Segment And Geographic Information (Segment Reporting Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Segment Reporting Information [Line Items]
Net external sales	$ 859,175	$ 968,372	$ 925,049	$ 867,252	$ 795,387	$ 779,677	$ 818,389	$ 778,334	$ 3,619,848	[1]	$ 3,171,787	[1]	$ 2,325,723	[1]
Intersegment sales									446,363		323,172		234,968
Income (loss) from operations	50,459	117,331	138,369	140,637	137,052	107,346	99,537	34,429	446,796		378,364		107,257
Depreciation and amortization									131,397		128,732		123,199
Other income, net									5,628		4,471		6,453
Provision for (benefit from) income taxes									142,466		121,567		25,758
Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									2,567,842		2,261,212		1,611,451
Intersegment sales									444,889		322,125		233,746
Income (loss) from operations									459,266		460,027		177,101
Depreciation and amortization									86,915		86,086		82,952
Other income, net									2,813		440		440
Provision for (benefit from) income taxes									149,033		147,296		44,987
Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									1,052,006		910,575		714,272
Intersegment sales									1,474		1,047		1,222
Income (loss) from operations									4,012		(62,429)		(57,445)
Depreciation and amortization									43,877		42,062		39,843
Other income, net									194		399		478
Provision for (benefit from) income taxes									(2,193)		(24,519)		(31,287)
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations									(16,482)		(19,234)		(12,399)
Depreciation and amortization									605		584		404
Other income, net									2,621		3,632		5,535
Provision for (benefit from) income taxes									(4,374)		(1,210)		12,058
Polyethylene [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									1,772,144		1,656,203		1,210,706
Ethylene, Styrene And Other [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									795,698		605,009		400,745
Building Products [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									294,692		352,419		315,447
PVC, Caustic Soda And Other [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									$ 757,314		$ 558,156		$ 398,825

[1] Revenues are attributed to countries based on location of customer.