Note 6 - Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 28, 2019	Sep. 28, 2019
Options outstanding, balance (in shares)	388
Weighted average exercise price per share (in dollars per share)	$ 26.16
Options outstanding, exercised (in shares)
Weighted average exercise price per share, exercised (in dollars per share)
Aggregate intrinsic value, exercised
Options outstanding, balance (in shares)	388	388
Weighted average exercise price per share (in dollars per share)	$ 26.16	$ 26.16
Contractual term - weighted average, balance (Year)	7 years 204 days
Aggregate intrinsic value, balance	$ 508
Options outstanding, vested and anticipated to vest in future (in shares)	384
Weighted average exercise price per share, vested and anticipated to vest in future (in dollars per share)	$ 26.17
Contractual term - weighted average, vested and anticipated to vest in future (Year)	7 years 200 days
Aggregate intrinsic value, vested and anticipated to vest in future	$ 503
Options outstanding, exercisable (in shares)	184
Weighted average exercise price per share, exercisable (in dollars per share)	$ 27.62
Contractual term - weighted average, exercisable (Year)	6 years 29 days
Aggregate intrinsic value, exercisable	$ 246
Minimum [Member]
Exercise price per share, balance, lower (in dollars per share)	$ 10.23	10.23
Exercise price per share, exercised, lower (in dollars per share)
Maximum [Member]
Exercise price per share, balance, upper (in dollars per share)	41.85	$ 41.85
Exercise price per share, exercised, upper (in dollars per share)