Note 8 - Deposits (Details Textual) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deposit Liabilities, Accrued Interest	$ 10.5	$ 4.4	$ 2.9
Geographic Distribution, Domestic [Member]
Time Deposits, at or Above FDIC Insurance Limit	2,800.0	1,900.0
Geographic Distribution, Foreign [Member]
Time Deposits, at or Above FDIC Insurance Limit	$ 174.4	$ 152.0