Note 1 - Summary of Significant Accounting Policies - Net Income Per Share Computation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator for net income per share - basic:
Net income	$ 31,800	$ 37,466	$ 37,260
Allocation of distributed and undistributed income to unvested restricted stock shareholders	(16)	(18)	(57)
Net income attributable to common shareholders	$ 31,784	$ 37,448	$ 37,203
Denominator for net income per share - basic:
Weighted average common shares outstanding – basic (in shares)	24,922	25,422	25,170
Net income per share – basic (in dollars per share)	$ 1.28	$ 1.47	$ 1.48
Numerator for net income per share - diluted:
Net income attributable to common shareholders	$ 31,784	$ 37,448	$ 37,203
Weighted average common shares outstanding – basic (in shares)	24,922	25,422	25,170
Weighted average effect of dilutive securities – stock options (in shares)	130	218	526
Denominator for diluted earnings per share – adjusted weighted average shares (in shares)	25,052	25,640	25,696
Net income per share – diluted (in dollars per share)	$ 1.27	$ 1.46	$ 1.45