Reconciliations of Equity - Reconciliations of Total Equity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Reconciliations of total equity
Beginning Balance	$ 536,944		$ 553,741
Beginning Balance	535,546
Beginning Balance	1,398
Net income	21,286		13,008
Net income	16		(10)
Dividends	(4,047)		(3,800)
Common stock purchases	(273)	[1]	(531)	[1]
Stock option exercises	167		904
Pension liability adjustment, net of tax (Note 10)	749		410
Translation adjustments	(25,152)		94
Derivative instrument activity, net of tax	(42)		3
Other	846	[2]	466	[2]
Ending Balance	530,478		564,295
Ending Balance	529,079
Ending Balance	1,399
Stepan Company Equity [Member]
Reconciliations of total equity
Beginning Balance	535,546		552,286
Net income	21,270		13,018
Dividends	(4,047)		(3,800)
Common stock purchases	(273)	[1]	(531)	[1]
Stock option exercises	167		904
Pension liability adjustment, net of tax (Note 10)	749		410
Translation adjustments	(25,137)		117
Derivative instrument activity, net of tax	(42)		3
Other	846	[2]	466	[2]
Ending Balance	529,079		562,873
Noncontrolling Interests' Equity [Member]
Reconciliations of total equity
Beginning Balance	1,398	[3]	1,455	[3]
Net income	16	[3]	(10)	[3]
Translation adjustments	(15)	[3]	(23)	[3]
Ending Balance	$ 1,399	[3]	$ 1,422	[3]

[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.