Note 11 - Regulatory Matters - Actual Capital Levels and Minimum Levels (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
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	$ 455,797	$ 429,038
Total capital, ratio	0.138	0.131
Total capital minimum required for capital adequacy, amount	$ 263,844	$ 262,141
Total capital minimum required for capital adequacy, ratio	0.080	0.080
Tier 1 capital, amount	$ 420,225	$ 405,148
Tier 1 capital, ratio	0.127	0.124
Tier 1 capital minimum required for capital adequacy, amount	$ 197,883	$ 196,606
Tier 1 capital minimum required for capital adequacy, ratio	0.060	0.060
Common equity tier 1, amount	$ 374,907	$ 360,342
Common equity tier 1, ratio	0.114	0.110
Common equity tier 1 minimum required for capital adequacy, amount	$ 148,413	$ 147,454
Common equity tier 1 capital minimum required for capital adequacy, ratio	0.045	0.045
Tier 1 capital to average assets, amount	$ 420,225	$ 405,148
Tier 1 capital to average assets, ratio	0.098	0.113
Tier 1 capital to average assets, minimum required for capital adequacy, amount	$ 171,494	$ 143,689
Tier 1 capital to average assets minimum required for capital adequacy, ratio	0.040	0.040
Bank [Member]
Total capital, amount	$ 446,072	$ 424,917
Total capital, ratio	0.135	0.130
Total capital minimum required for capital adequacy, amount	$ 263,787	$ 262,088
Total capital minimum required for capital adequacy, ratio	0.080	0.080
Total capital to be well capitalized, amount	$ 329,734	$ 327,610
Total capital to be well capitalized, ratio	0.100	0.100
Tier 1 capital, amount	$ 410,500	$ 401,027
Tier 1 capital, ratio	0.125	0.122
Tier 1 capital minimum required for capital adequacy, amount	$ 197,840	$ 196,566
Tier 1 capital minimum required for capital adequacy, ratio	0.060	0.060
Tier 1 capital to be well capitalized, amount	$ 263,787	$ 262,088
Tier 1 capital to be well capitalized, ratio	0.080	0.080
Common equity tier 1, amount	$ 410,500	$ 401,027
Common equity tier 1, ratio	0.125	0.122
Common equity tier 1 minimum required for capital adequacy, amount	$ 148,380	$ 147,425
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	$ 214,327	$ 212,947
Common equity tier 1 capital to be well capitalized, ratio	0.065	0.065
Tier 1 capital to average assets, amount	$ 410,500	$ 401,027
Tier 1 capital to average assets, ratio	0.096	0.112
Tier 1 capital to average assets, minimum required for capital adequacy, amount	$ 171,466	$ 143,670
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	$ 214,333	$ 179,588
Tier 1 capital to average assets to be well capitalized, ratio	0.050	0.050