Note 6 - Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 30, 2017 USD ($) $ / shares shares
Options outstanding, beginning balance (in shares) | shares	392
Exercise price per share, beginning balance (in dollars per share)	$ 9.16
Exercise price per share, ending balance (in dollars per share)	37.06
Weighted average exercise price per share, beginning balance (in dollars per share)	$ 23.40
Options outstanding, exercised (in shares) | shares
Weighted average exercise price per share, exercised (in dollars per share)
Aggregate intrinsic value, exercised | $
Options outstanding, ending balance (in shares) | shares	392
Weighted average exercise price per share, ending balance (in dollars per share)	$ 23.40
Contractual term - weighted average, ending balance (Year)	7 years 142 days
Aggregate intrinsic value, ending balance | $	$ 2,505
Options outstanding, vested and anticipated to vest in future (in shares) | shares	388
Weighted average exercise price per share, vested and anticipated to vest in future (in dollars per share)	$ 23.36
Contractual term - weighted average, vested and anticipated to vest in future (Year)	7 years 138 days
Aggregate intrinsic value, vested and anticipated to vest in future | $	$ 2,492
Options outstanding, exercisable (in shares) | shares	194
Weighted average exercise price per share, exercisable (in dollars per share)	$ 19.05
Contractual term - weighted average, exercisable (Year)	6 years 58 days
Aggregate intrinsic value, exercisable | $	$ 1,889