Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 35,843	$ 30,210	$ 63,382	$ 55,188
Other comprehensive income:
Foreign currency translation adjustments (Note 11)	[1]	3,539	4,290	(37,656)	7,997
Defined benefit pension adjustments, net of tax (Note 11)		808	542	1,616	1,085
Derivative instrument activity, net of tax (Note 11)		(2)	(2)	(4)	(4)
Total other comprehensive income		4,345	4,830	(36,044)	9,078
Comprehensive income		40,188	35,040	27,338	64,266
Comprehensive income attributable to noncontrolling interests (Note 2)		(138)	35	(119)	21
Comprehensive income attributable to Stepan Company		$ 40,050	$ 35,075	$ 27,219	$ 64,287

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