Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net Sales		$ 495,101	$ 454,603	$ 963,370	$ 900,500
Cost of Sales		405,135	361,672	781,306	714,070
Gross Profit		89,966	92,931	182,064	186,430
Operating Expenses:
Selling		13,259	14,572	26,744	28,262
Administrative		17,848	17,692	35,819	36,392
Research, development and technical services		14,296	14,256	27,717	28,038
Deferred compensation expense		5,016	2,434	5,392	5,154
Total Operating expenses		50,419	48,954	95,672	97,846
Business restructuring expenses (Note 14)		586	1,061	1,372	1,061
Operating Income		38,961	42,916	85,020	87,523
Other Income (Expense):
Interest, net		(2,863)	(3,417)	(5,855)	(7,031)
Other, net (Note 13)		965	(303)	2,228	(828)
Nonoperating Income (Expense), Total		(1,898)	(3,720)	(3,627)	(7,859)
Income Before Provision for Income Taxes		37,063	39,196	81,393	79,664
Provision for Income Taxes	[1]	9,167	10,695	21,585	23,244
Net Income	[1]	27,896	28,501	59,808	56,420
Net Income Attributable to Noncontrolling Interests (Note 2)		(14)	(5)	(13)	(8)
Net Income Attributable to Stepan Company	[1]	$ 27,882	$ 28,496	$ 59,795	$ 56,412
Net Income Per Common Share Attributable to Stepan Company (Note 9):
Basic	[1]	$ 1.21	$ 1.25	$ 2.61	$ 2.48
Diluted	[1]	$ 1.19	$ 1.24	$ 2.56	$ 2.46
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 9):
Basic		22,953	22,760	22,927	22,746
Diluted	[1]	23,381	23,004	23,356	22,950
Dividends Declared Per Common Share		$ 0.21	$ 0.19	$ 0.41	$ 0.38

[1] The 2016 amounts for the noted items have been immaterially changed from the amounts originally reported as a result of the Company’s fourth quarter 2016 adoption of Accounting Standards Update (ASU) No. 2016-9, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.