Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net Sales	$ 460,549	$ 473,003	$ 910,536	$ 962,173
Cost of Sales	362,054	380,044	732,772	784,605
Gross Profit	98,495	92,959	177,764	177,568
Operating Expenses:
Selling	12,921	14,140	26,453	28,109
Administrative	20,731	21,544	39,603	40,850
Research, development and technical services	13,531	13,365	27,358	26,755
Deferred compensation (income) expense	6,464	2,395	(859)	9,868
Total Operating expenses	53,647	51,444	92,555	105,582
Business restructuring expenses (Note 16)	(225)	(450)	(582)	(1,183)
Operating Income	44,623	41,065	84,627	70,803
Other Income (Expense):
Interest, net	(1,259)	(1,766)	(2,489)	(3,619)
Other, net (Note 15)	4,437	235	1,175	3,380
Nonoperating Income (Expense), Total	3,178	(1,531)	(1,314)	(239)
Income Before Provision for Income Taxes	47,801	39,534	83,313	70,564
Provision for Income Taxes	11,958	9,324	19,931	15,376
Net Income	35,843	30,210	63,382	55,188
Net (Income) Loss Attributable to Noncontrolling Interests (Note 2)	(136)	8	(130)	14
Net Income Attributable to Stepan Company	$ 35,707	$ 30,218	$ 63,252	$ 55,202
Net Income Per Common Share Attributable to Stepan Company (Note 10):
Basic	$ 1.56	$ 1.31	$ 2.75	$ 2.39
Diluted	$ 1.54	$ 1.30	$ 2.72	$ 2.37
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 10):
Basic	22,923	23,086	22,973	23,092
Diluted	23,184	23,329	23,235	23,329