Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net Sales	$ 464,480	$ 451,582	$ 1,375,016	$ 1,413,755
Cost of Sales	367,423	374,180	1,100,195	1,158,785
Gross Profit	97,057	77,402	274,821	254,970
Operating Expenses:
Selling	13,266	14,186	39,719	42,295
Administrative	21,354	19,708	60,957	60,558
Research, development and technical services	14,303	13,473	41,661	40,228
Deferred compensation expense	5,613	1,610	4,754	11,478
Total Operating expenses	54,536	48,977	147,091	154,559
Business restructuring expenses (Note 16)	(126)	(459)	(708)	(1,642)
Operating Income	42,395	27,966	127,022	98,769
Other Income (Expense):
Interest, net	(1,626)	(1,402)	(4,115)	(5,021)
Other, net (Note 15)	2,629	885	3,804	4,265
Nonoperating Income (Expense), Total	1,003	(517)	(311)	(756)
Income Before Provision for Income Taxes	43,398	27,449	126,711	98,013
Provision for Income Taxes	10,056	1,569	29,987	16,945
Net Income	33,342	25,880	96,724	81,068
Net (Income) Loss Attributable to Noncontrolling Interests (Note 2)	(174)	9	(304)	23
Net Income Attributable to Stepan Company	$ 33,168	$ 25,889	$ 96,420	$ 81,091
Net Income Per Common Share Attributable to Stepan Company (Note 10):
Basic	$ 1.45	$ 1.12	$ 4.20	$ 3.52
Diluted	$ 1.43	$ 1.11	$ 4.15	$ 3.48
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 10):
Basic	22,907	23,025	22,951	23,070
Diluted	23,237	23,300	23,236	23,320