Note 1 - Significant Accounting Policies and Related Matters - Computation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basic:
Net income available for common stockholders	$ 6,175	$ 6,504	$ 8,299	$ 5,929	$ 7,033	$ 7,513	$ 3,500	$ 3,174	$ 26,907	$ 21,220	$ 17,934
Weighted average shares outstanding (in shares)									21,157	20,246	19,813
Basic earnings per share (in dollars per share)	$ 0.28	$ 0.30	$ 0.40	$ 0.29	$ 0.35	$ 0.37	$ 0.17	$ 0.16	$ 1.27	$ 1.05	$ 0.91
Common stock equivalents, if dilutive (in shares)									318	233	513
Shares used in computing diluted earnings per common share (in shares)									21,475	20,479	20,326
Diluted earnings per share (in dollars per share)	$ 0.28	$ 0.30	$ 0.40	$ 0.28	$ 0.34	$ 0.37	$ 0.17	$ 0.16	$ 1.25	$ 1.04	$ 0.88
Shares excluded in computing diluted earnings per share as those shares would be anti-dilutive (in shares)									10	483	468