Segment Information (Segment Reporting Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Net external sales	$ 1,034,867	$ 867,252
Intersegment sales	101,845	106,590
Income (loss) from operations	145,625	140,637
Depreciation and amortization	35,394	32,578
Other income, net	1,347	1,207
Provision for (benefit from) income taxes	46,982	45,380
Capital expenditures	64,902	28,808
Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	732,271	605,080
Intersegment sales	101,457	106,270
Income (loss) from operations	129,207	145,256
Depreciation and amortization	23,763	21,644
Other income, net	956	180
Provision for (benefit from) income taxes	42,175	48,291
Capital expenditures	17,480	17,950
Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	302,596	262,172
Intersegment sales	388	320
Income (loss) from operations	21,082	(2,848)
Depreciation and amortization	11,509	10,774
Other income, net	240	511
Provision for (benefit from) income taxes	6,016	(2,153)
Capital expenditures	46,841	10,784
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(4,664)	(1,771)
Depreciation and amortization	122	160
Other income, net	151	516
Provision for (benefit from) income taxes	(1,209)	(758)
Capital expenditures	581	74
Polyethylene [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	445,420	446,703
Ethylene, Styrene And Other [Member] | Olefins [Member]
Segment Reporting Information [Line Items]
Net external sales	286,851	158,377
Building Products [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	88,213	70,315
PVC, Caustic Soda And Other [Member] | Vinyls [Member]
Segment Reporting Information [Line Items]
Net external sales	$ 214,383	$ 191,857