Note 18 - Regulatory Matters - Risk Based Capital Amounts and Ratios (Details) $ in Thousands		Mar. 31, 2021 USD ($)		Dec. 31, 2020 USD ($)
Total risk-based capital, actual amount	[1]	$ 483,547		$ 470,648
Total risk-based capital, actual ratio	[1]	0.1339		0.1336
Total risk-based capital, minimum for adequately capitalized amount	[1]	$ 288,967		$ 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		$ 444,896	[1]	$ 430,886
Common Equity Tier 1 risk-based capital, actual ratio		0.1232	[1]	0.1223
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized amount		$ 162,544	[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]	$ 444,896	[2]	$ 430,886
Tier 1 risk-based capita, actual ratio	[1]	0.1232		0.1223
Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 216,725		$ 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]	$ 444,896	[2]	$ 430,886
Leverage, actual ratio	[2]	0.0946		0.0957
Leverage, minimum for adequately capitalized amount	[2]	$ 188,063		$ 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]	$ 470,308		$ 456,302
Total risk-based capital, actual ratio	[1]	0.1306		0.1299
Total risk-based capital, minimum for adequately capitalized amount	[1]	$ 288,044		$ 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]	$ 360,055		$ 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		$ 431,657	[1]	$ 416,540
Common Equity Tier 1 risk-based capital, actual ratio		0.1199	[1]	0.1185
Common Equity Tier 1 risk-based capital, minimum for adequately capitalized amount		$ 162,025	[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		$ 234,036	[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]	$ 431,657		$ 416,540
Tier 1 risk-based capita, actual ratio	[1]	0.1199		0.1185
Tier 1 risk-based capital, minimum for adequately capitalized amount	[1]	$ 216,033		$ 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]	$ 288,044		$ 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]	$ 431,657		$ 416,540
Leverage, actual ratio	[2]	0.0920		0.0926
Leverage, minimum for adequately capitalized amount	[2]	$ 187,763		$ 179,845
Leverage, minimum for adequately capitalized ratio	[2]	0.0400		0.0400
Leverage, actual amount	[2]	$ 431,657		$ 416,540
Leverage, minimum for well capitalized amount	[2]	$ 234,703		$ 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.