Note 12 - Regulatory Matters - Actual Capital Levels and Minimum Levels (Details) $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Total capital minimum required for capital adequacy, ratio	0.105
Tier 1 capital minimum required for capital adequacy, ratio	0.085
Common equity tier 1 capital minimum required for capital adequacy, ratio	0.070
Consolidated Entities [Member]
Total capital, amount	$ 476,462	$ 468,113
Total capital, ratio	0.135	0.138
Total capital minimum required for capital adequacy, amount	$ 282,093	$ 271,325
Total capital minimum required for capital adequacy, ratio	0.080	0.080
Tier 1 capital, amount	$ 437,567	$ 430,146
Tier 1 capital, ratio	0.124	0.127
Tier 1 capital minimum required for capital adequacy, amount	$ 211,570	$ 203,494
Tier 1 capital minimum required for capital adequacy, ratio	0.060	0.060
Common equity tier 1, amount	$ 391,908	$ 384,658
Common equity tier 1, ratio	0.111	0.113
Common equity tier 1 minimum required for capital adequacy, amount	$ 158,678	$ 152,621
Common equity tier 1 capital minimum required for capital adequacy, ratio	0.045	0.045
Tier 1 capital to average assets, amount	$ 437,567	$ 430,146
Tier 1 capital to average assets, ratio	0.097	0.098
Tier 1 capital to average assets, minimum required for capital adequacy, amount	$ 180,944	$ 176,053
Tier 1 capital to average assets minimum required for capital adequacy, ratio	0.040	0.040
Bank [Member]
Total capital, amount	$ 467,325	$ 457,203
Total capital, ratio	0.133	0.135
Total capital minimum required for capital adequacy, amount	$ 281,968	$ 271,196
Total capital minimum required for capital adequacy, ratio	0.080	0.080
Total capital to be well capitalized, amount	$ 352,460	$ 338,995
Total capital to be well capitalized, ratio	0.100	0.100
Tier 1 capital, amount	$ 428,430	$ 419,236
Tier 1 capital, ratio	0.122	0.124
Tier 1 capital minimum required for capital adequacy, amount	$ 211,476	$ 203,397
Tier 1 capital minimum required for capital adequacy, ratio	0.060	0.060
Tier 1 capital to be well capitalized, amount	$ 281,968	$ 271,196
Tier 1 capital to be well capitalized, ratio	0.080	0.080
Common equity tier 1, amount	$ 428,430	$ 419,236
Common equity tier 1, ratio	0.122	0.124
Common equity tier 1 minimum required for capital adequacy, amount	$ 158,607	$ 152,548
Common equity tier 1 capital minimum required for capital adequacy, ratio	0.045	0.045
Common equity tier 1 capital to be well capitalized, amount	$ 229,099	$ 220,347
Common equity tier 1 capital to be well capitalized, ratio	0.065	0.065
Tier 1 capital to average assets, amount	$ 428,430	$ 419,236
Tier 1 capital to average assets, ratio	0.095	0.095
Tier 1 capital to average assets, minimum required for capital adequacy, amount	$ 180,882	$ 175,999
Tier 1 capital to average assets minimum required for capital adequacy, ratio	0.040	0.040
Tier 1 capital to average assets to be well capitalized, amount	$ 226,102	$ 219,999
Tier 1 capital to average assets to be well capitalized, ratio	0.050	0.050