Business Restructuring - Additional Information (Detail)	1 Months Ended	3 Months Ended				6 Months Ended
	Jun. 30, 2017 Employees	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)		Jun. 30, 2018 USD ($) Employees	Jun. 30, 2017 USD ($)		Dec. 31, 2017 USD ($)
Restructuring Cost And Reserve [Line Items]
Business restructuring		$ 273,000	$ 358,000	$ 586,000	[1]	$ 631,000	$ 1,372,000	[1]
Restructuring liability		452,000	493,000			452,000			$ 691,000
Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring liability		363,000	449,000			363,000			592,000
Other Expense [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring		273,000	358,000
Restructuring liability		89,000	$ 44,000			89,000			$ 99,000
Longford Mills [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						$ 5,470,000
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						3,876,000
Singapore [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Number positions eliminated | Employees	11
Restructuring liability		$ 0				$ 0
Singapore [Member] | Surfactants [Member] | Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring				$ 132,000			$ 132,000

[1] The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.