Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 36,923	$ 33,342	$ 120,837	$ 96,724
Other Comprehensive Income:
Foreign currency translation adjustments (Note 11)	[1]	(19,328)	8,631	(22,594)	(29,025)
Defined benefit pension adjustments, net of tax (Note 11)		800	839	2,550	2,455
Derivative instrument activity, net of tax (Note 11)		(2)	(3)	(7)	(7)
Total Other Comprehensive Income		(18,530)	9,467	(20,051)	(26,577)
Comprehensive Income		18,393	42,809	100,786	70,147
Comprehensive Income Attributable to Noncontrolling Interest (Note 2)		(6)	(211)	(49)	(330)
Comprehensive Income Attributable to Stepan Company		$ 18,387	$ 42,598	$ 100,737	$ 69,817

[1] Includes foreign currency translation adjustments related to noncontrolling interest.