Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 1,034	$ 1,339	$ 420
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	641	601	378
Stock-based compensation expense	22	23	14
Gain realized on previously held shares of Axiall common stock and from sales of securities	0	0	(54)
Loss from disposition of property, plant and equipment	44	22	9
Deferred income taxes	62	(534)	101
Other losses (gains), net	(20)	(3)	5
Changes in operating assets and liabilities, net of effect of business acquisitions
Accounts receivable	(58)	(40)	50
Inventories	(123)	(32)	(62)
Prepaid expenses and other current assets	(1)	26	11
Accounts payable	(100)	86	12
Accrued liabilities	(8)	115	48
Other, net	(84)	(75)	(65)
Net cash provided by operating activities	1,409	1,528	867
Cash flows from investing activities
Acquisition of business, net of cash acquired	0	(13)	(2,438)
Additions to property, plant and equipment	(702)	(577)	(629)
Additions to investments in unconsolidated subsidiaries	(68)	(66)	(17)
Proceeds from sales and maturities of securities	0	0	663
Purchase of securities	0	0	(138)
Other, net	16	4	(4)
Net cash used for investing activities	(754)	(652)	(2,563)
Cash flows from financing activities
Debt issuance costs	0	(6)	(36)
Dividends paid	(120)	(103)	(97)
Distributions to noncontrolling interests	(45)	(28)	(17)
Proceeds from notes payable and drawdown of revolver	14	978	2,037
Net proceeds from issuance of Westlake Chemical Partners LP common units	0	111	0
Repayment of term loan	0	(150)	0
Repayment of revolver	0	(550)	(125)
Redemption and repayment of notes payable	(1,179)	(257)	(13)
Repurchase of common stock for treasury	(106)	0	(67)
Other	9	11	5
Net cash provided by (used for) financing activities	(1,427)	6	1,687
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(7)	26	(8)
Net increase (decrease) in cash, cash equivalents and restricted cash	(779)	908	(17)
Cash, cash equivalents and restricted cash at beginning of the year	1,554	646	663
Cash, cash equivalents and restricted cash at end of the year	$ 775	$ 1,554	$ 646