Segment Reporting (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
Operating Segment
Net Sales	$ 427,259	$ 440,978	$ 470,231	$ 465,269	$ 444,170	$ 499,335	$ 476,989	$ 422,598	$ 1,803,737	$ 1,843,092	$ 1,431,122
Operating Income									128,716	118,456	107,897
Assets	985,478				901,118				985,478	901,118	811,431
Depreciation and amortization expenses									51,294	47,099	40,351
Reportable Segment [Member]
Operating Segment
Net Sales									1,803,737	1,843,092	1,431,122
Operating Income									178,963	155,027	144,413
Assets	950,714				852,750				950,714	852,750	731,838
Capital expenditures									81,317	82,273	81,919
Depreciation and amortization expenses									49,634	44,851	38,221
Surfactants [Member]
Operating Segment
Net Sales									1,305,800	1,361,956	1,057,982
Assets	692,891				624,425				692,891	624,425	548,297
Capital expenditures									56,236	63,295	56,562
Depreciation and amortization expenses									34,036	31,346	27,260
Surfactants [Member] | Operating Income Segments [Member]
Operating Segment
Operating Income									118,591	100,811	93,010
Polymers [Member]
Operating Segment
Net Sales									423,959	421,515	330,416
Assets	199,013				174,029				199,013	174,029	157,114
Capital expenditures									19,266	15,320	23,895
Depreciation and amortization expenses									13,328	11,697	9,519
Polymers [Member] | Operating Income Segments [Member]
Operating Segment
Operating Income									48,130	40,909	36,904
Specialty Products [Member]
Operating Segment
Net Sales									73,798	59,621	42,724
Assets	58,810				54,296				58,810	54,296	26,427
Capital expenditures									5,815	3,658	1,462
Depreciation and amortization expenses									2,270	1,808	1,442
Specialty Products [Member] | Operating Income Segments [Member]
Operating Segment
Operating Income									$ 12,242	$ 13,307	$ 14,499