Note 6 - Investments in Affordable Housing and Alternative Energy Partnerships - Investments in Affordable Housing and Alternative Energy Partnerships (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Investments in affordable housing partnerships, net	$ 295,740	$ 289,920
Other borrowings for affordable housing limited partnerships	15,787	22,600
Investments in affordable housing and alternative energy partnerships, unfunded commitments	106,452	133,491
Investments in alternative energy tax credit partnerships, net	$ 19,943	$ 37,208