Note 13 - 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	12 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Oct. 02, 2010	Oct. 02, 2010
Earnings (loss) from continuing operations	$ 1,809	$ (387)	$ 458	$ 458
Available to Insteel common shareholders	1,809	(387)	471
Basic weighted average shares outstanding (in Shares)	17,664	17,562	17,466	17,466
Dilutive effect of stock-based compensation (in Shares)	326		98
Diluted weighted average shares outstanding (in Shares)	17,990	17,562	17,564	17,564
Earnings (loss) from continuing operations (in Dollars per share)	$ 0.10	$ (0.02)	$ 0.03
Loss from discontinued operations (in Dollars per share)	$ 0	$ 0	$ 0
Net earnings (loss) (in Dollars per share)	$ 0.10	$ (0.02)	$ 0.03
Net earnings (loss)	1,809	(387)	473	473
Earnings from discontinued operations net of income taxes			15	15
Continuing Operations [Member]
Less allocation to participating securities			(2)
Available to Insteel common shareholders	1,809	(387)	456
Discontinued Operations [Member]
Less allocation to participating securities	0	0	0
Available to Insteel common shareholders			15
Total [Member]
Less allocation to participating securities			$ (2)