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Note 9 - Stock-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017	Feb. 17, 2015
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount	$ 282,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	1 year 233 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 7.15	$ 12.06	$ 11.08
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Share-based Payment Arrangement, Expense	$ 889,000	$ 906,000	$ 1,000,000
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Expense	$ 1,168,000	$ 1,172,000	$ 1,238,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	1 year 270 days
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 482,000
Restricted Stock Units (RSUs) [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Restricted Stock Units (RSUs) [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
The 2015 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized				900,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	143,000

X

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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