Note 2 - Investment Securities - Credit Quality (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Held to maturity	$ 306,403	$ 515,598
AAA/AA/A [Member]
Held to maturity	155,594
BBB [Member]
Held to maturity	561
BB/B/NR [Member]
Held to maturity	150,248
Agency Residential MBS [Member]
Held to maturity	147,632	240,332
Agency Residential MBS [Member] | AAA/AA/A [Member]
Held to maturity	177
Agency Residential MBS [Member] | BBB [Member]
Held to maturity	0
Agency Residential MBS [Member] | BB/B/NR [Member]
Held to maturity	147,455
Non-agency Residential MBS [Member]
Held to maturity	758	1,344
Non-agency Residential MBS [Member] | AAA/AA/A [Member]
Held to maturity	149
Non-agency Residential MBS [Member] | BBB [Member]
Held to maturity	561
Non-agency Residential MBS [Member] | BB/B/NR [Member]
Held to maturity	48
US States and Political Subdivisions Debt Securities [Member]
Held to maturity	158,013	$ 273,922
US States and Political Subdivisions Debt Securities [Member] | AAA/AA/A [Member]
Held to maturity	155,268
US States and Political Subdivisions Debt Securities [Member] | BBB [Member]
Held to maturity	0
US States and Political Subdivisions Debt Securities [Member] | BB/B/NR [Member]
Held to maturity	$ 2,745