Note 21 - Regulatory Matters - Risk Based Capital Amounts and Ratios (Details) $ in Thousands		Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Total risk-based capital, actual amount	[1]	$ 872,434	$ 849,836
Total risk-based capital, actual ratio	[1]	0.1269	0.1256
Total risk-based capital, minimum for adequately capitalized amount	[1]	$ 549,896	$ 541,370
Total risk-based capital, minimum for adequately capitalized ratio	[1]	0.08	0.08
Common Equity Tier 1 risk-based capital, actual amount	[1]	$ 763,818	$ 747,376
Common Equity Tier 1 risk-based capital, actual ratio	[1]	0.1111	0.1104
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 309,316	$ 304,521
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized ratio	[1]	0.045	0.045
Tier 1 risk-based capital, actual amount	[1]	$ 789,818	$ 773,376
Tier 1 risk-based capita, actual ratio	[1]	0.1149	0.1143
Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 412,422	$ 406,027
Tier 1 risk-based capital, minimum for adequately capitalized ratio	[1]	0.06	0.06
Leverage, actual amount		$ 789,818	$ 773,376
Leverage, actual ratio		0.0982	0.0962
Leverage, minimum for adequately capitalized amount		$ 321,766	$ 321,713
Leverage, minimum for adequately capitalized ratio		0.04	0.04
Tier 1 risk-based capital, actual amount	[1]	$ 789,818	$ 773,376
Subsidiaries [Member]
Total risk-based capital, actual amount	[1]	$ 847,856	$ 823,275
Total risk-based capital, actual ratio	[1]	0.1237	0.1221
Total risk-based capital, minimum for adequately capitalized amount	[1]	$ 548,183	$ 539,609
Total risk-based capital, minimum for adequately capitalized ratio	[1]	0.08	0.08
Total risk-based capital, minimum for well capitalized amount	[1]	$ 685,228	$ 674,511
Total risk-based capital, minimum for well capitalized ratio	[1]	0.10	0.10
Common Equity Tier 1 risk-based capital, actual amount	[1]	$ 765,240	$ 746,815
Common Equity Tier 1 risk-based capital, actual ratio	[1]	0.1117	0.1107
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 308,353	$ 303,530
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized ratio	[1]	0.045	0.045
Common Equity Tier 1 risk-based capital, minimum for well capitalized amount	[1]	$ 445,398	$ 438,432
Common Equity Tier 1 risk-based capital, minimum for well capitalized ratio	[1]	0.065	0.065
Tier 1 risk-based capital, actual amount	[1]	$ 765,240	$ 746,815
Tier 1 risk-based capita, actual ratio	[1]	0.1117	0.1107
Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 411,137	$ 404,707
Tier 1 risk-based capital, minimum for adequately capitalized ratio	[1]	0.06	0.06
Tier 1 risk-based capital, minimum for well capitalized amount	[1]	$ 548,183	$ 539,609
Tier 1 risk-based capital, minimum for well capitalized ratio	[1]	0.08	0.08
Leverage, actual amount		$ 765,240	$ 746,815
Leverage, actual ratio		0.0952	0.093
Leverage, minimum for adequately capitalized amount		$ 321,523	$ 321,323
Leverage, minimum for adequately capitalized ratio		0.04	0.04
Leverage, minimum for well capitalized amount		$ 401,903	$ 401,654
Leverage, minimum for well capitalized ratio		0.05	0.05
Tier 1 risk-based capital, actual amount	[1]	$ 765,240	$ 746,815

[1] Ratio is computed in relation to risk-weighted assets.