Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliations of total equity
Beginning Balance				$ 536,944	$ 553,741
Beginning Balance				535,546
Beginning Balance				1,398
Net income		$ 16,941	$ 24,368	38,227	37,376
Net income		27	15	43	5
Dividends				(8,061)	(7,592)
Common stock purchases	[1]			(273)	(5,058)
Stock option exercises				359	1,449
Pension liability adjustment, net of tax (Note 10)		750	410	1,499	820
Translation adjustments		5,957	3,718	(19,195)	3,812
Derivative instrument activity, net of tax		16	1	(26)	4
Other	[2]			2,488	1,825
Ending Balance		551,962	586,377	551,962	586,377
Ending Balance		550,519		550,519
Ending Balance		1,443		1,443
Noncontrolling Interests' Equity [Member]
Reconciliations of total equity
Beginning Balance	[3]			1,398	1,455
Net income	[3]			43	5
Translation adjustments	[3]			2	(47)
Ending Balance	[3]	1,443	1,413	1,443	1,413
Stepan Company Equity [Member]
Reconciliations of total equity
Beginning Balance				535,546	552,286
Net income				38,184	37,371
Dividends				(8,061)	(7,592)
Common stock purchases	[1]			(273)	(5,058)
Stock option exercises				359	1,449
Pension liability adjustment, net of tax (Note 10)				1,499	820
Translation adjustments				(19,197)	3,859
Derivative instrument activity, net of tax				(26)	4
Other	[2]			2,488	1,825
Ending Balance		$ 550,519	$ 584,964	$ 550,519	$ 584,964

[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 excess tax benefits.

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