Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 519,866	$ 495,101	$ 1,019,201	$ 963,370
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	323,669	302,144	632,362	593,686
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	114,534	120,520	238,337	230,467
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	57,212	49,519	99,727	94,322
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	24,451	22,918	48,775	44,895
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales	356,884	329,334	715,824	651,937
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	218,029	199,016	438,434	397,259
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	66,065	65,289	144,436	128,712
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	56,579	48,559	98,267	92,064
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	16,211	16,470	34,687	33,902
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	140,867	141,187	262,800	267,797
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	86,966	86,925	160,440	165,289
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	45,028	46,854	86,812	89,257
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	633	960	1,460	2,258
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	8,240	6,448	14,088	10,993
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	22,115	24,580	40,577	43,636
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	18,674	16,203	33,488	31,138
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 3,441	$ 8,377	$ 7,089	$ 12,498