Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Segment Reporting Information [Line Items]
Net sales		$ 420,636	$ 445,030	$ 454,603	$ 445,897	$ 419,291	$ 444,011	$ 452,414	$ 460,451	$ 1,766,166	[1]	$ 1,776,167	[1]	$ 1,927,213	[1]
Operating income		9,932	$ 28,738	$ 42,916	$ 44,607	20,223	$ 38,794	$ 28,595	$ 35,178	126,193		122,790		90,694
Assets	[2]	1,353,890				1,238,392				1,353,890		1,238,392		1,162,014
Capital expenditures										103,076		119,349		101,819
Depreciation and amortization expenses										74,967		66,985		63,804
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales										1,766,166		1,776,167		1,927,213
Operating income										207,282		189,419		131,955
Assets		1,208,697				1,124,918				1,208,697		1,124,918		1,129,905
Capital expenditures										100,205		116,867		98,823
Depreciation and amortization expenses										73,122		65,322		62,708
Surfactants [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales										1,181,563		1,205,849		1,296,638
Operating income										99,796		104,080		60,778
Assets		831,324				758,524				831,324		758,524		741,677
Capital expenditures										64,121		79,171		70,796
Depreciation and amortization expenses										48,643		42,122		41,483
Polymers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales										498,826		491,488		550,966
Operating income										96,788		80,942		60,690
Assets		301,890				293,790				301,890		293,790		320,640
Capital expenditures										31,890		31,309		22,409
Depreciation and amortization expenses										20,275		19,541		18,433
Specialty Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales										85,777		78,830		79,609
Operating income										10,698		4,397		10,487
Assets		$ 75,483				$ 72,604				75,483		72,604		67,588
Capital expenditures										4,194		6,387		5,618
Depreciation and amortization expenses										$ 4,204		$ 3,659		$ 2,792

[1] Net sales are attributed to countries based on the location of the Company facility making the sales.

[2] The 2015 amounts in the noted line items have been changed from the amounts originally reported due to the reclassification of debt issuance costs pursuant to the Company’s adoption of ASU No. 2015-3. See Note 1 for further information.