Acquisitions - Additional Information (Detail)				3 Months Ended									12 Months Ended
		Oct. 03, 2016 USD ($) Customer T	Jun. 15, 2015 USD ($) T	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($) ft² T	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 BRL	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)		Mar. 31, 2017 BRL	Dec. 31, 2016 BRL	Oct. 03, 2016 BRL Customer T
Business Acquisition [Line Items]
Paid from cash on hand													$ 4,339,000		$ 23,510,000		$ 5,133,000
Goodwill				$ 25,118,000				$ 25,308,000					25,118,000		25,308,000		11,265,000
Net sales				473,823,000	$ 487,814,000	$ 495,101,000	$ 468,269,000	420,636,000		$ 445,030,000	$ 454,603,000	$ 445,897,000	1,925,007,000	[1]	1,766,166,000	[1]	1,776,167,000	[1]
Net income				9,884,000	$ 21,899,000	$ 27,882,000	31,913,000	8,417,000		$ 21,362,000	$ 28,496,000	$ 27,916,000	91,578,000		86,191,000		75,968,000
Capital expenditures													$ 78,613,000		103,076,000		119,349,000
Sun Products Corporation's (SUN's) Pasadena, Texas [Member]
Business Acquisition [Line Items]
Capital expenditures																	13,000,000
Acquisition of land																	3,377,000
Acquisition of manufacturing assets																	9,623,000
Non-compete Agreements [Member]
Business Acquisition [Line Items]
Amortization periods for the identifiable intangible assets at the time of acquisition													5 years
Minimum [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization periods for the identifiable intangible assets at the time of acquisition													10 years
Maximum [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization periods for the identifiable intangible assets at the time of acquisition													13 years
Brazil [Member]
Business Acquisition [Line Items]
Net sales	[1]												$ 109,960,000		74,961,000		63,439,000
Surfactants [Member]
Business Acquisition [Line Items]
Goodwill				$ 19,160,000				19,491,000					$ 19,160,000		19,491,000		5,402,000
Tebras And PBC [Member]
Business Acquisition [Line Items]
Goodwill		$ 14,207,000
Acquisition of intangible assets		7,354,000
Acquisition of property, plant and equipment		5,716,000
Acquisition of liabilities		3,487,000
Tebras And PBC [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquisition of intangible assets		$ 4,331,000
Amortization periods for the identifiable intangible assets at the time of acquisition		13 years
Tebras And PBC [Member] | Supply Contract [Member]
Business Acquisition [Line Items]
Acquisition of intangible assets		$ 2,555,000
Amortization periods for the identifiable intangible assets at the time of acquisition		4 years
Tebras And PBC [Member] | Non-compete Agreements [Member]
Business Acquisition [Line Items]
Acquisition of intangible assets		$ 468,000
Amortization periods for the identifiable intangible assets at the time of acquisition		5 years
Tebras And PBC [Member] | Before purchase accounting adjustments [Member]
Business Acquisition [Line Items]
Goodwill							14,327,000
Tebras And PBC [Member] | After purchase accounting adjustments [Member]
Business Acquisition [Line Items]
Goodwill							14,207,000
Tebras And PBC [Member] | Brazil [Member]
Business Acquisition [Line Items]
Net sales																	28,000,000
Tebras And PBC [Member] | Brazil [Member] | Maximum [Member]
Business Acquisition [Line Items]
Net income																	$ 2,000,000
Tebras And PBC [Member] | Surfactants [Member] | Brazil [Member]
Business Acquisition [Line Items]
Capacity of production facility expected to be acquired | T		25,000																			25,000
Original purchase price of acquisitions		$ 29,075,000																			BRL 93,309,000
Paid from cash on hand								21,812,000	BRL 70,000,000
Deposited in escrow								2,804,000							2,804,000					BRL 9,000,000
Unpaid working capital adjustments								$ 4,459,000							$ 4,459,000					BRL 14,309,000
Working capital adjustment amount paid							4,339,000												BRL 13,925,000
Adjusted purchase price of the acquisitions							$ 28,955,000												BRL 92,925,000
Tebras And PBC [Member] | Surfactants [Member] | Brazil [Member] | Minimum [Member]
Business Acquisition [Line Items]
Number of customers | Customer		1,200																			1,200
Procter and Gamble Company [Member] | Brazil [Member]
Business Acquisition [Line Items]
Capacity of production facility | T			30,000
Paid from cash on hand			$ 5,133,000
Goodwill			0
Acquisition of intangible assets			0
Acquisition of property, plant and equipment			6,007,000
Acquisition of liabilities			$ 874,000
2017 Acquisition Agreement [Member] | BASF Mexicana, S.A. DE C.V. [Member] | Surfactants [Member] | Ecatepec, Mexico [Member]
Business Acquisition [Line Items]
Capacity of production facility expected to be acquired | T						50,000
Warehouse space, laboratory and office space currently expected to be acquired | ft²						124,000

[1] Net sales are attributed to countries based on the location of the Company facility making the sales.