Note 11 - Earnings Per Common Share - Earnings Per Common Share and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net income (numerator)	$ 20,147	$ 16,962
Weighted average number of common shares outstanding - basic (in shares)	26,821	27,068
Basic earnings per common share (in dollars per share)	$ 0.75	$ 0.63
Add common stock equivalents for options (in shares)	21	71
Weighted average number of common shares outstanding - diluted (denominator) (in shares)	26,842	27,139
Diluted earnings per common share (in dollars per share)	$ 0.75	$ 0.63