Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 499,335	$ 468,269
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	308,693	291,542
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	123,803	109,947
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	42,515	44,803
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	24,324	21,977
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales	358,940	322,603
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	220,405	198,243
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	78,371	63,423
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	41,688	43,505
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	18,476	17,432
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	121,933	126,610
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	73,474	78,364
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	41,784	42,403
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	827	1,298
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	5,848	4,545
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	18,462	19,056
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	14,814	14,935
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 3,648	$ 4,121