10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-Q

x	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
	For the quarterly period ended March 31, 2018

or

¨	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
	For the Transition Period from                    to

Commission File No. 001-36567

Westlake Chemical Partners LP

(Exact name of Registrant as specified in its charter)

Delaware	32-0436529
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

2801 Post Oak Boulevard, Suite 600

Houston, Texas 77056

(Address of principal executive offices, including zip code)

(713) 585-2900

(Registrant's telephone number, including area code)

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     YesxNo¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).     YesxNo¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a smaller reporting company, or an emerging growth company. See definitions of "large accelerated filer," "accelerated filer", "smaller reporting company" and "emerging growth company" in Rule 12b-2 of the Exchange Act (Check one):

Large accelerated filer	¨	Accelerated filer	x
Non-accelerated filer	¨ (Do not check if a smaller reporting company)	Smaller reporting company	¨
		Emerging growth company	¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act)     Yes¨Nox

The registrant had 32,237,266 common units outstanding as of April 26, 2018.

INDEX

Item	Page
PART I. FINANCIAL INFORMATION
1) Financial Statements	1
2) Management's Discussion and Analysis of Financial Condition and Results of Operations	13
3) Quantitative and Qualitative Disclosures about Market Risk	22
4) Controls and Procedures	22
PART II. OTHER INFORMATION
1) Legal Proceedings	24
1A) Risk Factors	24
6) Exhibits	25

PART I. FINANCIAL INFORMATION

Item 1. Financial Statements

WESTLAKE CHEMICAL PARTNERS LP

CONSOLIDATED BALANCE SHEETS

(Unaudited)

	March 31, 2018			December 31, 2017
	(in thousands of dollars, except unit amounts)
ASSETS
Current assets
Cash and cash equivalents	$	24,980		$	27,008
Receivable under the Investment Management Agreement—Westlake Chemical    Corporation ("Westlake")	134,712			136,510
Accounts receivable, net—Westlake	43,257			43,884
Accounts receivable, net—third parties	19,017			18,083
Inventories	5,171			5,590
Prepaid expenses and other current assets	161			314
Total current assets	227,298			231,389
Property, plant and equipment, net	1,183,409			1,196,245
Goodwill	5,814			5,814
Deferred charges and other assets, net	76,083			81,828
Total assets	$	1,492,604		$	1,515,276
LIABILITIES
Current liabilities
Accounts payable—Westlake	$	14,339		$	14,027
Accounts payable—third parties	7,798			10,516
Accrued liabilities	15,150			15,697
Total current liabilities	37,287			40,240
Long-term debt payable to Westlake	477,608			473,960
Deferred income taxes	2,272			2,220
Other liabilities	114			107
Total liabilities	517,281			516,527
Commitments and contingencies (Note 12)
EQUITY
Common unitholders—public (18,115,036 and 18,112,500 units issued and outstanding at March 31, 2018 and December 31, 2017, respectively)	410,786			411,228
Common unitholder—Westlake (14,122,230 and 14,122,230 units issued and outstanding at March 31, 2018 and December 31, 2017, respectively)	49,872			50,265
General partner—Westlake	(241,839		)	(241,958		)
Accumulated other comprehensive income	298			279
Total Westlake Chemical Partners LP partners' capital	219,117			219,814
Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo")	756,206			778,935
Total equity	975,323			998,749
Total liabilities and equity	$	1,492,604		$	1,515,276

The accompanying notes are an integral part of these consolidated financial statements.

1

WESTLAKE CHEMICAL PARTNERS LP

CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited)

	Three Months Ended March 31,
	2018			2017
	(in thousands of dollars, except unit amounts and per unit data)
Revenue
Net sales—Westlake	$	235,031		$	212,930
Net co-product, ethylene and other sales—third parties	49,241			64,518
Total net sales	284,272			277,448
Cost of sales	191,767			179,487
Gross profit	92,505			97,961
Selling, general and administrative expenses	7,133			7,828
Income from operations	85,372			90,133
Other income (expense)
Interest expense—Westlake	(4,866		)	(5,460		)
Other income, net	491			1,658
Income before income taxes	80,997			86,331
Provision for income taxes	283			303
Net income	80,714			86,028
Less: Net income attributable to noncontrolling interest in OpCo	68,419			76,264
Net income attributable to Westlake Chemical Partners LP	$	12,295		$	9,764
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic    and diluted)
Common units	$	0.36		$	0.35
Subordinated units	$	—		$	0.35
Weighted average limited partner units outstanding (basic and diluted)
Common units—public	18,115,036			12,937,500
Common units—Westlake	14,122,230			1,436,115
Subordinated units—Westlake	—			12,686,115
Distributions per common unit	$	0.3864		$	0.3450

The accompanying notes are an integral part of these consolidated financial statements.

2

WESTLAKE CHEMICAL PARTNERS LP

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

(Unaudited)

		Partnership
		Common Unitholders— Public			Common Unitholder— Westlake			Subordinated Unitholder— Westlake			General Partner— Westlake			Accumulated Other Comprehensive  Income (Loss)		Noncontrolling Interests in OpCo			Total
	(in thousands of dollars)
Balances at December 31, 2016		$	297,367		$	4,813		$	42,534		$	(242,430	)	$	200	$	818,479		$	920,963
Net income		4,559			505			4,469			231			—		76,264			86,028
Net effect of cash flow hedge		—			—			—			—			89		—			89
Quarterly distributions to unitholders		(4,464		)	(495		)	(4,377		)	(142		)	—		—			(9,478		)
Quarterly distribution to noncontrolling interest retained in    OpCo by Westlake		—			—			—			—			—		(89,617		)	(89,617		)
Balances at March 31, 2017		$	297,462		$	4,823		$	42,626		$	(242,341	)	$	289	$	805,126		$	907,985
Balances at December 31, 2017		$	411,228		$	50,265		$	—		$	(241,958	)	$	279	$	778,935		$	998,749
Net income		6,498			5,064			—			733			—		68,419			80,714
Net effect of cash flow hedge		—			—			—			—			19		—			19
Units issued for vested phantom units		60			—			—			—			—		—			60
Quarterly distributions to unitholders		(7,000		)	(5,457		)	—			(614		)	—		—			(13,071		)
Quarterly distribution to noncontrolling interest retained in    OpCo by Westlake		—			—			—			—			—		(91,148		)	(91,148		)
Balances at March 31, 2018		$	410,786		$	49,872		$	—		$	(241,839	)	$	298	$	756,206		$	975,323

The accompanying notes are an integral part of these consolidated financial statements.

3

WESTLAKE CHEMICAL PARTNERS LP

CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

	Three Months Ended March 31,
	2018			2017
	(in thousands of dollars)
Cash flows from operating activities
Net income	$	80,714		$	86,028
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	27,698			30,150
Loss (gain) from disposition of property, plant and equipment	567			(127		)
Other losses (gains), net	357			(488		)
Changes in operating assets and liabilities
Accounts receivable—third parties	(1,239		)	(8,753		)
Net accounts receivable—Westlake	737			40,010
Inventories	419			(842		)
Prepaid expenses and other current assets	153			115
Accounts payable	(2,835		)	5,150
Accrued and other liabilities	(487		)	7,461
Other, net	138			(9,626		)
Net cash provided by operating activities	106,222			149,078
Cash flows from investing activities
Additions to property, plant and equipment	(9,679		)	(23,168		)
Maturities of investments with Westlake under the Investment Management Agreement	112,000			—
Investments with Westlake under the Investment Management Agreement	(110,000		)	—
Other	—			1,682
Net cash used for investing activities	(7,679		)	(21,486		)
Cash flows from financing activities
Proceeds from debt payable to Westlake	3,648			17,000
Repayment of debt payable to Westlake	—			(11,423		)
Quarterly distributions to noncontrolling interest retained in OpCo by Westlake	(91,148		)	(89,617		)
Quarterly distributions to unitholders	(13,071		)	(9,478		)
Net cash used for financing activities	(100,571		)	(93,518		)
Net increase (decrease) in cash and cash equivalents	(2,028		)	34,074
Cash and cash equivalents at beginning of period	27,008			88,900
Cash and cash equivalents at end of period	$	24,980		$	122,974

The accompanying notes are an integral part of these consolidated financial statements.

4

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

1.Description of Business and Basis of Presentation

Description of Business

Westlake Chemical Partners LP (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 its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests. On September 29, 2017, the Partnership completed its secondary offering of 5,175,000 common units at a price of $22.00 per unit.

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. On April 29, 2015, the Partnership purchased an additional 2.7% newly-issued limited partner interest in OpCo for approximately $135,341, resulting in an aggregate 13.3% limited partner interest in OpCo effective April 1, 2015. On September 29, 2017, the Partnership purchased an additional 5.0% newly-issued limited partner interest in OpCo for approximately $229,207, resulting in an aggregate 18.3% limited partner interest in OpCo, effective as of July 1, 2017. The remaining 81.7% limited partner interest in OpCo is owned by Westlake Chemical Corporation.

OpCo owns three ethylene production facilities and a common carrier ethylene pipeline.

Basis of Presentation

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2017 consolidated financial statements and notes thereto of the Partnership included in the annual report on Form 10-K for the fiscal year ended December 31, 2017 (the "2017 Form 10-K"), filed with the SEC on March 1, 2018. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Partnership for the fiscal year ended December 31, 2017 with the exceptions of those accounting standards adopted in the first quarter of 2018 as discussed in Note 1.

References to "Westlake" refer collectively to Westlake Chemical Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.

The Partnership holds an 18.3% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 81.7% limited partner interest in OpCo is owned 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 81.7% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.

In the opinion of the Partnership's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Partnership's financial position as of March 31, 2018, its results of operations for the three months ended March 31, 2018 and 2017 and the changes in its cash position for the three months ended March 31, 2018 and 2017.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2018 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP 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 materially from those estimates.

5

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

Recent Accounting Pronouncements

Leases (ASU No. 2016-02)

In February 2016, the FASB issued an accounting standards update on a new lease standard that will supersede the existing lease guidance. The standard requires a lessee to recognize assets and liabilities related to long-term leases that are classified as operating leases under current guidance on its balance sheet. An asset would be recognized related to the right to use the underlying asset and a liability would be recognized related to the obligation to make lease payments over the term of the lease. The standard also requires expanded disclosures related to leases. The accounting standard will be effective for reporting periods beginning after December 15, 2018. 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.

Credit Losses (ASU No. 2016-13)

In June 2016, the FASB issued an accounting standards update providing new guidance for the accounting for credit losses on loans and other financial instruments. The new guidance introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. The standard also modifies the impairment model for available-for-sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Partnership's consolidated financial position, results of operations and cash flows.

Recently Adopted Accounting Standards

Revenue from Contracts with Customers (ASU No. 2014-09)

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that supersedes virtually all previously issued 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 are 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 "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 Partnership adopted ASC No. 2014-09, Revenue from Contracts with Customers (“ASC 606”), effective January 1, 2018. The Company applied the modified retrospective transition method to all contracts that were not completed as of the adoption date. Periods prior to January 1, 2018 were not adjusted and are reported under the accounting standards that were in place during those periods. There was no cumulative effect to the Partnership’s consolidated January 1, 2018 balance sheet for the adoption of this accounting standard. There was no impact of ASC 606 adoption on the financial statements for the three months ended March 31, 2017 as compared with the guidance that was in effect prior to January 1, 2018.

Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement.

The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales.

6

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (i) have an original expected duration of one year or less or (ii) have only variable consideration which is allocated to wholly unsatisfied performance obligations that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations.

The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement (discussed in Note 2 to the 2017 Form 10-K). The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. Partnership’s direct commodity price risk is limited to the sales to third parties. Refer to the Partnership’s Consolidated Statement of Operations for the disaggregation of net sales to Westlake and net sales to third parties.

Cash Flows (ASU No. 2016-15)

In August 2016, the FASB issued an accounting standards update providing new guidance on the classification of certain cash receipts and payments including debt extinguishment costs, debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments, proceeds from the settlement of insurance claims and life insurance policies and distributions received from equity method investees in the statement of cash flows. This update is required to be applied using the retrospective transition method to each period presented unless it is impracticable to be applied retrospectively. In such situation, this guidance is to be applied prospectively. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow.

Business Combinations (ASU No. 2017-01)

In January 2017, the FASB issued an accounting standards update to assist entities with evaluating when a set of transferred assets and activities is a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in the FASB ASC Topic 606, Revenue from contracts with customers. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow. 

Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (ASU No. 2017-05)

In February 2017, the FASB issued an accounting standards update to clarify the scope of guidance related to other income—gains and losses from the derecognition of nonfinancial assets, and to add guidance for partial sales of nonfinancial assets. The new guidance clarifies that an in substance nonfinancial asset is an asset or group of assets for which substantially all of the fair value consists of nonfinancial assets and the group or subsidiary is not a business. The guidance also outlines that when an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling interest, it will measure the retained interest at fair value resulting in full gain or loss recognition upon sale of the controlling interest. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow.

2.Accounts Receivable—Third Parties

Accounts receivable—third parties consist of the following:

	March 31, 2018			December 31, 2017
Trade customers	$	20,033		$	18,794
Allowance for doubtful accounts	(1,016		)	(711		)
Accounts receivable, net—third parties	$	19,017		$	18,083

7

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

3.Inventories

Inventories consist of the following:

	March 31, 2018		December 31, 2017
Finished products	$	4,844	$	5,244
Feedstock, additives and chemicals	327		346
Inventories	$	5,171	$	5,590

4.Property, Plant and Equipment

Depreciation expense on property, plant and equipment of $22,157 and $23,413 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2018 and 2017, respectively.

5.Other Assets

Amortization expense on other assets of $5,541 and $6,737 is included in costs of sales in the consolidated statements of operations for the three months ended March 31, 2018 and 2017, respectively.

6.Distributions and Net Income Per Limited Partner Unit

On April 30, 2018, the board of directors of Westlake Chemical Partners GP LLC ("Westlake GP"), the Partnership's general partner, declared a quarterly cash distribution for the period from January 1, 2018 through March 31, 2018 of $0.3975 per unit and of $733 to the holder of the Partnership's incentive distribution rights ("IDR Holder"). This distribution is payable on May 24, 2018 to the unitholders and IDR Holder of record as of May 10, 2018.

The Partnership Agreement provides that the Partnership will distribute cash each quarter in the following manner: first, to all the unitholders, until each unit has received the minimum quarterly distribution of $0.2750, plus any arrearages from prior quarters; and second, to all the unitholders, pro-rata, until each unit has received a distribution of $0.3163. If cash distributions to the Partnership's unitholders exceed $0.3163 per 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	%

For the three months ended March 31, 2018, the Partnership's distribution exceeded the $0.3163 per common unit target, which resulted in distributions to the IDR Holder.

The distributions are declared subsequent to quarter end; therefore, the table below represents total distributions declared from earnings of the related periods pertaining to such distributions.

	Three Months Ended March 31,
	2018			2017
Net income attributable to the Partnership	$	12,295		$	9,764
Less:
Limited partners' distributions declared on common units	12,814			5,101
Limited partners' distributions declared on subordinated units	—			4,502
Distributions declared with respect to the incentive distribution rights	733			231
Distribution in excess of net income	$	(1,252	)	$	(70	)

8

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

Net income per unit applicable to common limited partner units is computed by dividing the respective limited partners' interest in net income by the weighted-average number of common units outstanding for the period. 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 incentive distribution rights. Net income attributable to the Partnership is allocated to the unitholders in accordance with their respective ownership percentages in preparation of the consolidated statement of equity. However, when distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions is first allocated to the general partner before the remaining net income is allocated to the unitholders based on their respective ownership percentages. 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.

The 12,686,115 subordinated units, all of which were owned by Westlake, were converted into common units during the third quarter of 2017 and were considered converted as of July 1, 2017 for purposes of calculating net income per unit. Therefore, the subordinated units did not share in the distribution of cash generated nor did the partnership allocate any earnings to the subordinated unitholders for the determination of net income per unit subsequent to June 30, 2017.

	Three Months Ended March 31, 2018
	Limited Partners' Common Units			Incentive Distribution Rights		Total
Net income attributable to the Partnership:
Distribution declared	$	12,814		$	733	$	13,547
Distribution in excess of net income	(1,252		)	—		(1,252		)
Net income	$	11,562		$	733	$	12,295
Weighted average units outstanding:
Basic and diluted	32,236,449					32,236,449
Net income per limited partner unit:
Basic and diluted	$	0.36

	Three Months Ended March 31, 2017
	Limited Partners' Common Units			Limited Partners' Subordinated Units			Incentive Distribution Rights		Total
Net income attributable to the Partnership:
Distribution declared	$	5,101		$	4,502		$	231	$	9,834
Distribution in excess of net income	(37		)	(33		)	—		(70		)
Net income	$	5,064		$	4,469		$	231	$	9,764
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	$	0.35		$	0.35

7.Partners' Equity

Following the Partnership’s cash distribution for the second quarter of 2017, the requirement under the Partnership’s partnership agreement for the conversion of all subordinated units was satisfied. As a result, effective August 30, 2017, the 12,686,115 subordinated units owned by Westlake were converted into common units on a one-for-one basis and thereafter participate on terms equal with all other common units in distributions of available cash. As discussed in Note 6, the subordinated units were considered converted as of July 1, 2017 for purposes of calculating net income per unit and, therefore, the subordinated units did not share in the distribution of cash generated nor did the Partnership allocate any earnings to the subordinated unitholders for the determination of net income per unit subsequent to June 30, 2017.

9

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

On September 29, 2017, the Partnership completed its secondary offering of 5,175,000 common units at a price of $22.00 per unit. Net proceeds to the Partnership from the sale of the units were $110,739, net of underwriting discounts, structuring fees and estimated offering expenses of approximately $3,111.

8.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 each charges Westlake a fee.

Sales to related parties were as follows:

	Three Months Ended March 31,
	2018		2017
Net sales—Westlake	$	235,031	$	212,930

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.

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

	Three Months Ended March 31,
	2018		2017
Feedstock purchased from Westlake and included in cost of sales	$	105,415	$	97,113
Other charges from Westlake and included in cost of sales	28,406		25,417
Total	$	133,821	$	122,530

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.

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

	Three Months Ended March 31,
	2018		2017
Services received from Westlake and included in selling, general and administrative    expenses	$	6,251	$	6,732

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.

10

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

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

	Three Months Ended March 31,
	2018		2017
Goods and services purchased from Westlake and capitalized as assets	$	346	$	1,405

Receivable under the Investment Management Agreement

On August 1, 2017, the Partnership, OpCo and Westlake executed an investment management agreement (the "Investment Management Agreement") that authorized Westlake to invest the Partnership and OpCo’s excess cash with Westlake for a term of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. Accrued interest earned of $540 and $340 was included in the receivable under the Investment Management Agreement balance at March 31, 2018 and December 31, 2017, respectively.

The Partnership's receivable under the Investment Management Agreement was as follows:

	March 31, 2018		December 31, 2017
Receivable under the Investment Management Agreement	$	134,712	$	136,510

Accounts Receivables

The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake under the Ethylene Sales Agreement.

The Partnership's accounts receivable from Westlake were as follows:

	March 31, 2018		December 31, 2017
Accounts receivable—Westlake	$	43,257	$	43,884

Accounts Payable to Related Parties

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.

The related party accounts payable balances were as follows:

	March 31, 2018		December 31, 2017
Accounts payable—Westlake	$	14,339	$	14,027

Debt Payable to Related Parties

See Note 9 for a description of related party debt payable balances. Interest on related party debt payable balances for the three months ended March 31, 2018 and 2017 was $4,866 and $5,460, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. Interest capitalized as a component of property, plant and equipment on related party debt was $15 and $398 for the three months ended March 31, 2018 and 2017, respectively. At March 31, 2018 and December 31, 2017, accrued interest on related party debt was $4,864 and $4,590, respectively, and is reflected as a component of accrued liabilities in the consolidated balance sheets.

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WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

Debt payable to related parties was as follows:

	March 31, 2018		December 31, 2017
Long-term debt payable to Westlake	$	477,608	$	473,960

Major Customer and Concentration of Credit Risk

During the three months ended March 31, 2018 and 2017, Westlake accounted for approximately 82.7% and 76.7%, respectively, of the Partnership's net sales.

General

In 2015, the Partnership entered into an interest rate contract with Westlake to fix the London Interbank Offered Rate ("LIBOR") component of the interest rate for a portion of the MLP Revolver balance.

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

9.Long-term Debt Payable to Westlake

Long-term debt payable to Westlake consists of the following:

	March 31, 2018		December 31, 2017
OpCo Revolver (variable interest rate of LIBOR plus 3.0%, original scheduled maturity of    August 4, 2019)	$	224,064	$	220,416
MLP Revolver (variable interest rate of LIBOR plus 2.0%, original scheduled maturity of    April 29, 2021)	253,544		253,544
	$	477,608	$	473,960

The weighted average interest rate on all long-term debt was 4.08% and 3.76% at March 31, 2018 and December 31, 2017, respectively.

As of March 31, 2018, the Partnership was in compliance with all of the covenants under the OpCo Revolver and the MLP Revolver.

10.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.

The Partnership has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include accounts receivable, net, accounts payable and long-term debt payable to Westlake, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for 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 long-term debt at March 31, 2018 and December 31, 2017 are summarized in the table below. The Partnership's long-term debt includes the OpCo Revolver and the MLP Revolver at March 31, 2018. 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

12

WESTLAKE CHEMICAL PARTNERS LP

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—Continued

(Unaudited)

(in thousands of dollars, except unit amounts and per unit data)

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.

	March 31, 2018				December 31, 2017
	Carrying Value		Fair Value		Carrying Value		Fair Value
OpCo Revolver	$	224,064	$	230,649	$	220,416	$	228,180
MLP Revolver	253,544		256,588		253,544		258,234

11.Supplemental Information

Accrued Liabilities

Accrued liabilities were $15,150 and $15,697 at March 31, 2018 and December 31, 2017, respectively. The accrued interest, accrued maintenance, capital expenditures accrual and accrued taxes, which are components of accrued liabilities, were $4,864, $3,406, $2,179 and $2,115, respectively, at March 31, 2018, and $4,590, $3,698, $3,197 and $1,422, respectively, at December 31, 2017. No other component of accrued liabilities was more than five percent of total current liabilities.

Non-cash Investing Activity

The change in capital expenditure accrual reducing additions to property, plant and equipment was $117 for the three months ended March 31, 2018. The change in capital expenditure accrual reducing additions to property, plant and equipment was $1,159 for the three months ended March 31, 2017.

12.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.

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.

Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations

This Management's Discussion and Analysis of Financial Condition and Results of Operations section should be read in conjunction with the accompanying consolidated financial statements and the notes thereto and the consolidated financial statements and notes thereto included in Westlake Chemical Partners LP's annual report on Form 10-K for the fiscal year ended December 31, 2017 (the "2017 Form 10-K"), as filed with the SEC on March 1, 2018. Unless otherwise indicated, references in this report to "we," "our," "us" or like terms, refer to Westlake Chemical Partners LP (the "Partnership"), Westlake Chemical OpCo LP ("OpCo") and Westlake Chemical OpCo GP LLC ("OpCo GP"). References to "Westlake" refer to Westlake Chemical Corporation and its consolidated subsidiaries other than the Partnership, OpCo GP and OpCo. The following discussion contains forward-looking statements. Please read "Forward-Looking Statements" for a discussion of limitations inherent in such statements.

Partnership Overview

We are a Delaware limited partnership formed by Westlake to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, we closed our initial public offering (the "IPO") of 12,937,500 common units. In

13

connection with the IPO, we acquired a 10.6% interest in OpCo and a 100% interest in OpCo GP, which is the general partner of OpCo. On April 29, 2015, we purchased an additional 2.7% newly-issued limited partner interest in OpCo for approximately $135.3 million, resulting in an aggregate 13.3% limited partner interest in OpCo effective April 1, 2015. On September 29, 2017, we completed a secondary public offering of 5,175,000 common units and purchased an additional 5.0% newly-issued limited partner interest in OpCo for approximately $229.2 million, resulting in an aggregate 18.3% limited partner interest in OpCo, effective as of July 1, 2017.

Currently, our sole revenue generating asset is our 18.3% limited partner interest in OpCo, a limited partnership formed by Westlake and us in anticipation of the IPO to own and operate an ethylene production business. We control OpCo through our ownership of its general partner. Westlake retains the remaining 81.7% limited partner interest in OpCo as well as a significant interest in us through its ownership of our general partner, 43.8% of our limited partner units (consisting of 14,122,230 common units ) and our incentive distribution rights. OpCo's assets include (1) two ethylene production facilities ("Petro 1" and "Petro 2" and, collectively, "Lake Charles Olefins") at Westlake's Lake Charles, Louisiana site; (2) one ethylene production facility ("Calvert City Olefins") at Westlake's Calvert City, Kentucky site; and (3) a 200-mile common carrier ethylene pipeline (the "Longview Pipeline") that runs from Mont Belvieu, Texas to Westlake's Longview, Texas facility.

How We Generate Revenue

We generate revenue primarily by selling ethylene and the resulting co-products we produce. OpCo and Westlake have entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which we generate a substantial majority of our revenue. The Ethylene Sales Agreement is a long-term, fee-based agreement with a minimum purchase commitment and includes variable pricing based on OpCo's actual feedstock and natural gas costs and estimated other costs of producing ethylene (including OpCo's estimated operating costs and a five-year average of OpCo's expected future maintenance capital expenditures and other turnaround expenditures based on OpCo's planned ethylene production capacity for the year), plus a fixed margin per pound of $0.10 less revenue from co-products sales.

Westlake has an option to take 95% of volumes in excess of the minimum commitment on an annual basis under the Ethylene Sales Agreement if we produce more than our planned production. Under the Ethylene Sales Agreement, the price for the sale of such excess ethylene to Westlake is based on a formula similar to that used for the minimum purchase commitment, with the exception of certain fixed costs. In addition, under the Ethylene Sales Agreement, if production costs billed to Westlake on an annual basis are less than 95% of the actual production costs incurred by OpCo during the contract year, OpCo is entitled to recover the shortfall in such production costs (proportionate to the volume sold to Westlake) in the subsequent year ("Shortfall"). The Shortfall is recognized during the period in which the related operating, maintenance or turnaround activities occur.

Operating Expenses, Maintenance Capital Expenditures and Turnaround Costs

Our management seeks to maximize the profitability of our operations by effectively managing operating expenses, maintenance capital expenditures and turnaround costs. Our operating expenses are comprised primarily of feedstock costs and natural gas, labor expenses (including contractor services), utility costs (other than natural gas) and turnaround and maintenance expenses. With the exception of feedstock, including natural gas, and utilities-related expenses, operating expenses generally remain relatively stable across broad ranges of production volumes but can fluctuate from period to period depending on the circumstances, particularly maintenance and turnaround activities. Our maintenance capital expenditures and turnaround costs are comprised primarily of maintenance of our ethylene production facilities and the amortization of capitalized turnaround costs. These capital expenditures relate to the maintenance and integrity of our facilities. We capitalize the costs of major maintenance activities, or turnarounds, and amortize the costs over the period until the next planned turnaround of the affected facility.

Operating expenses, maintenance capital expenditures and turnaround costs are built into the price per pound of ethylene charged to Westlake under the Ethylene Sales Agreement. Because the expenses other than feedstock costs and natural gas are based on forecasted amounts and remain a fixed component of the price per pound of ethylene sold under the Ethylene Sales Agreement for any given 12-month period, our ability to manage operating expenses, maintenance expenditures and turnaround cost may directly affect our profitability and cash flows. The impact on profitability is partially mitigated by the fact that we recognize any Shortfall as revenue in the period such costs and expenses are incurred. We seek to manage our operating and maintenance expenses on our ethylene production facilities by scheduling maintenance and turnarounds over time to avoid significant variability in our operating margins and minimize the impact on our cash flows, without compromising our commitment to safety and environmental stewardship. In addition, we reserve cash on an annual basis from what we would otherwise distribute to minimize the impact of turnaround costs in the year of incurrence. The purchase price under the Ethylene Sales Agreement is not designed to cover capital expenditures for expansions.

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MLP Distributable Cash Flow and EBITDA

We use each of MLP distributable cash flow and EBITDA to analyze our performance. We define distributable cash flow as net income plus depreciation, amortization and disposition of property, plant and equipment, less contributions for turnaround reserves and maintenance capital expenditures. We define MLP distributable cash flow as distributable cash flow less distributable cash flow attributable to Westlake's noncontrolling interest in OpCo and distributions attributable to the incentive distribution rights holder. MLP distributable cash flow does not reflect changes in working capital balances. We define EBITDA as net income before interest expense, income taxes, depreciation and amortization. MLP distributable cash flow and EBITDA are non-GAAP supplemental financial measures that management and external users of our consolidated financial statements, such as industry analysts, investors, lenders and rating agencies, may use to assess:

• our operating performance as compared to other publicly traded partnerships;

• our ability to incur and service debt and fund capital expenditures;

• the viability of acquisitions and other capital expenditure projects and the returns on investment of various investment opportunities.

We believe that the presentation of MLP distributable cash flow and EBITDA provides useful information to investors in assessing our financial condition and results of operations. The GAAP measures most directly comparable to MLP distributable cash flow are net income and net cash provided by operating activities. MLP distributable cash flow should not be considered as an alternative to GAAP net income or net cash provided by operating activities. MLP distributable cash flow has important limitations as an analytical tool because it excludes some but not all items that affect net income and net cash provided by operating activities. The GAAP measures most directly comparable to EBITDA are net income and net cash provided by operating activities, but EBITDA should not be considered an alternative to such GAAP measures. EBITDA has important limitations as an analytical tool because it excludes (1) interest expense, which is a necessary element of our costs and ability to generate revenues because we have borrowed money to finance our operations, (2) depreciation, which is a necessary element of our costs and ability to generate revenues because we use capital assets and (3) income taxes, which was a necessary element of the operations of our predecessor. MLP distributable cash flow and EBITDA should not be considered in isolation or as a substitute for analysis of our results as reported under GAAP. See reconciliations for each of MLP distributable cash flow and EBITDA under "Results of Operations" below.

15

Results of Operations

	Three Months Ended March 31,
	2018			2017
	(dollars in thousands)
Revenue
Net sales—Westlake	$	235,031		$	212,930
Net co-product, ethylene and other sales—third parties	49,241			64,518
Total net sales	284,272			277,448
Cost of sales	191,767			179,487
Gross profit	92,505			97,961
Selling, general and administrative expenses	7,133			7,828
Income from operations	85,372			90,133
Other income (expense)
Interest expense—Westlake	(4,866		)	(5,460		)
Other income, net	491			1,658
Income before income taxes	80,997			86,331
Provision for income taxes	283			303
Net income	80,714			86,028
Less: Net income attributable to noncontrolling interest in OpCo	68,419			76,264
Net income attributable to Westlake Chemical Partners LP	$	12,295		$	9,764
MLP distributable cash flow (1)	$	14,510		$	11,447
EBITDA (2)	$	113,561		$	121,941
____________
(1) See "Reconciliation of MLP Distributable Cash Flow to Net Income and Net Cash Provided by Operating Activities" below.
(2) See "Reconciliation of EBITDA to Net Income and Net Cash Provided by Operating Activities" below.

	Three Months Ended March 31, 2018
	Average Sales Price		Volume
Product sales prices and volume percentage change from prior-year period	-3.1	%	+5.6	%
	Three Months Ended March 31,
	2018		2017
Average industry prices (1)
Ethane (cents/lb)	8.5		7.8
Propane (cents/lb)	20.2		16.9
Ethylene (cents/lb) (2)	23.6		31.2

_____________

(1) Industry pricing data was obtained through IHS Markit ("IHS"). We have not independently verified the data.

(2) Represents average North American spot prices of ethylene over the period as reported by IHS.

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Reconciliation of MLP Distributable Cash Flow to Net Income and Net Cash Provided by Operating Activities

The following table presents reconciliations of MLP distributable cash flow to net income and net cash provided by operating activities, the most directly comparable GAAP financial measures, for each of the periods indicated.

	Three Months Ended March 31,
	2018			2017
	(dollars in thousands)
Net cash provided by operating activities	$	106,222		$	149,078
Gain (loss) from disposition of fixed assets	(567		)	127
Changes in operating assets and liabilities and other	(24,941		)	(63,177		)
Net Income	80,714			86,028
Add:
Depreciation, amortization and disposition of property, plant and equipment	28,265			30,150
Less:
Contribution to turnaround reserves	(4,148		)	(7,239		)
Maintenance capital expenditures	(7,979		)	(8,490		)
Incentive distribution rights	(733		)	(231		)
Distributable cash flow attributable to noncontrolling interest in OpCo	(81,609		)	(88,771		)
MLP distributable cash flow	$	14,510		$	11,447

Reconciliation of EBITDA to Net Income and Net Cash Provided by Operating Activities

The following table presents reconciliations of EBITDA to net income and net cash provided by operating activities, the most directly comparable GAAP financial measures, for each of the periods indicated.

	Three Months Ended March 31,
	2018			2017
	(dollars in thousands)
Net cash provided by operating activities	$	106,222		$	149,078
Gain (loss) from disposition of fixed assets	(567		)	127
Changes in operating assets and liabilities and other	(24,941		)	(63,177		)
Net Income	80,714			86,028
Add:
Depreciation and amortization	27,698			30,150
Interest expense	4,866			5,460
Provision for income taxes	283			303
EBITDA	$	113,561		$	121,941

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Summary

For the quarter ended March 31, 2018, net income was $80.7 million on net sales of $284.3 million. This represents a decrease in net income of $5.3 million as compared to the quarter ended March 31, 2017 net income of $86.0 million on net sales of $277.4 million. Net income for the first quarter of 2018 as compared to the first quarter of 2017 was lower primarily as a result of lower third party sales prices, partially offset by higher sales volumes to Westlake and third parties due to higher production primarily at our Calvert City Olefins facility. Our Calvert City Olefins facility production was lower in the first quarter of 2017 because of an upgrade and expansion project in March and April 2017. Net income attributable to Westlake Chemical Partners LP for the quarter ended March 31, 2018 was $12.3 million as compared to $9.8 million for the quarter ended March 31, 2017, an increase of $2.5 million, which was primarily due to a 5% increase in the Partnership's interest in OpCo, effective as of July 1, 2017. Net sales for the first quarter of 2018increased by $6.9 million as compared to net sales for the first quarter of 2017 mainly due to increased sales to Westlake and higher volumes of co-product sales to third parties, partially offset by lower sales prices for co-products to third parties. Income from operations was $85.4 million for the first quarter of 2018 as compared to $90.1 million for the first quarter of 2017. Income from operations for the first quarter of 2018decreased mainly as a result of the lower third party sales prices, partially offset by higher sales volume resulting primarily from higher production at our Calvert City Olefins facility as compared to the first quarter of 2017.

RESULTS OF OPERATIONS

First Quarter 2018 Compared with First Quarter 2017

Net Sales. Total net sales increased by $6.9 million, or 2.5%, to $284.3 million in the first quarter of 2018 from $277.4 million in the first quarter of 2017. The overall increase in sales volumes for the first quarter of 2018 contributed to a 5.6%increase in net sales, as compared to the first quarter of 2017, which was mainly due to higher sales volumes to Westlake and third parties. The average sales price contributed to a decrease in net sales by 3.1% in the first quarter of 2018 compared to the first quarter of 2017, primarily as a result of lower sales price to third parties.

Gross Profit. Gross profit decreased to $92.5 million for the first quarter of 2018 from $98.0 million for the first quarter of 2017. The gross profit margin in the first quarter of 2018 was 32.5%, as compared to 35.3% for the first quarter of 2017. The first quarter of 2018 gross profit margin was lower mainly due to the lower third party sales prices, partially offset by higher sales volumes to Westlake and third parties as a result of higher production primarily at our Calvert City Olefins facility, as compared to the first quarter of 2017. Our Calvert City Olefins facility production was lower in the first quarter of 2017 because of an upgrade and expansion project in March and April 2017.

Selling, General and Administrative Expenses. Selling, general and administrative expenses decreased by $0.7 million, or 9.0%, to $7.1 million in the first quarter of 2018 as compared to $7.8 million in the first quarter of 2017. The decrease was mainly attributable to the lower provision for doubtful accounts in the first quarter of 2018, as compared to the prior-year period.

Interest Expense. Interest expense decreased by $0.6 million to $4.9 million in the first quarter of 2018 from $5.5 million in the first quarter of 2017, largely due to a lower average debt balance in the first quarter of 2018. The lower debt balance was due to the partial repayment of borrowings under the OpCo Revolver and full repayment of the August 2013 Promissory Notes during the second half of 2017, in both cases using the funds generated from the secondary equity offering.

Other Income. The decrease in other income in the first quarter of 2018 as compared to the first quarter of 2017 was primarily due to the recognition in the first quarter of 2017 of an insurance recovery received for the 2016 Calvert City Olefins facility unplanned shut-down.

MLP Distributable Cash Flow. MLP distributable cash flow increased by $3.1 million to $14.5 million in the first quarter of 2018 from $11.4 million in the first quarter of 2017. The increase in MLP distributable cash flow in the first quarter of 2018 as compared to the prior-year period was primarily due to the 5% increase in the Partnership's interest in OpCo, effective as of July 1, 2017.

EBITDA. EBITDA decreased by $8.4 million to $113.6 million in the first quarter of 2018 from $121.9 million in the first quarter of 2017. The decrease in EBITDA as compared to the prior-year period was primarily due to lower third party sales prices, partially offset by higher sales volumes to Westlake and third parties primarily as a result of higher production at our Calvert City Olefins facility.

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CASH FLOW DISCUSSION FOR THE THREE MONTHS ENDED MARCH 31,2018 AND 2017

Operating Activities

Operating activities provided cash of $106.2 million in the first three months of 2018 compared to cash provided by operating activities of $149.1 million in the first three months of 2017. The $42.9 milliondecrease in cash flows from operating activities was mainly due to lower operating income and an increase in use of cash in working capital, partially offset by a decrease in cash used for turnaround related expenditures during the three months endedMarch 31, 2018 as compared to the prior-year period. Changes in components of working capital, which we define for the purposes of this cash flow discussion as accounts receivable—Westlake, accounts receivable, net—third parties, inventories, prepaid expenses and other current assets less accounts payable—Westlake, accounts payable—third parties and accrued liabilities, used cash of $3.2 million in the first three months of 2018 as compared to $43.2 million of cash provided in the first three months of 2017, resulting in an overall unfavorable change of $46.4 million. The unfavorable change in working capital was mainly attributable to the unfavorable changes in the accounts receivable—Westlake, third party accounts payable and accrued liabilities balances, partially offset by a favorable change in third party accounts receivables. The cash provided in the first three months of 2017 primarily related to the partial recovery of the Shortfall that was recognized in 2016 as an accounts receivable from Westlake.

Investing Activities

Net cash used for investing activities during the first three months of 2018 was $7.7 million as compared to net cash used for investing activities of $21.5 million in the first three months of 2017, mainly due to lower capital expenditures at our facilities in the first three months of 2018 as compared to the prior-year period. Capital expenditures during the first three months of 2018 were primarily related to planned and unplanned outages at our facilities while those during the same period in 2017 primarily reflected capital expenditures incurred for the Calvert City expansion project. Other investing activities in the first three months of 2018 related to investments with Westlake under the Investment Management Agreement.

Financing Activities

Net cash used for financing activities during the first three months of 2018 was $100.6 million as compared to net cash used for financing activities of $93.5 million in the first three months of 2017. The cash outflows during the first three months of 2018 were related to the distribution of $91.1 million to Westlake and of $13.1 million to other unitholders by the Partnership. The distributions in the first three months of 2018 were partially offset by borrowings under the OpCo Revolver of $3.6 million. The cash outflows during the first three months of 2017 were related to the distribution of $89.6 million to Westlake and of $9.5 million to other unitholders by the Partnership and the repayment of $11.4 million of borrowings under the OpCo Revolver. The distributions and repayment in the first three months of 2017 were partially offset by borrowings under the OpCo Revolver of $17.0 million to fund capital expenditures.

LIQUIDITY AND CAPITAL RESOURCES

Liquidity and Financing Arrangements

Based on the terms of our cash distribution policy, we expect that we will distribute to our partners most of the excess cash generated by our operations. To the extent we do not generate sufficient cash flow to fund capital expenditures, we expect to fund them primarily from external sources, including borrowing directly from Westlake, as well as future issuances of equity and debt interests.

The Partnership maintains separate bank accounts, but Westlake continues to provide treasury services on our behalf under the Services and Secondment Agreement. Our sources of liquidity include cash generated from operations, the OpCo Revolver, the MLP Revolver and, if necessary and possible under then current market conditions, the issuance of additional common units representing limited partner interests of the Partnership, other classes of units representing limited partners interests of the Partnership or debt securities. We believe that cash generated from these sources will be sufficient to meet our short-term working capital requirements and long-term capital expenditure requirements and to make quarterly cash distributions. Westlake may also provide other direct and indirect financing to us from time to time although it is not required to do so.

In order to fund non-annual turnaround expenditures, we cause OpCo to reserve approximately $30.0 million during each twelve-month period for turnaround activities. Each of OpCo's ethylene production facilities requires turnaround maintenance approximately every five years. By reserving additional cash annually, we intend to reduce the variability in OpCo's cash flow. Westlake's purchase price for ethylene purchased under the Ethylene Sales Agreement includes a component (adjusted annually) designed to cover, over the long term, substantially all of OpCo's turnaround expenditures.

19

Our cash is generated from cash distributions from OpCo. OpCo was a restricted subsidiary and guarantor under Westlake's credit facility and the indentures governing its senior notes until August 2016, but OpCo remains a restricted subsidiary under Westlake's credit facility and indentures governing its senior notes. The guarantees were released in August 2016. The indentures governing Westlake's senior notes prevent OpCo from making distributions to us if any default or event of default (as defined in the indentures) exists. Westlake's credit facility does not prevent OpCo from making distributions to us.

On April 30, 2018, the board of directors of Westlake Chemical Partners GP LLC, our general partner, approved a quarterly distribution of $0.3975 per unit payable on May 24, 2018 to unitholders of record as of May 10, 2018 and a distribution to the incentive distribution rights holder ("IDR Holder"), which equates to a total amount of approximately $13.5 million per quarter, or approximately $54.2 million per year in aggregate (in each case, including the distribution to the IDR Holder), based on the number of common units outstanding on March 31, 2018. We do not have a legal or contractual obligation to pay distributions on a quarterly basis or any other basis at our minimum quarterly distribution rate or any other rate.

Capital Expenditures

Westlake has historically funded expansion capital expenditures related to Lake Charles Olefins and Calvert City Olefins. During the three months ended March 31, 2018 and 2017, Westlake loaned OpCo $3.6 million and $17.0 million, respectively. The $3.6 million was used to fund working capital needs in the first three months of 2018, while the $17.0 million was used to fund the expansion capital expenditures in 2017. The total capital expenditures, which include expansion and capital maintenance costs, for 2018 are expected to be approximately $60.4 million, of which $9.7 million was spent during the three months ended March 31, 2018. We expect thatWestlake will loan additional cash to OpCo to fund its expansion capital expenditures in the future, but Westlake is under no obligation to do so.

Cash and Cash Equivalents

As of March 31, 2018, our cash and cash equivalents totaled $25.0 million. In addition, we have cash invested under the Investment Management Agreement (as described below) and a revolving credit facility with Westlake available to supplement cash if needed, as described under "Indebtedness" below.

In August 2017, the Partnership, OpCo and Westlake executed the Investment Management Agreement that authorized Westlake to invest the Partnership and OpCo’s excess cash with Westlake for a term of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. The Partnership had $134.2 million of cash invested under the Investment Management Agreement at March 31, 2018.

Indebtedness

OpCo Revolver

In connection with the IPO, OpCo entered into a $600.0 million revolving credit facility with Westlake (the "OpCo Revolver") that may be used to fund growth projects and working capital needs. As of March 31, 2018, outstanding borrowings under the OpCo Revolver totaled $224.1 million and bore interest at the LIBOR rate plus 3.0%, which is accrued in arrears quarterly. The OpCo Revolver is scheduled to mature in August 2019.

MLP Revolver

In 2015, we entered into a senior, unsecured revolving credit agreement with Westlake Chemical Finance Corporation, an affiliate of Westlake (the "MLP Revolver"). The MLP Revolver has a borrowing capacity of $600 million and is scheduled to mature in 2021. Borrowings under the MLP Revolver bear interest at LIBOR plus a spread ranging from 2.0% to 3.0% (depending on our consolidated leverage ratio), payable quarterly. The MLP Revolver provides that we may pay all or a portion of the interest on any borrowings in kind, in which case any such amounts would be added to the principal amount of the loan. The MLP Revolver requires that we maintain a consolidated leverage ratio of either (1) during any one-year period following certain types of acquisitions (including acquisitions of additional interests in OpCo), 5.50:1.0 or less, or (2) during any other period, 4.50:1.0 or less. The MLP Revolver also contains certain other customary covenants. The repayment of borrowings under the MLP Revolver is subject to acceleration upon the occurrence of an event of default. As of March 31, 2018, outstanding borrowings under the MLP Revolver totaled $253.5 million. We intend to use the MLP Revolver to purchase additional limited partnership interests in OpCo in the future, in the event OpCo desires to sell such additional interests to us, for other acquisitions and for general corporate purposes.

20

Off-Balance Sheet Arrangements

None.

FORWARD-LOOKING STATEMENTS

Certain of the statements contained in this report are forward-looking statements. All statements, other than statements of historical facts, included in this report that address activities, events or developments that we expect, project, believe or anticipate will or may occur in the future are forward-looking statements. Forward-looking statements can be identified by the use of words such as "believes," "intends," "may," "should," "could," "anticipates," "expects," "will" or comparable terminology, or by discussions of strategies or trends. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give any assurances that these expectations will prove to be correct. Forward-looking statements relate to matters such as:

• the amount of ethane that we are able to process, which could be adversely affected by, among other things, operating difficulties;

• the volume of ethylene that we are able to sell;

• the price at which we are able to sell ethylene;

• industry market outlook, including prices and margins in third-party ethylene and co-products sales;

• the parties to whom we will sell ethylene and on what basis;

• volumes of ethylene that Westlake may purchase, in addition to the minimum commitment under the Ethylene Sales Agreement;

• timing, funding and results of capital projects;

• our intended minimum quarterly distributions and the manner of making such distributions;

• our ability to meet our liquidity needs;

• timing of and amount of capital expenditures;

• potential loans from Westlake to OpCo to fund OpCo's expansion capital expenditures in the future;

• expected mitigation of exposure to commodity price fluctuations;

• turnaround activities and the variability of OpCo's cash flow;

• compliance with present and future environmental regulations and costs associated with environmentally related penalties, capital expenditures, remedial actions and proceedings, including any new laws, regulations or treaties that may come into force to limit or control carbon dioxide and other greenhouse gas emissions or to address other issues of climate change; and

• effects of pending legal proceedings.

We have based these statements on assumptions and analysis in light of our experience and perception of historical trends, current conditions, expected future developments and other factors we believe were appropriate in the circumstances when the statements were made. Forward-looking statements by their nature involve substantial risks and uncertainties that could significantly impact expected results, and actual future results could differ materially from those described in such statements. These statements are subject to a number of assumptions, risks and uncertainties, including those described under "Risk Factors" in the 2017 Form 10-K and the following:

• general economic and business conditions;

• the cyclical nature of the chemical industry;

• the availability, cost and volatility of raw materials and energy;

• uncertainties associated with the United States and worldwide economies, including those due to political tensions and unrest in the Middle East, the Commonwealth of Independent States (including Ukraine) and elsewhere;

• current and potential governmental regulatory actions in the United States and regulatory actions and political unrest in other countries;

• industry production capacity and operating rates;

• the supply/demand balance for our product;

• competitive products and pricing pressures;

21

• instability in the credit and financial markets;

• access to capital markets;

• terrorist acts;

• operating interruptions (including leaks, explosions, fires, weather-related incidents, mechanical failure, unscheduled downtime, labor difficulties, transportation interruptions, spills and releases and other environmental risks);

• changes in laws or regulations;

• technological developments;

• our ability to integrate acquired businesses;

• foreign currency exchange risks;

• our ability to implement our business strategies; and

• creditworthiness of our customers.

Many of these factors are beyond our ability to control or predict. Any of the factors, or a combination of these factors, could materially affect our future results of operations and the ultimate accuracy of the forward-looking statements. These forward-looking statements are not guarantees of our future performance, and our actual results and future developments may differ materially from those projected in the forward-looking statements. Management cautions against putting undue reliance on forward-looking statements or projecting any future results based on such statements or present or prior earnings levels. Every forward-looking statement speaks only as of the date of the particular statement, and we undertake no obligation to publicly update or revise any forward-looking statements.

Item 3. Quantitative and Qualitative Disclosures about Market Risk

Commodity Price Risk

A substantial portion of the Partnership's products and raw materials are commodities whose prices fluctuate as market supply and demand fundamentals change. However, our direct exposure to commodity price risk is limited to approximately 5% of our total ethylene production, which is the portion sold to third parties. We believe we have substantially mitigated our indirect exposure to commodity price fluctuations during the term of the Ethylene Sales Agreement through the minimum commitment and the cost-plus based pricing.

Interest Rate Risk

We are exposed to interest rate risk with respect to our outstanding debt, all of which is variable rate debt. At March 31, 2018, we had variable rate debt of $477.6 million outstanding, all of which was owed to wholly-owned subsidiaries of Westlake, $224.1 million of which currently accrues interest at a variable rate of LIBOR plus 300 basis points and the remaining $253.5 million of which currently accrues interest at a variable rate of LIBOR plus 200 basis points. During August 2015, the Partnership entered into an interest rate contract with Westlake to fix the LIBOR component of the interest rate for a portion of the debt. The weighted average variable interest rate of our debt, excluding the effectively fixed rate portion through the interest rate contract, as of March 31, 2018 was 4.2%. We will continue to be subject to interest rate risk with respect to our variable rate debt as well as the risk of higher interest cost if and when this debt is refinanced. A hypothetical increase in our average interest rate on variable rate debt (excluding the effectively fixed rate debt portion through the interest rate contract) by 100 basis points would increase our annual interest expense by approximately $4.1 million, based on the March 31, 2018 debt balance.

Item 4. Controls and Procedures

We carried out an evaluation, under the supervision and with the participation of our management, including our President and Chief Executive Officer and our Executive Vice President and Chief Financial Officer, of the effectiveness of our disclosure controls and procedures pursuant to Rules 13a-15 or 15d-15 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), as of the end of the period covered by this report. Based upon that evaluation, our President and Chief Executive Officer and our Executive Vice President and Chief Financial Officer concluded that our disclosure controls and procedures are effective with respect to (i) the accumulation and communication to our management, including our Chief Executive Officer and our Chief Financial Officer, of information required to be disclosed by us in the reports that we submit under the Exchange Act, and (ii) the recording, processing, summarizing and reporting of such information within the time periods specified in the SEC's rules and forms.

22

There were no changes in our internal control over financial reporting that occurred during the three months ended March 31, 2018 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

23

PART II. OTHER INFORMATION

Item 1. Legal Proceedings

The 2017 Form 10-K, filed on March 1, 2018, contained a description of various legal proceedings in which we are involved, including environmental proceedings. See below and Note 12 to the unaudited consolidated financial statements within this Quarterly Report on Form 10-Q for a description of certain of those proceedings, which information is incorporated by reference herein. In addition, under the Omnibus Agreement, Westlake has agreed to indemnify the Partnership for certain environmental and other liabilities relating to OpCo's processing facilities and related assets.

Potential Flare Modifications. For several years, the Environmental Protection Agency ("EPA") has been conducting an enforcement initiative against petroleum refineries and petrochemical plants with respect to emissions from flares. 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. 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 indicated that it is seeking a consent decree that would obligate Westlake to take corrective actions relating to the alleged noncompliance. The Partnership believes the resolution of these matters may require the payment of a monetary sanction in excess of $100,000.

Risk Management Program Investigation. Region 4 of the EPA has conducted inspections and information requests to assess compliance with Risk Management Program requirements under the Clean Air Act at the Calvert City facility. EPA Region 4 has identified concerns with the facility’s compliance under the Risk Management Program and Release Prevention regulations in connection with certain emissions release events between 2011 and 2015. Westlake has engaged in communications with EPA Region 4 to resolve these concerns. The Partnership believes the resolution of these matters may require the payment of a monetary sanction in excess of $100,000.

Kentucky Notices of Violation. In October 2017, the Enforcement Division of the Kentucky Department of Environmental Protection (KDEP) indicated that it intended to proceed with enforcement on two Notices of Violation (NOVs) received by the Calvert City facility in December 2016 and May 2017. The NOVs allege violations of state and federal air requirements in connection with the operation of the olefins unit at the facility. Westlake has engaged in negotiations with KDEP to resolve these alleged violations. The Partnership believes the resolution of these matters may require the payment of a monetary sanction in excess of $100,000.

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.

Item 1A. Risk Factors

For a discussion of risk factors, please read Item IA, "Risk Factors" in the 2017 Form 10-K. There have been no material changes from those risk factors.

24

Item 6. Exhibits

EXHIBIT INDEX

Exhibit No.	Description
10.1	Form of Phantom Unit Agreement (incorporated by reference to Exhibit 10.12 to Westlake Chemical Partners LP's Annual Report on Form 10-K for the year ended December 31, 2017 (file No. 01-36567) filed on March 1, 2018)
31.1†	Rule 13a – 14(a) / 15d – 14(a) Certification (Principal Executive Officer)
31.2†	Rule 13a – 14(a) / 15d – 14(a) Certification (Principal Financial Officer)
32.1#	Section 1350 Certification (Principal Executive Officer and Principal Financial Officer)
101.INS†	XBRL Instance Document
101.SCH†	XBRL Taxonomy Extension Schema Document
101.CAL†	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF†	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB†	XBRL Taxonomy Extension Label Linkbase Document
101.PRE†	XBRL Taxonomy Extension Presentation Linkbase Document

_____________

† Filed herewith.

# Furnished herewith.

25

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		WESTLAKE CHEMICAL PARTNERS LP
Date:	May 3, 2018	By:	/S/    ALBERT CHAO
			Albert Chao
			President, Chief Executive Officer and Director of Westlake Chemical Partners GP LLC (Principal Executive Officer)
Date:	May 3, 2018	By:	/S/    M. STEVEN BENDER
			M. Steven Bender
			Senior Vice President, Chief Financial Officer and Director of Westlake Chemical Partners GP LLC (Principal Financial Officer)

26

EX-31.1

Exhibit 31.1

CERTIFICATIONS

I, Albert Chao, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Westlake Chemical Partners LP;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	May 3, 2018	/S/    ALBERT CHAO
		Albert Chao
		President, Chief Executive Officer and Director of Westlake Chemical Partners GP LLC (Principal Executive Officer)

EX-31.2

Exhibit 31.2

CERTIFICATIONS

I, M. Steven Bender, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Westlake Chemical Partners LP;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recent fiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date:	May 3, 2018	/S/ M. STEVEN BENDER
		M. Steven Bender
		Senior Vice President, Chief Financial Officer and Director of Westlake Chemical Partners GP LLC (Principal Financial Officer)

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Westlake Chemical Partners LP (the "Partnership") on Form 10-Q for the fiscal quarter ended March 31, 2018 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), I, Albert Chao, President, Chief Executive Officer and Director of the Partnership, and I, M. Steven Bender, Executive Vice President, Chief Financial Officer and Director of the Partnership, certify, to the best of our knowledge, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) The information contained in the Report fairly presents, in all material aspects, the financial condition and results of operations of the Partnership.

Date:	May 3, 2018	/S/    ALBERT CHAO
		Albert Chao
		President, Chief Executive Officer and Director of Westlake Chemical Partners GP LLC (Principal Executive Officer)
Date:	May 3, 2018	/S/    M. STEVEN BENDER
		M. Steven Bender
		Senior Vice President, Chief Financial Officer and Director of Westlake Chemical Partners GP LLC (Principal Financial Officer)

XML

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 26, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Trading Symbol	WLKP
Entity Registrant Name	WESTLAKE CHEMICAL PARTNERS LP
Entity Central Index Key	0001604665
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Units, Units Outstanding		32,237,266

XML

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 24,980	$ 27,008
Receivables under Investment Management Agreements with Related Parties, Current	134,712	136,510
Accounts receivable, net—Westlake	43,257	43,884
Accounts receivable, net—third parties	19,017	18,083
Inventories	5,171	5,590
Prepaid expenses and other current assets	161	314
Total current assets	227,298	231,389
Property, plant and equipment, net	1,183,409	1,196,245
Other assets, net
Goodwill	5,814	5,814
Deferred charges and other assets, net	76,083	81,828
Total assets	1,492,604	1,515,276
Current liabilities
Accounts payable—Westlake	14,339	14,027
Accounts payable—third parties	7,798	10,516
Accrued liabilities	15,150	15,697
Total current liabilities	37,287	40,240
Long-term debt payable to Westlake	477,608	473,960
Deferred income taxes	2,272	2,220
Other liabilities	114	107
Total liabilities	517,281	516,527
Commitments and contingencies (Note 12)
EQUITY
Accumulated other comprehensive income	298	279
Total Westlake Chemical Partners LP partners' capital	219,117	219,814
Noncontrolling interest in Westlake Chemical OpCo LP (OpCo)	756,206	778,935
Total equity	975,323	998,749
Total liabilities and equity	1,492,604	1,515,276
Limited Partner [Member] | Common units [Member] | Public [Member]
EQUITY
Limited Partners' Capital Account	410,786	411,228
Total equity	410,786	411,228
Limited Partner [Member] | Common units [Member] | Westlake [Member]
EQUITY
Limited Partners' Capital Account	49,872	50,265
Total equity	49,872	50,265
Limited Partner [Member] | Subordinated units [Member] | Westlake [Member]
EQUITY
Total equity	0	0
General Partner [Member] | Westlake [Member]
EQUITY
General partner—Westlake	(241,839)	(241,958)
Total equity	$ (241,839)	$ (241,958)

XML

Consolidated Balance Sheets (Parenthetical) - shares	Mar. 31, 2018	Dec. 31, 2017
Common units [Member] | Public [Member]
Units issued	18,115,036	18,112,500
Units outstanding	18,115,036	18,112,500
Common units [Member] | Westlake [Member]
Units issued	14,122,230	14,122,230
Units outstanding	14,122,230	14,122,230
Subordinated units [Member] | Westlake [Member]
Units issued	0	0
Units outstanding	0	0

XML

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net sales—Westlake	$ 235,031	$ 212,930
Net co-product, ethylene and other sales—third parties	49,241	64,518
Total net sales	284,272	277,448
Cost of sales	191,767	179,487
Gross profit	92,505	97,961
Selling, general and administrative expenses	7,133	7,828
Income from operations	85,372	90,133
Other income (expense)
Interest expense—Westlake	(4,866)	(5,460)
Other income, net	491	1,658
Income before income taxes	80,997	86,331
Provision for income taxes	283	303
Net income	80,714	86,028
Less: Net income attributable to noncontrolling interest in OpCo	68,419	76,264
Net income attributable to Westlake Chemical Partners LP	$ 12,295	$ 9,764
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in shares)	32,236,449	27,059,730
Distributions per common unit (usd per share)	$ 0.3864	$ 0.345
Common units [Member]
Other income (expense)
Net income attributable to Westlake Chemical Partners LP	$ 11,562	$ 5,064
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)
Income per limited partner unit (usd per share)	$ 0.36	$ 0.35
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in shares)	32,236,449	14,373,615
Common units [Member] | Public [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in shares)	18,115,036	12,937,500
Common units [Member] | Westlake [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in shares)	14,122,230	1,436,115
Subordinated units [Member]
Other income (expense)
Net income attributable to Westlake Chemical Partners LP		$ 4,469
Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted)
Income per limited partner unit (usd per share)	$ 0.00	$ 0.35
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in shares)		12,686,115
Subordinated units [Member] | Westlake [Member]
Weighted average limited partner units outstanding (basic and diluted)
Weighted average limited partner units outstanding (basic and diluted) (in shares)	0	12,686,115

XML

Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss) [Member]	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 at Dec. 31, 2016	$ 920,963	$ 200	$ 818,479	$ (242,430)	$ 297,367	$ 4,813	$ 42,534
Net income	86,028	0	76,264	231	4,559	505	4,469
Net effect of cash flow hedge	89	89	0	0	0	0	0
Quarterly distributions to unitholders	(9,478)	0	0	(142)	(4,464)	(495)	(4,377)
Quarterly distribution to noncontrolling interest retained in OpCo by Westlake	(89,617)	0	(89,617)	0	0	0	0
Equity, ending balance at Mar. 31, 2017	907,985	289	805,126	(242,341)	297,462	4,823	42,626
Equity, beginning balance at Dec. 31, 2017	998,749	279	778,935	(241,958)	411,228	50,265	0
Net income	80,714	0	68,419	733	6,498	5,064	0
Net effect of cash flow hedge	19	19	0	0	0	0	0
Units issued for vested phantom units	60	0	0	0	60	0	0
Quarterly distributions to unitholders	(13,071)	0	0	(614)	(7,000)	(5,457)	0
Quarterly distribution to noncontrolling interest retained in OpCo by Westlake	(91,148)	0	(91,148)	0	0	0	0
Equity, ending balance at Mar. 31, 2018	$ 975,323	$ 298	$ 756,206	$ (241,839)	$ 410,786	$ 49,872	$ 0

XML

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income	$ 80,714	$ 86,028
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	27,698	30,150
Loss (gain) from disposition of property, plant and equipment	567	(127)
Other losses (gains), net	357	(488)
Changes in operating assets and liabilities
Accounts receivable—third parties	(1,239)	(8,753)
Net accounts receivable—Westlake	737	40,010
Inventories	419	(842)
Prepaid expenses and other current assets	153	115
Accounts payable	(2,835)	5,150
Accrued and other liabilities	(487)	7,461
Other, net	138	(9,626)
Cash flows from investing activities	106,222	149,078
Cash flows from investing activities
Additions to property, plant and equipment	(9,679)	(23,168)
Maturities of investments with Westlake under the Investment Management Agreement	112,000	0
Investments with Westlake under the Investment Management Agreement	(110,000)	0
Other	0	1,682
Net cash used for investing activities	(7,679)	(21,486)
Cash flows from financing activities
Proceeds from debt payable to Westlake	3,648	17,000
Repayment of debt payable to Westlake	0	(11,423)
Quarterly distributions to noncontrolling interest retained in OpCo by Westlake	(91,148)	(89,617)
Quarterly distributions to unitholders	(13,071)	(9,478)
Net cash used for financing activities	(100,571)	(93,518)
Net increase (decrease) in cash and cash equivalents	(2,028)	34,074
Cash and cash equivalents at beginning of period	27,008	88,900
Cash and cash equivalents at end of period	$ 24,980	$ 122,974

XML

Description of Business and Basis of Presentation

3 Months Ended

Mar. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of Business and Basis of Presentation

Description of Business and Basis of Presentation

Description of Business

Westlake Chemical Partners LP (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 its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests. On September 29, 2017, the Partnership completed its secondary offering of 5,175,000 common units at a price of $22.00 per unit.

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. On April 29, 2015, the Partnership purchased an additional 2.7% newly-issued limited partner interest in OpCo for approximately $135,341, resulting in an aggregate 13.3% limited partner interest in OpCo effective April 1, 2015. On September 29, 2017, the Partnership purchased an additional 5.0% newly-issued limited partner interest in OpCo for approximately $229,207, resulting in an aggregate 18.3% limited partner interest in OpCo, effective as of July 1, 2017. The remaining 81.7% limited partner interest in OpCo is owned by Westlake Chemical Corporation.

OpCo owns three ethylene production facilities and a common carrier ethylene pipeline.

Basis of Presentation

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2017 consolidated financial statements and notes thereto of the Partnership included in the annual report on Form 10-K for the fiscal year ended December 31, 2017 (the "2017 Form 10-K"), filed with the SEC on March 1, 2018. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Partnership for the fiscal year ended December 31, 2017 with the exceptions of those accounting standards adopted in the first quarter of 2018 as discussed in Note 1.

References to "Westlake" refer collectively to Westlake Chemical Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.

The Partnership holds an 18.3% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 81.7% limited partner interest in OpCo is owned 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 81.7% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.

In the opinion of the Partnership's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Partnership's financial position as of March 31, 2018, its results of operations for the three months ended March 31, 2018 and 2017 and the changes in its cash position for the three months ended March 31, 2018 and 2017.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2018 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP 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 materially from those estimates.

Recent Accounting Pronouncements

Leases (ASU No. 2016-02)

In February 2016, the FASB issued an accounting standards update on a new lease standard that will supersede the existing lease guidance. The standard requires a lessee to recognize assets and liabilities related to long-term leases that are classified as operating leases under current guidance on its balance sheet. An asset would be recognized related to the right to use the underlying asset and a liability would be recognized related to the obligation to make lease payments over the term of the lease. The standard also requires expanded disclosures related to leases. The accounting standard will be effective for reporting periods beginning after December 15, 2018. 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.

Credit Losses (ASU No. 2016-13)

In June 2016, the FASB issued an accounting standards update providing new guidance for the accounting for credit losses on loans and other financial instruments. The new guidance introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. The standard also modifies the impairment model for available-for-sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Partnership's consolidated financial position, results of operations and cash flows.

Recently Adopted Accounting Standards

Revenue from Contracts with Customers (ASU No. 2014-09)

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that supersedes virtually all previously issued 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 are 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 "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 Partnership adopted ASC No. 2014-09, Revenue from Contracts with Customers (“ASC 606”), effective January 1, 2018. The Company applied the modified retrospective transition method to all contracts that were not completed as of the adoption date. Periods prior to January 1, 2018 were not adjusted and are reported under the accounting standards that were in place during those periods. There was no cumulative effect to the Partnership’s consolidated January 1, 2018 balance sheet for the adoption of this accounting standard. There was no impact of ASC 606 adoption on the financial statements for the three months ended March 31, 2017 as compared with the guidance that was in effect prior to January 1, 2018.

Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement.

The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales.

The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (i) have an original expected duration of one year or less or (ii) have only variable consideration which is allocated to wholly unsatisfied performance obligations that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations.

The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement (discussed in Note 2 to the 2017 Form 10-K). The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. Partnership’s direct commodity price risk is limited to the sales to third parties. Refer to the Partnership’s Consolidated Statement of Operations for the disaggregation of net sales to Westlake and net sales to third parties.

Cash Flows (ASU No. 2016-15)

In August 2016, the FASB issued an accounting standards update providing new guidance on the classification of certain cash receipts and payments including debt extinguishment costs, debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments, proceeds from the settlement of insurance claims and life insurance policies and distributions received from equity method investees in the statement of cash flows. This update is required to be applied using the retrospective transition method to each period presented unless it is impracticable to be applied retrospectively. In such situation, this guidance is to be applied prospectively. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow.

Business Combinations (ASU No. 2017-01)

In January 2017, the FASB issued an accounting standards update to assist entities with evaluating when a set of transferred assets and activities is a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in the FASB ASC Topic 606, Revenue from contracts with customers. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow. 

Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (ASU No. 2017-05)

In February 2017, the FASB issued an accounting standards update to clarify the scope of guidance related to other income—gains and losses from the derecognition of nonfinancial assets, and to add guidance for partial sales of nonfinancial assets. The new guidance clarifies that an in substance nonfinancial asset is an asset or group of assets for which substantially all of the fair value consists of nonfinancial assets and the group or subsidiary is not a business. The guidance also outlines that when an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling interest, it will measure the retained interest at fair value resulting in full gain or loss recognition upon sale of the controlling interest. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow.

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Accounts Receivable - Third Parties

3 Months Ended

Mar. 31, 2018

Accounts Receivable, Net [Abstract]

Accounts Receivable - Third Parties

Accounts Receivable—Third Parties

Accounts receivable—third parties consist of the following:

	March 31, 2018			December 31, 2017
Trade customers	$	20,033		$	18,794
Allowance for doubtful accounts	(1,016		)	(711		)
Accounts receivable, net—third parties	$	19,017		$	18,083

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Inventories

3 Months Ended

Mar. 31, 2018

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consist of the following:

	March 31, 2018		December 31, 2017
Finished products	$	4,844	$	5,244
Feedstock, additives and chemicals	327		346
Inventories	$	5,171	$	5,590

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Property, Plant and Equipment

3 Months Ended

Mar. 31, 2018

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

Depreciation expense on property, plant and equipment of $22,157 and $23,413 is included in cost of sales in the consolidated statements of operations for the three months ended March 31, 2018 and 2017, respectively.

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Other Assets

3 Months Ended

Mar. 31, 2018

Other Assets, Noncurrent [Abstract]

Other Assets

Other Assets

Amortization expense on other assets of $5,541 and $6,737 is included in costs of sales in the consolidated statements of operations for the three months ended March 31, 2018 and 2017, respectively.

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Distributions and Net Income Per Limited Partner Unit

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Distributions and Net Income Per Limited Partner Unit

Distributions and Net Income Per Limited Partner Unit

On April 30, 2018, the board of directors of Westlake Chemical Partners GP LLC ("Westlake GP"), the Partnership's general partner, declared a quarterly cash distribution for the period from January 1, 2018 through March 31, 2018 of $0.3975 per unit and of $733 to the holder of the Partnership's incentive distribution rights ("IDR Holder"). This distribution is payable on May 24, 2018 to the unitholders and IDR Holder of record as of May 10, 2018.

The Partnership Agreement provides that the Partnership will distribute cash each quarter in the following manner: first, to all the unitholders, until each unit has received the minimum quarterly distribution of $0.2750, plus any arrearages from prior quarters; and second, to all the unitholders, pro-rata, until each unit has received a distribution of $0.3163. If cash distributions to the Partnership's unitholders exceed $0.3163 per 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	%

For the three months ended March 31, 2018, the Partnership's distribution exceeded the $0.3163 per common unit target, which resulted in distributions to the IDR Holder.

The distributions are declared subsequent to quarter end; therefore, the table below represents total distributions declared from earnings of the related periods pertaining to such distributions.

	Three Months Ended March 31,
	2018			2017
Net income attributable to the Partnership	$	12,295		$	9,764
Less:
Limited partners' distributions declared on common units	12,814			5,101
Limited partners' distributions declared on subordinated units	—			4,502
Distributions declared with respect to the incentive distribution rights	733			231
Distribution in excess of net income	$	(1,252	)	$	(70	)

Net income per unit applicable to common limited partner units is computed by dividing the respective limited partners' interest in net income by the weighted-average number of common units outstanding for the period. 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 incentive distribution rights. Net income attributable to the Partnership is allocated to the unitholders in accordance with their respective ownership percentages in preparation of the consolidated statement of equity. However, when distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions is first allocated to the general partner before the remaining net income is allocated to the unitholders based on their respective ownership percentages. 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.

The 12,686,115 subordinated units, all of which were owned by Westlake, were converted into common units during the third quarter of 2017 and were considered converted as of July 1, 2017 for purposes of calculating net income per unit. Therefore, the subordinated units did not share in the distribution of cash generated nor did the partnership allocate any earnings to the subordinated unitholders for the determination of net income per unit subsequent to June 30, 2017.

	Three Months Ended March 31, 2018
	Limited Partners' Common Units			Incentive Distribution Rights		Total
Net income attributable to the Partnership:
Distribution declared	$	12,814		$	733	$	13,547
Distribution in excess of net income	(1,252		)	—		(1,252		)
Net income	$	11,562		$	733	$	12,295
Weighted average units outstanding:
Basic and diluted	32,236,449					32,236,449
Net income per limited partner unit:
Basic and diluted	$	0.36

	Three Months Ended March 31, 2017
	Limited Partners' Common Units			Limited Partners' Subordinated Units			Incentive Distribution Rights		Total
Net income attributable to the Partnership:
Distribution declared	$	5,101		$	4,502		$	231	$	9,834
Distribution in excess of net income	(37		)	(33		)	—		(70		)
Net income	$	5,064		$	4,469		$	231	$	9,764
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	$	0.35		$	0.35

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Partners' Equity

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Equity

7.Partners' Equity

Following the Partnership’s cash distribution for the second quarter of 2017, the requirement under the Partnership’s partnership agreement for the conversion of all subordinated units was satisfied. As a result, effective August 30, 2017, the 12,686,115 subordinated units owned by Westlake were converted into common units on a one-for-one basis and thereafter participate on terms equal with all other common units in distributions of available cash. As discussed in Note 6, the subordinated units were considered converted as of July 1, 2017 for purposes of calculating net income per unit and, therefore, the subordinated units did not share in the distribution of cash generated nor did the Partnership allocate any earnings to the subordinated unitholders for the determination of net income per unit subsequent to June 30, 2017.

On September 29, 2017, the Partnership completed its secondary offering of 5,175,000 common units at a price of $22.00 per unit. Net proceeds to the Partnership from the sale of the units were $110,739, net of underwriting discounts, structuring fees and estimated offering expenses of approximately $3,111.

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Related Party Transactions

3 Months Ended

Mar. 31, 2018

Related Party Transactions [Abstract]

Related Party Transactions

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 each charges Westlake a fee.

Sales to related parties were as follows:

	Three Months Ended March 31,
	2018		2017
Net sales—Westlake	$	235,031	$	212,930

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.

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

	Three Months Ended March 31,
	2018		2017
Feedstock purchased from Westlake and included in cost of sales	$	105,415	$	97,113
Other charges from Westlake and included in cost of sales	28,406		25,417
Total	$	133,821	$	122,530

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.

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

	Three Months Ended March 31,
	2018		2017
Services received from Westlake and included in selling, general and administrative    expenses	$	6,251	$	6,732

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.

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

	Three Months Ended March 31,
	2018		2017
Goods and services purchased from Westlake and capitalized as assets	$	346	$	1,405

Receivable under the Investment Management Agreement

On August 1, 2017, the Partnership, OpCo and Westlake executed an investment management agreement (the "Investment Management Agreement") that authorized Westlake to invest the Partnership and OpCo’s excess cash with Westlake for a term of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. Accrued interest earned of $540 and $340 was included in the receivable under the Investment Management Agreement balance at March 31, 2018 and December 31, 2017, respectively.

The Partnership's receivable under the Investment Management Agreement was as follows:

	March 31, 2018		December 31, 2017
Receivable under the Investment Management Agreement	$	134,712	$	136,510

Accounts Receivables

The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake under the Ethylene Sales Agreement.

The Partnership's accounts receivable from Westlake were as follows:

	March 31, 2018		December 31, 2017
Accounts receivable—Westlake	$	43,257	$	43,884

Accounts Payable to Related Parties

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.

The related party accounts payable balances were as follows:

	March 31, 2018		December 31, 2017
Accounts payable—Westlake	$	14,339	$	14,027

Debt Payable to Related Parties

See Note 9 for a description of related party debt payable balances. Interest on related party debt payable balances for the three months ended March 31, 2018 and 2017 was $4,866 and $5,460, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. Interest capitalized as a component of property, plant and equipment on related party debt was $15 and $398 for the three months ended March 31, 2018 and 2017, respectively. At March 31, 2018 and December 31, 2017, accrued interest on related party debt was $4,864 and $4,590, respectively, and is reflected as a component of accrued liabilities in the consolidated balance sheets.

Debt payable to related parties was as follows:

	March 31, 2018		December 31, 2017
Long-term debt payable to Westlake	$	477,608	$	473,960

Major Customer and Concentration of Credit Risk

During the three months ended March 31, 2018 and 2017, Westlake accounted for approximately 82.7% and 76.7%, respectively, of the Partnership's net sales.

General

In 2015, the Partnership entered into an interest rate contract with Westlake to fix the London Interbank Offered Rate ("LIBOR") component of the interest rate for a portion of the MLP Revolver balance.

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

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Long-term Debt Payable to Westlake

3 Months Ended

Mar. 31, 2018

Related Party Transactions [Abstract]

Long-term Debt Payable to Westlake

Long-term Debt Payable to Westlake

Long-term debt payable to Westlake consists of the following:

	March 31, 2018		December 31, 2017
OpCo Revolver (variable interest rate of LIBOR plus 3.0%, original scheduled maturity of    August 4, 2019)	$	224,064	$	220,416
MLP Revolver (variable interest rate of LIBOR plus 2.0%, original scheduled maturity of    April 29, 2021)	253,544		253,544
	$	477,608	$	473,960

The weighted average interest rate on all long-term debt was 4.08% and 3.76% at March 31, 2018 and December 31, 2017, respectively.

As of March 31, 2018, the Partnership was in compliance with all of the covenants under the OpCo Revolver and the MLP Revolver.

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Fair Value Measurements

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

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.

The Partnership has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include accounts receivable, net, accounts payable and long-term debt payable to Westlake, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for 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 long-term debt at March 31, 2018 and December 31, 2017 are summarized in the table below. The Partnership's long-term debt includes the OpCo Revolver and the MLP Revolver at March 31, 2018. 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.

	March 31, 2018				December 31, 2017
	Carrying Value		Fair Value		Carrying Value		Fair Value
OpCo Revolver	$	224,064	$	230,649	$	220,416	$	228,180
MLP Revolver	253,544		256,588		253,544		258,234

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Supplemental Information

3 Months Ended

Mar. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Information

Supplemental Information

Accrued Liabilities

Accrued liabilities were $15,150 and $15,697 at March 31, 2018 and December 31, 2017, respectively. The accrued interest, accrued maintenance, capital expenditures accrual and accrued taxes, which are components of accrued liabilities, were $4,864, $3,406, $2,179 and $2,115, respectively, at March 31, 2018, and $4,590, $3,698, $3,197 and $1,422, respectively, at December 31, 2017. No other component of accrued liabilities was more than five percent of total current liabilities.

Non-cash Investing Activity

The change in capital expenditure accrual reducing additions to property, plant and equipment was $117 for the three months ended March 31, 2018. The change in capital expenditure accrual reducing additions to property, plant and equipment was $1,159 for the three months ended March 31, 2017.

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

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.

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.

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Description of Business and Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Basis of Presentation

The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the December 31, 2017 consolidated financial statements and notes thereto of the Partnership included in the annual report on Form 10-K for the fiscal year ended December 31, 2017 (the "2017 Form 10-K"), filed with the SEC on March 1, 2018. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Partnership for the fiscal year ended December 31, 2017 with the exceptions of those accounting standards adopted in the first quarter of 2018 as discussed in Note 1.

References to "Westlake" refer collectively to Westlake Chemical Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.

The Partnership holds an 18.3% limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 81.7% limited partner interest in OpCo is owned 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 81.7% is recorded as noncontrolling interest in the Partnership's consolidated financial statements.

In the opinion of the Partnership's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Partnership's financial position as of March 31, 2018, its results of operations for the three months ended March 31, 2018 and 2017 and the changes in its cash position for the three months ended March 31, 2018 and 2017.

Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2018 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP 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 materially from those estimates.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Leases (ASU No. 2016-02)

In February 2016, the FASB issued an accounting standards update on a new lease standard that will supersede the existing lease guidance. The standard requires a lessee to recognize assets and liabilities related to long-term leases that are classified as operating leases under current guidance on its balance sheet. An asset would be recognized related to the right to use the underlying asset and a liability would be recognized related to the obligation to make lease payments over the term of the lease. The standard also requires expanded disclosures related to leases. The accounting standard will be effective for reporting periods beginning after December 15, 2018. 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.

Credit Losses (ASU No. 2016-13)

In June 2016, the FASB issued an accounting standards update providing new guidance for the accounting for credit losses on loans and other financial instruments. The new guidance introduces an approach based on expected losses to estimate credit losses on certain types of financial instruments. The standard also modifies the impairment model for available-for-sale debt securities and provides for a simplified accounting model for purchased financial assets with credit deterioration since their origination. The accounting standard will be effective for reporting periods beginning after December 15, 2019 and is not expected to have a material impact on the Partnership's consolidated financial position, results of operations and cash flows.

Recently Adopted Accounting Standards

Revenue from Contracts with Customers (ASU No. 2014-09)

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update on a comprehensive new revenue recognition standard that supersedes virtually all previously issued 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 are 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 "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 Partnership adopted ASC No. 2014-09, Revenue from Contracts with Customers (“ASC 606”), effective January 1, 2018. The Company applied the modified retrospective transition method to all contracts that were not completed as of the adoption date. Periods prior to January 1, 2018 were not adjusted and are reported under the accounting standards that were in place during those periods. There was no cumulative effect to the Partnership’s consolidated January 1, 2018 balance sheet for the adoption of this accounting standard. There was no impact of ASC 606 adoption on the financial statements for the three months ended March 31, 2017 as compared with the guidance that was in effect prior to January 1, 2018.

Revenue is recognized when OpCo transfers control of inventories to customers. Amounts recognized as revenues reflect the consideration to which OpCo expects to be entitled in exchange for those inventories. The Partnership and OpCo incorporate production volume and production cost forecasts in the estimated transaction prices from sales to Westlake under the Ethylene Sales Agreement.

The Partnership recognizes revenue and accounts receivable upon transferring control of inventories to its customers. Ethylene sold to Westlake under the Ethylene Sales Agreement is transferred to Westlake immediately after production and recognized in sales. Control of inventories sold to third parties generally transfers upon shipment to the customer. The Partnership excludes taxes collected on behalf of customers from the estimated contract price. Provisions for discounts, rebates and returns are incorporated in the estimate of variable consideration and reflected as reduction to revenue in the same period as the related sales.

The Partnership does not disclose the value of unsatisfied performance obligations because its contracts with customers (i) have an original expected duration of one year or less or (ii) have only variable consideration which is allocated to wholly unsatisfied performance obligations that is calculated based on market prices at a specified date and is allocated to wholly unsatisfied performance obligations.

The Partnership generates a substantial majority of its revenue from sales to Westlake under the Ethylene Sales Agreement (discussed in Note 2 to the 2017 Form 10-K). The Ethylene Sales Agreement is intended to generate a long-term, fixed cash margin per pound. Partnership’s direct commodity price risk is limited to the sales to third parties. Refer to the Partnership’s Consolidated Statement of Operations for the disaggregation of net sales to Westlake and net sales to third parties.

Cash Flows (ASU No. 2016-15)

In August 2016, the FASB issued an accounting standards update providing new guidance on the classification of certain cash receipts and payments including debt extinguishment costs, debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments, proceeds from the settlement of insurance claims and life insurance policies and distributions received from equity method investees in the statement of cash flows. This update is required to be applied using the retrospective transition method to each period presented unless it is impracticable to be applied retrospectively. In such situation, this guidance is to be applied prospectively. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow.

Business Combinations (ASU No. 2017-01)

In January 2017, the FASB issued an accounting standards update to assist entities with evaluating when a set of transferred assets and activities is a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in the FASB ASC Topic 606, Revenue from contracts with customers. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow. 

Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (ASU No. 2017-05)

In February 2017, the FASB issued an accounting standards update to clarify the scope of guidance related to other income—gains and losses from the derecognition of nonfinancial assets, and to add guidance for partial sales of nonfinancial assets. The new guidance clarifies that an in substance nonfinancial asset is an asset or group of assets for which substantially all of the fair value consists of nonfinancial assets and the group or subsidiary is not a business. The guidance also outlines that when an entity transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling interest, it will measure the retained interest at fair value resulting in full gain or loss recognition upon sale of the controlling interest. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Partnership adopted this accounting standard effective January 1, 2018, and the adoption did not have any impact on the Partnership's consolidated financial position, results of operations and cash flow.

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Accounts Receivable - Third Parties (Tables)

3 Months Ended

Mar. 31, 2018

Accounts Receivable, Net [Abstract]

Schedule Of Accounts Receivable - Third Parties

Accounts receivable—third parties consist of the following:

	March 31, 2018			December 31, 2017
Trade customers	$	20,033		$	18,794
Allowance for doubtful accounts	(1,016		)	(711		)
Accounts receivable, net—third parties	$	19,017		$	18,083

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Inventories (Tables)

3 Months Ended

Mar. 31, 2018

Inventory Disclosure [Abstract]

Schedule Of Inventory

Inventories consist of the following:

	March 31, 2018		December 31, 2017
Finished products	$	4,844	$	5,244
Feedstock, additives and chemicals	327		346
Inventories	$	5,171	$	5,590

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Distributions and Net Income Per Limited Partner Unit (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share [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 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	%

For the three months ended March 31, 2018, the Partnership's distribution exceeded the $0.3163 per common unit target, which resulted in distributions to the IDR Holder.

The distributions are declared subsequent to quarter end; therefore, the table below represents total distributions declared from earnings of the related periods pertaining to such distributions.

	Three Months Ended March 31,
	2018			2017
Net income attributable to the Partnership	$	12,295		$	9,764
Less:
Limited partners' distributions declared on common units	12,814			5,101
Limited partners' distributions declared on subordinated units	—			4,502
Distributions declared with respect to the incentive distribution rights	733			231
Distribution in excess of net income	$	(1,252	)	$	(70	)

Schedule of Earnings Per Share, Basic and Diluted

Net income attributable to the Partnership is allocated to the unitholders in accordance with their respective ownership percentages in preparation of the consolidated statement of equity. However, when distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions is first allocated to the general partner before the remaining net income is allocated to the unitholders based on their respective ownership percentages. 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.

The 12,686,115 subordinated units, all of which were owned by Westlake, were converted into common units during the third quarter of 2017 and were considered converted as of July 1, 2017 for purposes of calculating net income per unit. Therefore, the subordinated units did not share in the distribution of cash generated nor did the partnership allocate any earnings to the subordinated unitholders for the determination of net income per unit subsequent to June 30, 2017.

	Three Months Ended March 31, 2018
	Limited Partners' Common Units			Incentive Distribution Rights		Total
Net income attributable to the Partnership:
Distribution declared	$	12,814		$	733	$	13,547
Distribution in excess of net income	(1,252		)	—		(1,252		)
Net income	$	11,562		$	733	$	12,295
Weighted average units outstanding:
Basic and diluted	32,236,449					32,236,449
Net income per limited partner unit:
Basic and diluted	$	0.36

	Three Months Ended March 31, 2017
	Limited Partners' Common Units			Limited Partners' Subordinated Units			Incentive Distribution Rights		Total
Net income attributable to the Partnership:
Distribution declared	$	5,101		$	4,502		$	231	$	9,834
Distribution in excess of net income	(37		)	(33		)	—		(70		)
Net income	$	5,064		$	4,469		$	231	$	9,764
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	$	0.35		$	0.35

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Related Party Transactions (Tables)

3 Months Ended

Mar. 31, 2018

Related Party Transactions [Abstract]

Schedule of Related Party Transactions

The related party accounts payable balances were as follows:

	March 31, 2018		December 31, 2017
Accounts payable—Westlake	$	14,339	$	14,027

Sales to related parties were as follows:

	Three Months Ended March 31,
	2018		2017
Net sales—Westlake	$	235,031	$	212,930

Debt payable to related parties was as follows:

	March 31, 2018		December 31, 2017
Long-term debt payable to Westlake	$	477,608	$	473,960

The Partnership's receivable under the Investment Management Agreement was as follows:

	March 31, 2018		December 31, 2017
Receivable under the Investment Management Agreement	$	134,712	$	136,510

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

	Three Months Ended March 31,
	2018		2017
Services received from Westlake and included in selling, general and administrative    expenses	$	6,251	$	6,732

The Partnership's accounts receivable from Westlake were as follows:

	March 31, 2018		December 31, 2017
Accounts receivable—Westlake	$	43,257	$	43,884

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

	Three Months Ended March 31,
	2018		2017
Goods and services purchased from Westlake and capitalized as assets	$	346	$	1,405

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

	Three Months Ended March 31,
	2018		2017
Feedstock purchased from Westlake and included in cost of sales	$	105,415	$	97,113
Other charges from Westlake and included in cost of sales	28,406		25,417
Total	$	133,821	$	122,530

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Long-term Debt Payable to Westlake (Tables)

3 Months Ended

Mar. 31, 2018

Related Party Transactions [Abstract]

Related Party Transactions, Long-term Debt

Long-term debt payable to Westlake consists of the following:

	March 31, 2018		December 31, 2017
OpCo Revolver (variable interest rate of LIBOR plus 3.0%, original scheduled maturity of    August 4, 2019)	$	224,064	$	220,416
MLP Revolver (variable interest rate of LIBOR plus 2.0%, original scheduled maturity of    April 29, 2021)	253,544		253,544
	$	477,608	$	473,960

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Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Summary Of Carrying And Fair Values Of Long-Term Debt

The carrying and fair values of the Partnership's long-term debt at March 31, 2018 and December 31, 2017 are summarized in the table below. The Partnership's long-term debt includes the OpCo Revolver and the MLP Revolver at March 31, 2018. 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.

	March 31, 2018				December 31, 2017
	Carrying Value		Fair Value		Carrying Value		Fair Value
OpCo Revolver	$	224,064	$	230,649	$	220,416	$	228,180
MLP Revolver	253,544		256,588		253,544		258,234

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Description of Business and Basis of Presentation (Details) $ / shares in Units, $ in Thousands	Sep. 30, 2017	Sep. 29, 2017 USD ($) $ / shares shares	Apr. 29, 2015 USD ($)	Apr. 01, 2015	Aug. 04, 2014 shares	Mar. 31, 2018 production_facility
Limited Partners' Capital Account [Line Items]
Underwriting discounts, structuring fees and offering expenses on issuance of equity		$ 3,111
Westlake Chemical OpCo LP [Member] | Affiliated Entity [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest	18.30%	18.30%		13.30%	10.60%
Limited partner interest, additional ownership		5.00%		2.70%
Amount paid to purchase additional limited partner interest		$ 229	$ 135,341
Westlake Chemical OpCo GP LLC [Member] | Limited Liability Company [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest					100.00%
Westlake [Member] | Westlake Chemical OpCo LP [Member] | Majority-Owned Subsidiary, Unconsolidated [Member]
Limited Partners' Capital Account [Line Items]
Limited partner interest		81.70%		81.70%
Westlake Chemical OpCo LP [Member]
Limited Partners' Capital Account [Line Items]
Number of ethylene production facilities | production_facility						3
Limited Partner [Member]
Limited Partners' Capital Account [Line Items]
Number of units sold in public offering | shares		5,175,000			12,937,500
Units sold in secondary offering price per unit (in dollars per share) | $ / shares		$ 22.00

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Accounts Receivable - Third Parties Accounts Receivable—Third Parties (Schedule Of Accounts Receivable) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts Receivable, Net [Abstract]
Trade customers	$ 20,033	$ 18,794
Allowance for doubtful accounts	(1,016)	(711)
Accounts receivable, net—third parties	$ 19,017	$ 18,083

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Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished products	$ 4,844	$ 5,244
Feedstock, additives and chemicals	327	346
Inventories	$ 5,171	$ 5,590

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Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense on property, plant and equipment	$ 22,157	$ 23,413

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Other Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Assets [Member]
Other Assets [Line Items]
Amortization expense	$ 5,541	$ 6,737

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Distributions and Net Income Per Limited Partner Unit (Distributions Declared) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Apr. 30, 2018	Mar. 31, 2018	Mar. 31, 2017
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		$ 12,295	$ 9,764
Distributions declared		13,547	9,834
Distribution in excess of net income		(1,252)	(70)
IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		733	231
Distributions declared with respect to the incentive distribution rights		733	231
Distribution in excess of net income		0	0
Common units [Member]
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership		11,562	5,064
Distributions declared		12,814	5,101
Distribution in excess of net income		(1,252)	(37)
Subordinated units [Member]
Distribution Made to Limited Partner [Line Items]
Net income attributable to the Partnership			4,469
Distributions declared			4,502
Distribution in excess of net income			(33)
Cash Distribution [Member] | IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Distributions declared with respect to the incentive distribution rights		$ 733	231
Cash Distribution [Member] | IDR Holders [Member] | Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Distribution declared and paid to IDR holders	$ 733
Cash Distribution [Member] | Common units [Member]
Distribution Made to Limited Partner [Line Items]
Minimum quarterly distribution per unit (in usd per unit)		$ 0.2750
Distributions declared		$ 12,814	5,101
Cash Distribution [Member] | Subordinated units [Member]
Distribution Made to Limited Partner [Line Items]
Distributions declared		$ 0	$ 4,502
Cash Distribution [Member] | Common And Subordinated Units [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		$ 0.3163
Cash Distribution [Member] | Common And Subordinated Units [Member] | Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Distribution declared per unit (in usd per unit)	$ 0.3975
Above $0.3163 up to $0.3438 | Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		0.3163
Above $0.3163 up to $0.3438 | Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		$ 0.3438
Above $0.3163 up to $0.3438 | IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions		15.00%
Above $0.3163 up to $0.3438 | Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions		85.00%
Above $0.3438 up to $0.4125 | Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		$ 0.3438
Above $0.3438 up to $0.4125 | Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Quarterly incentive distribution, per unit, distribution threshold		$ 0.4125
Above $0.3438 up to $0.4125 | IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions		25.00%
Above $0.3438 up to $0.4125 | Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions		75.00%
Above $0.4125 | Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Quarterly incentive distribution, per unit, distribution threshold		$ 0.4125
Above $0.4125 | IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions		50.00%
Above $0.4125 | Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions		50.00%

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Distributions and Net Income Per Limited Partner Unit (Income In Excess Of Distribution) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership	$ 12,295	$ 9,764
Distributions declared	13,547	9,834
Distribution in excess of net income	(1,252)	(70)
IDR Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership	733	231
Distributions declared with respect to the incentive distribution rights	733	231
Distribution in excess of net income	0	0
Common units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership	11,562	5,064
Distributions declared	12,814	5,101
Distribution in excess of net income	(1,252)	(37)
Subordinated units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Net income attributable to the Partnership		4,469
Distributions declared		4,502
Distribution in excess of net income		(33)
Cash Distribution [Member] | IDR Holders [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distributions declared with respect to the incentive distribution rights	733	231
Cash Distribution [Member] | Common units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distributions declared	12,814	5,101
Cash Distribution [Member] | Subordinated units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distributions declared	$ 0	$ 4,502

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Distributions and Net Income Per Limited Partner Unit (Basic and Diluted Income Per Limited Partner Unit) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Limited Partners' Capital Account [Line Items]
Distributions declared	$ 13,547	$ 9,834
Distribution in excess of net income	(1,252)	(70)
Net income	$ 12,295	$ 9,764
Weighted average units outsanding:
Basic and diluted (shares)	32,236,449	27,059,730
Common units [Member]
Limited Partners' Capital Account [Line Items]
Distributions declared	$ 12,814	$ 5,101
Distribution in excess of net income	(1,252)	(37)
Net income	$ 11,562	$ 5,064
Weighted average units outsanding:
Basic and diluted (shares)	32,236,449	14,373,615
Net income per limited partner unit:
Income per limited partner unit (usd per share)	$ 0.36	$ 0.35
Subordinated units [Member]
Limited Partners' Capital Account [Line Items]
Distributions declared		$ 4,502
Distribution in excess of net income		(33)
Net income		$ 4,469
Weighted average units outsanding:
Basic and diluted (shares)		12,686,115
Net income per limited partner unit:
Income per limited partner unit (usd per share)	$ 0.00	$ 0.35
IDR Holders [Member]
Limited Partners' Capital Account [Line Items]
Subsequent distribution to IDR holders	$ 733	$ 231
Distribution in excess of net income	0	0
Net income	$ 733	$ 231

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Partners' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 29, 2017	Aug. 04, 2014	Mar. 31, 2018	Dec. 31, 2017	Aug. 30, 2017
Class of Stock [Line Items]
Proceeds from secondary public offering, net of finance and other offering costs	$ 110,739
Underwriting discounts, structuring fees and offering expenses on issuance of equity	$ 3,111
Westlake [Member] | Subordinated units [Member]
Class of Stock [Line Items]
Units outstanding			0	0	12,686,115
Limited Partner [Member]
Class of Stock [Line Items]
Number of units sold in public offering	5,175,000	12,937,500
Units sold in secondary offering price per unit (in dollars per share)	$ 22.00

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Related Party Transactions (Sales to Related Parties) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Related Party Transaction [Line Items]
Net sales—Westlake	$ 235,031	$ 212,930

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Related Party Transactions (Cost of Sales from Related Parties) (Details) - Affiliated Entity [Member] - Westlake [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	$ 133,821	$ 122,530
Feedstock purchased [Member]
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	105,415	97,113
Other service charges [Member]
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	$ 28,406	$ 25,417

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Related Party Transactions (Services from Related Parties Included in SG&A Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Services received from Westlake and included in selling, general and administrative expenses	$ 6,251	$ 6,732

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Related Party Transactions (Goods and Services from Related Parties that have been Capitalized) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Goods and services purchased from Westlake and capitalized as assets	$ 346	$ 1,405

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Related Party Transactions (Accounts Receivable from and Accounts Payable to Related Parties) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Receivables under Investment Management Agreements with Related Parties, Current	$ 134,712	$ 136,510
Accounts payable—Westlake	(14,339)	(14,027)
Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Accounts receivable—Westlake, current and non-current	$ 43,257	$ 43,884

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Related Party Transactions (Debt Payable to Related Parties) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Interest on related party debt payable	$ 4,866	$ 5,460
Accrued interest on related party debt	4,864		$ 4,590
Long-term debt payable to Westlake	477,608		473,960
Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Interest capitalized	15	398
Other income (expense) | Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Interest on related party debt payable	4,866	$ 5,460
Accrued Liabilities [Member] | Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Accrued interest on related party debt	$ 4,864		$ 4,590

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Related Party Transactions (General) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accrued Liabilities [Member] | Affiliated Entity [Member] | Westlake [Member]
Related Party Transaction [Line Items]
Accrued interest included in receivable under IMA	$ 540	$ 340

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Related Party Transactions (Site Lease Agreements) (Details) - Westlake Chemical OpCo LP [Member] - Affiliated Entity [Member] - Site Lease Agreement [Member]	3 Months Ended
	Mar. 31, 2018 USD ($) lease
Related Party Transaction [Line Items]
Number of site lease agreements | lease	2
Lease term	50 years
Operating lease rent expense | $	$ 1

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Related Party Transactions (Major Customer and Concentration Risk) (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Affiliated Entity [Member] | Westlake [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	82.70%	76.70%

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Long-term Debt Payable to Westlake (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Long-term debt payable to Westlake	$ 477,608	$ 473,960
Weighted average interest rate	4.08%	3.76%
Limited Partner [Member] | August 2013 Promissory Note [Member] | Senior Notes [Member] | Prime Rate [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	1.50%	1.50%
Limited Partner [Member] | OpCo Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake	$ 224,064	$ 220,416
Limited Partner [Member] | OpCo Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member] | LIBOR [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	3.00%	3.00%
Limited Partner [Member] | MLP Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member]
Related Party Transaction [Line Items]
Long-term debt payable to Westlake	$ 253,544	$ 253,544
Limited Partner [Member] | MLP Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member] | LIBOR [Member]
Related Party Transaction [Line Items]
Basis spread on variable rate, percent	2.00%	2.00%

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Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, carrying value	$ 477,608	$ 473,960
OpCo Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, fair value	230,649	228,180
OpCo Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member] | Limited Partner [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, carrying value	224,064	220,416
MLP Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, fair value	256,588	258,234
MLP Revolver [Member] | Senior Unsecured Revolving Credit Facility [Member] | Limited Partner [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt payable to Westlake, carrying value	$ 253,544	$ 253,544

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Supplemental Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accrued Liabilities [Abstract]
Accrued liabilities	$ 15,150		$ 15,697
Accrued capital expenditures	2,179		3,197
Accrued interest	4,864		4,590
Accrued taxes	2,115		1,422
Accrued maintenance	3,406		$ 3,698
Increase (reduction) in capital expenditure accrual	$ (117)	$ (1,159)