Note 6 - Investments in Affordable Housing and Alternative Energy Partnerships - Investments in Affordable Housing and Alternative Energy Partnerships (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments in affordable housing partnerships, net	$ 259,046	$ 260,112
Other borrowings for affordable housing limited partnerships	17,298	17,481
Investments in affordable housing and alternative energy partnerships, unfunded commitments	113,046	124,657
Investments in alternative energy tax credit partnerships, net	$ 23,688	$ 12,759