Note 7 - Stock-based Compensation - RSU Activity (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	9 Months Ended
	Jun. 27, 2020 $ / shares shares
Restricted stock units outstanding, beginning balance (in shares) | shares	115
Weighted average grant date fair value, beginning balance (in dollars per share) | $ / shares	$ 26.16
Restricted stock units outstanding, granted (in shares) | shares	43
Weighted average grant date fair value, granted (in dollars per share) | $ / shares	$ 22.09
Restricted stock units outstanding, released (in shares) | shares	(26)
Weighted average grant date fair value, released (in dollars per share) | $ / shares	$ 28.66
Restricted stock units outstanding, forfeited (in shares) | shares	(5)
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	$ 25.49
Restricted stock units outstanding, ending balance (in shares) | shares	127
Weighted average grant date fair value, ending balance (in dollars per share) | $ / shares	$ 24.29