Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	[1]	$ 21,853	$ 21,367	$ 81,661	$ 77,787
Other comprehensive income (loss):
Foreign currency translation adjustments (Note 10)		9,837	(2,213)	26,288	7,685
Pension liability adjustment, net of tax (Note 10)		539	497	1,671	1,626
Derivative instrument activity, net of tax (Note 10)		(2)		(7)	(27)
Other comprehensive income (loss)		10,374	(1,716)	27,952	9,284
Comprehensive income		32,227	19,651	109,613	87,071
Comprehensive (income) loss attributable to noncontrolling interests (Note 2)		20	(1)	(26)	24
Comprehensive income attributable to Stepan Company		$ 32,247	$ 19,650	$ 109,587	$ 87,095

[1] The 2016 amounts for the noted items have been immaterially changed from the amounts originally reported as a result of the Company’s fourth quarter 2016 adoption of Accounting Standards Update (ASU) No. 2016-9, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.