Note 4 - Loans and Allowance for Loan Losses (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	$ 15.5	$ 24.6
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	6.2	13.1
Impaired Financing Receivable, Interest Income, Accrual Method	1.2	2.4	$ 1.8
Impaired Financing Receivable, Interest Income, Cash Basis Method	0.1	1.7	0.1
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	$ 0.1	$ 0.3	$ 0.1
Minimum Number of Days Past Due at Period End For Loans Modified as Troubled Debt Restructurings	30 days