Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Investments in Affordable Housing and Alternative Energy Partnerships (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investments in affordable housing partnerships, net	$ 279,981	$ 276,506
Other borrowings for affordable housing limited partnerships	23,714	29,022
Investments in affordable housing and alternative energy partnerships, unfunded commitments	103,060	114,541
Investments in alternative energy tax credit partnerships, net	$ 29,035	$ 32,175