Note 19 - Regulatory Matters - Risk Based Capital Amounts and Ratios (Details) $ in Thousands		Sep. 30, 2021 USD ($)		Dec. 31, 2020 USD ($)
Total risk-based capital, actual amount	[1]	$ 581,998		$ 470,648
Total risk-based capital, actual ratio	[1]	0.1261		0.1336
Total risk-based capital, minimum for adequately capitalized amount	[1]	$ 369,314		$ 281,887
Total risk-based capital, minimum for adequately capitalized ratio	[1]	0.0800		0.0800
Common Equity Tier 1 risk-based capital, actual amount		$ 539,601	[1]	$ 430,886
Common Equity Tier 1 risk-based capital, actual ratio		0.1169	[1]	0.1223
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized amount		$ 207,739	[1]	$ 158,556
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized ratio		0.0450	[1]	0.0450
Tier 1 risk-based capital, actual amount	[1]	$ 539,601	[2]	$ 430,886
Tier 1 risk-based capita, actual ratio	[1]	0.1169		0.1223
Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 276,985		$ 211,407
Tier 1 risk-based capital, minimum for adequately capitalized ratio	[1]	0.0600		0.0600
Tier 1 risk-based capital, actual amount	[1]	$ 539,601	[2]	$ 430,886
Leverage, actual ratio	[2]	0.0898		0.0957
Leverage, minimum for adequately capitalized amount	[2]	$ 240,340		$ 180,123
Leverage, minimum for adequately capitalized ratio		0.0400	[1]	0.0400	[2]
Leverage, actual amount	[2]			$ 430,886
Subsidiaries [Member]
Total risk-based capital, actual amount	[1]	$ 564,054		$ 456,302
Total risk-based capital, actual ratio	[1]	0.1226		0.1299
Total risk-based capital, minimum for adequately capitalized amount	[1]	$ 368,132		$ 281,106
Total risk-based capital, minimum for adequately capitalized ratio	[1]	0.0800		0.0800
Total risk-based capital, minimum for well capitalized amount	[1]	$ 460,166		$ 351,383
Total risk-based capital, minimum for well capitalized ratio	[1]	0.100		0.1000
Common Equity Tier 1 risk-based capital, actual amount		$ 564,051	[1]	$ 416,540
Common Equity Tier 1 risk-based capital, actual ratio		0.1134	[1]	0.1185
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized amount		$ 207,074	[1]	$ 158,122
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized ratio		0.0450	[1]	0.0450
Common Equity Tier 1 risk-based capital, minimum for well capitalized amount		$ 299,108	[1]	$ 228,399
Common Equity Tier 1 risk-based capital, minimum for well capitalized ratio		0.065	[1]	0.0650
Tier 1 risk-based capital, actual amount	[1]	$ 564,051		$ 416,540
Tier 1 risk-based capita, actual ratio	[1]	0.1134		0.1185
Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 276,099		$ 210,830
Tier 1 risk-based capital, minimum for adequately capitalized ratio	[1]	0.0600		0.0600
Tier 1 risk-based capital, minimum for well capitalized amount	[1]	$ 368,132		$ 281,106
Tier 1 risk-based capital, minimum for well capitalized ratio	[1]	0.080		0.0800
Tier 1 risk-based capital, actual amount	[1]	$ 564,051		$ 416,540
Leverage, actual ratio	[2]	0.0869		0.0926
Leverage, minimum for adequately capitalized amount	[2]	$ 240,011		$ 179,845
Leverage, minimum for adequately capitalized ratio	[2]	0.0400		0.0400
Leverage, actual amount	[2]	$ 564,051		$ 416,540
Leverage, minimum for well capitalized amount	[2]	$ 300,014		$ 224,807
Leverage, minimum for well capitalized ratio	[2]	0.050		0.0500

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

[2] Ratio is computed in relation to average assets.