Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Net external sales	$ 1,103,531us-gaap_SalesRevenueNet	$ 1,027,676us-gaap_SalesRevenueNet
Income (loss) from operations	229,280us-gaap_OperatingIncomeLoss	248,055us-gaap_OperatingIncomeLoss
Depreciation and amortization	58,641	45,972
Other income, net	9,096us-gaap_NonoperatingIncomeExpense	2,509us-gaap_NonoperatingIncomeExpense
Provision for (benefit from) income taxes	78,378us-gaap_IncomeTaxExpenseBenefit	83,375us-gaap_IncomeTaxExpenseBenefit
Capital expenditures	95,822	110,741
Olefins
Segment Reporting Information [Line Items]
Net external sales	583,077	722,798
Income (loss) from operations	191,103	272,333
Depreciation and amortization	26,939	26,647
Other income, net	2,552	1,454
Provision for (benefit from) income taxes	66,457	93,550
Capital expenditures	55,300	29,074
Vinyls
Segment Reporting Information [Line Items]
Net external sales	520,454	304,878
Income (loss) from operations	47,086	(21,114)
Depreciation and amortization	31,584	19,168
Other income, net	5,503	(34)
Provision for (benefit from) income taxes	12,805	(10,070)
Capital expenditures	36,855	81,120
Corporate and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(8,909)	(3,164)
Depreciation and amortization	118	157
Other income, net	1,041	1,089
Provision for (benefit from) income taxes	(884)	(105)
Capital expenditures	3,667	547
Polyethylene \| Olefins
Segment Reporting Information [Line Items]
Net external sales	409,432	487,144
Ethylene, Styrene And Other \| Olefins
Segment Reporting Information [Line Items]
Net external sales	173,645	235,654
PVC, Caustic Soda And Other \| Vinyls
Segment Reporting Information [Line Items]
Net external sales	416,988	190,527
Building Products \| Vinyls
Segment Reporting Information [Line Items]
Net external sales	103,466	114,351
Intersegment sales
Segment Reporting Information [Line Items]
Net external sales	23,832	57,196
Intersegment sales \| Olefins
Segment Reporting Information [Line Items]
Net external sales	23,462	56,853
Intersegment sales \| Vinyls
Segment Reporting Information [Line Items]
Net external sales	$ 370	$ 343

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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