Note 7 - Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Jun. 27, 2020 USD ($) $ / shares shares
Options outstanding, balance (in shares) | shares	388
Weighted average exercise price per share (in dollars per share)	$ 26.16
Options outstanding, granted (in shares) | shares	67
Weighted average exercise price per share, granted (in dollars per share)	$ 22.09
Options outstanding, exercised (in shares) | shares	0
Weighted average exercise price per share, exercised (in dollars per share)	$ 0
Options outstanding, forfeited (in shares) | shares	(27)
Weighted average exercise price per share, forfeited (in dollars per share)	$ 25.88
Options outstanding, balance (in shares) | shares	428
Weighted average exercise price per share (in dollars per share)	$ 25.55
Contractual term - weighted average, balance (Year)	7 years 5 months 19 days
Aggregate intrinsic value, balance | $	$ 64
Options outstanding, vested and anticipated to vest in future (in shares) | shares	424
Weighted average exercise price per share, vested and anticipated to vest in future (in dollars per share)	$ 25.56
Contractual term - weighted average, vested and anticipated to vest in future (Year)	7 years 5 months 12 days
Aggregate intrinsic value, vested and anticipated to vest in future | $	$ 64
Options outstanding, exercisable (in shares) | shares	210
Weighted average exercise price per share, exercisable (in dollars per share)	$ 27.73
Contractual term - weighted average, exercisable (Year)	6 years
Aggregate intrinsic value, exercisable | $	$ 64
Minimum [Member]
Exercise price per share, balance, lower (in dollars per share)	$ 10.23
Exercise price per share, granted, lower (in dollars per share)	22.09
Exercise price per share, exercised, lower (in dollars per share)	0
Exercise price per share, forfeited, lower (in dollars per share)	18.05
Maximum [Member]
Exercise price per share, balance, upper (in dollars per share)	41.85
Exercise price per share, granted, upper (in dollars per share)	22.09
Exercise price per share, exercised, upper (in dollars per share)	0
Exercise price per share, forfeited, upper (in dollars per share)	$ 41.85