Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 507,997	$ 487,814	$ 1,527,198	$ 1,451,184
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	309,629	286,106		879,792
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	116,490	125,734		356,201
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	59,538	52,559		146,881
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	22,340	23,415		68,310
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales	346,884	321,444	1,062,708	973,381
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	205,032	184,889		582,148
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	68,120	69,325		198,037
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	58,560	51,241		143,305
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	15,172	15,989		49,891
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	141,646	147,754	404,446	415,551
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	87,720	86,002		251,291
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	45,780	53,008		142,265
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	978	1,318		3,576
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	7,168	7,426		18,419
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	19,467	18,616	$ 60,044	62,252
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	16,877	15,215		46,353
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 2,590	$ 3,401		$ 15,899