Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Net Sales	$ 445,030	$ 444,011	$ 1,345,530	$ 1,356,876
Surfactants [Member]
Segment Reporting Information [Line Items]
Net Sales	290,467	290,830	899,014	921,124
Polymers [Member]
Segment Reporting Information [Line Items]
Net Sales	134,144	134,726	382,540	377,703
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 20,419	$ 18,455	$ 63,976	$ 58,049