Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net sales	$ 464,480	$ 451,582	$ 1,375,016	$ 1,413,755
Surfactants [Member]
Segment Reporting Information [Line Items]
Net sales	333,839	299,719	993,245	962,749
Polymers [Member]
Segment Reporting Information [Line Items]
Net sales	116,682	135,089	335,582	395,904
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net sales	$ 13,959	$ 16,774	$ 46,189	$ 55,102