Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Net Sales	$ 495,101	$ 454,603	$ 963,370	$ 900,500
Surfactants [Member]
Segment Reporting Information [Line Items]
Net Sales	329,334	298,587	651,937	608,547
Polymers [Member]
Segment Reporting Information [Line Items]
Net Sales	141,187	134,498	267,797	248,396
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 24,580	$ 21,518	$ 43,636	$ 43,557