Note 9 - Goodwill and Core Deposit Intangible - Net - Core Deposit Intangible (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Balance—beginning of period	$ 10,353
Amortization expense	(1,021)	$ (1,021)	$ (724)
Balance—end of period	9,332	10,353
Core Deposits [Member]
Balance—beginning of period	10,353	11,374	7,338
Finite-lived iIntangible assets acquired			4,760
Amortization expense	(1,021)	(1,021)	(724)
Balance—end of period	$ 9,332	$ 10,353	$ 11,374