Note 5 - Loans and the Allowance for Credit Losses - Composition of Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Gross loans	$ 8,188,210	$ 8,109,161
Net deferred loan fees	(7,101)	(9,472)
Total loans receivable	8,181,109	8,099,689
Commercial Portfolio Segment [Member]
Gross loans	1,475,571	1,472,734
Commercial Real Estate Portfolio Segment [Member]
Gross loans	5,837,539	5,795,228
Commercial Construction Portfolio Segment [Member]
Gross loans	622,748	574,139
Residential Portfolio Segment [Member]
Gross loans	251,416	264,748
Consumer Portfolio Segment [Member]
Gross loans	$ 936	$ 2,312