Note 13 - Business Segment Information - Net Sales By Product Line (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015
Revenue	$ 388,871	$ 418,547	$ 447,504
Welded Wire Reinforcement [Member]
Revenue	239,522	256,801	255,219
PC Strand [Member]
Revenue	$ 149,349	$ 161,746	$ 192,285

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration