Segment And Geographic Information (Segment Reporting Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Net external sales	$ 801,041	$ 821,175	$ 913,958	$ 1,034,867	$ 859,175	$ 968,372	$ 925,049	$ 867,252	$ 3,571,041	[1]	$ 3,619,848	[1]	$ 3,171,787	[1]
Intersegment sales									319,925		446,363		323,172
Income (loss) from operations	156,231	142,517	170,978	145,625	50,459	117,331	138,369	140,637	615,351		446,796		378,364
Depreciation and amortization									144,541		131,397		128,732
Other income, net									3,520		5,628		4,471
Provision for income taxes									199,614		142,466		121,567
Property, Plant and Equipment, Additions									386,882		176,843		81,269
Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									2,499,978		2,567,842		2,261,212
Intersegment sales									318,322		444,889		322,125
Income (loss) from operations									552,762		459,266		460,027
Depreciation and amortization									97,906		86,915		86,086
Other income, net									3,899		2,813		440
Provision for income taxes									177,176		149,033		147,296
Property, Plant and Equipment, Additions									135,886		90,641		37,865
Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									1,071,063		1,052,006		910,575
Intersegment sales									1,603		1,474		1,047
Income (loss) from operations									85,942		4,012		(62,429)
Depreciation and amortization									46,146		43,877		42,062
Other income, net									(965)		194		399
Provision for income taxes									22,389		(2,193)		(24,519)
Property, Plant and Equipment, Additions									246,827		84,192		42,371
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations									(23,353)		(16,482)		(19,234)
Depreciation and amortization									489		605		584
Other income, net									586		2,621		3,632
Provision for income taxes									49		(4,374)		(1,210)
Property, Plant and Equipment, Additions									4,169		2,010		1,033
Polyethylene [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									1,658,551		1,772,144		1,656,203
Ethylene, Styrene And Other [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									841,427		795,698		605,009
Building Products [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									327,788		294,692		352,419
PVC, Caustic Soda And Other [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									$ 743,275		$ 757,314		$ 558,156

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