Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Income [Abstract]
Net Sales (Note 1)	$ 1,803,737	$ 1,843,092	$ 1,431,122
Cost of Sales	1,512,184	1,587,539	1,195,144
Gross Profit	291,553	255,553	235,978
Operating Expenses:
Selling (Note 1)	53,145	45,807	40,273
Administrative (Note 1)	63,979	50,766	49,501
Research, development and technical services (Note 1)	45,713	40,524	38,307
Total Operating Expenses	162,837	137,097	128,081
Operating Income	128,716	118,456	107,897
Other Income (Expense):
Interest, net (Note 6)	(9,599)	(9,095)	(6,341)
Loss from equity in joint ventures (Note 1)	(4,724)	(3,616)	(1,663)
Other, net (Note 8)	1,329	(851)	1,586
Total Other Income (Expense)	(12,994)	(13,562)	(6,418)
Income Before Provision For Income Taxes	115,722	104,894	101,479
Provision for Income Taxes (Note 9)	36,035	32,292	35,888
Net Income	79,687	72,602	65,591
Net Income Attributable to Noncontrolling Interests (Note 1)	(291)	(626)	(164)
Net Income Attributable to Stepan Company	$ 79,396	$ 71,976	$ 65,427
Net Income Per Common Share Attributable to Stepan Company (Note 18):
Basic	$ 3.71	$ 3.44	$ 3.18
Diluted	$ 3.49	$ 3.21	$ 2.95
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 18):
Basic	21,273	20,726	20,326
Diluted	22,730	22,440	22,180