Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net Sales	$ 449,987	$ 489,170
Cost of Sales	370,718	404,561
Gross Profit	79,269	84,609
Operating Expenses:
Selling	13,532	13,969
Administrative	18,872	19,306
Research, development and technical services	13,827	13,390
Deferred compensation (income) expense	(7,323)	7,473
Total Operating expenses	38,908	54,138
Business restructuring expenses (Note 16)	(357)	(733)
Operating Income	40,004	29,738
Other Income (Expense):
Interest, net	(1,230)	(1,853)
Other, net (Note 15)	(3,262)	3,145
Nonoperating Income (Expense), Total	(4,492)	1,292
Income Before Provision for Income Taxes	35,512	31,030
Provision for Income Taxes	7,973	6,052
Net Income	27,539	24,978
Net Loss Attributable to Noncontrolling Interests (Note 2)	6	6
Net Income Attributable to Stepan Company	$ 27,545	$ 24,984
Net Income Per Common Share Attributable to Stepan Company (Note 10):
Basic	$ 1.20	$ 1.08
Diluted	$ 1.18	$ 1.07
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 10):
Basic	23,023	23,099
Diluted	23,285	23,332