Note 5 - Loans and the Allowance for Credit Losses - Collateral Dependent Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Gross loans	$ 8,162,500	$ 8,351,841
Real Estate [Member]
Gross loans	34,279	59,576
Other Collateral Pledged [Member]
Gross loans	10,174	10,387
Collateral Pledged [Member]
Gross loans	44,453	69,963
Commercial Portfolio Segment [Member]
Gross loans	1,501,732	1,578,730
Commercial Portfolio Segment [Member] | Real Estate [Member]
Gross loans	1,677	4,949
Commercial Portfolio Segment [Member] | Other Collateral Pledged [Member]
Gross loans	10,174	10,387
Commercial Portfolio Segment [Member] | Collateral Pledged [Member]
Gross loans	11,851	15,336
Commercial Real Estate Portfolio Segment [Member]
Gross loans	5,763,869	5,895,545
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Gross loans	29,585	39,986
Commercial Real Estate Portfolio Segment [Member] | Other Collateral Pledged [Member]
Gross loans	0	0
Commercial Real Estate Portfolio Segment [Member] | Collateral Pledged [Member]
Gross loans	29,585	39,986
Commercial Construction Portfolio Segment [Member]
Gross loans	639,168	620,496
Commercial Construction Portfolio Segment [Member] | Real Estate [Member]
Gross loans	2,204	8,700
Commercial Construction Portfolio Segment [Member] | Other Collateral Pledged [Member]
Gross loans	0	0
Commercial Construction Portfolio Segment [Member] | Collateral Pledged [Member]
Gross loans	2,204	8,700
Residential Portfolio Segment [Member]
Gross loans	256,786	256,041
Residential Portfolio Segment [Member] | Real Estate [Member]
Gross loans	813	5,941
Residential Portfolio Segment [Member] | Other Collateral Pledged [Member]
Gross loans	0	0
Residential Portfolio Segment [Member] | Collateral Pledged [Member]
Gross loans	$ 813	$ 5,941