Note 6 - Stock-based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	3 Months Ended
	Dec. 31, 2022 $ / shares shares
Restricted stock units outstanding, beginning balance (in shares) | shares	120
Weighted average grant date fair value, beginning balance (in dollars per share) | $ / shares	$ 29.88
Restricted stock units outstanding, forfeited (in shares) | shares	(10)
Weighted average grant date fair value, forfeited (in dollars per share) | $ / shares	$ 30.36
Restricted stock units outstanding, released (in shares) | shares	0
Weighted average grant date fair value, released (in dollars per share) | $ / shares	$ 0
Restricted stock units outstanding, ending balance (in shares) | shares	110
Weighted average grant date fair value, ending balance (in dollars per share) | $ / shares	$ 29.84