Note 4 - Earnings Per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Net income	$ 6,357	$ 4,704	$ 15,272	$ 8,336
Weighted average number of shares of common stock outstanding (in shares)	22,660,477	22,581,916	22,650,123	22,570,305
Effect of dilutive securities (in shares)	159,049	155,730	139,991	144,793
Weighted average number of shares of common stock outstanding including effect of dilutive securities (in shares)	22,819,526	22,737,646	22,790,114	22,715,098
Basic earnings per share (in dollars per share)	$ 0.28	$ 0.21	$ 0.67	$ 0.37
Diluted earnings per share (in dollars per share)	$ 0.28	$ 0.21	$ 0.67	$ 0.37