Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities
Net income	$ 548,888	$ 497,631
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	180,229	148,394
Recovery of doubtful accounts	778	295
Amortization of debt issuance costs	1,504	1,172
Stock-based compensation expense	7,544	6,856
Loss from disposition of fixed assets	2,590	2,635
Gain from sales of equity securities	(3,795)	0
Gain on acquisition, net of loss on the fair value remeasurement of preexisting equity interest	(21,045)	0
Impairment of equity method investment	4,925	0
Deferred income taxes	7,585	34,459
Windfall tax benefits from share-based payment arrangements	(2,452)	(6,670)
Income from equity method investments, net of dividends	(1,016)	(3,199)
Other losses (gains), net	3,584	(495)
Changes in operating assets and liabilities
Accounts receivable	54,937	6,055
Inventories	105,899	80,492
Prepaid expenses and other current assets	(5,496)	458
Accounts payable	(30,511)	(98,769)
Accrued liabilities	(10,893)	111,965
Other, net	(1,955)	(5,155)
Net cash provided by operating activities	841,300	776,124
Cash flows from investing activities
Acquisition of business, net of cash acquired	15,782	(611,087)
Additions to property, plant and equipment	(329,236)	(311,183)
Proceeds from disposition of assets	17	145
Proceeds from disposition of equity method investment	27,865	0
Proceeds from repayment of loan acquired	0	45,923
Proceeds from sales and maturities of securities	16,056	342,045
Purchase of securities	(282,542)	(117,332)
Settlements of derivative instruments	(1,535)	(689)
Net cash used for investing activities	(553,593)	(652,178)
Cash flows from financing activities
Capitalized debt issuance costs	0	(1,167)
Dividends paid	(67,852)	(55,690)
Distributions to noncontrolling interests	(10,982)	0
Net proceeds from issuance of Westlake Partners common units	0	286,088
Proceeds from exercise of stock options	984	5,502
Proceeds from issuance of notes payable	19,483	0
Repayment of notes payable	(32,954)	0
Repurchase of common stock for treasury	(114,254)	(9,495)
Windfall tax benefits from share-based payment arrangements	2,452	6,670
Net cash provided by financing activities	(203,123)	231,908
Effect of exchange rate changes on cash and cash equivalents	(3,260)	(3,687)
Net increase in cash and cash equivalents	81,324	352,167
Cash and cash equivalents at beginning of period	880,601	461,301
Cash and cash equivalents at end of period	$ 961,925	$ 813,468