings per common unitholder ⁽¹⁾⁽²⁾					$	0.19	$	0.32
Basic and diluted earnings per subordinated unitholder ⁽¹⁾⁽²⁾					$	0.19	$	0.32

	Three Months Ended
	March 31, 2013		June 30, 2013		September 30, 2013		December 31, 2013
	Predecessor		Predecessor		Predecessor		Predecessor
Net sales	$	500,917	$	524,759	$	540,133	$	561,938
Gross profit	190,010		238,155		212,981		231,461
Income from operations	183,839		231,391		206,590		225,336
Net income	120,725		149,034		132,581		144,206

______________________________


(1)	Represents quarterly net income per common and subordinated unit since the completion of the Partnership's IPO on August 4, 2014. See Note 10 to the combined and consolidated financial statements.

(2)

Basic and diluted earnings per common and subordinated unit ("EPU") for each quarter is computed using the weighted average units outstanding during that quarter, while EPU for the period from August 4, 2014 through December 31, 2014 is computed using the weighted average units outstanding for the period. As a result, the sum of the EPU for each of the quarters subsequent to the IPO may not equal the EPU for the period from August 4, 2014 through December 31, 2014.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2014

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

SCHEDULE II

VALUATION AND QUALIFYING ACCOUNTS

(dollars in thousands)



Accounts Receivable Allowance for Doubtful Accounts	Balance at Beginning of Year		Charged to Expense		Additions/ (Deductions) ⁽¹⁾			Balance at End of Year
2014	$	2,105	$	65	$	(2,170	)	$	—
2013	2,065		40		—			2,105
2012	1,983		82		—			2,065

______________________________


(1)	Represents adjustment for assets retained by Westlake pursuant to the IPO.

Description Of Business And Significant Accounting Policies (Policy)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description Of Business

Description of Business, Formation of Partnership and Initial Public Offering

Basis of Presentation

The accompanying combined and consolidated financial statements have been prepared in conformity with the accounting principles generally accepted in the United States.


•	The consolidated statement of operations for the year ended December 31, 2014 consists of the consolidated results of the Partnership for the period from August 4, 2014 through December 31, 2014 and the combined results of the Predecessor for the period from January 1, 2014 through August 3, 2014 and for the years ended December 31, 2013 and 2012.


•	The consolidated balance sheet as of December 31, 2014 consists of the consolidated balances of the Partnership, while the combined balance sheet as of December 31, 2013 consists of the combined balances of the Predecessor.


•	The consolidated statement of cash flows for the year ended December 31, 2014 consists of the consolidated results of the Partnership for the period from August 4, 2014 through December 31, 2014 and the combined results of the Predecessor for the period from January 1, 2014 through August 3, 2014 and for the years ended December 31, 2013 and 2012.

•

Cash And Cash Equivalents

Cash and Cash Equivalents

Cash equivalents consist of highly liquid investments that are readily convertible into cash and have a maturity of three months or less at the date of acquisition.

Allowance For Doubtful Accounts

Allowance for Doubtful Accounts

Inventories

Inventories primarily include product, material and supplies. Inventories are stated at the lower of cost or market. Cost is determined using the first-in, first-out ("FIFO") or average method.

Property, Plant and Equipment

Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:



Classification		Years

Buildings and improvements		25
Plant and equipment		25
Ethylene pipeline		35
Other		3-10

Impairment Of Long-Lived Assets and Intangible Assets

Impairment of Long-Lived Assets

Impairment of Intangible Assets

Turnaround Costs

Exchanges

Concentration Of Credit Risk

Concentration of Credit Risk

Revenue Recognition

Net Income per Unit

Price Risk Management

Environmental Costs

Fair Value Of Financial Instruments

Fair Value of Financial Instruments

Income Taxes

Employee Benefit Plans

Segment Reporting

Use Of Estimates

Use of Estimates

Other Assets

Certain other assets (see Note 8) are amortized over periods ranging from five to 20 years using the straight-line method.

Comprehensive Income

The Partnership has reported no comprehensive income due to the absence of items of other comprehensive income in the years presented.

Description Of Business And Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule Of Estimated Useful Lives Of Assets

Depreciation is provided by utilizing the straight-line method over the estimated useful lives of the assets as follows:



Classification		Years

Buildings and improvements		25
Plant and equipment		25
Ethylene pipeline		35
Other		3-10

Accounts Receivable—Third Parties (Tables)

12 Months Ended

Dec. 31, 2014

Accounts Receivable, Net [Abstract]

Schedule Of Accounts Receivable

Accounts receivable—third parties consist of the following:



	December 31,
	2014		2013
			Predecessor
Trade customers	$	37,514	$	73,594
Allowance for doubtful accounts	—		(2,105		)
	37,514		71,489
Other	6		323
Accounts receivable, net—third parties	$	37,520	$	71,812

Inventories (Tables)

12 Months Ended

Dec. 31, 2014

Inventory, Net [Abstract]

Schedule Of Inventory

Inventories consist of the following:



	December 31,
	2014		2013
			Predecessor
Finished products	$	6,257	$	21,330
Feedstock, additives and chemicals	377		80,407
Materials and supplies	—		14,640
Inventories	$	6,634	$	116,377

Property, Plant And Equipment (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment, Net [Abstract]

Schedule Of Property, Plant And Equipment

Property, plant and equipment consist of the following:



	December 31,
	2014			2013
				Predecessor
Land	$	—		$	4,126
Building and improvements	14,961			32,941
Plant and equipment	1,151,091			1,058,304
Other	61,533			55,478
	1,227,585			1,150,849
Less: Accumulated depreciation	(550,568		)	(561,301		)
	677,017			589,548
Construction in progress	165,040			173,424
Property, plant and equipment, net	$	842,057		$	762,972

Other Assets (Tables)

12 Months Ended

Dec. 31, 2014

Other Assets [Abstract]

Schedule Of Other Assets

Other assets consist of the following:



	December 31, 2014							December 31, 2013							Weighted Average Life
								Predecessor
	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
Intangible assets:
Technology	$	—	$	—		$	—	$	9,618	$	(9,618	)	$	—
Goodwill	5,814		—			5,814		5,814		—			5,814
Other	—		—			—		59		—			59
Total intangible assets	5,814		—			5,814		15,491		(9,618		)	5,873
Turnaround costs	96,835		(51,536		)	45,299		96,678		(34,537		)	62,141		5
Other	8,662		(2,042		)	6,620		8,662		(1,479		)	7,183		15
Total deferred charges and other assets	105,497		(53,578		)	51,919		105,340		(36,016		)	69,324
Other assets, net	$	111,311	$	(53,578	)	$	57,733	$	120,831	$	(45,634	)	$	75,197

Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Schedule Of Long-Term Debt

Long-term debt consists of the following:



	December 31,
	2014		2013
			Predecessor
2006 Pipeline Note (variable interest rate of prime plus 0.25%, original scheduled maturity of November 30, 2016)	$	—	$	14,400
August 2013 Promissory Notes (variable interest rate of prime plus 1.5%, original scheduled maturity of August 1, 2023)	167,116		238,573
Senior unsecured revolving credit facility (variable interest rate of LIBOR plus 3.0%, original scheduled maturity of August 4, 2019)	60,522		—
Long-term debt payable to Westlake	$	227,638	$	252,973

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

+ Details

Net Income Per Limited Partner Unit (Tables)

12 Months Ended

Dec. 31, 2014

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted



	Year Ended December 31, 2014
Net income attributable to the Partnership subsequent to the IPO	$	13,577
Less:
Limited partners' distribution declared on common units	6,403
Limited partners' distribution declared on subordinated units	5,649
Net income subsequent to the IPO in excess of distribution	$	1,525



	December 31, 2014
	Limited Partners' Common Units		Limited Partners' Subordinated Units		Incentive Distribution Rights		Total
Net income attributable to the Partnership subsequent to the IPO:
Distribution	$	6,403	$	5,649	$	—	$	12,052
Net income subsequent to the IPO in excess of distribution	810		715		—		1,525
Net income subsequent to the IPO	$	7,213	$	6,364	$	—	$	13,577
Weighted average units outstanding:
Basic and diluted	14,373,615		12,686,115				27,059,730
Net income per limited partner unit:
Basic and diluted	$	0.50	$	0.50			$	0.50

Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2014

Schedule of Related Party Transactions

Charges from related parties in cost of sales were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Feedstock purchased from Westlake and included in cost of sales	$	155,232	$	—	$	—
Other charges from Westlake and included in cost of sales	60,264		61,770		57,454
Total	$	215,496	$	61,770	$	57,454

Sales to related parties were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Net sales—Westlake	$	1,292,089	$	1,603,043	$	1,507,501

The related party accounts receivable and accounts payable balances were as follows:



	December 31,
	2014		2013
			Predecessor
Accounts receivable, net—Westlake	$	18,529	$	—
Accounts payable—Westlake	7,470		—

Charges from related parties for goods and services capitalized as assets were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Goods and services purchased from Westlake and capitalized as assets	$	5,823	$	20,222	$	8,902

Charges from related parties included within selling, general and administrative expenses were as follows:



	Year Ended December 31,
	2014		2013		2012
			Predecessor		Predecessor
Services received from Westlake and included in selling, general and administrative expenses	$	21,302	$	24,054	$	22,485

Debt payable to related parties was as follows:



	December 31,
	2014		2013
			Predecessor
Long-term debt payable to Westlake	$	227,638	$	252,973

Partners' Equity (Tables)

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Schedule of Incentive Distributions Made to Managing Members or General Partners by Distribution

If cash distributions to the Partnership's unitholders exceed $0.3163 per common unit and subordinated unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations:



	Marginal Percentage Interest in Distributions
Total Quarterly Distribution Per Unit	Unitholders		IDR Holders
Above $0.3163 up to $0.3438	85.0	%	15.0	%
Above $0.3438 up to $0.4125	75.0	%	25.0	%
Above $0.4125	50.0	%	50.0	%

Derivative Commodity Instruments (Tables)

12 Months Ended

Dec. 31, 2014

Derivative Instruments and Hedges, Assets [Abstract]

Fair Values Of Derivative Instruments In Consolidated Balance Sheets

The fair values of derivative instruments in the combined and consolidated balance sheets were as follows:



	Asset Derivatives
	Balance Sheet Location	Fair Value as of December 31,
	Balance Sheet Location	2014		2013
				Predecessor
Not designated as hedging instruments
Commodity forward contracts	Accounts receivable, net	$	—	$	296
Total asset derivatives		$	—	$	296

	Liability Derivatives
	Balance Sheet Location	Fair Value as of December 31,
	Balance Sheet Location	2014		2013
				Predecessor
Not designated as hedging instruments
Commodity forward contracts	Accrued liabilities	$	—	$	176
Total liability derivatives		$	—	$	176

Impact Of Derivative Instruments Designated As Fair Value Hedges



Derivatives in Fair Value Hedging Relationships	Location of Gain (Loss) Recognized in Income on Derivative	Year Ended December 31,
Derivatives in Fair Value Hedging Relationships	Location of Gain (Loss) Recognized in Income on Derivative	2014		2013			2012
				Predecessor			Predecessor
Commodity forward contracts	Cost of sales	$	—	$	(303	)	$	17,163



Hedged Items in Fair Value Hedging Relationships	Location of Gain (Loss) Recognized in Income on Hedged Items	Year Ended December 31,
Hedged Items in Fair Value Hedging Relationships		2014		2013		2012
				Predecessor		Predecessor
Firm commitment designated as the hedged item	Cost of sales	$	—	$	143	$	(18,394	)

Impact Of Derivative Instruments Not Designated As Fair Value Hedges

The impact of derivative instruments that have not been designated as hedges in the combined and consolidated statements of operations were as follows:



Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized in Income on Derivative	Year Ended December 31,
Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized in Income on Derivative	2014			2013		2012
					Predecessor		Predecessor
Commodity forward contracts	Gross profit	$	(9,244	)	$	5,438	$	(11,961	)

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Schedule Of Assets And Liabilities On A Recurring Basis

The following table summarizes, by level within the fair value hierarchy, the Predecessor's assets and liabilities that were accounted for at fair value on a recurring basis at December 31, 2013:



	December 31, 2013
	Level 1		Level 2			Total

	Predecessor
Derivative instruments
Risk management assets - Commodity forward contracts	$	48	$	248		$	296
Risk management liabilities - Commodity forward contracts	—		(176		)	(176		)

Schedule Of Carrying And Fair Values Of Long-Term Debt

The carrying and fair values of the Partnership's and the Predecessor's long-term debt at December 31, 2014 and 2013 are summarized in the table below. The Partnership's long-term debt includes the August 2013 Promissory Notes and the senior unsecured revolving credit facility. The fair value of debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate.



	December 31, 2014				December 31, 2013
	Carrying Value		Fair Value		Carrying Value		Fair Value

					Predecessor
2006 Pipeline Note	$	—	$	—	$	14,400	$	13,922
August 2013 Promissory Notes	167,116		167,116		238,573		238,573
Senior unsecured revolving credit facility	60,522		60,522		—		—

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule Of The Provision For (Benefit From) Income Taxes

The components of income tax disaggregated between the Partnership and the Predecessor are as follows:



	Partnership		Predecessor
	Period from August 4, 2014 to December 31, 2014		Period from January 1, 2014 to August 3, 2014		Year Ended December 31,
	Period from August 4, 2014 to December 31, 2014		Period from January 1, 2014 to August 3, 2014			2013		2012
Current
Federal	$	—	$	168,773		$	233,014	$	196,467
State and local	800		21,207			30,211		22,507
	800		189,980			263,225		218,974
Deferred
Federal	—		6,890			32,675		(8,137		)
State and local	265		1,453			4,379		41
	265		8,343			37,054		(8,096		)
Total provision	$	1,065	$	198,323		$	300,279	$	210,878

Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense

The reconciliation of income tax expense at the U.S. statutory rate to the income tax expense disaggregated between the Partnership and the Predecessor is as follows:



	Partnership			Predecessor
	Period from August 4, 2014 to December 31, 2014			Period from January 1, 2014 to August 3, 2014			Year Ended December 31,
	Period from August 4, 2014 to December 31, 2014			Period from January 1, 2014 to August 3, 2014				2013			2012
Provision for federal income tax, at statutory rate	$	52,343		$	195,880			$	296,389		$	212,379
State income tax provision, net of federal income tax effect	1,065			14,729				22,484			14,656
Partnership income not subject to entity-level tax	(52,343		)	—				—			—
Manufacturing deduction	—			(12,214		)		(18,270		)	(16,065		)
Other, net	—			(72		)		(324		)	(92		)
	$	1,065		$	198,323			$	300,279		$	210,878

Schedule Of Deferred Tax Assets And Liabilities

The tax effects of the principal temporary differences between financial reporting and income tax reporting are as follows:



	December 31,
	2014			2013
				Predecessor
Credit carryforward	$	—		$	25
Accruals	—			3,570
Allowance for doubtful accounts	—			(136		)
Inventories	—			1,313
Other	—			(373		)
Deferred taxes assets—total	—			4,399
Property, plant and equipment	(1,650		)	(159,033		)
Turnaround costs	(198		)	(23,773		)
Deferred tax liabilities—total	(1,848		)	(182,806		)
Total net deferred tax liabilities	$	(1,848	)	$	(178,407	)

Balance sheet classifications
Current deferred tax asset	$	—		$	4,448
Noncurrent deferred tax liability	(1,848		)	(182,855		)
Total net deferred tax liabilities	$	(1,848	)	$	(178,407	)

Supplemental Information (Tables)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Liabilities Retained By Parent Company

Net Liabilities Retained by Westlake

Net liabilities of the Predecessor that were retained by Westlake and not assumed by OpCo in connection with the IPO are composed of the following:



Net liabilities retained by Westlake
Accounts receivable, net—third parties	$	64,650
Inventories	85,057
Prepaid expenses and other current assets	669
Deferred income taxes	4,448
Property, plant and equipment, net	62,886
Equity investments	9,338
Accounts payable—third parties	(101,671		)
Accrued liabilities	(37,451		)
Deferred income taxes	(189,615		)
Long-term debt	(137,103		)
Other liabilities	(914		)
Total	$	(239,706	)

Schedule Of Other Income, Net



	Year Ended December 31,
	2014			2013			2012
				Predecessor			Predecessor
Income from equity method investment	$	2,973		$	4,711		$	4,172
Claims recovery	—			3,158			—
Franchise taxes	(11		)	(172		)	(144		)
Other	189			4			158
Other income, net	$	3,151		$	7,701		$	4,186

Commitments And Contingencies (Tables)

12 Months Ended

Dec. 31, 2014

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Lease Commitments

Several of the leases provide for renewal terms. At December 31, 2014, future minimum lease commitments were as follows:



2015	$	1,041
2016	604
2017	443
2018	127
2019	59
Thereafter	98
	$	2,372

Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Summary Of Quarterly Financial Information



	Three Months Ended
	March 31, 2014		June 30, 2014		September 30, 2014		December 31, 2014
	Predecessor		Predecessor
Net sales	$	560,014	$	524,135	$	392,008	$	273,543
Gross profit	232,314		246,546		164,993		101,959
Income from operations	224,536		240,381		156,133		95,506
Net income	143,874		153,844		118,173		93,929
Net income attributable to Westlake Chemical Partners LP subsequent to the IPO and limited partners' interest in net income
Basic and diluted earnings per common unitholder ⁽¹⁾⁽²⁾					$	0.19	$	0.32
Basic and diluted earnings per subordinated unitholder ⁽¹⁾⁽²⁾					$	0.19	$	0.32

	Three Months Ended
	March 31, 2013		June 30, 2013		September 30, 2013		December 31, 2013
	Predecessor		Predecessor		Predecessor		Predecessor
Net sales	$	500,917	$	524,759	$	540,133	$	561,938
Gross profit	190,010		238,155		212,981		231,461
Income from operations	183,839		231,391		206,590		225,336
Net income	120,725		149,034		132,581		144,206

______________________________


(1)	Represents quarterly net income per common and subordinated unit since the completion of the Partnership's IPO on August 4, 2014. See Note 10 to the combined and consolidated financial statements.

(2)

Description Of Business And Significant Accounting Policies (Narrative) (Details) $ in Thousands, lb in Billions		5 Months Ended	12 Months Ended
	Aug. 04, 2014 production_facility lb $ / lb shares	Dec. 31, 2014 USD ($)	Dec. 31, 2014 USD ($) Segment
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of reportable segments \| Segment			1
Threshold period past due accounts receivable reviewed			90 days
Capitalized interest		$ 2,638
Goodwill		$ 5,814	$ 5,814
Amortization period, minimum (in years)			3 years
Amortization period, maximum (in years)			6 years
Other assets amortization period, minimum (in years)			5 years
Other assets amortization period, maximum (in years)			20 years
Affiliated Entity [Member] \| OpCo LP [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest	10.60%
Limited Liability Company [Member] \| Westlake Chemical OpCo GP LLC [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest	100.00%
Westlake [Member] \| Majority-Owned Subsidiary, Unconsolidated [Member] \| OpCo LP [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest	89.40%
Westlake [Member] \| Ethylene Sales Agreement [Member] \| Investee [Member] \| OpCo LP [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Term of sales agreement	12 years
Minimum percentage required to be purchased	95.00%
Maximum mass required to be purchased \| lb	3.8
Purchase commitment, fixed margin on variable pricing \| $ / lb	0.10
Expected percentage of production to be sold	95.00%
OpCo LP [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of production facilities \| production_facility	3
Limited Partner [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of units sold in public offering \| shares	12,937,500
Limited Partner [Member] \| Westlake [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Partnership's ownership interest	5.80%

Description Of Business And Significant Accounting Policies (Schedule Of Estimated Useful Lives Of Assets) (Details)	12 Months Ended
	Dec. 31, 2014
Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	25 years
Plant And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	25 years
Ethylene Pipeline [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	35 years
Minimum [Member] \| Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	3 years
Maximum [Member] \| Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	10 years

Initial Public Offering (Details) $ / shares in Units, lb in Billions		5 Months Ended	12 Months Ended
	Aug. 04, 2014 USD ($) lease lb $ / shares $ / lb shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2014 USD ($) shares	Aug. 03, 2014 USD ($)	Jul. 31, 2013 USD ($)	Aug. 05, 2014 USD ($)	Dec. 31, 2013 shares
Limited Partners' Capital Account [Line Items]
Net proceeds from issuance of common units			$ 286,088,000
Payments of unit issuance costs	$ 24,412,000
OpCo LP [Member] \| Loans Payable [Member] \| 2013 Promissory Note [Member]
Limited Partners' Capital Account [Line Items]
Debt assumed by acquiree						$ 167,116,000
OpCo LP [Member] \| IPO [Member]
Limited Partners' Capital Account [Line Items]
Net proceeds from issuance of common units	286,088,000
OpCo LP [Member] \| IPO [Member] \| Preformation Capital Expenditure [Member]
Limited Partners' Capital Account [Line Items]
Use of proceeds from public offering	151,729,000
OpCo LP [Member] \| IPO [Member] \| Cash Reserve Turnaround [Member]
Limited Partners' Capital Account [Line Items]
Use of proceeds from public offering	55,419,000
OpCo LP [Member] \| IPO [Member] \| Intercompany Debt [Member]
Limited Partners' Capital Account [Line Items]
Use of proceeds from public offering	$ 78,940,000
Westlake [Member]
Limited Partners' Capital Account [Line Items]
Excess cash paid over carrying value of partnership interest		$ 242,572,000
Capital expenditures				$ 246,056,000	$ 151,729,000
Common units [Member] \| Westlake [Member]
Limited Partners' Capital Account [Line Items]
Units outstanding \| shares	1,436,115
Subordinated units [Member] \| Westlake [Member]
Limited Partners' Capital Account [Line Items]
Units outstanding \| shares	12,686,115
Westlake [Member]
Limited Partners' Capital Account [Line Items]
Number of units sold in public offering \| shares	12,937,500
Price per unit \| $ / shares	$ 24.00
Price per unit, net of underwriting discount \| $ / shares	$ 22.53
Westlake [Member] \| Over-Allotment Option [Member]
Limited Partners' Capital Account [Line Items]
Number of units sold in public offering \| shares	1,687,500
Westlake [Member] \| Westlake [Member]
Limited Partners' Capital Account [Line Items]
Partnership's ownership interest	5.80%
OpCo LP [Member] \| Affiliated Entity [Member]
Limited Partners' Capital Account [Line Items]
Partnership's ownership interest	10.60%
Additional ownership interest acquired	4.80%
Carrying value of additional partnership interest purchased	$ 43,516,000
OpCo LP [Member] \| Westlake [Member] \| Majority-Owned Subsidiary, Unconsolidated [Member]
Limited Partners' Capital Account [Line Items]
Partnership's ownership interest	89.40%
OpCo LP [Member] \| Westlake [Member] \| Ethylene Sales Agreement [Member] \| Investee [Member]
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Term of sales agreement	12 years
Minimum percentage required to be purchased	95.00%
Maximum mass required to be purchased \| lb	3.8
Number of years used to calculate average expenses	5 years
Purchase commitment, fixed margin on variable pricing \| $ / lb	0.10
Purchase commitment, renewal term	12 months
OpCo LP [Member] \| Westlake [Member] \| Excess Production Option [Member] \| Investee [Member]
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Percentage of excess production that can be purchased	95.00%
Purchase commitment, fixed margin on variable pricing \| $ / lb	0.10
OpCo LP [Member] \| Westlake [Member] \| Feedstock Supply Agreement [Member] \| Investee [Member]
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Related party transactions, term of agreements	12 months
OpCo LP [Member] \| Westlake [Member] \| Services And Secondment Agreement [Member] \| Investee [Member]
Long-term Commitment (Excluding Unconditional Purchase Obligation) [Abstract]
Related party transactions, term of agreements	12 years
Period of default in performance that can allow a party to terminate agreement	30 days
OpCo LP [Member] \| Westlake [Member] \| Site Lease Agreement [Member] \| Investee [Member]
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
Westlake Chemical OpCo GP LLC [Member] \| Limited Liability Company [Member]
Limited Partners' Capital Account [Line Items]
Partnership's ownership interest	100.00%
Westlake [Member] \| OpCo LP [Member] \| Loans Payable [Member] \| 2013 Promissory Note [Member] \| Investor [Member]
Limited Partners' Capital Account [Line Items]
Debt assumed by acquiree	$ 246,056,000
Westlake [Member] \| Common units [Member]
Limited Partners' Capital Account [Line Items]
Units outstanding \| shares		1,436,115	1,436,115				0
Westlake [Member] \| Subordinated units [Member]
Limited Partners' Capital Account [Line Items]
Units outstanding \| shares		12,686,115	12,686,115				0

Financial Instruments (Cash Equivalents) (Details) $ in Thousands	Dec. 31, 2014 USD ($)
Held-to-maturity securities
Cash Equivalents [Line Items]
Cash equivalents	$ 40,003

Accounts Receivable—Third Parties (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Entity Information [Line Items]
Trade customers	$ 37,514
Allowance for doubtful accounts	0
Receivables from trade customers and affiliates, net	37,514
Other	6
Accounts receivable, net—third parties	$ 37,520
Predecessor [Member]
Entity Information [Line Items]
Trade customers		$ 73,594
Allowance for doubtful accounts		(2,105)
Receivables from trade customers and affiliates, net		71,489
Other		323
Accounts receivable, net—third parties		$ 71,812

Inventories (Schedule Of Inventory) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Entity Information [Line Items]
Finished products	$ 6,257
Feedstock, additives, and chemicals	377
Materials and supplies	0
Inventories	$ 6,634
Predecessor [Member]
Entity Information [Line Items]
Finished products		$ 21,330
Feedstock, additives, and chemicals		80,407
Materials and supplies		14,640
Inventories		$ 116,377

Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Land	$ 0
Building and improvements	14,961
Plant and equipment	1,151,091
Other	61,533
Property, plant and equipment, gross	1,227,585
Less: Accumulated depreciation	(550,568)
Property, plant and equipment, net, before construction in progress	677,017
Construction in progress	165,040
Property, plant and equipment, net	842,057
Depreciation expense	$ 60,004	$ 57,299	$ 53,125
Predecessor [Member]
Property, Plant and Equipment [Line Items]
Land		4,126
Building and improvements		32,941
Plant and equipment		1,058,304
Other		55,478
Property, plant and equipment, gross		1,150,849
Less: Accumulated depreciation		(561,301)
Property, plant and equipment, net, before construction in progress		589,548
Construction in progress		173,424
Property, plant and equipment, net		$ 762,972

Other Assets (Schedule Of Intangible and Other Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Schedule of Finite-Lived And Indefinite-Lived Intangible Assets [Line Items]
Goodwill, Cost	$ 5,814
Goodwill, Net	5,814
Total intangible assets	5,814
Total intangible assets, Accumulated Amortization	0
Total intangible assets, net	5,814
Other Assets [Line Items]
Turnaround costs, Cost	96,835
Turnaround costs, Accumulated Amortization	(51,536)
Turnaround costs, Net	45,299
Other, Costs	8,662
Other, Accumulated Amortization	(2,042)
Other, Net	6,620
Total deferred charges and other assets, Cost	105,497
Total deferred charges and other assets, Accumulated Amortization	(53,578)
Total deferred charges and other assets, Net	51,919
Other assets, Cost	111,311
Other assets, Accumulated Amortization	(53,578)
Total other assets, net	57,733
Other [Member]
Schedule of Finite-Lived And Indefinite-Lived Intangible Assets [Line Items]
Other intangible assets, Net	0
Technology [Member]
Schedule of Finite-Lived And Indefinite-Lived Intangible Assets [Line Items]
Intangible Assets, Cost	0
Intangible assets, Accumulated Amortization	0
Intangible Assets, Net	$ 0
Predecessor [Member]
Schedule of Finite-Lived And Indefinite-Lived Intangible Assets [Line Items]
Goodwill, Cost		$ 5,814
Goodwill, Net		5,814
Total intangible assets		15,491
Total intangible assets, Accumulated Amortization		(9,618)
Total intangible assets, net		5,873
Other Assets [Line Items]
Turnaround costs, Cost		96,678
Turnaround costs, Accumulated Amortization		(34,537)
Turnaround costs, Net		62,141
Other, Costs		8,662
Other, Accumulated Amortization		(1,479)
Other, Net		7,183
Total deferred charges and other assets, Cost		105,340
Total deferred charges and other assets, Accumulated Amortization		(36,016)
Total deferred charges and other assets, Net		69,324
Other assets, Cost		120,831
Other assets, Accumulated Amortization		(45,634)
Total other assets, net		75,197
Predecessor [Member] \| Other [Member]
Schedule of Finite-Lived And Indefinite-Lived Intangible Assets [Line Items]
Other intangible assets, Net		59
Predecessor [Member] \| Technology [Member]
Schedule of Finite-Lived And Indefinite-Lived Intangible Assets [Line Items]
Intangible Assets, Cost		9,618
Intangible assets, Accumulated Amortization		(9,618)
Intangible Assets, Net		$ 0
Deferred Turnaround Costs [Member]
Other Assets [Line Items]
Other Assets, Weighted Average Life	5 years
Other Amortizable Assets [Member]
Other Assets [Line Items]
Other Assets, Weighted Average Life	15 years

Other Assets (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended
Other Assets (Narrative) (Details) - USD ($)	Oct. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Assets [Abstract]
Amortization expense of other assets		$ 17,607,000	$ 16,164,000	$ 11,132,000
Change in carrying amount of goodwill		$ 0
Discounted cash flow projections period	9 years
Rate used to discount future cash flows for goodwill impairment test	8.80%
Percentage future cash flows of segment could decrease by and not be impaired		10.00%

Long-Term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 04, 2014	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 227,638
Weighted average interest rate on all long-term debt		4.35%	4.69%
Predecessor [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake			$ 252,973
Limited Partner [Member] \| Senior Notes [Member] \| Pipeline Note, 2006 [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 0
Limited Partner [Member] \| Senior Notes [Member] \| Pipeline Note, 2006 [Member] \| Prime Rate [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate		0.25%	0.25%
Limited Partner [Member] \| Senior Notes [Member] \| Pipeline Note, 2006 [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake			$ 14,400
Limited Partner [Member] \| Senior Notes [Member] \| 2013 Promissory Note [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 167,116
Limited Partner [Member] \| Senior Notes [Member] \| 2013 Promissory Note [Member] \| Prime Rate [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate		1.50%	1.50%
Limited Partner [Member] \| Senior Notes [Member] \| 2013 Promissory Note [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake			$ 238,573
Limited Partner [Member] \| Line of Credit [Member] \| Senior Unsecured Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 60,522
Limited Partner [Member] \| Line of Credit [Member] \| Senior Unsecured Revolving Credit Facility [Member] \| OpCo LP [Member] \| LIBOR
Related Party Transaction [Line Items]
Basis spread on variable rate	3.00%
Limited Partner [Member] \| Line of Credit [Member] \| Senior Unsecured Revolving Credit Facility [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake			$ 0

Net Income Per Limited Partner Unit (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 30, 2015	Oct. 28, 2014
Subsequent Event [Line Items]
Distribution declared per unit		$ 0.1704
Distribution declared		$ 4,611
Subsequent Event [Member]
Subsequent Event [Line Items]
Distribution declared per unit	$ 0.2750
Distribution declared	$ 7,441

Net Income Per Limited Partner Unit (Income In Excess Of Distribution) (Details) - USD ($) $ in Thousands	3 Months Ended		5 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2014
Limited partners' interest in net income subsequent to IPO	$ 93,929	$ 118,173	$ 13,577
Distribution declared			12,052
Net income subsequent to the IPO in excess of distribution			1,525
Common units [Member]
Limited partners' interest in net income subsequent to IPO			7,213
Distribution declared			6,403
Net income subsequent to the IPO in excess of distribution			810
Subordinated units [Member]
Limited partners' interest in net income subsequent to IPO			6,364
Distribution declared			5,649
Net income subsequent to the IPO in excess of distribution			$ 715

- 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
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: 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=31042434&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: 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 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

Net Income Per Limited Partner Unit (Basic and Diluted Income Per Limited Partner Unit) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		5 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2014
Limited Partners' Capital Account [Line Items]
Distribution			$ 12,052
Net income subsequent to the IPO in excess of distribution			1,525
Limited partners' interest in net income subsequent to IPO	$ 93,929	$ 118,173	$ 13,577
Weighted average units outsanding:
Basic and diluted (units)			27,059,730
Net income per limited partner unit:
Income per limited partner unit (usd per unit)			$ 0.50
Limited Partners' Common Units [Member]
Limited Partners' Capital Account [Line Items]
Distribution			$ 6,403
Net income subsequent to the IPO in excess of distribution			810
Limited partners' interest in net income subsequent to IPO			$ 7,213
Weighted average units outsanding:
Basic and diluted (units)			14,373,615
Net income per limited partner unit:
Income per limited partner unit (usd per unit)	$ 0.32	$ 0.19	$ 0.50
Limited Partners' Subordinated Units [Member]
Limited Partners' Capital Account [Line Items]
Distribution			$ 5,649
Net income subsequent to the IPO in excess of distribution			715
Limited partners' interest in net income subsequent to IPO			$ 6,364
Weighted average units outsanding:
Basic and diluted (units)			12,686,115
Net income per limited partner unit:
Income per limited partner unit (usd per unit)	$ 0.32	$ 0.19	$ 0.50

Related Party Transactions (Sales to Related Parties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Net sales - Westlake	$ 1,292,089
Predecessor [Member]
Related Party Transaction [Line Items]
Net sales - Westlake		$ 1,603,043	$ 1,507,501
Affiliated Entity [Member] \| Westlake [Member]
Related Party Transaction [Line Items]
Net sales - Westlake	$ 1,292,089
Affiliated Entity [Member] \| Westlake [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Net sales - Westlake		$ 1,603,043	$ 1,507,501

Related Party Transactions (Cost of Sales from Related Parties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Cost of sales	$ 1,003,888
Predecessor [Member]
Related Party Transaction [Line Items]
Cost of sales		$ 1,255,140	$ 1,613,446
Affiliated Entity [Member] \| Westlake [Member]
Related Party Transaction [Line Items]
Feedstock purchased from Westlake and included in cost of sales	155,232
Other charges from Westlake and included in cost of sales	60,264
Cost of sales	$ 215,496
Affiliated Entity [Member] \| Westlake [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Feedstock purchased from Westlake and included in cost of sales		0	0
Other charges from Westlake and included in cost of sales		61,770	57,454
Cost of sales		$ 61,770	$ 57,454

Related Party Transactions (Services from Related Parties Included in SG&A Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses	$ 29,256
Predecessor [Member]
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses		$ 25,451	$ 24,103
Affiliated Entity [Member] \| Westlake [Member]
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses	$ 21,302
Affiliated Entity [Member] \| Westlake [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses		$ 24,054	$ 22,485

Related Party Transactions (Goods and Services from Related Parties that have been Capitalized) (Details) - Affiliated Entity [Member] - Westlake [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Goods and services purchased from Westlake and capitalized as assets	$ 5,823
Predecessor [Member]
Related Party Transaction [Line Items]
Goods and services purchased from Westlake and capitalized as assets		$ 20,222	$ 8,902

Related Party Transactions (Accounts Receivable from and Accounts Payable to Related Parties) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Accounts receivable, net—Westlake	$ 18,529
Accounts payable—Westlake	(7,470)
Predecessor [Member]
Related Party Transaction [Line Items]
Accounts receivable, net—Westlake		$ 0
Accounts payable—Westlake		$ 0
Affiliated Entity [Member] \| Westlake [Member]
Related Party Transaction [Line Items]
Accounts receivable, net—Westlake	18,529
Accounts payable—Westlake	$ (7,470)

Related Party Transactions (Debt Payable to Related Parties) (Details) - USD ($) $ in Thousands	5 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Capitalized interest	$ 2,638
Accrued interest on related party debt	2,403
Long-term debt payable to Westlake	227,638
Predecessor [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 252,973
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Accrued interest on related party debt	2,403	504
Affiliated Entity [Member] \| Westlake [Member]
Related Party Transaction [Line Items]
Accrued interest	7,506
Long-term debt payable to Westlake	$ 227,638
Affiliated Entity [Member] \| Westlake [Member] \| Predecessor [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake		$ 252,973

Related Party Transactions (General) (Details) - Investee [Member] - Westlake [Member]	Aug. 04, 2014 USD ($) lease	Dec. 31, 2014 USD ($)
Site Lease Agreement [Member] \| OpCo LP [Member]
Related Party Transaction [Line Items]
Number of lease agreements \| lease	2
Term of operating lease	50 years
Operating lease, rental amount	$ 1
Senior Notes [Member]
Related Party Transaction [Line Items]
Outstanding debt		$ 754,000,000
Unamortized discount on senior notes		892,000
Senior unsecured revolving credit facility [Member]
Related Party Transaction [Line Items]
Outstanding letters of credit		$ 31,392,000

Partners' Equity (Incentive Distribution Rights) (Details)	12 Months Ended
	Dec. 31, 2014 $ / shares
Distribution Made to Limited Partner [Line Items]
Percentage of minimum quarterly distribution partnership must pay to end subordination period	150.00%
Threshold of distributions per unit to payout additional distributions	$ 0.3163
Cash Distribution [Member] \| Common units [Member]
Distribution Made to Limited Partner [Line Items]
Minimum quarterly distribution per unit	0.2750
Cash Distribution [Member] \| Subordinated units [Member]
Distribution Made to Limited Partner [Line Items]
Minimum quarterly distribution per unit	0.2750
Cash Distribution [Member] \| Common and Subordinated units [Member]
Distribution Made to Limited Partner [Line Items]
Minimum quarterly distribution per unit	$ 0.3163

Partners' Equity (Schedule of Quarterly Distributions Per Unit) (Details)	12 Months Ended
	Dec. 31, 2014 $ / shares
Above $0.3163 up to $0.3438 \| Minimum [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Incentive Distribution, Quarterly Distribution Per Unit, In Excess Of Minimum	$ 0.3163
Above $0.3163 up to $0.3438 \| Maximum [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Incentive Distribution, Quarterly Distribution Per Unit, In Excess Of Minimum	$ 0.3438
Above $0.3163 up to $0.3438 \| Unit Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Marginal Percentage Interest in Distributions	85.00%
Above $0.3163 up to $0.3438 \| IDR Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Marginal Percentage Interest in Distributions	15.00%
Above $0.3438 up to $0.4125 \| Minimum [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Incentive Distribution, Quarterly Distribution Per Unit, In Excess Of Minimum	$ 0.3438
Above $0.3438 up to $0.4125 \| Maximum [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Incentive Distribution, Quarterly Distribution Per Unit, In Excess Of Minimum	$ 0.4125
Above $0.3438 up to $0.4125 \| Unit Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Marginal Percentage Interest in Distributions	75.00%
Above $0.3438 up to $0.4125 \| IDR Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Marginal Percentage Interest in Distributions	25.00%
Above $0.4125 \| Minimum [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Incentive Distribution, Quarterly Distribution Per Unit, In Excess Of Minimum	$ 0.4125
Above $0.4125 \| Unit Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Marginal Percentage Interest in Distributions	50.00%
Above $0.4125 \| IDR Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Marginal Percentage Interest in Distributions	50.00%

Unit-Based Compensation (Details) - Westlake Chemical Partners LP Long-Term Incentive Plan [Member] - USD ($) $ in Thousands	5 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Jul. 15, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units authorized			1,270,000
Number of units forfeited		0
Total units available for grant	1,265,596	1,265,596
Unrecognized compensation cost	$ 111	$ 111
Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost	$ 15
Phantom units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units granted	4,404
DERs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units granted	4,404

Derivative Commodity Instruments (Narrative) (Details)	Dec. 31, 2014 derivative
Derivative [Line Items]
Number of contracts	0
Derivatives Not Designated As Hedging Instrument [Member]
Derivative [Line Items]
Number of contracts	0
Fair Value Hedging [Member] \| Designated as Fair Value Hedges [Member]
Derivative [Line Items]
Number of contracts	0

Derivative Commodity Instruments (Fair Values Of Derivative Instruments In Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Total asset derivatives	$ 0
Total liability derivatives	0
Predecessor [Member]
Derivative [Line Items]
Total asset derivatives		$ 296
Total liability derivatives		176
Accounts receivable, net [Member] \| Commodity forward contracts [Member]
Derivative [Line Items]
Not designated as hedging instruments, Asset Derivatives	0
Accounts receivable, net [Member] \| Commodity forward contracts [Member] \| Predecessor [Member]
Derivative [Line Items]
Not designated as hedging instruments, Asset Derivatives		296
Accrued liabilities [Member] \| Commodity forward contracts [Member]
Derivative [Line Items]
Not designated as hedging instruments, Liability Derivatives	$ 0
Accrued liabilities [Member] \| Commodity forward contracts [Member] \| Predecessor [Member]
Derivative [Line Items]
Not designated as hedging instruments, Liability Derivatives		$ 176

Derivative Commodity Instruments (Impact Of Derivative Instruments Designated As Fair Value Hedges) (Details) - Designated as Fair Value Hedges [Member] - Cost of Sales [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commodity forward contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ 0	$ (303)	$ 17,163
Firm commitment designated as the hedged item [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ 0
Firm commitment designated as the hedged item [Member] \| Predecessor [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative		$ 143	$ (18,394)

Derivative Commodity Instruments (Impact Of Derivative Instruments Not Designated As Fair Value Hedges) (Details) - Commodity forward contracts [Member] - Derivatives Not Designated As Hedging Instrument [Member] - Cost of Sales [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative	$ (9,244)
Predecessor [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivative		$ 5,438	$ (11,961)

Fair Value Measurements (Schedule Of Assets And Liabilities On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Risk management assets	$ 0
Risk management liabilities	$ 0
Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Risk management assets		$ 296
Risk management liabilities		(176)
Fair Value, Measurements, Recurring [Member] \| Commodity forward contracts [Member] \| Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Risk management assets		296
Risk management liabilities		(176)
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Commodity forward contracts [Member] \| Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Risk management assets		48
Risk management liabilities		0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Commodity forward contracts [Member] \| Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Risk management assets		248
Risk management liabilities		$ (176)

Fair Value Measurements (Schedule Of Carrying And Fair Values Of Long-Term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
3.60% Senior Notes Due 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value	$ 0
Senior Notes, Fair Value	0
3.60% Senior Notes Due 2022 [Member] \| Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value		$ 14,400
Senior Notes, Fair Value		13,922
GO Zone 6 1/2% Senior Notes Due 2029 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value	167,116
Senior Notes, Fair Value	167,116
GO Zone 6 1/2% Senior Notes Due 2029 [Member] \| Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value		238,573
Senior Notes, Fair Value		238,573
GO Zone 6 3/4% Senior Notes Due 2032 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value	60,522
Senior Notes, Fair Value	$ 60,522
GO Zone 6 3/4% Senior Notes Due 2032 [Member] \| Predecessor [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Carrying Value		0
Senior Notes, Fair Value		$ 0

Income Taxes (Schedule Of The Provision For (Benefit From) Income Taxes) (Details) - USD ($) $ in Thousands	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2014	Aug. 03, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Entity Information [Line Items]
Federal	$ 0
State and local	800
Total Current	800
Federal	0
State and local	265
Total deferred	265		$ 8,608
Total provision	$ 1,065		$ 199,388
Predecessor [Member]
Entity Information [Line Items]
Federal		$ 168,773		$ 233,014	$ 196,467
State and local		21,207		30,211	22,507
Total Current		189,980		263,225	218,974
Federal		6,890		32,675	(8,137)
State and local		1,453		4,379	41
Total deferred		8,343		37,054	(8,096)
Total provision		$ 198,323		$ 300,279	$ 210,878

Income Taxes (Reconciliation Of Taxes Computed At The Statutory Rate To Income Tax Expense) (Details) - USD ($) $ in Thousands	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2014	Aug. 03, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Entity Information [Line Items]
Provision for federal income tax, at statutory rate	$ 52,343
State income tax provision, net of federal income tax effect	1,065
Partnership income not subject to entity-level tax	(52,343)
Manufacturing deduction	0
Other, net	0
Provision for income taxes	$ 1,065		$ 199,388
Predecessor [Member]
Entity Information [Line Items]
Provision for federal income tax, at statutory rate		$ 195,880		$ 296,389	$ 212,379
State income tax provision, net of federal income tax effect		14,729		22,484	14,656
Partnership income not subject to entity-level tax		0		0	0
Manufacturing deduction		(12,214)		(18,270)	(16,065)
Other, net		(72)		(324)	(92)
Provision for income taxes		$ 198,323		$ 300,279	$ 210,878

Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Entity Information [Line Items]
Credit carryforward	$ 0
Accruals	0
Allowance for doubtful accounts	0
Inventories	0
Other	0
Deferred taxes assets, total	0
Property, plant and equipment	(1,650)
Turnaround costs	(198)
Deferred tax liabilities-total	(1,848)
Total net deferred tax liabilities	(1,848)
Balance sheet classifications
Current deferred tax asset	0
Noncurrent deferred tax liability	(1,848)
Total net deferred tax liabilities	$ (1,848)
Predecessor [Member]
Entity Information [Line Items]
Credit carryforward		$ 25
Accruals		3,570
Allowance for doubtful accounts		(136)
Inventories		1,313
Other		(373)
Deferred taxes assets, total		4,399
Property, plant and equipment		(159,033)
Turnaround costs		(23,773)
Deferred tax liabilities-total		(182,806)
Total net deferred tax liabilities		(178,407)
Balance sheet classifications
Current deferred tax asset		4,448
Noncurrent deferred tax liability		(182,855)
Total net deferred tax liabilities		$ (178,407)

Supplemental Information (Liabilities Retained by Westlake) (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Aug. 04, 2014
Entity Information [Line Items]
Accounts receivable, net—third parties	$ 37,520
Inventories	6,634
Prepaid expenses and other current assets	212
Deferred income taxes	0
Property, plant and equipment, net	842,057
Equity investments	0
Accounts payable - third parties	(12,614)
Accrued liabilities	(11,900)
Deferred income taxes	$ (1,848)
Westlake [Member]
Entity Information [Line Items]
Accounts receivable, net—third parties		$ 64,650
Inventories		85,057
Prepaid expenses and other current assets		669
Deferred income taxes		4,448
Property, plant and equipment, net		62,886
Equity investments		9,338
Accounts payable - third parties		(101,671)
Accrued liabilities		(37,451)
Deferred income taxes		(189,615)
Long-term debt payable to Westlake		(137,103)
Other liabilities		(914)
Total		$ (239,706)

Supplemental Information (Accrued Liabilities and Other Income, Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accrued Liabilities
Accrued liabilities	$ 11,900
Accrued taxes	1,622
Interest accrued on long-term debt	2,403
Accrual related to capital expenditures	5,026
Accrued employee payroll and benefits		$ 10,598
Other Income, Net
Income from equity method investment	2,973
Claims recovery	0
Franchise taxes	11
Other	189
Other income, net	$ 3,151
Predecessor [Member]
Accrued Liabilities
Accrued liabilities		26,688
Other Income, Net
Income from equity method investment		4,711	$ 4,172
Claims recovery		3,158	0
Franchise taxes		172	144
Other		4	158
Other income, net		$ 7,701	$ 4,186

Supplemental Information (Cash Flow Information) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Reduction in capital expenditure accrual	$ (418,000)	$ (7,937,000)	$ (1,333,000)
Interest paid, net of interest capitalized	1,366,000
Westlake [Member] \| Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party notes payable deemed settled through net investment		238,600,000
Cash transferred in related party notes payable settlement		0
Predecessor [Member] \| Westlake [Member] \| Affiliated Entity [Member]
Related Party Transaction [Line Items]
Interest incurred, added to principal on promissory notes outstanding	$ 9,315,000	$ 7,506,000

Major Customer and Concentration Risk (Details)	12 Months Ended
Major Customer and Concentration Risk (Details)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net sales [Member] \| Customer Concentration Risk [Member] \| Westlake [Member] \| Affiliated Entity [Member]
Concentration Risk [Line Items]
Concentration risk percentage	73.80%	75.30%	67.00%

Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Pending Litigation [Member]
Loss Contingencies [Line Items]
Costs sought to be recovered by plaintiffs	$ 1,400
Threatened Litigation [Member]
Loss Contingencies [Line Items]
Costs sought to be recovered by plaintiffs	$ 100
Polyone [Member]
Loss Contingencies [Line Items]
Environmental costs percentage net of recoveries from third parties	100.00%
Costs incurred for environmental remediation services	$ 2,805	$ 3,284

Commitments And Contingencies (Future Minimum Lease Commitments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
2015	$ 1,041
2016	604
2017	443
2018	127
2019	59
Thereafter	98
Total future minimum lease commitments	2,372
Approximate rental expense	$ 3,558	$ 3,933	$ 2,999

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 30, 2015	Oct. 28, 2014
Subsequent Event [Line Items]
Distribution declared per unit		$ 0.1704
Distribution declared		$ 4,611
Subsequent Event [Member]
Subsequent Event [Line Items]
Distribution declared per unit	$ 0.2750
Distribution declared	$ 7,441

Quarterly Financial Information (Unaudited) (Summary Of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Aug. 03, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net sales	$ 273,543	$ 392,008									$ 1,749,700
Gross profit	101,959	164,993									745,812
Income from operations	95,506	156,133									$ 716,556
Net income	$ 93,929	$ 118,173							$ 13,577
Basic and diluted earnings per common unit holder (usd per unit)									$ 0.50
Common units [Member]
Net income									$ 7,213
Basic and diluted earnings per common unit holder (usd per unit)	$ 0.32	$ 0.19							$ 0.50
Subordinated units [Member]
Net income									$ 6,364
Basic and diluted earnings per common unit holder (usd per unit)	$ 0.32	$ 0.19							$ 0.50
Predecessor [Member]
Net sales			$ 524,135	$ 560,014	$ 561,938	$ 540,133	$ 524,759	$ 500,917				$ 2,127,747	$ 2,249,098
Gross profit			246,546	232,314	231,461	212,981	238,155	190,010				872,607	635,652
Income from operations			240,381	224,536	225,336	206,590	231,391	183,839				$ 847,156	$ 611,549
Net income			$ 153,844	$ 143,874	$ 144,206	$ 132,581	$ 149,034	$ 120,725		$ 361,334

- Definition

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

+ References

+ Details

Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 2,105	$ 2,065	$ 1,983
Charged to Expense	65	40	82
Additions/ (Deductions)	(2,170)	0	0
Balance at End of Year	$ 0	$ 2,105	$ 2,065

Label	Element	Value
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders, Reimbursement	wlkp_NoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHoldersReimbursement	$ 151,729,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	448,101,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	4,611,000
Partners' Capital Account, Public Sale of Units	us-gaap_PartnersCapitalAccountPublicSaleOfUnits	286,088,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	51,655,000
Partners' Capital, Predecessor Net Liabilities Not Assumed By Subsidiary	wlkp_PartnersCapitalPredecessorNetLiabilitiesNotAssumedBySubsidiary	239,706,000
Predecessor [Member]
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	448,101,000
Partners' Capital, Predecessor Net Liabilities Not Assumed By Subsidiary	wlkp_PartnersCapitalPredecessorNetLiabilitiesNotAssumedBySubsidiary	239,706,000
Partners' Capital Allocation Of Net Investment To Unitholders	wlkp_PartnersCapitalAllocationOfNetInvestmentToUnitholders	(608,371,000)
Noncontrolling Interest [Member]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders, Reimbursement	wlkp_NoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHoldersReimbursement	151,729,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	134,909,000
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	242,572,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	51,655,000
Partners' Capital Allocation Of Net Investment To Unitholders	wlkp_PartnersCapitalAllocationOfNetInvestmentToUnitholders	573,329,000
Unidentified Third Parties [Member] \| Common Units [Member] \| Limited Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	6,493,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	2,204,000
Partners' Capital Account, Public Sale of Units	us-gaap_PartnersCapitalAccountPublicSaleOfUnits	286,088,000
Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] \| General Partner [Member]
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	(242,572,000)
Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] \| Common Units [Member] \| Limited Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	720,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	245,000
Partners' Capital Allocation Of Net Investment To Unitholders	wlkp_PartnersCapitalAllocationOfNetInvestmentToUnitholders	3,563,000
Parent Company And Subsidiaries, Excluding Reporting Entity And Subsidiaries [Member] \| Subordinated Units [Member] \| Limited Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	6,364,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	2,162,000
Partners' Capital Allocation Of Net Investment To Unitholders	wlkp_PartnersCapitalAllocationOfNetInvestmentToUnitholders	$ 31,479,000