Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Consolidated Statements of Income [Abstract]
Net Sales	$ 470,231	$ 476,989	$ 935,500	$ 899,587
Cost of Sales	396,835	407,404	785,320	768,216
Gross Profit	73,396	69,585	150,180	131,371
Operating Expenses:
Selling	12,985	12,171	26,636	23,001
Administrative	14,086	12,680	31,038	23,554
Research, development and technical services	11,504	10,656	22,285	20,887
Administrative Marketing Research Development Expenses	38,575	35,507	79,959	67,442
Operating Income	34,821	34,078	70,221	63,929
Other Income (Expense):
Interest, net	(2,086)	(2,194)	(4,690)	(4,257)
Loss from equity in joint ventures	(1,300)	(805)	(2,441)	(1,770)
Other, net (Note 12)	83	253	1,148	565
Total Other Income (Expense)	(3,303)	(2,746)	(5,983)	(5,462)
Income Before Provision for Income Taxes	31,518	31,332	64,238	58,467
Provision for Income Taxes	10,007	10,326	20,363	18,645
Net Income	21,511	21,006	43,875	39,822
Net Income Attributable to Noncontrolling Interests (Note 2)	(86)	(139)	(148)	(194)
Net Income Attributable to Stepan Company	$ 21,425	$ 20,867	$ 43,727	$ 39,628
Net Income Per Common Share Attributable to Stepan Company (Note 9):
Basic	$ 2.01	$ 2.00	$ 4.12	$ 3.80
Diluted	$ 1.89	$ 1.87	$ 3.85	$ 3.55
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 9):
Basic	10,550	10,345	10,537	10,335
Diluted	11,357	11,178	11,345	11,175
Dividends Declared Per Common Share	$ 0.28	$ 0.26	$ 0.56	$ 0.52