Note 10 - Earnings (Loss) Per Share (Detail) - Basic and Diluted Earnings (Loss) Per Share Attributable to Common Shareholders (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011
Net earnings (loss) (in Dollars)	$ 894	$ 3,650	$ 976	$ (1,359)
Less allocation to participating securities (in Dollars)		(6)
Available to Insteel common shareholders (in Dollars)	$ 894	$ 3,644	$ 976	$ (1,359)
Basic weighted average shares outstanding	17,690	17,587	17,650	17,550
Dilutive effect of stock-based compensation	303	268	339
Diluted weighted average shares outstanding	17,993	17,855	17,989	17,550
Per share basic:
Net earnings (loss) (in Dollars per share)	$ 0.05	$ 0.21	$ 0.06	$ (0.08)
Per share diluted:
Net earnings (loss) (in Dollars per share)	$ 0.05	$ 0.20	$ 0.05	$ (0.08)