Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Net sales	$ 466,659	$ 507,997	$ 519,866	$ 499,335	$ 473,823	$ 487,814	$ 495,101	$ 468,269	$ 1,993,857	[1]	$ 1,925,007	[1]	$ 1,766,166	[1]
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									1,223,153		1,159,579		1,114,089
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales									461,678		477,277		407,551
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									216,287		195,253		155,869
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales									92,739		92,898		88,657
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales									1,385,932		1,297,555		1,181,563
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									831,592		763,044		724,619
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales									276,742		275,121		237,489
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									212,824		190,802		151,229
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales									64,774		68,588		68,226
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales									527,420		546,634		498,826
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									323,360		329,629		319,769
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales									172,632		188,244		153,986
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									3,463		4,451		4,640
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales									27,965		24,310		20,431
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales									80,505		80,818		85,777
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales									68,201		66,906		69,701
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales									$ 12,304		$ 13,912		$ 16,076

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