Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net income	$ 523,278	$ 314,570
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	448,533	227,193
Provision for doubtful accounts	3,771	1,176
Amortization of debt issuance costs	3,471	1,018
Stock-based compensation expense	16,740	6,588
Loss from disposition of property, plant and equipment	14,319	6,541
Gains realized on previously held shares of Axiall common stock and from sales of securities	0	(53,720)
Write-off of debt issuance costs	659	0
Deferred income taxes	23,294	105,910
Windfall tax benefits from share-based payment arrangements	0	(1,190)
Dividends in excess of income from equity method investments	(2,132)	(61)
Gain on involuntary conversion of assets	(1,672)	0
Other losses (gains), net	(6,659)	833
Changes in operating assets and liabilities, net of effect of business acquisitions
Accounts receivable	(185,153)	(92,311)
Inventories	23,945	(6,124)
Prepaid expenses and other current assets	16,788	1,631
Accounts payable	60,899	34,109
Accrued liabilities	57,419	73,157
Other, net	(34,836)	(75,160)
Net cash provided by (used for) operating activities	962,664	544,160
Cash flows from investing activities
Acquisition of business, net of cash acquired	0	(2,437,829)
Additions to property, plant and equipment	(414,271)	(467,330)
Additions to cost method investment	(47,000)	(4,000)
Proceeds from disposition of assets	171	213
Proceeds from involuntary conversion of assets	1,672	0
Proceeds from sales and maturities of securities	0	662,938
Purchase of securities	0	(138,422)
Settlements of derivative instruments	(7)	(4,655)
Net cash used for investing activities	(459,435)	(2,389,085)
Cash flows from financing activities
Debt issuance costs	(376)	(35,207)
Dividends paid	(76,491)	(71,933)
Distributions to noncontrolling interests	(20,767)	(12,300)
Net proceeds from issuance of Westlake Chemical Partners LP common units	110,739	0
Proceeds from debt issuance	0	1,428,512
Proceeds from issuance of notes payable	5,946	5,597
Proceeds from term loan and drawdown of revolver	225,000	600,000
Restricted cash associated with term loan	154,000	(154,000)
Repayment of term loan	(150,000)	0
Repayment of notes payable	(6,695)	(10,602)
Repayment of revolver	(550,000)	(125,000)
Repurchase of common stock for treasury	0	(67,406)
Other	2,204	2,840
Net cash provided by (used for) financing activities	(306,440)	1,560,501
Effect of exchange rate changes on cash and cash equivalents	21,991	2,418
Net increase (decrease) in cash and cash equivalents	218,780	(282,006)
Cash and cash equivalents at beginning of period	459,453	662,525
Cash and cash equivalents at end of period	$ 678,233	$ 380,519