Westlake (WLK) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 26, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	WLK
Entity Registrant Name	WESTLAKE CHEMICAL CORP
Entity Central Index Key	1,262,823
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		129,656,702

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 482	$ 1,531
Accounts receivable, net	1,261	1,001
Inventories	905	900
Prepaid expenses and other current assets	46	31
Total current assets	2,694	3,463
Property, plant and equipment, net	6,468	6,412
Goodwill	1,006	1,012
Customer relationships, net	569	616
Other intangible assets, net	149	161
Other assets, net	460	412
Total assets	11,346	12,076
Current liabilities
Accounts payable	582	600
Accrued liabilities	604	657
Current portion of long-term debt, net	0	710
Total current liabilities	1,186	1,967
Long-term debt, net	2,666	3,127
Deferred income taxes	1,153	1,111
Pension and other post-retirement benefits	332	344
Other liabilities	163	158
Total liabilities	5,500	6,707
Stockholders' equity
Preferred stock, $0.01 par value, 50,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.01 par value, 300,000,000 shares authorized; 134,651,380 and 134,651,380 shares issued at June 30, 2018 and December 31, 2017, respectively	1	1
Common stock, held in treasury, at cost; 4,999,765 and 5,232,875 shares at June 30, 2018 and December 31, 2017, respectively	(289)	(302)
Additional Paid in Capital	558	555
Retained earnings	5,125	4,613
Accumulated other comprehensive income (loss)	(33)	7
Total Westlake Chemical Corporation stockholders' equity	5,362	4,874
Noncontrolling interests	484	495
Total equity	5,846	5,369
Total liabilities and equity	$ 11,346	$ 12,076

Consolidated Balance Sheets (U3

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Preferred stock, par value, in dollars per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value, in dollars per share	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common Stock [Member]
Common Stock, Shares, Issued	134,651,380	134,651,380
Common Stock, Held in Treasury [Member]
Treasury Stock, Shares	4,999,765	5,232,875

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 2,235	$ 1,979	$ 4,385	$ 3,922
Cost of sales	1,683	1,576	3,291	3,153
Gross profit	552	403	1,094	769
Selling, general and administrative expenses	115	101	223	200
Amortization of Intangibles	25	30	51	55
Integration-related costs	8	8	15	16
Income (loss) from operations	404	264	805	498
Other income (expense)
Interest expense	(31)	(39)	(68)	(79)
Other income, net	8	2	30	9
Income before income taxes	381	227	767	428
Provision for income taxes	93	68	182	124
Net income	288	159	585	304
Net income attributable to noncontrolling interests	10	6	20	13
Net income attributable to Westlake Chemical Corporation	$ 278	$ 153	$ 565	$ 291
Earnings per common share attributable to Westlake Chemical Corporation:
Basic (usd per share)	$ 2.13	$ 1.18	$ 4.34	$ 2.24
Diluted (usd per share)	$ 2.12	$ 1.17	$ 4.31	$ 2.23
Weighted average common shares outstanding:
Basic (in shares)	129,624,291	129,051,227	129,554,528	129,015,507
Diluted (in shares)	130,306,615	129,786,714	130,249,084	129,739,643
Dividends per common share (usd per share)	$ 0.2100	$ 0.1906	$ 0.4200	$ 0.3812

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Other comprehensive income (loss)	$ (40)	$ 53	$ (42)	$ 70
Net income	288	159	585	304
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect [Abstract]
Amortization of benefits liability	0	1	0	1
Foreign Currency Translation Adjustment, by Component [Abstract]
Foreign currency translation	(37)	52	(43)	71
Income tax benefit (provision) on foreign currency translation	(3)	0	1	(2)
Comprehensive income	248	212	543	374
Comprehensive income attributable to noncontrolling interests, net of tax of $1 for the three months ended June 30, 2018 and 2017; and net of tax of $2 for the six months ended June 30, 2018 and 2017	6	7	18	15
Comprehensive income attributable to Westlake Chemical Corporation	$ 242	$ 205	$ 525	$ 359

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Income (Unaudited) OCI Parenthetical - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
OCI Parenthetical [Abstract]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest	$ 1	$ 1	$ 2	$ 2

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Stockholders' Equity Statement - USD ($) $ in Millions	Total	Common Stock [Member]	Common Stock, Held in Treasury [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Beginning balances at Dec. 31, 2016	$ 3,892	$ 1	$ (319)	$ 551	$ 3,412	$ (121)	$ 368
Beginning balance, shares issued at Dec. 31, 2016		134,651,380
Beginning balance, Treasury shares at Dec. 31, 2016			5,726,377
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	304				291		13
Other comprehensive income (loss)	70					67	3
Shares issued—stock- based compensation (in shares)			(127,901)
Shares issued—stock- based compensation	(1)		$ (3)	(2)
Stock-based compensation, net of tax on stock options exercised	7			7
Dividends declared	(49)				(49)
Distributions to noncontrolling interests	(16)						(16)
Ending balances at Jun. 30, 2017	4,209	$ 1	$ (316)	556	3,654	(54)	368
Ending balance, shares issued at Jun. 30, 2017		134,651,380
Ending balance, Treasury shares at Jun. 30, 2017			5,598,476
Beginning balances at Dec. 31, 2017	5,369	$ 1	$ (302)	555	4,613	7	495
Beginning balance, shares issued at Dec. 31, 2017		134,651,380
Beginning balance, Treasury shares at Dec. 31, 2017			5,232,875
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	585				565		20
Other comprehensive income (loss)	(42)					(40)	(2)
Shares issued—stock- based compensation (in shares)			(233,110)
Shares issued—stock- based compensation	(8)		$ (13)	(5)
Stock-based compensation, net of tax on stock options exercised	8			8
Dividends declared	(54)				(54)
Distributions to noncontrolling interests	(29)						(29)
Ending balances at Jun. 30, 2018	5,846	$ 1	$ (289)	$ 558	5,125	$ (33)	$ 484
Ending balance, shares issued at Jun. 30, 2018		134,651,380
Ending balance, Treasury shares at Jun. 30, 2018			4,999,765
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 1				$ 1

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net income	$ 585	$ 304
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	312	295
Stock-based compensation expense	11	11
Loss from disposition of property, plant and equipment	15	7
Deferred income taxes	45	15
Other gains, net	0	(1)
Changes in operating assets and liabilities
Accounts receivable	(272)	(142)
Inventories	(9)	21
Prepaid expenses and other current assets	(13)	5
Accounts payable	(11)	82
Accrued liabilities	(70)	(87)
Other, net	(44)	(30)
Net cash provided by operating activities	549	480
Cash flows from investing activities
Additions to property, plant and equipment	(312)	(281)
Additions to investments in unconsolidated subsidiaries	(45)	(31)
Other	3	2
Net cash used for investing activities	(354)	(310)
Cash flows from financing activities
Dividends paid	(54)	(49)
Distributions to noncontrolling interests	(29)	(16)
Proceeds from notes payable and drawdown of revolver	6	178
Repayment of term loan	0	(150)
Repayment of revolver	0	(360)
Redemption and repayment of notes payable	(1,173)	(5)
Other	8	1
Net cash used for financing activities	(1,242)	(401)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(2)	13
Net decrease in cash, cash equivalents and restricted cash	(1,049)	(218)
Cash, cash equivalents and restricted cash at beginning of period	1,554	646
Cash, cash equivalents and restricted cash at end of period	$ 505	$ 428

Basis of Financial Statements

Basis of Financial Statements	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Financial Statements	Basis of Financial Statements 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 Westlake Chemical Corporation (the "Company") 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 February 21, 2018 . These consolidated 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 Company for the fiscal year ended December 31, 2017 with the exception of those accounting standards adopted in the first quarter of 2018 as discussed in Note 1. In the opinion of the Company'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 Company's financial position as of June 30, 2018 , its results of operations for the three and six months ended June 30, 2018 and 2017 and the changes in its cash position for the six months ended June 30, 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 consolidated 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 from those estimates. Certain reclassifications have been made to the prior-year financial statements to conform to the current-year presentation. Recent Accounting Pronouncements Leases (ASU No. 2016-02) In February 2016, the Financial Accounting Standards Board ("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 standard requires adoption using a modified retrospective approach and allows for the election of certain transition practical expedients. The Company is in the process of reviewing its existing lease agreements and evaluating the impact that the new accounting guidance will have on the Company's 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 Company's consolidated financial position, results of operations and cash flows. Intangibles - Goodwill and Other (ASU No. 2017-04) In January 2017, the FASB issued an accounting standards update to simplify the subsequent measurement of goodwill. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. 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 Company's consolidated financial position, results of operations and cash flows. Income Statement - Reporting Comprehensive Income (ASU 2018-02) In February 2018, the FASB issued an accounting standards update to (1) allow reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (the "Tax Act"); and (2) require certain disclosures about stranded tax effects. The accounting standard will be effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The Company is in the process of evaluating the impact that the new accounting guidance will have on the Company'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 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 Company adopted ASU 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. The cumulative effects of changes to the Company's consolidated January 1, 2018 balance sheet for the adoption of this accounting standard were immaterial. The impact of ASC 606 adoption on the financial statements for the three and six months ended June 30, 2017 as compared with the guidance that was in effect prior to January 1, 2018 was immaterial. Revenue is recognized when the Company transfers control of inventories to its customers. Amounts recognized as revenues reflect the consideration to which the Company expects to be entitled in exchange for those inventories. 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. Control of inventories generally transfers upon shipment for domestic sales. The Company excludes taxes collected on behalf of customers from the estimated contract price. For export contracts, the point at which control passes to the customer varies depending on the terms specified in the customer contract. The Company generally invoices customers and recognizes revenue and accounts receivable upon transferring control of inventories. In limited circumstances, the Company transfers control of inventories shortly before it has an unconditional right to receive consideration, resulting in recognition of contract assets. The Company also receives advance payments from certain customers, resulting in recognition of contract liabilities. Contract assets and liabilities are generally settled within the period and are not material to the consolidated balance sheets. The Company expenses sales commissions when incurred. These costs are recorded within selling, general and administrative expenses. The Company 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 that is calculated based on market prices at specified dates and is allocated to wholly unsatisfied performance obligations. ASC 606 requires disclosure of disaggregated revenue into categories that depict the nature of how the Company's revenue and cash flows are affected by economic factors. The Company discloses revenues by product and segment in Note 13 to this quarterly report on Form 10-Q. Recognition and Measurement of Financial Assets and Financial Liabilities (ASU No. 2016-01) In January 2016, the FASB issued an accounting standards update making certain changes principally to the current guidance for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. Among other things, the guidance (1) requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value, with changes in fair value recognized in net income; (2) allows entities to elect to measure equity investments without readily determinable fair values at cost, less impairment, adjusted for subsequent observable price changes (changes in the basis of these equity investments to be reported in net income); (3) requires an entity that has elected the fair value option for financial liabilities to recognize changes in fair value due to instrument-specific credit risk separately in other comprehensive income; (4) clarified current guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities; and (5) requires specific disclosure pertaining to financial assets and financial liabilities in the financial statements. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. The Company is party to a joint venture investment with Lotte Chemical USA Corporation to build an ethylene facility, LACC, LLC ("LACC"). The Company measures its investment in LACC at cost, adjusted for observable price changes because the investment does not have a readily determinable fair value. 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 Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Cash Flows (ASU No. 2016-18) In November 2016, the FASB issued an accounting standards update to clarify certain existing principles in Accounting Standards Codification 230, Cash flows, including providing additional guidance related to transfers between cash and restricted cash and how entities present, in their statement of cash flows, the cash receipts and cash payments that directly affect the restricted cash accounts. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018. Upon adoption, the Company retrospectively adjusted its financial statements to reflect restricted cash in the beginning and ending cash and restricted cash balances within the statements of cash flows. As a result of this retrospective adoption and reclassification of restricted cash and cash equivalents, net cash provided by (used for) financing activities on the consolidated statement of cash flows for the six months ended June 30, 2017 has been adjusted to $(401) from the originally reported $(247) to reflect the retrospective application of the new accounting guidance. Previously reported cash and cash equivalents at beginning of the period and cash and cash equivalents at end of the period for the six months ended June 30, 2017 have been adjusted to include restricted cash of $186 and $32 , respectively. 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 ASC 606. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted the accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. 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 Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Compensation - Retirement Benefits (ASU No. 2017-07) In March 2017, the FASB issued an accounting standards update to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. The new guidance requires employers to disaggregate the service cost component from the other components of net periodic benefit cost and report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The amendments also allow only the service cost component to be eligible for capitalization when applicable. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Compensation - Stock Compensation (ASU No. 2017-09) In May 2017, the FASB issued an accounting standards update to provide clarity and reduce both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in this update provide guidance about which changes to the terms or conditions of a share-based payment award require the application of modification accounting in Topic 718. Essentially, an entity will not have to account for the effects of a modification if: (1) the fair value of the modified award is the same immediately before and after the modification; (2) the vesting conditions of the modified award are the same immediately before and after the modification; and (3) the classification of the modified award as either an equity instrument or liability instrument is the same immediately before and after the modification. This update is to be applied prospectively to an award modified on or after the adoption date. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities (ASU No. 2017-12) In August 2017, the FASB issued an accounting standards update to improve financial reporting of hedging relationships, to better portray the economic results of an entity's risk management activities in the financial statements and to simplify application of hedge accounting guidance. The accounting standard eliminates certain hedge effectiveness measurement and reporting requirements and expands the types of permissible hedging strategies. The accounting standard will be effective for reporting periods beginning after December 15, 2018, and interim periods within those fiscal years. Early application is permitted in any interim period after issuance, to be applied retrospectively to the beginning of the fiscal year. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Financial Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Financial Instruments	Financial Instruments Cash Equivalents The Company had $85 and $644 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at June 30, 2018 and December 31, 2017 , respectively. The Company's investments in held-to-maturity securities were held at amortized cost, which approximates fair value. Restricted Cash and Cash Equivalents The Company had restricted cash and cash equivalents of $23 at June 30, 2018 and December 31, 2017 . The Company's restricted cash and cash equivalents are related to balances that are restricted for payment of distributions to certain of the Company's current and former employees and are reflected primarily in other assets, net in the consolidated balance sheets.

Accounts Receivable

Accounts Receivable	6 Months Ended
	Jun. 30, 2018
Accounts Receivable, Net [Abstract]
Accounts Receivable	Accounts Receivable Accounts receivable consist of the following: June 30, December 31, Trade customers $ 1,198 $ 974 Affiliates 12 9 Allowance for doubtful accounts (24 ) (22 ) 1,186 961 Federal and state taxes 48 7 Other 27 33 Accounts receivable, net $ 1,261 $ 1,001

Inventories

Inventories	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: June 30, December 31, Finished products $ 552 $ 549 Feedstock, additives and chemicals 209 221 Materials and supplies 144 130 Inventories $ 905 $ 900

Goodwill (Notes)

Goodwill (Notes)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill Disclosure [Text Block]	Goodwill The gross carrying amounts and changes in the carrying amount of goodwill for the six months ended June 30, 2018 were as follows: Olefins Segment Vinyls Segment Total Balances at December 31, 2017 $ 30 $ 982 $ 1,012 Effects of changes in foreign exchange rates — (6 ) (6 ) Balances at June 30, 2018 $ 30 $ 976 $ 1,006 The Company performed its annual impairment analysis for the Vinyls reporting units during the second quarter of 2018 . The Company elected to perform a qualitative assessment (commonly known as "step zero") for the purposes of its annual goodwill impairment analysis for the Vinyls reporting units. Based upon this assessment, the Company determined that it is more likely than not that the fair value of each of the Vinyls reporting units exceeds its carrying value. Factors considered in the qualitative assessment included macroeconomic conditions, industry and market considerations, cost factors related to raw materials and labor, overall financial performance (both current and projected), changes in management or strategy, and market capitalization.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt consists of the following: June 30, 2018 December 31, 2017 Principal Unamortized Discount Net Principal Unamortized Net 3.60% senior notes due 2022 (the "3.60% 2022 Senior Notes") $ 250 $ (1 ) $ 249 $ 250 $ (1 ) $ 249 3.60% senior notes due 2026 (the "3.60% 2026 Senior Notes") 750 (9 ) 741 750 (10 ) 740 Loan related to tax-exempt waste disposal revenue bonds due 2027 11 — 11 11 — 11 6 ½% senior notes due 2029 (the "6 ½% 2029 GO Zone Senior Notes") 100 (1 ) 99 100 (1 ) 99 6 ½% senior notes due 2035 (the "6 ½% 2035 GO Zone Senior Notes") 89 (1 ) 88 89 (1 ) 88 6 ½% senior notes due 2035 (the "6 ½% 2035 IKE Zone Senior Notes") 65 (1 ) 64 65 — 65 5.0% senior notes due 2046 (the "5.0% 2046 Senior Notes") 700 (25 ) 675 700 (25 ) 675 4.375% senior notes due 2047 (the "4.375% 2047 Senior Notes") 500 (9 ) 491 500 (9 ) 491 3.50% senior notes due 2032 (the "3.50% 2032 GO Zone Refunding Senior Notes") 250 (2 ) 248 250 (2 ) 248 4.625% senior notes due 2021 (the "4.625% Westlake 2021 Senior Notes") — — — 625 20 645 4.625% senior notes due 2021 (the "4.625% Subsidiary 2021 Senior Notes") — — — 63 2 65 4.875% senior notes due 2023 (the "4.875% Westlake 2023 Senior Notes") — — — 434 11 445 4.875% senior notes due 2023 (the "4.875% Subsidiary 2023 Senior Notes") — — — 16 — 16 Total Long-term debt 2,715 (49 ) 2,666 3,853 (16 ) 3,837 Less: Current portion - 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes — — — 688 22 710 Long-term debt, net of current portion $ 2,715 $ (49 ) $ 2,666 $ 3,165 $ (38 ) $ 3,127 Credit Agreement As of June 30, 2018 , the Company had a $1,000 revolving credit facility that was scheduled to mature on August 23, 2021 (the "Credit Agreement"). The Credit Agreement bore interest at either (a) LIBOR plus a spread ranging from 1.00% to 1.75% or (b) Alternate Base Rate plus a spread ranging from 0.00% to 0.75% in each case depending on the credit rating of the Company. At June 30, 2018 , the Company had no borrowings outstanding under the Credit Agreement. As of June 30, 2018 , the Company had outstanding letters of credit totaling $4 and borrowing availability of $996 under the Credit Agreement. The obligations of the Company under the Credit Agreement were guaranteed by current and future material domestic subsidiaries of the Company, subject to certain exceptions. The Credit Agreement contained certain affirmative and negative covenants, including a quarterly total leverage ratio financial maintenance covenant. The Credit Agreement also contained certain events of default and if and for so long as an event of default had occurred and was continuing, any amounts outstanding under the Credit Agreement would accrue interest at an increased rate, the Lenders could terminate their commitments thereunder and payments of any outstanding amounts could be accelerated by the Lenders. As of June 30, 2018 , the Company was in compliance with the total leverage ratio financial maintenance covenant. New Credit Agreement On July 24, 2018, the Company entered into a new $1,000 revolving credit facility that is scheduled to mature on July 24, 2023 (the "New Credit Agreement") and, in connection therewith, terminated the existing Credit Agreement. The New Credit Agreement bears interest at either (a) LIBOR plus a spread ranging from 1.00% to 1.75% or (b) Alternate Base Rate plus a spread ranging from 0.00% to 0.75% in each case depending on the credit rating of the Company. The New Credit Agreement contains certain affirmative and negative covenants, including a quarterly total leverage ratio financial maintenance covenant. The New Credit Agreement also contains certain events of default and if and for so long as certain events of default have occurred and are continuing, any overdue amounts outstanding under the New Credit Agreement will accrue interest at an increased rate, the lenders can terminate their commitments thereunder and payments of any outstanding amounts could be accelerated by the lenders. None of the Company's subsidiaries are required to guarantee the obligations of the Company under the New Credit Agreement. The New Credit Agreement includes a $150 sub-limit for letters of credit, and any outstanding letters of credit will be deducted from availability under the facility. The New Credit Agreement also provides for a discretionary $50 commitment for swingline loans to be provided on a same-day basis. The Company may also increase the size of the facility, in increments of at least $25 , up to a maximum of $500 , subject to certain conditions and if certain lenders agree to commit to such an increase. In connection with the Company's entry into the New Credit Agreement and termination of the existing Credit Agreement on July 24, 2018, all guarantees by the Guarantor Subsidiaries of the Company's payment obligations under the 4.375% 2047 Senior Notes, the 3.60% 2022 Senior Notes, the 3.60% 2026 Senior Notes and the 5.0% 2046 Senior Notes were released. 4.625% Senior Notes due 2021 In December 2017, the Company delivered irrevocable notices for the optional redemption of all of the outstanding 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes (collectively, the "2021 Notes"). The 2021 Notes were redeemed on February 15, 2018 at a redemption price equal to 102.313% of the principal amount of the 2021 Notes plus accrued and unpaid interest on the 2021 Notes to the redemption date. The Company recognized a $6 gain in other income upon redemption of the 2021 Notes. 4.875% Senior Notes due 2023 In March 2018, the Company delivered irrevocable notices for the optional redemption of all of the outstanding 4.875% Westlake 2023 Senior Notes and 4.875% Subsidiary 2023 Senior Notes (collectively, the "2023 Notes"). The 2023 Notes were redeemed on May 15, 2018 at a redemption price equal to 102.438% of the principal amount of the 2023 Notes plus accrued and unpaid interest on the 2023 Notes to the redemption date. As of June 30, 2018 , the Company was in compliance with all of the covenants with respect to the 3.60% 2022 Senior Notes, the 3.60% 2026 Senior Notes, the 5.0% 2046 Senior Notes, the 4.375% 2047 Senior Notes, the 6 ½% 2029 GO Zone Senior Notes, the 3.50% 2032 GO Zone Refunding Senior Notes, the 6 ½% 2035 GO Zone Senior Notes, the 6 ½% 2035 IKE Zone Senior Notes, the Credit Agreement and the waste disposal revenue bonds. Unamortized debt issuance costs on long-term debt were $25 and $26 at June 30, 2018 and December 31, 2017 , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss) (Notes)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive Income (Loss) Changes in accumulated other comprehensive income (loss) by component for the six months ended June 30, 2018 and 2017 were as follows: Benefits Liability, Net of Tax Cumulative Foreign Currency Exchange, Net of Tax Total Balances at December 31, 2016 $ 29 $ (150 ) $ (121 ) Other comprehensive income before reclassifications — 66 66 Amounts reclassified from accumulated other 1 — 1 Net other comprehensive income attributable 1 66 67 Balances at June 30, 2017 $ 30 $ (84 ) $ (54 ) Balances at December 31, 2017 $ 43 $ (36 ) $ 7 Other comprehensive loss before reclassifications — (40 ) (40 ) Net other comprehensive loss attributable to Westlake Chemical Corporation — (40 ) (40 ) Balances at June 30, 2018 $ 43 $ (76 ) $ (33 )

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company 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 Company has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and long-term debt, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Company's long-term debt (including the current portion of long-term debt) are summarized in the table below. The Company's long-term debt instruments are publicly-traded. A market approach, based upon quotes from financial reporting services, is used to measure the fair value of the Company's long-term debt. Because the Company's long-term debt instruments may not be actively traded, the inputs used to measure the fair value of the Company's long-term debt are classified as Level 2 inputs within the fair value hierarchy. June 30, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value 3.60% 2022 Senior Notes $ 249 $ 247 $ 249 $ 255 3.60% 2026 Senior Notes 741 711 740 757 Loan related to tax-exempt waste disposal revenue bonds due 2027 11 11 11 11 6 ½% 2029 GO Zone Senior Notes 99 109 99 111 6 ½% 2035 GO Zone Senior Notes 88 98 88 99 6 ½% 2035 IKE Zone Senior Notes 64 71 65 74 5.0% 2046 Senior Notes 675 708 675 787 4.375% 2047 Senior Notes 491 462 491 518 3.50% 2032 GO Zone Refunding Senior Notes 248 247 248 256 4.625% Westlake 2021 Senior Notes — — 645 639 4.625% Subsidiary 2021 Senior Notes — — 65 65 4.875% Westlake 2023 Senior Notes — — 445 449 4.875% Subsidiary 2023 Senior Notes — — 16 16

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective income tax rate was 24.4% for the second quarter of 2018 as compared to the effective income tax rate of 30.0% for the second quarter of 2017 . The lower tax rate in the second quarter of 2018 as compared to the second quarter of 2017 was a result of the changes enacted under the Tax Act, which was signed into law on December 22, 2017. The effective income tax rate for the second quarter of 2018 was above the U.S. federal statutory rate of 21.0% primarily due to certain discrete adjustments related to foreign and state corporate rate changes and state and foreign taxes. The effective income tax rate for the second quarter of 2017 was below the U.S. federal statutory rate of 35.0% primarily due to certain discrete adjustments, a higher domestic manufacturing deduction, depletion deductions, income attributable to noncontrolling interests, research and development credits and the foreign earnings rate differential, partially offset by state income taxes. The effective income tax rate was 23.7% for the six months ended June 30, 2018 . The effective income tax rate for the six months ended June 30, 2018 was above the U.S. federal statutory rate of 21.0% primarily due to certain discrete adjustments related to foreign and state corporate rate changes and state and foreign taxes. The effective income tax rate was 29.0% for the six months ended June 30, 2017 . The effective income tax rate for the 2017 period was below the U.S. federal statutory rate of 35.0% primarily due to certain discrete adjustments, a higher domestic manufacturing deduction, depletion deductions, income attributable to noncontrolling interests, research and development credits and the foreign earnings rate differential, partially offset by state income taxes. The Tax Act, among other changes, reduced U.S. corporate income tax rate from 35.0% to 21.0%, effective January 1, 2018, and also required a one-time deemed repatriation of foreign earnings at specified rates. The accounting guidance on income taxes requires that the effect on deferred tax assets and liabilities of a change in tax rates be recognized in the period the tax rate change was enacted. The SEC staff guidance allows registrants to record provisional amounts during a measurement period when it does not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete its accounting for the change in tax law. The measurement period ends when a company has obtained, prepared and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year. The corporate income tax rate change resulted in a revaluation of the Company's deferred tax assets and liabilities. At December 31, 2017, under the above guidance, the Company made a provisional adjustment of $591 of income tax benefit in the 2017 consolidated financial statements for items that the Company could reasonably estimate such as revaluation of deferred tax assets and liabilities and a one-time U.S. tax on the mandatory deemed repatriation of the Company's post-1986 foreign earnings. The Company will continue to assess the income tax effects of the Tax Act based on further standard setting activities, any transition provisions, and changes in the facts and circumstances of the Company's tax position, during the measurement period. No measurement period adjustment was made for the six months ended June 30, 2018 .

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The Company has unvested restricted stock units outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share includes the effect of certain stock options. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net income attributable to Westlake Chemical Corporation $ 278 $ 153 $ 565 $ 291 Less: Net income attributable to participating securities (2 ) (1 ) (3 ) (2 ) Net income attributable to common shareholders $ 276 $ 152 $ 562 $ 289 The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Weighted average common shares—basic 129,624,291 129,051,227 129,554,528 129,015,507 Plus incremental shares from: Assumed exercise of options 682,324 735,487 694,556 724,136 Weighted average common shares—diluted 130,306,615 129,786,714 130,249,084 129,739,643 Earnings per common share attributable to Westlake Chemical Corporation: Basic $ 2.13 $ 1.18 $ 4.34 $ 2.24 Diluted $ 2.12 $ 1.17 $ 4.31 $ 2.23 Excluded from the computation of diluted earnings per share are options to purchase 172,642 and 583,585 shares of common stock for the three months ended June 30, 2018 and 2017 , respectively, and 128,892 and 511,085 shares of common stock for the six months ended June 30, 2018 and 2017 , respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.

Supplemental Information

Supplemental Information	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental Information Accrued Liabilities Accrued liabilities were $604 and $657 at June 30, 2018 and December 31, 2017 , respectively. Accrued rebates, which are components of accrued liabilities, were $94 and $108 at June 30, 2018 and December 31, 2017 , respectively. No other component of accrued liabilities was more than five percent of total current liabilities. Accrued liabilities with affiliates were $42 and $37 at June 30, 2018 and December 31, 2017 , respectively. Non-cash Investing Activity The change in capital expenditure accrual resulted in a decrease in additions to property, plant and equipment by $18 for the six months ended June 30, 2018 . The change in capital expenditure accrual resulted in an increase in additions to property, plant and equipment by $11 for the six months ended June 30, 2017 .

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company is involved in a number of legal and regulatory matters, principally environmental in nature, that are incidental to the normal conduct of its business, including lawsuits, investigations and claims. The outcomes of these matters are inherently unpredictable. The Company believes that, in the aggregate, the outcome of all known legal and regulatory matters will not have a material adverse effect on its consolidated financial statements; however, specific outcomes with respect to such matters may be material to the Company's consolidated statements of operations in any particular period in which costs, if any, are recognized. The Company's assessment of the potential impact of environmental matters, in particular, is subject to uncertainty due to the complex, ongoing and evolving process of investigation and remediation of such environmental matters, and the potential for technological and regulatory developments. In addition, the impact of evolving claims and programs, such as natural resource damage claims, industrial site reuse initiatives and state remediation programs creates further uncertainty of the ultimate resolution of these matters. The Company anticipates that the resolution of many legal and regulatory matters, and in particular environmental matters, will occur over an extended period of time. Environmental. As of June 30, 2018 and December 31, 2017 , the Company had reserves for environmental contingencies totaling approximately $53 and $49 , respectively, most of which were classified as noncurrent liabilities. The Company's assessment of the potential impact of these environmental contingencies is subject to considerable uncertainty due to the complex, ongoing and evolving process of investigation and remediation, if necessary, of such environmental contingencies, and the potential for technological and regulatory developments. Calvert City Proceedings. For several years, the Environmental Protection Agency (the "EPA") has been conducting remedial investigation and feasibility studies at the Company's Calvert City, Kentucky facility pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 ("CERCLA"). As the current owner of the Calvert City facility, the Company was named by the EPA as a potentially responsible party ("PRP") along with Goodrich Corporation ("Goodrich") and its successor-in-interest, PolyOne Corporation ("PolyOne"). On November 30, 2017, the EPA published a draft Proposed Plan, incorporating by reference an August 2015 draft Remedial Investigation ("RI") report, an October 2017 draft Feasibility Study ("FS") report and a new Technical Impracticability Waiver document dated December 19, 2017. The draft Proposed Plan described a preferred remedy that included a containment wall with targeted treatment and supplemental hydraulic containment, as well as active treatment of historical groundwater contamination under the Tennessee River. The EPA estimated that the total remedy would cost $200 to $250 with an estimated $1 to $3 in annual operation and maintenance ("O&M") costs. Each PRP, including the Company, submitted comments to the Proposed Plan and associated documents. The Company's comments also proposed alternative removal options for the groundwater contamination under the Tennessee River. On June 18, 2018, the EPA published an amendment to its Proposed Plan. The amended Proposed Plan addresses the comments filed on the river excavation remedy outlined in the original Proposed Plan. Under the amended Proposed Plan, the EPA proposes an interim approach to address the contamination under the river that would include recovery of any mobile contaminants by an extraction well along with further study of the extent of the contamination and potential treatment options. The EPA's revised estimated cost of implementation is $107 , with the estimated annual O&M costs remaining unchanged. The Company's allocation of liability for remedial or O&M costs, if any, will be determined by the outcome of the contractual dispute with Goodrich/PolyOne, which is the subject of a pending arbitration proceeding as described below. In connection with the 1990 and 1997 acquisitions of the Goodrich chemical manufacturing complex in Calvert City, Goodrich agreed to indemnify the Company for any liabilities related to preexisting contamination at the complex. For its part, the Company agreed to indemnify Goodrich for post-closing contamination caused by the Company's operations. The soil and groundwater at the complex, which does not include the Company's nearby PVC facility, had been extensively contaminated by Goodrich's operations. In 1993, Goodrich spun off the predecessor of PolyOne, and that predecessor assumed Goodrich's indemnification obligations relating to preexisting contamination. In 2003, litigation arose among the Company, Goodrich and PolyOne with respect to the allocation of the cost of remediating contamination at the site. The parties settled this litigation in December 2007 and the case was dismissed. In the settlement, the parties agreed that, among other things: (1) PolyOne would pay 100% of the costs (with specified exceptions), net of recoveries or credits from third parties, incurred with respect to environmental issues at the Calvert City site from August 1, 2007 forward; and (2) either the Company or PolyOne might, from time to time in the future (but not more than once every five years), institute an arbitration proceeding to adjust that percentage. In May 2017, PolyOne filed a demand for arbitration. In this proceeding, PolyOne seeks to readjust the percentage allocation of costs and to recover approximately $17 from the Company in reimbursement of previously paid remediation costs. The Company has filed a cross demand for arbitration seeking unreimbursed remediation costs incurred during the relevant period. On October 6, 2017, PolyOne filed suit against the Company in the U.S. District Court for the Western District of Kentucky seeking for the court, instead of the arbitration panel, to resolve claims asserted by the Company in the arbitration proceedings related to reimbursement of costs incurred by the Company at the Calvert City complex. On May 30, 2018, the U.S. District Court for the Western District of Kentucky granted the Company's motion to dismiss, concluding that all of PolyOne's claims were the proper subject of the current arbitration panel's jurisdiction, and dismissed PolyOne's action before the court. On July 10, 2018, PolyOne filed another action in the U.S. District Court for the Western District of Kentucky, seeking for the court to issue an injunction against continued proceedings in the arbitration. PolyOne's motion is currently pending before the Court. At this time, the Company is not able to estimate the impact, if any, that the arbitration proceeding could have on the Company's consolidated financial statements either in the current period or in later periods. Any cash expenditures that the Company might incur in the future with respect to the remediation of contamination at the Calvert City complex would likely be spread out over an extended period. As a result, the Company believes it is unlikely that any remediation costs allocable to it will be material in terms of expenditures made in any individual reporting period. Environmental Remediation: Reasonably Possible Matters. The Company's assessment of the potential impact of environmental contingencies is subject to considerable uncertainty due to the complex, ongoing and evolving process of investigation and remediation, if necessary, of such environmental contingencies, and the potential for technological and regulatory developments. As such, in addition to the amounts currently reserved, the Company may be subject to reasonably possible loss contingencies related to environmental matters in the range of $55 to $110 . Commitments. The Company became a party to a joint venture investment with Lotte Chemical USA Corporation to build an ethylene facility, LACC. The ethylene facility is located adjacent to the Company's vinyls facility in Lake Charles. Pursuant to the contribution and subscription agreement, the Company agreed to make a maximum capital commitment to LACC of up to $225 to fund the construction costs of the ethylene plant, which represents approximately 10% of the interests in LACC. The construction of the ethylene plant commenced in January 2016, with an anticipated start-up in 2019. As of June 30, 2018 , the Company had funded approximately $160 of the Company's portion of the construction costs of the ethylene plant.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The Company operates in two principal operating segments: Olefins and Vinyls. These segments are strategic business units that offer a variety of different products. The Company manages each segment separately as each business requires different technology and marketing strategies. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net external sales Olefins Polyethylene $ 387 $ 358 $ 756 $ 744 Styrene, feedstock and other 95 131 229 288 Total Olefins 482 489 985 1,032 Vinyls PVC, caustic soda and other 1,396 1,157 2,754 2,288 Building products 357 333 646 602 Total Vinyls 1,753 1,490 3,400 2,890 $ 2,235 $ 1,979 $ 4,385 $ 3,922 Intersegment sales Olefins $ 112 $ 98 $ 232 $ 184 Vinyls 1 — 1 — $ 113 $ 98 $ 233 $ 184 Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Income (loss) from operations Olefins $ 158 $ 143 $ 321 $ 323 Vinyls 271 141 537 211 Corporate and other (25 ) (20 ) (53 ) (36 ) $ 404 $ 264 $ 805 $ 498 Depreciation and amortization Olefins $ 33 $ 35 $ 67 $ 76 Vinyls 120 107 238 214 Corporate and other 3 3 7 5 $ 156 $ 145 $ 312 $ 295 Other income, net Olefins $ 1 $ 1 $ 3 $ 2 Vinyls 4 — 16 6 Corporate and other 3 1 11 1 $ 8 $ 2 $ 30 $ 9 Provision for (benefit from) income taxes Olefins $ 36 $ 36 $ 73 $ 94 Vinyls 69 39 130 54 Corporate and other (12 ) (7 ) (21 ) (24 ) $ 93 $ 68 $ 182 $ 124 Capital expenditures Olefins $ 26 $ 24 $ 48 $ 49 Vinyls 128 114 258 222 Corporate and other 4 9 6 10 $ 158 $ 147 $ 312 $ 281 A reconciliation of total segment income from operations to consolidated income before income taxes is as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Income from operations $ 404 $ 264 $ 805 $ 498 Interest expense (31 ) (39 ) (68 ) (79 ) Other income, net 8 2 30 9 Income before income taxes $ 381 $ 227 $ 767 $ 428 June 30, December 31, Total assets Olefins $ 2,044 $ 2,006 Vinyls 8,863 8,853 Corporate and other 439 1,217 $ 11,346 $ 12,076

Subsequent Events (Notes)

Subsequent Events (Notes)	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events New Credit Agreement On July 24, 2018, the Company entered into a new $1,000 revolving credit facility that is scheduled to mature on July 24, 2023 and, in connection therewith, terminated the existing Credit Agreement. For additional information on the New Credit Agreement, see Note 6. Westlake Chemical Partners LP The Company has an 81.7% limited partner interest in Westlake Chemical OpCo LP ("OpCo"), a 43.8% limited partner interest in Westlake Chemical Partners LP ("Westlake Partners"), a general partner interest in Westlake Partners and incentive distribution rights ("IDRs"). On July 27, 2018, the Westlake Partners' partnership agreement was amended to revise the minimum quarterly distribution thresholds for Westlake Partners' IDRs. The amended agreement provides that Westlake Partners will distribute cash each quarter to all the unitholders, pro rata, until each unit has received a distribution of $1.2938 . If cash distributions to Westlake Partners' unitholders exceed $1.2938 per unit in any quarter, Westlake Partners' unitholders and Westlake, as the holder of the Westlake Partners' incentive distribution rights, will receive distributions according to the following percentage allocations per the amendment: Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Above $1.2938 up to $1.4063 85.0 % 15.0 % Above $1.4063 up to $1.6875 75.0 % 25.0 % Above $1.6875 50.0 % 50.0 % The Westlake Partners' distribution for the three months ended June 30, 2018 did not exceed the $1.2938 per unit threshold, and, as a result of the amendment, no distribution was made with respect to Westlake Partners' IDRs to Westlake, as the holder of the Westlake Partners' IDRs. Prior to the amendment, Westlake Partners' partnership agreement provided that Westlake Partners' unitholders and Westlake, as the holder of Westlake Partners' IDRs, would 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 %

Guarantor Disclosures

Guarantor Disclosures	6 Months Ended
	Jun. 30, 2018
Guarantees [Abstract]
Guarantor Disclosures	Guarantor Disclosures The Company's payment obligations under the 4.375% 2047 Senior Notes, the 3.60% 2022 Senior Notes, the 3.60% 2026 Senior Notes and the 5.0% 2046 Senior Notes were, as of June 30, 2018, required to be fully and unconditionally guaranteed by each of its current and future domestic subsidiaries that guarantee other debt of the Company or of another guarantor of those notes in excess of $5 (the "Guarantor Subsidiaries"). Each Guarantor Subsidiary is 100% owned by Westlake Chemical Corporation (the " 100% Owned Guarantor Subsidiaries"). During 2016 and 2017, the Company executed a Joinder Agreement with the Administrative Agent of the Credit Agreement, whereby certain subsidiaries of the Company were added as Guarantor Subsidiaries. These guarantees were the joint and several obligations of the Guarantor Subsidiaries. The following unaudited condensed consolidating financial information presents the financial condition, results of operations and cash flows of Westlake Chemical Corporation, the 100% Owned Guarantor Subsidiaries, and the remaining subsidiaries that did not guarantee the 4.375% 2047 Senior Notes, the 3.60% 2022 Senior Notes, the 3.60% 2026 Senior Notes and the 5.0% 2046 Senior Notes as of June 30, 2018 (the "Non-Guarantor Subsidiaries"), together with consolidating eliminations necessary to present the Company's results on a consolidated basis. Condensed Consolidating Financial Information as of June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 258 $ 40 $ 184 $ — $ 482 Accounts receivable, net 4,963 5,488 666 (9,856 ) 1,261 Inventories — 651 254 — 905 Prepaid expenses and other current assets 158 39 23 (174 ) 46 Total current assets 5,379 6,218 1,127 (10,030 ) 2,694 Property, plant and equipment, net — 4,466 2,002 — 6,468 Goodwill — 855 151 — 1,006 Customer relationships, net — 447 122 — 569 Other intangible assets, net — 81 68 — 149 Other assets, net 11,188 800 1,312 (12,840 ) 460 Total assets $ 16,567 $ 12,867 $ 4,782 $ (22,870 ) $ 11,346 Current liabilities Accounts payable $ 8,356 $ 1,675 $ 231 $ (9,680 ) $ 582 Accrued liabilities 183 514 255 (348 ) 604 Total current liabilities 8,539 2,189 486 (10,028 ) 1,186 Long-term debt, net 2,656 4,161 224 (4,375 ) 2,666 Deferred income taxes — 1,072 94 (13 ) 1,153 Pension and other liabilities 10 336 149 — 495 Total liabilities 11,205 7,758 953 (14,416 ) 5,500 Total Westlake Chemical Corporation stockholders' equity 5,362 5,109 3,345 (8,454 ) 5,362 Noncontrolling interests — — 484 — 484 Total equity 5,362 5,109 3,829 (8,454 ) 5,846 Total liabilities and equity $ 16,567 $ 12,867 $ 4,782 $ (22,870 ) $ 11,346 Condensed Consolidating Financial Information as of December 31, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 1,089 $ 57 $ 385 $ — $ 1,531 Accounts receivable, net 3,331 4,128 580 (7,038 ) 1,001 Inventories — 654 246 — 900 Prepaid expenses and other current assets 52 27 31 (79 ) 31 Total current assets 4,472 4,866 1,242 (7,117 ) 3,463 Property, plant and equipment, net — 4,374 2,038 — 6,412 Goodwill — 855 157 — 1,012 Customer relationships, net — 479 137 — 616 Other intangible assets, net — 88 73 — 161 Other assets, net 10,706 798 1,271 (12,363 ) 412 Total assets $ 15,178 $ 11,460 $ 4,918 $ (19,480 ) $ 12,076 Current liabilities Accounts payable $ 6,367 $ 864 $ 224 $ (6,855 ) $ 600 Accrued liabilities 189 484 246 (262 ) 657 Current portion of long-term debt, net 710 — — — 710 Total current liabilities 7,266 1,348 470 (7,117 ) 1,967 Long-term debt, net 3,034 4,242 220 (4,369 ) 3,127 Deferred income taxes — 1,026 92 (7 ) 1,111 Pension and other liabilities 4 347 151 — 502 Total liabilities 10,304 6,963 933 (11,493 ) 6,707 Total Westlake Chemical Corporation stockholders' equity 4,874 4,497 3,490 (7,987 ) 4,874 Noncontrolling interests — — 495 — 495 Total equity 4,874 4,497 3,985 (7,987 ) 5,369 Total liabilities and equity $ 15,178 $ 11,460 $ 4,918 $ (19,480 ) $ 12,076 Condensed Consolidating Financial Information for the Three Months Ended June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 1,826 $ 878 $ (469 ) $ 2,235 Cost of sales — 1,465 680 (462 ) 1,683 Gross profit — 361 198 (7 ) 552 Selling, general and administrative expenses — 86 36 (7 ) 115 Amortization of intangibles — 19 6 — 25 Integration-related costs — 8 — — 8 Income from operations — 248 156 — 404 Other income (expense) Interest expense (31 ) (52 ) (3 ) 55 (31 ) Other income (expense), net 41 8 14 (55 ) 8 Income (loss) before income taxes 10 204 167 — 381 Provision (benefit) for income taxes 2 71 20 — 93 Equity in net income of subsidiaries 270 — — (270 ) — Net income 278 133 147 (270 ) 288 Net income attributable to noncontrolling interests — — 10 — 10 Net income attributable to Westlake Chemical Corporation $ 278 $ 133 $ 137 $ (270 ) $ 278 Comprehensive income attributable to Westlake Chemical Corporation $ 242 $ 133 $ 99 $ (232 ) $ 242 Condensed Consolidating Financial Information for the Three Months Ended June 30, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 1,597 $ 804 $ (422 ) $ 1,979 Cost of sales — 1,350 640 (414 ) 1,576 Gross profit — 247 164 (8 ) 403 Selling, general and administrative expenses — 73 36 (8 ) 101 Amortization of intangibles — 23 7 — 30 Integration-related costs — 8 — — 8 Income from operations — 143 121 — 264 Other income (expense) Interest expense (38 ) (46 ) — 45 (39 ) Other income (expense), net 37 6 4 (45 ) 2 Income (loss) before income taxes (1 ) 103 125 — 227 Provision (benefit) for income taxes 4 52 12 — 68 Equity in net income of subsidiaries 158 — — (158 ) — Net income 153 51 113 (158 ) 159 Net income attributable to noncontrolling interests — — 6 — 6 Net income attributable to Westlake Chemical Corporation $ 153 $ 51 $ 107 $ (158 ) $ 153 Comprehensive income attributable to Westlake Chemical Corporation $ 205 $ 52 $ 148 $ (200 ) $ 205 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 3,572 $ 1,717 $ (904 ) $ 4,385 Cost of sales — 2,870 1,312 (891 ) 3,291 Gross profit — 702 405 (13 ) 1,094 Selling, general and administrative expenses — 163 73 (13 ) 223 Amortization of intangibles — 38 13 — 51 Integration-related costs — 15 — — 15 Income from operations — 486 319 — 805 Other income (expense) Interest expense (69 ) (100 ) (5 ) 106 (68 ) Other income (expense), net 86 16 34 (106 ) 30 Income (loss) before income taxes 17 402 348 — 767 Provision (benefit) for income taxes 4 134 44 — 182 Equity in net income of subsidiaries 552 — — (552 ) — Net income 565 268 304 (552 ) 585 Net income attributable to noncontrolling interests — — 20 — 20 Net income attributable to Westlake Chemical Corporation $ 565 $ 268 $ 284 $ (552 ) $ 565 Comprehensive income attributable to Westlake Chemical Corporation $ 525 $ 268 $ 244 $ (512 ) $ 525 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 3,177 $ 1,540 $ (795 ) $ 3,922 Cost of sales — 2,712 1,222 (781 ) 3,153 Gross profit — 465 318 (14 ) 769 Selling, general and administrative expenses 1 146 67 (14 ) 200 Amortization of intangibles — 42 13 — 55 Integration-related costs — 16 — — 16 Income from operations (1 ) 261 238 — 498 Other income (expense) Interest expense (76 ) (92 ) (1 ) 90 (79 ) Other income (expense), net 74 9 16 (90 ) 9 Income (loss) before income taxes (3 ) 178 253 — 428 Provision (benefit) for income taxes (1 ) 105 20 — 124 Equity in net income of subsidiaries 293 — — (293 ) — Net income 291 73 233 (293 ) 304 Net income attributable to noncontrolling interests — — 13 — 13 Net income attributable to Westlake Chemical Corporation $ 291 $ 73 $ 220 $ (293 ) $ 291 Comprehensive income attributable to Westlake Chemical Corporation $ 359 $ 73 $ 259 $ (332 ) $ 359 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Cash Flows Cash flows from operating activities Net income $ 565 $ 268 $ 304 $ (552 ) $ 585 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization — 208 104 — 312 Deferred income taxes 1 40 4 — 45 Net changes in working capital and other (533 ) (459 ) 47 552 (393 ) Net cash provided by operating activities 33 57 459 — 549 Cash flows from investing activities Additions to property, plant and equipment — (248 ) (64 ) — (312 ) Additions to investments in unconsolidated subsidiaries — (35 ) (10 ) — (45 ) Other — 3 — — 3 Net cash used for investing activities — (280 ) (74 ) — (354 ) Cash flows from financing activities Intercompany financing 347 (1 ) (346 ) — — Dividends paid (54 ) — — — (54 ) Distributions to noncontrolling interests — 207 (236 ) — (29 ) Proceeds from notes payable and drawdown of revolver — — 6 — 6 Redemption and repayment of notes payable (1,165 ) — (8 ) — (1,173 ) Other 8 — — — 8 Net cash used for financing activities (864 ) 206 (584 ) — (1,242 ) Effect of exchange rate changes on cash, cash equivalents and restricted cash — — (2 ) — (2 ) Net decrease in cash, cash equivalents and restricted cash (831 ) (17 ) (201 ) — (1,049 ) Cash, cash equivalents and restricted cash at beginning of period 1,089 79 386 — 1,554 Cash, cash equivalents and restricted cash at end of period $ 258 $ 62 $ 185 $ — $ 505 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Cash Flows Cash flows from operating activities Net income $ 291 $ 73 $ 233 $ (293 ) $ 304 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization — 194 101 — 295 Deferred income taxes — 15 — — 15 Net changes in working capital and other (400 ) (26 ) (1 ) 293 (134 ) Net cash provided by (used for) operating activities (109 ) 256 333 — 480 Cash flows from investing activities Additions to property, plant and equipment — (199 ) (82 ) — (281 ) Additions to investments in unconsolidated subsidiaries — (31 ) — — (31 ) Other — 2 — — 2 Net cash used for investing activities — (228 ) (82 ) — (310 ) Cash flows from financing activities Intercompany financing 242 (254 ) 12 — — Dividends paid (49 ) — — — (49 ) Distributions to noncontrolling interests — 189 (205 ) — (16 ) Proceeds from notes payable and drawdown of revolver 175 — 3 — 178 Repayment of term loan — — (150 ) — (150 ) Repayment of revolver (360 ) — — — (360 ) Redemption and repayment of notes payable — (1 ) (4 ) — (5 ) Other 1 — — — 1 Net cash used for financing activities 9 (66 ) (344 ) — (401 ) Effect of exchange rate changes on cash, cash equivalents and restricted cash — — 13 — 13 Net decrease in cash, cash equivalents and restricted cash (100 ) (38 ) (80 ) — (218 ) Cash, cash equivalents and restricted cash at beginning of period 147 78 421 — 646 Cash, cash equivalents and restricted cash at end of period $ 47 $ 40 $ 341 $ — $ 428

Basis of Financial Statements (

Basis of Financial Statements (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Financial Statements	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 Westlake Chemical Corporation (the "Company") 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 February 21, 2018 . These consolidated 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 Company for the fiscal year ended December 31, 2017 with the exception of those accounting standards adopted in the first quarter of 2018 as discussed in Note 1. In the opinion of the Company'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 Company's financial position as of June 30, 2018 , its results of operations for the three and six months ended June 30, 2018 and 2017 and the changes in its cash position for the six months ended June 30, 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 consolidated 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 from those estimates. Certain reclassifications have been made to the prior-year financial statements to conform to the current-year presentation.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Leases (ASU No. 2016-02) In February 2016, the Financial Accounting Standards Board ("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 standard requires adoption using a modified retrospective approach and allows for the election of certain transition practical expedients. The Company is in the process of reviewing its existing lease agreements and evaluating the impact that the new accounting guidance will have on the Company's 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 Company's consolidated financial position, results of operations and cash flows. Intangibles - Goodwill and Other (ASU No. 2017-04) In January 2017, the FASB issued an accounting standards update to simplify the subsequent measurement of goodwill. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. 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 Company's consolidated financial position, results of operations and cash flows. Income Statement - Reporting Comprehensive Income (ASU 2018-02) In February 2018, the FASB issued an accounting standards update to (1) allow reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (the "Tax Act"); and (2) require certain disclosures about stranded tax effects. The accounting standard will be effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The Company is in the process of evaluating the impact that the new accounting guidance will have on the Company'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 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 Company adopted ASU 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. The cumulative effects of changes to the Company's consolidated January 1, 2018 balance sheet for the adoption of this accounting standard were immaterial. The impact of ASC 606 adoption on the financial statements for the three and six months ended June 30, 2017 as compared with the guidance that was in effect prior to January 1, 2018 was immaterial. Revenue is recognized when the Company transfers control of inventories to its customers. Amounts recognized as revenues reflect the consideration to which the Company expects to be entitled in exchange for those inventories. 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. Control of inventories generally transfers upon shipment for domestic sales. The Company excludes taxes collected on behalf of customers from the estimated contract price. For export contracts, the point at which control passes to the customer varies depending on the terms specified in the customer contract. The Company generally invoices customers and recognizes revenue and accounts receivable upon transferring control of inventories. In limited circumstances, the Company transfers control of inventories shortly before it has an unconditional right to receive consideration, resulting in recognition of contract assets. The Company also receives advance payments from certain customers, resulting in recognition of contract liabilities. Contract assets and liabilities are generally settled within the period and are not material to the consolidated balance sheets. The Company expenses sales commissions when incurred. These costs are recorded within selling, general and administrative expenses. The Company 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 that is calculated based on market prices at specified dates and is allocated to wholly unsatisfied performance obligations. ASC 606 requires disclosure of disaggregated revenue into categories that depict the nature of how the Company's revenue and cash flows are affected by economic factors. The Company discloses revenues by product and segment in Note 13 to this quarterly report on Form 10-Q. Recognition and Measurement of Financial Assets and Financial Liabilities (ASU No. 2016-01) In January 2016, the FASB issued an accounting standards update making certain changes principally to the current guidance for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. Among other things, the guidance (1) requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value, with changes in fair value recognized in net income; (2) allows entities to elect to measure equity investments without readily determinable fair values at cost, less impairment, adjusted for subsequent observable price changes (changes in the basis of these equity investments to be reported in net income); (3) requires an entity that has elected the fair value option for financial liabilities to recognize changes in fair value due to instrument-specific credit risk separately in other comprehensive income; (4) clarified current guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities; and (5) requires specific disclosure pertaining to financial assets and financial liabilities in the financial statements. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. The Company is party to a joint venture investment with Lotte Chemical USA Corporation to build an ethylene facility, LACC, LLC ("LACC"). The Company measures its investment in LACC at cost, adjusted for observable price changes because the investment does not have a readily determinable fair value. 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 Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Cash Flows (ASU No. 2016-18) In November 2016, the FASB issued an accounting standards update to clarify certain existing principles in Accounting Standards Codification 230, Cash flows, including providing additional guidance related to transfers between cash and restricted cash and how entities present, in their statement of cash flows, the cash receipts and cash payments that directly affect the restricted cash accounts. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018. Upon adoption, the Company retrospectively adjusted its financial statements to reflect restricted cash in the beginning and ending cash and restricted cash balances within the statements of cash flows. As a result of this retrospective adoption and reclassification of restricted cash and cash equivalents, net cash provided by (used for) financing activities on the consolidated statement of cash flows for the six months ended June 30, 2017 has been adjusted to $(401) from the originally reported $(247) to reflect the retrospective application of the new accounting guidance. Previously reported cash and cash equivalents at beginning of the period and cash and cash equivalents at end of the period for the six months ended June 30, 2017 have been adjusted to include restricted cash of $186 and $32 , respectively. 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 ASC 606. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted the accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. 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 Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Compensation - Retirement Benefits (ASU No. 2017-07) In March 2017, the FASB issued an accounting standards update to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. The new guidance requires employers to disaggregate the service cost component from the other components of net periodic benefit cost and report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The amendments also allow only the service cost component to be eligible for capitalization when applicable. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Compensation - Stock Compensation (ASU No. 2017-09) In May 2017, the FASB issued an accounting standards update to provide clarity and reduce both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in this update provide guidance about which changes to the terms or conditions of a share-based payment award require the application of modification accounting in Topic 718. Essentially, an entity will not have to account for the effects of a modification if: (1) the fair value of the modified award is the same immediately before and after the modification; (2) the vesting conditions of the modified award are the same immediately before and after the modification; and (3) the classification of the modified award as either an equity instrument or liability instrument is the same immediately before and after the modification. This update is to be applied prospectively to an award modified on or after the adoption date. The accounting standard became effective for reporting periods beginning after December 15, 2017. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows. Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities (ASU No. 2017-12) In August 2017, the FASB issued an accounting standards update to improve financial reporting of hedging relationships, to better portray the economic results of an entity's risk management activities in the financial statements and to simplify application of hedge accounting guidance. The accounting standard eliminates certain hedge effectiveness measurement and reporting requirements and expands the types of permissible hedging strategies. The accounting standard will be effective for reporting periods beginning after December 15, 2018, and interim periods within those fiscal years. Early application is permitted in any interim period after issuance, to be applied retrospectively to the beginning of the fiscal year. The Company adopted this accounting standard effective January 1, 2018 and the adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows.

Accounts Receivable (Tables)

Accounts Receivable (Tables)	6 Months Ended
	Jun. 30, 2018
Accounts Receivable, Net [Abstract]
Schedule Of Accounts Receivable	Accounts receivable consist of the following: June 30, December 31, Trade customers $ 1,198 $ 974 Affiliates 12 9 Allowance for doubtful accounts (24 ) (22 ) 1,186 961 Federal and state taxes 48 7 Other 27 33 Accounts receivable, net $ 1,261 $ 1,001

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Schedule Of Inventory	Inventories consist of the following: June 30, December 31, Finished products $ 552 $ 549 Feedstock, additives and chemicals 209 221 Materials and supplies 144 130 Inventories $ 905 $ 900

Goodwill (Tables)

Goodwill (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	Olefins Segment Vinyls Segment Total Balances at December 31, 2017 $ 30 $ 982 $ 1,012 Effects of changes in foreign exchange rates — (6 ) (6 ) Balances at June 30, 2018 $ 30 $ 976 $ 1,006

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	Long-term debt consists of the following: June 30, 2018 December 31, 2017 Principal Unamortized Discount Net Principal Unamortized Net 3.60% senior notes due 2022 (the "3.60% 2022 Senior Notes") $ 250 $ (1 ) $ 249 $ 250 $ (1 ) $ 249 3.60% senior notes due 2026 (the "3.60% 2026 Senior Notes") 750 (9 ) 741 750 (10 ) 740 Loan related to tax-exempt waste disposal revenue bonds due 2027 11 — 11 11 — 11 6 ½% senior notes due 2029 (the "6 ½% 2029 GO Zone Senior Notes") 100 (1 ) 99 100 (1 ) 99 6 ½% senior notes due 2035 (the "6 ½% 2035 GO Zone Senior Notes") 89 (1 ) 88 89 (1 ) 88 6 ½% senior notes due 2035 (the "6 ½% 2035 IKE Zone Senior Notes") 65 (1 ) 64 65 — 65 5.0% senior notes due 2046 (the "5.0% 2046 Senior Notes") 700 (25 ) 675 700 (25 ) 675 4.375% senior notes due 2047 (the "4.375% 2047 Senior Notes") 500 (9 ) 491 500 (9 ) 491 3.50% senior notes due 2032 (the "3.50% 2032 GO Zone Refunding Senior Notes") 250 (2 ) 248 250 (2 ) 248 4.625% senior notes due 2021 (the "4.625% Westlake 2021 Senior Notes") — — — 625 20 645 4.625% senior notes due 2021 (the "4.625% Subsidiary 2021 Senior Notes") — — — 63 2 65 4.875% senior notes due 2023 (the "4.875% Westlake 2023 Senior Notes") — — — 434 11 445 4.875% senior notes due 2023 (the "4.875% Subsidiary 2023 Senior Notes") — — — 16 — 16 Total Long-term debt 2,715 (49 ) 2,666 3,853 (16 ) 3,837 Less: Current portion - 4.625% Westlake 2021 Senior Notes and 4.625% Subsidiary 2021 Senior Notes — — — 688 22 710 Long-term debt, net of current portion $ 2,715 $ (49 ) $ 2,666 $ 3,165 $ (38 ) $ 3,127

Accumulated Other Comprehensi29

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Changes in accumulated other comprehensive income (loss) by component for the six months ended June 30, 2018 and 2017 were as follows: Benefits Liability, Net of Tax Cumulative Foreign Currency Exchange, Net of Tax Total Balances at December 31, 2016 $ 29 $ (150 ) $ (121 ) Other comprehensive income before reclassifications — 66 66 Amounts reclassified from accumulated other 1 — 1 Net other comprehensive income attributable 1 66 67 Balances at June 30, 2017 $ 30 $ (84 ) $ (54 ) Balances at December 31, 2017 $ 43 $ (36 ) $ 7 Other comprehensive loss before reclassifications — (40 ) (40 ) Net other comprehensive loss attributable to Westlake Chemical Corporation — (40 ) (40 ) Balances at June 30, 2018 $ 43 $ (76 ) $ (33 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Summary Of Carrying And Fair Values Of Long-Term Debt	June 30, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value 3.60% 2022 Senior Notes $ 249 $ 247 $ 249 $ 255 3.60% 2026 Senior Notes 741 711 740 757 Loan related to tax-exempt waste disposal revenue bonds due 2027 11 11 11 11 6 ½% 2029 GO Zone Senior Notes 99 109 99 111 6 ½% 2035 GO Zone Senior Notes 88 98 88 99 6 ½% 2035 IKE Zone Senior Notes 64 71 65 74 5.0% 2046 Senior Notes 675 708 675 787 4.375% 2047 Senior Notes 491 462 491 518 3.50% 2032 GO Zone Refunding Senior Notes 248 247 248 256 4.625% Westlake 2021 Senior Notes — — 645 639 4.625% Subsidiary 2021 Senior Notes — — 65 65 4.875% Westlake 2023 Senior Notes — — 445 449 4.875% Subsidiary 2023 Senior Notes — — 16 16

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule Of Net Income Attributable To Common Stockholders	Diluted earnings per share includes the effect of certain stock options. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net income attributable to Westlake Chemical Corporation $ 278 $ 153 $ 565 $ 291 Less: Net income attributable to participating securities (2 ) (1 ) (3 ) (2 ) Net income attributable to common shareholders $ 276 $ 152 $ 562 $ 289
Reconciliation Of Denominator For Basic And Diluted Earnings Per Share	The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Weighted average common shares—basic 129,624,291 129,051,227 129,554,528 129,015,507 Plus incremental shares from: Assumed exercise of options 682,324 735,487 694,556 724,136 Weighted average common shares—diluted 130,306,615 129,786,714 130,249,084 129,739,643 Earnings per common share attributable to Westlake Chemical Corporation: Basic $ 2.13 $ 1.18 $ 4.34 $ 2.24 Diluted $ 2.12 $ 1.17 $ 4.31 $ 2.23

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting Information	Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net external sales Olefins Polyethylene $ 387 $ 358 $ 756 $ 744 Styrene, feedstock and other 95 131 229 288 Total Olefins 482 489 985 1,032 Vinyls PVC, caustic soda and other 1,396 1,157 2,754 2,288 Building products 357 333 646 602 Total Vinyls 1,753 1,490 3,400 2,890 $ 2,235 $ 1,979 $ 4,385 $ 3,922 Intersegment sales Olefins $ 112 $ 98 $ 232 $ 184 Vinyls 1 — 1 — $ 113 $ 98 $ 233 $ 184 Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Income (loss) from operations Olefins $ 158 $ 143 $ 321 $ 323 Vinyls 271 141 537 211 Corporate and other (25 ) (20 ) (53 ) (36 ) $ 404 $ 264 $ 805 $ 498 Depreciation and amortization Olefins $ 33 $ 35 $ 67 $ 76 Vinyls 120 107 238 214 Corporate and other 3 3 7 5 $ 156 $ 145 $ 312 $ 295 Other income, net Olefins $ 1 $ 1 $ 3 $ 2 Vinyls 4 — 16 6 Corporate and other 3 1 11 1 $ 8 $ 2 $ 30 $ 9 Provision for (benefit from) income taxes Olefins $ 36 $ 36 $ 73 $ 94 Vinyls 69 39 130 54 Corporate and other (12 ) (7 ) (21 ) (24 ) $ 93 $ 68 $ 182 $ 124 Capital expenditures Olefins $ 26 $ 24 $ 48 $ 49 Vinyls 128 114 258 222 Corporate and other 4 9 6 10 $ 158 $ 147 $ 312 $ 281
Reconciliation Of Total Segment Income From Operations To Consolidated Income Before Income Taxes	A reconciliation of total segment income from operations to consolidated income before income taxes is as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Income from operations $ 404 $ 264 $ 805 $ 498 Interest expense (31 ) (39 ) (68 ) (79 ) Other income, net 8 2 30 9 Income before income taxes $ 381 $ 227 $ 767 $ 428
Total Assets	June 30, December 31, Total assets Olefins $ 2,044 $ 2,006 Vinyls 8,863 8,853 Corporate and other 439 1,217 $ 11,346 $ 12,076

Subsequent Events (Tables)

Subsequent Events (Tables)	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Schedule of Incentive Distributions Made to Managing Members or General Partners by Distribution [Table Text Block]	Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Above $1.2938 up to $1.4063 85.0 % 15.0 % Above $1.4063 up to $1.6875 75.0 % 25.0 % Above $1.6875 50.0 % 50.0 % Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Above $1.2938 up to $1.4063 85.0 % 15.0 % Above $1.4063 up to $1.6875 75.0 % 25.0 % Above $1.6875 50.0 % 50.0 % The Westlake Partners' distribution for the three months ended June 30, 2018 did not exceed the $1.2938 per unit threshold, and, as a result of the amendment, no distribution was made with respect to Westlake Partners' IDRs to Westlake, as the holder of the Westlake Partners' IDRs. Prior to the amendment, Westlake Partners' partnership agreement provided that Westlake Partners' unitholders and Westlake, as the holder of Westlake Partners' IDRs, would 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 % 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 %

Guarantor Disclosures (Tables)

Guarantor Disclosures (Tables)	6 Months Ended
	Jun. 30, 2018
Guarantees [Abstract]
Condensed Consolidating Financial Information Balance Sheet	Condensed Consolidating Financial Information as of June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 258 $ 40 $ 184 $ — $ 482 Accounts receivable, net 4,963 5,488 666 (9,856 ) 1,261 Inventories — 651 254 — 905 Prepaid expenses and other current assets 158 39 23 (174 ) 46 Total current assets 5,379 6,218 1,127 (10,030 ) 2,694 Property, plant and equipment, net — 4,466 2,002 — 6,468 Goodwill — 855 151 — 1,006 Customer relationships, net — 447 122 — 569 Other intangible assets, net — 81 68 — 149 Other assets, net 11,188 800 1,312 (12,840 ) 460 Total assets $ 16,567 $ 12,867 $ 4,782 $ (22,870 ) $ 11,346 Current liabilities Accounts payable $ 8,356 $ 1,675 $ 231 $ (9,680 ) $ 582 Accrued liabilities 183 514 255 (348 ) 604 Total current liabilities 8,539 2,189 486 (10,028 ) 1,186 Long-term debt, net 2,656 4,161 224 (4,375 ) 2,666 Deferred income taxes — 1,072 94 (13 ) 1,153 Pension and other liabilities 10 336 149 — 495 Total liabilities 11,205 7,758 953 (14,416 ) 5,500 Total Westlake Chemical Corporation stockholders' equity 5,362 5,109 3,345 (8,454 ) 5,362 Noncontrolling interests — — 484 — 484 Total equity 5,362 5,109 3,829 (8,454 ) 5,846 Total liabilities and equity $ 16,567 $ 12,867 $ 4,782 $ (22,870 ) $ 11,346 Condensed Consolidating Financial Information as of December 31, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Balance Sheet Current assets Cash and cash equivalents $ 1,089 $ 57 $ 385 $ — $ 1,531 Accounts receivable, net 3,331 4,128 580 (7,038 ) 1,001 Inventories — 654 246 — 900 Prepaid expenses and other current assets 52 27 31 (79 ) 31 Total current assets 4,472 4,866 1,242 (7,117 ) 3,463 Property, plant and equipment, net — 4,374 2,038 — 6,412 Goodwill — 855 157 — 1,012 Customer relationships, net — 479 137 — 616 Other intangible assets, net — 88 73 — 161 Other assets, net 10,706 798 1,271 (12,363 ) 412 Total assets $ 15,178 $ 11,460 $ 4,918 $ (19,480 ) $ 12,076 Current liabilities Accounts payable $ 6,367 $ 864 $ 224 $ (6,855 ) $ 600 Accrued liabilities 189 484 246 (262 ) 657 Current portion of long-term debt, net 710 — — — 710 Total current liabilities 7,266 1,348 470 (7,117 ) 1,967 Long-term debt, net 3,034 4,242 220 (4,369 ) 3,127 Deferred income taxes — 1,026 92 (7 ) 1,111 Pension and other liabilities 4 347 151 — 502 Total liabilities 10,304 6,963 933 (11,493 ) 6,707 Total Westlake Chemical Corporation stockholders' equity 4,874 4,497 3,490 (7,987 ) 4,874 Noncontrolling interests — — 495 — 495 Total equity 4,874 4,497 3,985 (7,987 ) 5,369 Total liabilities and equity $ 15,178 $ 11,460 $ 4,918 $ (19,480 ) $ 12,076
Condensed Consolidating Financial Information Statement Of Operations	Condensed Consolidating Financial Information for the Three Months Ended June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 1,826 $ 878 $ (469 ) $ 2,235 Cost of sales — 1,465 680 (462 ) 1,683 Gross profit — 361 198 (7 ) 552 Selling, general and administrative expenses — 86 36 (7 ) 115 Amortization of intangibles — 19 6 — 25 Integration-related costs — 8 — — 8 Income from operations — 248 156 — 404 Other income (expense) Interest expense (31 ) (52 ) (3 ) 55 (31 ) Other income (expense), net 41 8 14 (55 ) 8 Income (loss) before income taxes 10 204 167 — 381 Provision (benefit) for income taxes 2 71 20 — 93 Equity in net income of subsidiaries 270 — — (270 ) — Net income 278 133 147 (270 ) 288 Net income attributable to noncontrolling interests — — 10 — 10 Net income attributable to Westlake Chemical Corporation $ 278 $ 133 $ 137 $ (270 ) $ 278 Comprehensive income attributable to Westlake Chemical Corporation $ 242 $ 133 $ 99 $ (232 ) $ 242 Condensed Consolidating Financial Information for the Three Months Ended June 30, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 1,597 $ 804 $ (422 ) $ 1,979 Cost of sales — 1,350 640 (414 ) 1,576 Gross profit — 247 164 (8 ) 403 Selling, general and administrative expenses — 73 36 (8 ) 101 Amortization of intangibles — 23 7 — 30 Integration-related costs — 8 — — 8 Income from operations — 143 121 — 264 Other income (expense) Interest expense (38 ) (46 ) — 45 (39 ) Other income (expense), net 37 6 4 (45 ) 2 Income (loss) before income taxes (1 ) 103 125 — 227 Provision (benefit) for income taxes 4 52 12 — 68 Equity in net income of subsidiaries 158 — — (158 ) — Net income 153 51 113 (158 ) 159 Net income attributable to noncontrolling interests — — 6 — 6 Net income attributable to Westlake Chemical Corporation $ 153 $ 51 $ 107 $ (158 ) $ 153 Comprehensive income attributable to Westlake Chemical Corporation $ 205 $ 52 $ 148 $ (200 ) $ 205 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 3,572 $ 1,717 $ (904 ) $ 4,385 Cost of sales — 2,870 1,312 (891 ) 3,291 Gross profit — 702 405 (13 ) 1,094 Selling, general and administrative expenses — 163 73 (13 ) 223 Amortization of intangibles — 38 13 — 51 Integration-related costs — 15 — — 15 Income from operations — 486 319 — 805 Other income (expense) Interest expense (69 ) (100 ) (5 ) 106 (68 ) Other income (expense), net 86 16 34 (106 ) 30 Income (loss) before income taxes 17 402 348 — 767 Provision (benefit) for income taxes 4 134 44 — 182 Equity in net income of subsidiaries 552 — — (552 ) — Net income 565 268 304 (552 ) 585 Net income attributable to noncontrolling interests — — 20 — 20 Net income attributable to Westlake Chemical Corporation $ 565 $ 268 $ 284 $ (552 ) $ 565 Comprehensive income attributable to Westlake Chemical Corporation $ 525 $ 268 $ 244 $ (512 ) $ 525 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Operations Net sales $ — $ 3,177 $ 1,540 $ (795 ) $ 3,922 Cost of sales — 2,712 1,222 (781 ) 3,153 Gross profit — 465 318 (14 ) 769 Selling, general and administrative expenses 1 146 67 (14 ) 200 Amortization of intangibles — 42 13 — 55 Integration-related costs — 16 — — 16 Income from operations (1 ) 261 238 — 498 Other income (expense) Interest expense (76 ) (92 ) (1 ) 90 (79 ) Other income (expense), net 74 9 16 (90 ) 9 Income (loss) before income taxes (3 ) 178 253 — 428 Provision (benefit) for income taxes (1 ) 105 20 — 124 Equity in net income of subsidiaries 293 — — (293 ) — Net income 291 73 233 (293 ) 304 Net income attributable to noncontrolling interests — — 13 — 13 Net income attributable to Westlake Chemical Corporation $ 291 $ 73 $ 220 $ (293 ) $ 291 Comprehensive income attributable to Westlake Chemical Corporation $ 359 $ 73 $ 259 $ (332 ) $ 359
Condensed Consolidating Financial Information Statement Of Cash Flows	Condensed Consolidating Financial Information for the Six Months Ended June 30, 2018 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Cash Flows Cash flows from operating activities Net income $ 565 $ 268 $ 304 $ (552 ) $ 585 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization — 208 104 — 312 Deferred income taxes 1 40 4 — 45 Net changes in working capital and other (533 ) (459 ) 47 552 (393 ) Net cash provided by operating activities 33 57 459 — 549 Cash flows from investing activities Additions to property, plant and equipment — (248 ) (64 ) — (312 ) Additions to investments in unconsolidated subsidiaries — (35 ) (10 ) — (45 ) Other — 3 — — 3 Net cash used for investing activities — (280 ) (74 ) — (354 ) Cash flows from financing activities Intercompany financing 347 (1 ) (346 ) — — Dividends paid (54 ) — — — (54 ) Distributions to noncontrolling interests — 207 (236 ) — (29 ) Proceeds from notes payable and drawdown of revolver — — 6 — 6 Redemption and repayment of notes payable (1,165 ) — (8 ) — (1,173 ) Other 8 — — — 8 Net cash used for financing activities (864 ) 206 (584 ) — (1,242 ) Effect of exchange rate changes on cash, cash equivalents and restricted cash — — (2 ) — (2 ) Net decrease in cash, cash equivalents and restricted cash (831 ) (17 ) (201 ) — (1,049 ) Cash, cash equivalents and restricted cash at beginning of period 1,089 79 386 — 1,554 Cash, cash equivalents and restricted cash at end of period $ 258 $ 62 $ 185 $ — $ 505 Condensed Consolidating Financial Information for the Six Months Ended June 30, 2017 Westlake Chemical Corporation 100% Owned Guarantor Subsidiaries Non- Guarantor Subsidiaries Eliminations Consolidated Statement of Cash Flows Cash flows from operating activities Net income $ 291 $ 73 $ 233 $ (293 ) $ 304 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization — 194 101 — 295 Deferred income taxes — 15 — — 15 Net changes in working capital and other (400 ) (26 ) (1 ) 293 (134 ) Net cash provided by (used for) operating activities (109 ) 256 333 — 480 Cash flows from investing activities Additions to property, plant and equipment — (199 ) (82 ) — (281 ) Additions to investments in unconsolidated subsidiaries — (31 ) — — (31 ) Other — 2 — — 2 Net cash used for investing activities — (228 ) (82 ) — (310 ) Cash flows from financing activities Intercompany financing 242 (254 ) 12 — — Dividends paid (49 ) — — — (49 ) Distributions to noncontrolling interests — 189 (205 ) — (16 ) Proceeds from notes payable and drawdown of revolver 175 — 3 — 178 Repayment of term loan — — (150 ) — (150 ) Repayment of revolver (360 ) — — — (360 ) Redemption and repayment of notes payable — (1 ) (4 ) — (5 ) Other 1 — — — 1 Net cash used for financing activities 9 (66 ) (344 ) — (401 ) Effect of exchange rate changes on cash, cash equivalents and restricted cash — — 13 — 13 Net decrease in cash, cash equivalents and restricted cash (100 ) (38 ) (80 ) — (218 ) Cash, cash equivalents and restricted cash at beginning of period 147 78 421 — 646 Cash, cash equivalents and restricted cash at end of period $ 47 $ 40 $ 341 $ — $ 428

Basis of Financial Statements A

Basis of Financial Statements Adoption Adjustments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2016
Item Effected [Line Items]
Net Cash Provided by (Used in) Financing Activities	$ (1,242)	$ (401)
Accounting Standards Update 2016-18 [Member]
Item Effected [Line Items]
Net Cash Provided by (Used in) Financing Activities		(247)
Restricted Cash		$ 32	$ 186

Financial Instruments (Cash Equ

Financial Instruments (Cash Equivalent) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Held-to-maturity Securities	$ 85	$ 644

Financial Instruments (Restrict

Financial Instruments (Restricted Cash Equivalents) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Restricted Cash and Cash Equivalents	$ 23	$ 23

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accounts Receivable, Net [Abstract]
Trade customers	$ 1,198	$ 974
Affiliates	12	9
Allowance for doubtful accounts	(24)	(22)
Accounts receivable from trade customers, net	1,186	961
Federal and state taxes	48	7
Other	27	33
Accounts receivable, net	$ 1,261	$ 1,001

Inventories (Inventories) (Deta

Inventories (Inventories) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished products	$ 552	$ 549
Feedstock, additives and chemicals	209	221
Materials and supplies	144	130
Inventories	$ 905	$ 900

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 1,006	$ 1,012
Effects of changes in foreign exchange rates	(6)
Olefins [Member]
Goodwill [Line Items]
Goodwill	30	30
Effects of changes in foreign exchange rates	0
Vinyls [Member]
Goodwill [Line Items]
Goodwill	976	$ 982
Effects of changes in foreign exchange rates	$ (6)

Long-Term Debt (Schedule of Lon

Long-Term Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal Amount	$ 2,715	$ 3,853
Unamortized Premium (Discount) and Debt Issuance Costs	(49)	(16)
Net, Long-term Debt	2,666	3,837
Long-term Debt, Current Maturities	0	710
Long-term Debt, Gross Excluding Current Maturities	2,715	3,165
Debt Instrument, Unamortized Premium (Discount) and Debt Issuance Cost, Net, Excluding Current Maturities	(49)	(38)
Long-term Debt, Excluding Current Maturities	$ 2,666	3,127
Senior Notes [Member] | 3.60% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,022
Stated interest rate (percent)	3.60%
Principal Amount	$ 250	250
Unamortized Premium (Discount) and Debt Issuance Costs	(1)	(1)
Net, Long-term Debt	$ 249	249
Senior Notes [Member] | 3.6% Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,026
Stated interest rate (percent)	3.60%
Principal Amount	$ 750	750
Unamortized Premium (Discount) and Debt Issuance Costs	(9)	(10)
Net, Long-term Debt	$ 741	740
Senior Notes [Member] | Loan related to tax-exempt waste disposal revenue bonds due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,027
Principal Amount	$ 11	11
Unamortized Premium (Discount) and Debt Issuance Costs	0	0
Net, Long-term Debt	$ 11	11
Senior Notes [Member] | 6 1/2% Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,029
Stated interest rate (percent)	6.50%
Principal Amount	$ 100	100
Unamortized Premium (Discount) and Debt Issuance Costs	(1)	(1)
Net, Long-term Debt	$ 99	99
Senior Notes [Member] | 2035 GO Zone 6 1/2% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,035
Stated interest rate (percent)	6.50%
Principal Amount	$ 89	89
Unamortized Premium (Discount) and Debt Issuance Costs	(1)	(1)
Net, Long-term Debt	$ 88	88
Senior Notes [Member] | 2035 IKE Zone 6 1/2% Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,035
Stated interest rate (percent)	6.50%
Principal Amount	$ 65	65
Unamortized Premium (Discount) and Debt Issuance Costs	(1)	0
Net, Long-term Debt	$ 64	65
Senior Notes [Member] | 5% Senior Notes Due 2046 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,046
Stated interest rate (percent)	5.00%
Principal Amount	$ 700	700
Unamortized Premium (Discount) and Debt Issuance Costs	(25)	(25)
Net, Long-term Debt	$ 675	675
Senior Notes [Member] | 4.375% Senior Notes Due 2047 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,047
Stated interest rate (percent)	4.375%
Principal Amount	$ 500	500
Unamortized Premium (Discount) and Debt Issuance Costs	(9)	(9)
Net, Long-term Debt	$ 491	491
Senior Notes [Member] | 3.50% Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,032
Stated interest rate (percent)	3.50%
Principal Amount	$ 250	250
Unamortized Premium (Discount) and Debt Issuance Costs	(2)	(2)
Net, Long-term Debt	$ 248	248
Senior Notes [Member] | 4.625% Senior Notes Due 2021 (New Westlake 2021 Notes) [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,021
Stated interest rate (percent)	4.625%
Principal Amount	$ 0	625
Unamortized Premium (Discount) and Debt Issuance Costs	0	20
Net, Long-term Debt	$ 0	645
Senior Notes [Member] | 4.625% Senior Notes Due 2021 (Existing Axiall 2021 Notes) [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,021
Stated interest rate (percent)	4.625%
Principal Amount	$ 0	63
Unamortized Premium (Discount) and Debt Issuance Costs	0	2
Net, Long-term Debt	$ 0	65
Senior Notes [Member] | 4.875% Senior Notes Due 2023 (New Westlake 2023 Notes) [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,023
Stated interest rate (percent)	4.875%
Principal Amount	$ 0	434
Unamortized Premium (Discount) and Debt Issuance Costs	0	11
Net, Long-term Debt	$ 0	445
Senior Notes [Member] | 4.875% Senior Notes Due 2023 (Existing Axiall 2023 Notes) [Member]
Debt Instrument [Line Items]
Debt Instrument Maturity	2,023
Stated interest rate (percent)	4.875%
Principal Amount	$ 0	16
Unamortized Premium (Discount) and Debt Issuance Costs	0	0
Net, Long-term Debt	0	16
Senior Notes [Member] | 4.625% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-Term Debt, Gross, Current Maturities	0	688
Debt Instrument, Unamortized Premium (Discount) and debt issuance cost, net, Current Maturities	0	22
Long-term Debt, Current Maturities	$ 0	$ 710

Long-Term Debt (Credit Agreemen

Long-Term Debt (Credit Agreement) (Details) - Credit Agreement [Member] - Revolving Credit Facility [Member] $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Minimum [Member] | Alternate Base Rate [Domain]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Maximum [Member] | Alternate Base Rate [Domain]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000
Line of Credit Facility, Fair Value of Amount Outstanding	0
Letters of Credit Outstanding, Amount	4
Line of Credit Facility, Remaining Borrowing Capacity	$ 996

Long-Term Debt (New Credit Agre

Long-Term Debt (New Credit Agreement) (Details) - New Credit Agreement [Member] - Subsequent Event [Member] - Line of Credit [Member] $ in Millions	Jul. 24, 2018USD ($)
Minimum [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Permitted Increase	$ 25
Maximum [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Permitted Increase	500
Short-term Debt, Type [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	50
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,000
Letter of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 150
Alternate Base Rate [Domain] | Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Alternate Base Rate [Domain] | Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%

Long-Term Debt (Senior Notes Du

Long-Term Debt (Senior Notes Due 2021) (Details) - 2021 Notes [Member] - USD ($) $ in Millions	Feb. 15, 2018	Jun. 30, 2018
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	102.313%
Gain on debt redemption		$ 6

Long-Term Debt (Senior Notes 45

Long-Term Debt (Senior Notes Due 2023) (Details)	May 15, 2018
2023 Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	102.438%

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Unamortized Debt Issuance Cost	$ 25	$ 26

Accumulated Other Comprehensi47

Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	$ 5,362		$ 5,362		$ 4,874
Accumulated other comprehensive income (loss)	(33)	$ (54)	(33)	$ (54)	7	$ (121)
Other comprehensive income (loss)	(40)	53	(42)	70
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	43	30	43	30	43	29
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				1
Other comprehensive income (loss)			0	1
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	$ (76)	$ (84)	(76)	(84)	$ (36)	$ (150)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(40)	66
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				0
Other comprehensive income (loss)			(40)	66
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(40)	66
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				1
Other comprehensive income (loss)			$ (40)	$ 67

Fair Value Measurements (Summar

Fair Value Measurements (Summary of Carrying and Fair Values of Long Term Debt) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 2,666	$ 3,837
3.60% Senior Notes Due 2022 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 249	249
Debt Instrument Maturity	2,022
Stated interest rate (percent)	3.60%
3.6% Senior Notes Due 2026 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 741	740
Debt Instrument Maturity	2,026
Stated interest rate (percent)	3.60%
Loan related to tax-exempt waste disposal revenue bonds due 2027 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 11	11
Debt Instrument Maturity	2,027
6 1/2% Senior Notes Due 2029 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 99	99
Debt Instrument Maturity	2,029
Stated interest rate (percent)	6.50%
2035 GO Zone 6 1/2% Notes [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 88	88
Debt Instrument Maturity	2,035
Stated interest rate (percent)	6.50%
2035 IKE Zone 6 1/2% Notes [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 64	65
Debt Instrument Maturity	2,035
Stated interest rate (percent)	6.50%
5% Senior Notes Due 2046 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 675	675
Debt Instrument Maturity	2,046
Stated interest rate (percent)	5.00%
4.375% Senior Notes Due 2047 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 491	491
Debt Instrument Maturity	2,047
Stated interest rate (percent)	4.375%
3.50% Senior Notes Due 2032 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 248	248
Debt Instrument Maturity	2,032
Stated interest rate (percent)	3.50%
4.625% Senior Notes Due 2021 (New Westlake 2021 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 0	645
Debt Instrument Maturity	2,021
Stated interest rate (percent)	4.625%
4.625% Senior Notes Due 2021 (Existing Axiall 2021 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 0	65
Debt Instrument Maturity	2,021
Stated interest rate (percent)	4.625%
4.875% Senior Notes Due 2023 (New Westlake 2023 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 0	445
Debt Instrument Maturity	2,023
Stated interest rate (percent)	4.875%
4.875% Senior Notes Due 2023 (Existing Axiall 2023 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 0	16
Debt Instrument Maturity	2,023
Stated interest rate (percent)	4.875%
Fair Value [Member] | 3.60% Senior Notes Due 2022 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 247	255
Fair Value [Member] | 3.6% Senior Notes Due 2026 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	711	757
Fair Value [Member] | Loan related to tax-exempt waste disposal revenue bonds due 2027 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	11	11
Fair Value [Member] | 6 1/2% Senior Notes Due 2029 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	109	111
Fair Value [Member] | 2035 GO Zone 6 1/2% Notes [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	98	99
Fair Value [Member] | 2035 IKE Zone 6 1/2% Notes [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	71	74
Fair Value [Member] | 5% Senior Notes Due 2046 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	708	787
Fair Value [Member] | 4.375% Senior Notes Due 2047 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	462	518
Fair Value [Member] | 3.50% Senior Notes Due 2032 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	247	256
Fair Value [Member] | 4.625% Senior Notes Due 2021 (New Westlake 2021 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	0	639
Fair Value [Member] | 4.625% Senior Notes Due 2021 (Existing Axiall 2021 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	0	65
Fair Value [Member] | 4.875% Senior Notes Due 2023 (New Westlake 2023 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	0	449
Fair Value [Member] | 4.875% Senior Notes Due 2023 (Existing Axiall 2023 Notes) [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 0	$ 16

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	24.40%	30.00%	23.70%	29.00%
U.S. federal statutory income tax rate	21.00%	35.00%	21.00%	35.00%
Provisional adjustment of income tax benefit					$ 591

Earnings per Share (Schedule of

Earnings per Share (Schedule of Net Income Attributable to Common Stockholders) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income attributable to Westlake Chemical Corporation	$ 278	$ 153	$ 565	$ 291
Net income attributable to participating securities	(2)	(1)	(3)	(2)
Net income attributable to common shareholders	$ 276	$ 152	$ 562	$ 289

Earnings per Share (Reconciliat

Earnings per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Weighted average common shares—basic	129,624,291	129,051,227	129,554,528	129,015,507
Incremental Shares From Assumed exercise of options	682,324	735,487	694,556	724,136
Weighted average common shares-diluted	130,306,615	129,786,714	130,249,084	129,739,643
Earnings per share attributable to Westlake Chemical Corporation: Basic	$ 2.13	$ 1.18	$ 4.34	$ 2.24
Earnings per share attributable to Westlake Chemical Corporation: Diluted	$ 2.12	$ 1.17	$ 4.31	$ 2.23

Earnings per Share (Additional

Earnings per Share (Additional Information) (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Number of options excluded from computation of diluted earnings per share	172,642	583,585	128,892	511,085

Supplemental Information ( Addi

Supplemental Information ( Additional Information) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accrued Liabilities [Abstract]
Accrued liabilities	$ 604		$ 657
Accrued Rebates, Current	94		108
Due to Affiliate, Current	42		$ 37
Increase (Decrease) in Capital Expenditure Accrual	$ (18)	$ 11

Commitments and Contingencies (

Commitments and Contingencies (Additional Information) (Detail) - USD ($) $ in Millions	Jun. 18, 2018	May 31, 2017	Jun. 30, 2018	Dec. 31, 2017
Environmental Loss Contingencies [Line Items]
Environmental Loss contingency accrual			$ 53	$ 49
Site Contingency, Percentage of Cost Potentially of Other Responsible Parties [Line Items]			100.00%
Ownership interest (in percent)			100.00%
PolyOne [Member] | Pending Litigation [Member]
Environmental Loss Contingencies [Line Items]
Maximum Expected Damages		$ 17
Minimum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss			$ 55
Maximum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss			110
Environmental Protection Agency [Member] | Minimum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Remediation Expense			200
Environmental Protection Agency [Member] | Maximum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Remediation Expense			250
Environmental Protection Agency [Member] | Operation and Maintenance [Member]
Environmental Loss Contingencies [Line Items]
Environmental Remediation Expense	$ 107
Environmental Protection Agency [Member] | Operation and Maintenance [Member] | Minimum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost			1
Environmental Protection Agency [Member] | Operation and Maintenance [Member] | Maximum [Member]
Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost			3
Affiliated Entity [Member] | LACC [Member]
Environmental Loss Contingencies [Line Items]
Maximum Capital Commitment			$ 225
Ownership interest (in percent)			10.00%
Funding to related parties			$ 160

Segment Information (Additional

Segment Information (Additional Information) (Detail)	6 Months Ended
	Jun. 30, 2018Segment
Segment Reporting [Abstract]
Number of segments	2

Segment Information (Segment Re

Segment Information (Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net sales	$ 2,235	$ 1,979	$ 4,385	$ 3,922
Income (loss) from operations	404	264	805	498
Depreciation and amortization	156	145	312	295
Other income (expense), net	8	2	30	9
Provision for (benefit from) income taxes	93	68	182	124
Additions to property, plant and equipment	158	147	312	281
Operating Segments [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net sales	482	489	985	1,032
Income (loss) from operations	158	143	321	323
Depreciation and amortization	33	35	67	76
Other income (expense), net	1	1	3	2
Provision for (benefit from) income taxes	36	36	73	94
Additions to property, plant and equipment	26	24	48	49
Operating Segments [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net sales	1,753	1,490	3,400	2,890
Income (loss) from operations	271	141	537	211
Depreciation and amortization	120	107	238	214
Other income (expense), net	4	0	16	6
Provision for (benefit from) income taxes	69	39	130	54
Additions to property, plant and equipment	128	114	258	222
Operating Segments [Member] | Polyethylene [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net sales	387	358	756	744
Operating Segments [Member] | Styrene, Feedstock And Other [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net sales	95	131	229	288
Operating Segments [Member] | PVC, Caustic Soda And Other [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net sales	1,396	1,157	2,754	2,288
Operating Segments [Member] | Building Products [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net sales	357	333	646	602
Corporate and other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(25)	(20)	(53)	(36)
Depreciation and amortization	3	3	7	5
Other income (expense), net	3	1	11	1
Provision for (benefit from) income taxes	(12)	(7)	(21)	(24)
Additions to property, plant and equipment	4	9	6	10
Intersegment sales [Member]
Segment Reporting Information [Line Items]
Net sales	113	98	233	184
Intersegment sales [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net sales	112	98	232	184
Intersegment sales [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net sales	$ 1	$ 0	$ 1	$ 0

Segment Information (Reconcilia

Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting [Abstract]
Income from operations	$ 404	$ 264	$ 805	$ 498
Interest expense	(31)	(39)	(68)	(79)
Other income (expense), net	8	2	30	9
Income before income taxes	$ 381	$ 227	$ 767	$ 428

Segment Information (Total Asse

Segment Information (Total Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 11,346	$ 12,076
Operating Segments [Member] | Olefins [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,044	2,006
Operating Segments [Member] | Vinyls [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	8,863	8,853
Corporate and other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 439	$ 1,217

Subsequent Events (New Credit A

Subsequent Events (New Credit Agreement) (Details) $ in Millions	Jul. 24, 2018USD ($)
New Credit Agreement [Member] | Line of Credit [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000

Subsequent Events (Westlake Che

Subsequent Events (Westlake Chemical Partners LP) (Details) - $ / shares	Jul. 27, 2018	Jun. 30, 2018
Cash Distribution [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Incentive Distribution, Distribution Per Unit	$ 1.2938
IDR Holders [Member] | Cash Distribution, Tranche One [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution		15.00%
IDR Holders [Member] | Cash Distribution, Tranche One [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution	15.00%
IDR Holders [Member] | Cash Distribution, Tranche Two [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution		25.00%
IDR Holders [Member] | Cash Distribution, Tranche Two [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution	25.00%
IDR Holders [Member] | Cash Distribution, Tranche Three [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution		50.00%
IDR Holders [Member] | Cash Distribution, Tranche Three [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution	50.00%
Unit Holders [Member] | Cash Distribution, Tranche One [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution		85.00%
Unit Holders [Member] | Cash Distribution, Tranche One [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution	85.00%
Unit Holders [Member] | Cash Distribution, Tranche Two [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution		75.00%
Unit Holders [Member] | Cash Distribution, Tranche Two [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution	75.00%
Unit Holders [Member] | Cash Distribution, Tranche Three [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution		50.00%
Unit Holders [Member] | Cash Distribution, Tranche Three [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum Percentage Of Income Distribution	50.00%
IPO [Member] | Limited Partner [Member] | Westlake Chemical OpCo LP [Member] | Subsidiary of Common Parent [Member]
Subsequent Event [Line Items]
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest		81.70%
IPO [Member] | Limited Partner [Member] | Westlake Chemical Partners LP [Member] | Subsidiary of Common Parent [Member]
Subsequent Event [Line Items]
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest		43.80%

Subsequent Events (Subsequent E

Subsequent Events (Subsequent Events Phantom) (Details) - $ / shares	Jul. 27, 2018	Jun. 30, 2018
Cash Distribution, Tranche One [Member] | Minimum [Member]
Subsequent Event [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		$ 0.3163
Cash Distribution, Tranche One [Member] | Minimum [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)	$ 1.2938
Cash Distribution, Tranche One [Member] | Maximum [Member]
Subsequent Event [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		0.3438
Cash Distribution, Tranche One [Member] | Maximum [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)	1.4063
Cash Distribution, Tranche Two [Member] | Minimum [Member]
Subsequent Event [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)		0.3438
Cash Distribution, Tranche Two [Member] | Minimum [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Target distribution per unit requiring marginal percentage distribution to IDR Holders (in usd per unit)	1.4063
Cash Distribution, Tranche Two [Member] | Maximum [Member]
Subsequent Event [Line Items]
Quarterly incentive distribution, per unit, distribution threshold		0.4125
Cash Distribution, Tranche Two [Member] | Maximum [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Quarterly incentive distribution, per unit, distribution threshold	1.6875
Cash Distribution, Tranche Three [Member] | Minimum [Member]
Subsequent Event [Line Items]
Quarterly incentive distribution, per unit, distribution threshold		$ 0.4125
Cash Distribution, Tranche Three [Member] | Minimum [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Quarterly incentive distribution, per unit, distribution threshold	$ 1.6875

Guarantor Disclosures (Addition

Guarantor Disclosures (Additional Information) (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Condensed Financial Statements, Captions [Line Items]
Ownership interest (in percent)	100.00%
3.60%, 5.0%, 4.375% Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Minimum debt amount guaranteed by subsidiaries	$ 5
4.375% Senior Notes Due 2047 [Member] | Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	4.375%
Debt Instrument Maturity	2,047
3.60% Senior Notes Due 2022 [Member] | Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	3.60%
Debt Instrument Maturity	2,022
3.6% Senior Notes Due 2026 [Member] | Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	3.60%
Debt Instrument Maturity	2,026
5% Senior Notes Due 2046 [Member] | Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Stated interest rate (percent)	5.00%
Debt Instrument Maturity	2,046

Guarantor Disclosures (Condense

Guarantor Disclosures (Condensed Consolidating Financial Information Balance Sheets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 482	$ 1,531
Accounts receivable, net	1,261	1,001
Inventories	905	900
Prepaid expenses and other current assets	46	31
Total current assets	2,694	3,463
Property, plant and equipment, net	6,468	6,412
Goodwill	1,006	1,012
Customer relationships, net	569	616
Other intangible assets, net	149	161
Other assets, net	460	412
Total assets	11,346	12,076
Accounts payable	582	600
Accrued liabilities	604	657
Current portion of long-term debt, net	0	710
Total current liabilities	1,186	1,967
Long-term debt, net	2,666	3,127
Deferred income taxes	1,153	1,111
Pension and other liabilities	495	502
Total liabilities	5,500	6,707
Total Westlake Chemical Corporation stockholders' equity	5,362	4,874
Noncontrolling interests	484	495
Total equity	5,846	5,369	$ 4,209	$ 3,892
Total liabilities and equity	11,346	12,076
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0
Accounts receivable, net	(9,856)	(7,038)
Inventories	0	0
Prepaid expenses and other current assets	(174)	(79)
Total current assets	(10,030)	(7,117)
Property, plant and equipment, net	0	0
Goodwill	0	0
Customer relationships, net	0	0
Other intangible assets, net	0	0
Other assets, net	(12,840)	(12,363)
Total assets	(22,870)	(19,480)
Accounts payable	(9,680)	(6,855)
Accrued liabilities	(348)	(262)
Current portion of long-term debt, net		0
Total current liabilities	(10,028)	(7,117)
Long-term debt, net	(4,375)	(4,369)
Deferred income taxes	(13)	(7)
Pension and other liabilities	0	0
Total liabilities	(14,416)	(11,493)
Total Westlake Chemical Corporation stockholders' equity	(8,454)	(7,987)
Noncontrolling interests	0	0
Total equity	(8,454)	(7,987)
Total liabilities and equity	(22,870)	(19,480)
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	258	1,089
Accounts receivable, net	4,963	3,331
Inventories	0	0
Prepaid expenses and other current assets	158	52
Total current assets	5,379	4,472
Property, plant and equipment, net	0	0
Goodwill	0	0
Customer relationships, net	0	0
Other intangible assets, net	0	0
Other assets, net	11,188	10,706
Total assets	16,567	15,178
Accounts payable	8,356	6,367
Accrued liabilities	183	189
Current portion of long-term debt, net		710
Total current liabilities	8,539	7,266
Long-term debt, net	2,656	3,034
Deferred income taxes	0	0
Pension and other liabilities	10	4
Total liabilities	11,205	10,304
Total Westlake Chemical Corporation stockholders' equity	5,362	4,874
Noncontrolling interests	0	0
Total equity	5,362	4,874
Total liabilities and equity	16,567	15,178
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	40	57
Accounts receivable, net	5,488	4,128
Inventories	651	654
Prepaid expenses and other current assets	39	27
Total current assets	6,218	4,866
Property, plant and equipment, net	4,466	4,374
Goodwill	855	855
Customer relationships, net	447	479
Other intangible assets, net	81	88
Other assets, net	800	798
Total assets	12,867	11,460
Accounts payable	1,675	864
Accrued liabilities	514	484
Current portion of long-term debt, net		0
Total current liabilities	2,189	1,348
Long-term debt, net	4,161	4,242
Deferred income taxes	1,072	1,026
Pension and other liabilities	336	347
Total liabilities	7,758	6,963
Total Westlake Chemical Corporation stockholders' equity	5,109	4,497
Noncontrolling interests	0	0
Total equity	5,109	4,497
Total liabilities and equity	12,867	11,460
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	184	385
Accounts receivable, net	666	580
Inventories	254	246
Prepaid expenses and other current assets	23	31
Total current assets	1,127	1,242
Property, plant and equipment, net	2,002	2,038
Goodwill	151	157
Customer relationships, net	122	137
Other intangible assets, net	68	73
Other assets, net	1,312	1,271
Total assets	4,782	4,918
Accounts payable	231	224
Accrued liabilities	255	246
Current portion of long-term debt, net		0
Total current liabilities	486	470
Long-term debt, net	224	220
Deferred income taxes	94	92
Pension and other liabilities	149	151
Total liabilities	953	933
Total Westlake Chemical Corporation stockholders' equity	3,345	3,490
Noncontrolling interests	484	495
Total equity	3,829	3,985
Total liabilities and equity	$ 4,782	$ 4,918

Guarantor Disclosures (Conden64

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 2,235	$ 1,979	$ 4,385	$ 3,922
Cost of sales	1,683	1,576	3,291	3,153
Gross profit	552	403	1,094	769
Selling, general and administrative expenses	115	101	223	200
Amortization of Intangibles	25	30	51	55
Integration-related costs	8	8	15	16
Income (loss) from operations	404	264	805	498
Interest expense	(31)	(39)	(68)	(79)
Other income (expense), net	8	2	30	9
Income before income taxes	381	227	767	428
Provision for (benefit from) income taxes	93	68	182	124
Equity in net income of subsidiaries	0	0	0	0
Net income	288	159	585	304
Net income attributable to noncontrolling interests	10	6	20	13
Net income attributable to Westlake Chemical Corporation	278	153	565	291
Comprehensive income attributable to Westlake Chemical Corporation	242	205	525	359
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(469)	(422)	(904)	(795)
Cost of sales	(462)	(414)	(891)	(781)
Gross profit	(7)	(8)	(13)	(14)
Selling, general and administrative expenses	(7)	(8)	(13)	(14)
Amortization of Intangibles	0	0	0	0
Integration-related costs	0	0	0	0
Income (loss) from operations	0	0	0	0
Interest expense	55	45	106	90
Other income (expense), net	(55)	(45)	(106)	(90)
Income before income taxes	0	0	0	0
Provision for (benefit from) income taxes	0	0	0	0
Equity in net income of subsidiaries	(270)	(158)	(552)	(293)
Net income	(270)	(158)	(552)	(293)
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	(270)	(158)	(552)	(293)
Comprehensive income attributable to Westlake Chemical Corporation	(232)	(200)	(512)	(332)
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	1
Amortization of Intangibles	0	0	0	0
Integration-related costs	0	0	0	0
Income (loss) from operations	0	0	0	(1)
Interest expense	(31)	(38)	(69)	(76)
Other income (expense), net	41	37	86	74
Income before income taxes	10	(1)	17	(3)
Provision for (benefit from) income taxes	2	4	4	(1)
Equity in net income of subsidiaries	270	158	552	293
Net income	278	153	565	291
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	278	153	565	291
Comprehensive income attributable to Westlake Chemical Corporation	242	205	525	359
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,826	1,597	3,572	3,177
Cost of sales	1,465	1,350	2,870	2,712
Gross profit	361	247	702	465
Selling, general and administrative expenses	86	73	163	146
Amortization of Intangibles	19	23	38	42
Integration-related costs	8	8	15	16
Income (loss) from operations	248	143	486	261
Interest expense	(52)	(46)	(100)	(92)
Other income (expense), net	8	6	16	9
Income before income taxes	204	103	402	178
Provision for (benefit from) income taxes	71	52	134	105
Equity in net income of subsidiaries	0	0	0	0
Net income	133	51	268	73
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to Westlake Chemical Corporation	133	51	268	73
Comprehensive income attributable to Westlake Chemical Corporation	133	52	268	73
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	878	804	1,717	1,540
Cost of sales	680	640	1,312	1,222
Gross profit	198	164	405	318
Selling, general and administrative expenses	36	36	73	67
Amortization of Intangibles	6	7	13	13
Integration-related costs	0	0	0	0
Income (loss) from operations	156	121	319	238
Interest expense	(3)	0	(5)	(1)
Other income (expense), net	14	4	34	16
Income before income taxes	167	125	348	253
Provision for (benefit from) income taxes	20	12	44	20
Equity in net income of subsidiaries	0	0	0	0
Net income	147	113	304	233
Net income attributable to noncontrolling interests	10	6	20	13
Net income attributable to Westlake Chemical Corporation	137	107	284	220
Comprehensive income attributable to Westlake Chemical Corporation	$ 99	$ 148	$ 244	$ 259

Guarantor Disclosures (Conden65

Guarantor Disclosures (Condensed Consolidating Financial Information Statement of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 505	$ 428	$ 505	$ 428	$ 1,554	$ 646
Net income	288	159	585	304
Depreciation and amortization	156	145	312	295
Deferred income taxes			45	15
Net changes in working capital and other			(393)	(134)
Net cash provided by operating activities			549	480
Additions to property, plant and equipment	(158)	(147)	(312)	(281)
Additions to investments in unconsolidated subsidiaries			(45)	(31)
Other			3	2
Net cash used for investing activities			(354)	(310)
Intercompany financing			0	0
Dividends paid			(54)	(49)
Distributions to noncontrolling interests			(29)	(16)
Proceeds from notes payable and drawdown of revolver			6	178
Repayment of term loan			0	(150)
Repayment of revolver			0	(360)
Redemption and repayment of notes payable			(1,173)	(5)
Other			8	1
Net cash used for financing activities			(1,242)	(401)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(2)	13
Net decrease in cash, cash equivalents and restricted cash			(1,049)	(218)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0	0	0	0	0	0
Net income	(270)	(158)	(552)	(293)
Depreciation and amortization			0	0
Deferred income taxes			0	0
Net changes in working capital and other			552	293
Net cash provided by operating activities			0	0
Additions to property, plant and equipment			0	0
Additions to investments in unconsolidated subsidiaries			0	0
Other			0	0
Net cash used for investing activities			0	0
Intercompany financing			0	0
Dividends paid			0	0
Distributions to noncontrolling interests			0	0
Proceeds from notes payable and drawdown of revolver			0	0
Repayment of term loan				0
Repayment of revolver				0
Redemption and repayment of notes payable			0	0
Other			0	0
Net cash used for financing activities			0	0
Effect of exchange rate changes on cash, cash equivalents and restricted cash			0	0
Net decrease in cash, cash equivalents and restricted cash			0	0
Westlake Chemical Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	258	47	258	47	1,089	147
Net income	278	153	565	291
Depreciation and amortization			0	0
Deferred income taxes			1	0
Net changes in working capital and other			(533)	(400)
Net cash provided by operating activities			33	(109)
Additions to property, plant and equipment			0	0
Additions to investments in unconsolidated subsidiaries			0	0
Other			0	0
Net cash used for investing activities			0	0
Intercompany financing			347	242
Dividends paid			(54)	(49)
Distributions to noncontrolling interests			0	0
Proceeds from notes payable and drawdown of revolver			0	175
Repayment of term loan				0
Repayment of revolver				(360)
Redemption and repayment of notes payable			(1,165)	0
Other			8	1
Net cash used for financing activities			(864)	9
Effect of exchange rate changes on cash, cash equivalents and restricted cash			0	0
Net decrease in cash, cash equivalents and restricted cash			(831)	(100)
100% Owned Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	62	40	62	40	79	78
Net income	133	51	268	73
Depreciation and amortization			208	194
Deferred income taxes			40	15
Net changes in working capital and other			(459)	(26)
Net cash provided by operating activities			57	256
Additions to property, plant and equipment			(248)	(199)
Additions to investments in unconsolidated subsidiaries			(35)	(31)
Other			3	2
Net cash used for investing activities			(280)	(228)
Intercompany financing			(1)	(254)
Dividends paid			0	0
Distributions to noncontrolling interests			207	189
Proceeds from notes payable and drawdown of revolver			0	0
Repayment of term loan				0
Repayment of revolver				0
Redemption and repayment of notes payable			0	(1)
Other			0	0
Net cash used for financing activities			206	(66)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			0	0
Net decrease in cash, cash equivalents and restricted cash			(17)	(38)
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	185	341	185	341	$ 386	$ 421
Net income	$ 147	$ 113	304	233
Depreciation and amortization			104	101
Deferred income taxes			4	0
Net changes in working capital and other			47	(1)
Net cash provided by operating activities			459	333
Additions to property, plant and equipment			(64)	(82)
Additions to investments in unconsolidated subsidiaries			(10)	0
Other			0	0
Net cash used for investing activities			(74)	(82)
Intercompany financing			(346)	12
Dividends paid			0	0
Distributions to noncontrolling interests			(236)	(205)
Proceeds from notes payable and drawdown of revolver			6	3
Repayment of term loan				(150)
Repayment of revolver				0
Redemption and repayment of notes payable			(8)	(4)
Other			0	0
Net cash used for financing activities			(584)	(344)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(2)	13
Net decrease in cash, cash equivalents and restricted cash			$ (201)	$ (80)