Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Reconciliations of total equity
Beginning Balance		$ 558,384	$ 536,944
Net income		27,657	21,286
Dividends		(4,237)	(4,047)
Common stock purchases	[1]	(1,143)	(273)
Stock option exercises		258	167
Defined benefit pension adjustments, net of tax		564	749
Translation adjustments		12,590	(25,152)
Derivative instrument activity, net of tax		(21)	(42)
Other	[2]	2,191	846
Ending Balance		596,243	530,478
Stepan Company Equity [Member]
Reconciliations of total equity
Beginning Balance		556,984	535,546
Net income		27,654	21,270
Dividends		(4,237)	(4,047)
Common stock purchases	[1]	(1,143)	(273)
Stock option exercises		258	167
Defined benefit pension adjustments, net of tax		564	749
Translation adjustments		12,579	(25,137)
Derivative instrument activity, net of tax		(21)	(42)
Other	[2]	2,191	846
Ending Balance		594,829	529,079
Noncontrolling Interests' Equity [Member]
Reconciliations of total equity
Beginning Balance	[3]	1,400	1,398
Net income	[3]	3	16
Translation adjustments	[3]	11	(15)
Ending Balance	[3]	$ 1,414	$ 1,399

[1] Includes the value of Company shares purchased in the open market and the value of Company common shares tendered by employees to settle minimum statutory withholding taxes related to distributions of deferred performance awards and deferred incentive compensation.

[2] Primarily comprised of activity related to stock-based compensation, deferred compensation and excess tax benefits.

[3] Reflects the noncontrolling interest in the Company’s China joint venture.