Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Investments in Affordable Housing and Alternative Energy Partnerships (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investments in affordable housing partnerships, net	$ 276,506	$ 259,046
Other borrowings for affordable housing limited partnerships	29,022	17,298
Investments in affordable housing and alternative energy partnerships, unfunded commitments	114,541	113,046
Investments in alternative energy tax credit partnerships, net	$ 32,175	$ 23,688