Note 7 - Core Deposit Intangible Assets, Net (Details Textual) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Core Deposits, Gross	$ 17,500,000	$ 17,500,000
Finite-Lived Intangible Assets, Accumulated Amortization	9,900,000	7,500,000
Finite-Lived Intangible Assets, Net	$ 7,600,000	$ 9,957,000