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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income applicable to common equity (numerator)	$ 19,562	$ 19,625	$ 36,524	$ 39,271
Weighted average number of common shares outstanding - basic (in shares)	26,935	26,942	27,001	26,892
Basic earnings per common share (in dollars per share)	$ 0.72	$ 0.73	$ 1.35	$ 1.46
Add common stock equivalents for options (in shares)	16	45	23	58
Weighted average number of common shares outstanding - diluted (denominator) (in shares)	26,951	26,987	27,024	26,950
Diluted earnings per common share (in dollars per share)	$ 0.72	$ 0.73	$ 1.35	$ 1.46