Business Restructuring - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended		17 Months Ended
	Jun. 30, 2017 Employees	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Employees
Restructuring Cost And Reserve [Line Items]
Business restructuring		$ 426,000		$ 1,798,000	$ 1,061,000
Longford Mills [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						$ 4,483,000
Number positions eliminated | Employees						30
Longford Mills [Member] | Surfactants [Member] | Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						$ 1,594,000
Longford Mills [Member] | Surfactants [Member] | Other Expense [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						2,889,000
Singapore Plant [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Number positions eliminated | Employees	11
Singapore Plant [Member] | Surfactants [Member] | Termination Expense [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring			$ 132,000
Restructuring liability		$ 0		$ 0		$ 0