Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 43,303	$ 35,843	$ 83,914	$ 63,382
Other Comprehensive Income:
Foreign currency translation adjustments (Note 11)	[1]	15,175	3,539	(3,266)	(37,656)
Defined benefit pension adjustments, net of tax (Note 11)		876	808	1,750	1,616
Derivative instrument activity, net of tax (Note 11)		(3)	(2)	(5)	(4)
Total Other Comprehensive Income		16,048	4,345	(1,521)	(36,044)
Comprehensive Income		59,351	40,188	82,393	27,338
Comprehensive Income Attributable to Noncontrolling Interest (Note 2)		(51)	(138)	(43)	(119)
Comprehensive Income Attributable to Stepan Company		$ 59,300	$ 40,050	$ 82,350	$ 27,219

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