Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Net sales	$ 595,511	$ 460,549	$ 1,133,251	$ 910,536
Surfactants [Member]
Segment Reporting Information [Line Items]
Net sales	384,002	332,335	754,938	659,406
Polymers [Member]
Segment Reporting Information [Line Items]
Net sales	190,538	112,409	340,923	218,900
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net sales	$ 20,971	$ 15,805	$ 37,390	$ 32,230