Segment And Geographic Information (Segment Reporting Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Net external sales	$ 1,135,871	$ 1,253,227	$ 998,576	$ 1,027,676	$ 951,625	$ 1,004,165	$ 939,047	$ 864,647	$ 4,415,350	[1]	$ 3,759,484	[1]	$ 3,571,041	[1]
Intersegment sales									147,924		322,411		319,925
Income (loss) from operations	302,387	306,761	266,788	248,055	257,580	266,602	235,227	194,055	1,123,991		953,464		615,351
Depreciation and amortization									208,486		157,808		144,541
Other (expense) income, net									(2,721)		6,790		3,520
Provision for income taxes									398,902		331,747		199,614
Property, Plant and Equipment, Additions									431,104		679,222		386,882
Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									2,723,690		2,553,669		2,499,978
Intersegment sales									146,539		320,909		318,322
Income (loss) from operations									1,013,825		833,249		552,762
Depreciation and amortization									106,244		102,938		97,906
Other (expense) income, net									6,102		7,410		3,899
Provision for income taxes									354,159		288,214		177,176
Property, Plant and Equipment, Additions									188,729		145,542		135,886
Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									1,691,660		1,205,815		1,071,063
Intersegment sales									1,385		1,502		1,603
Income (loss) from operations									142,740		154,684		85,942
Depreciation and amortization									101,666		54,371		46,146
Other (expense) income, net									2,680		(1,858)		(965)
Provision for income taxes									52,249		48,296		22,389
Property, Plant and Equipment, Additions									237,992		531,939		246,827
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations									(32,574)		(34,469)		(23,353)
Depreciation and amortization									576		499		489
Other (expense) income, net									(11,503)		1,238		586
Provision for income taxes									(7,506)		(4,763)		49
Property, Plant and Equipment, Additions									4,383		1,741		4,169
Polyethylene [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									1,922,535		1,750,292		1,658,551
Ethylene, Styrene And Other [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales									801,155		803,377		841,427
Building Products [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									488,328		405,157		327,788
PVC, Caustic Soda And Other [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales									$ 1,203,332		$ 800,658		$ 743,275

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