Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Net sales	$ 473,003	$ 519,866	$ 962,173	$ 1,019,201
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	294,221	323,669	595,866	632,362
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	101,365	114,534	218,264	238,337
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	55,407	57,212	106,416	99,727
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	22,010	24,451	41,627	48,775
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales	313,380	356,884	663,030	715,824
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	191,720	218,029	406,017	438,434
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	54,360	66,065	125,838	144,436
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	53,957	56,579	104,769	98,267
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	13,343	16,211	26,406	34,687
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	140,636	140,867	260,815	262,800
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	86,434	86,966	157,757	160,440
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	44,085	45,028	86,190	86,812
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,450	633	1,647	1,460
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	8,667	8,240	15,221	14,088
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	18,987	22,115	38,328	40,577
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	16,067	18,674	32,092	33,488
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	2,920	3,441	6,236	7,089
Specialty Products [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	0	0	0	0
Specialty Products [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0