Note 6 - Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Apr. 01, 2017 USD ($) $ / shares shares
Options outstanding, beginning balance (in shares) | shares	371
Exercise price per share, beginning balance (in dollars per share)	$ 20.81
Granted (in shares) | shares	36
Granted (in dollars per share)	$ 37.06
Options outstanding, exercised (in shares) | shares	(67)
Exercise price per share, exercised (in dollars per share)	$ 19.05
Aggregate intrinsic value, exercised | $	$ 1,212
Options outstanding, ending balance (in shares) | shares	340
Exercise price per share, ending balance (in dollars per share)	$ 22.88
Contractual term - weighted average, ending balance (Year)	7 years 292 days
Aggregate intrinsic value, ending balance | $	$ 4,536
Options outstanding, vested and anticipated to vest in the future (in shares) | shares	335
Weighted average, vested and anticipated to vest in future (in dollars per share)	$ 22.84
Contractual term - weighted average, vested and anticipated to vest in future (Year)	7 years 288 days
Aggregate intrinsic value, vested and anticipated to vest in future | $	$ 4,493
Options outstanding, exercisable (in shares) | shares	135
Weighted average, exercisable (in dollars per share)	$ 17.37
Contractual term - weighted average, exercisable (Year)	6 years 113 days
Aggregate intrinsic value, exercisable | $	$ 2,530
Minimum [Member]
Exercise price per share, beginning balance (in dollars per share)	$ 9.16
Granted (in dollars per share)	37.06
Exercise price per share, exercised (in dollars per share)	9.16
Exercise price per share, ending balance (in dollars per share)	9.16
Maximum [Member]
Exercise price per share, beginning balance (in dollars per share)	34.49
Granted (in dollars per share)	37.06
Exercise price per share, exercised (in dollars per share)	23.95
Exercise price per share, ending balance (in dollars per share)	$ 37.06