Note 9 - Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income used in the computation of basic and diluted net income per share (in thousands)	$ 15,174	$ 2,781	$ 18,541	$ 5,157
Weighted average shares outstanding - basic (in shares)	15,016,062	14,952,802	15,020,457	14,940,072
Dilutive common stock equivalents (in shares)	155,024	334,555	165,535	334,934
Weighted average number of shares outstanding during the period, diluted (in shares)	15,171,086	15,287,357	15,185,992	15,275,006
Basic (in dollars per share)	$ 1.01	$ 0.19	$ 1.23	$ 0.35
Diluted (in dollars per share)	$ 1.00	$ 0.18	$ 1.22	$ 0.34