Note 2 - Investment Securities - Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Securities available for sale, amortized cost	$ 257,586	$ 266,437
Securities available for sale, gross unrealized gains	3,062	862
Securities available for sale, gross unrealized losses	1,203	5,458
Securities available for sale, fair value	259,445	261,841
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale, amortized cost	85,363	94,746
Securities available for sale, gross unrealized gains	85
Securities available for sale, gross unrealized losses	790	3,489
Securities available for sale, fair value	84,658	91,257
Agency Collateralized Mortgage Obligations [Member]
Securities available for sale, amortized cost	40,181	33,222
Securities available for sale, gross unrealized gains	212	152
Securities available for sale, gross unrealized losses	167	382
Securities available for sale, fair value	40,226	32,992
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost	64,219	75,461
Securities available for sale, gross unrealized gains	480	59
Securities available for sale, gross unrealized losses	240	1,016
Securities available for sale, fair value	64,459	74,504
Municipal Notes [Member]
Securities available for sale, amortized cost	67,823	63,008
Securities available for sale, gross unrealized gains	2,285	651
Securities available for sale, gross unrealized losses	6	571
Securities available for sale, fair value	$ 70,102	$ 63,088