Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reconciliations of total equity
Beginning Balance				$ 558,384	$ 536,944
Net income		$ 27,870	$ 16,941	55,527	38,227
Dividends				(8,477)	(8,061)
Common stock purchases	[1]			(2,643)	(273)
Stock option exercises				1,351	359
Defined benefit pension adjustments, net of tax		565	750	1,129	1,499
Translation adjustments		(2,692)	5,957	9,898	(19,195)
Derivative instrument activity, net of tax		(6)	16	(27)	(26)
Other	[2]			5,117	2,488
Ending Balance		620,259	551,962	620,259	551,962
Stepan Company Equity [Member]
Reconciliations of total equity
Beginning Balance				556,984	535,546
Net income				55,519	38,184
Dividends				(8,477)	(8,061)
Common stock purchases	[1]			(2,643)	(273)
Stock option exercises				1,351	359
Defined benefit pension adjustments, net of tax				1,129	1,499
Translation adjustments				9,931	(19,197)
Derivative instrument activity, net of tax				(27)	(26)
Other	[2]			5,117	2,488
Ending Balance		618,884	550,519	618,884	550,519
Noncontrolling Interests' Equity [Member]
Reconciliations of total equity
Beginning Balance	[3]			1,400	1,398
Net income	[3]			8	43
Translation adjustments	[3]			(33)	2
Ending Balance	[3]	$ 1,375	$ 1,443	$ 1,375	$ 1,443

[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 the receipt of performance awards and deferred compensation distributions.

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

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