Note 3 - Securities - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Securities available for sale, amortized cost	$ 281,871	$ 278,379
Securities available for sale, gross unrealized holding gains	2,164	1,144
Securities available for sale, gross unrealized holding losses	1,998	3,508
Securities available for sale, at fair value	282,037	276,015
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost		12,152
Securities available for sale, gross unrealized holding gains		36
Securities available for sale, gross unrealized holding losses	0	0
Securities available for sale, at fair value		12,188
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale, amortized cost	144,518	119,919
Securities available for sale, gross unrealized holding gains	1,207	257
Securities available for sale, gross unrealized holding losses	1,025	2,303
Securities available for sale, at fair value	144,700	117,873
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Residential Mortgage [Member]
Securities available for sale, amortized cost	35,216	17,969
Securities available for sale, gross unrealized holding gains	221	155
Securities available for sale, gross unrealized holding losses	165	40
Securities available for sale, at fair value	35,272	18,084
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Commercial Loan [Member]
Securities available for sale, amortized cost	67,103	100,064
Securities available for sale, gross unrealized holding gains	7	154
Securities available for sale, gross unrealized holding losses	651	868
Securities available for sale, at fair value	66,459	99,350
Collateralized Mortgage Backed Securities [Member]
Securities available for sale, amortized cost	22,335	20,593
Securities available for sale, gross unrealized holding gains	258	159
Securities available for sale, gross unrealized holding losses	71	176
Securities available for sale, at fair value	22,522	20,576
Corporate Debt Securities [Member]
Securities available for sale, amortized cost	5,000	3,500
Securities available for sale, gross unrealized holding gains	445	339
Securities available for sale, gross unrealized holding losses		47
Securities available for sale, at fair value	5,445	3,792
Asset-backed Securities [Member]
Securities available for sale, amortized cost	3,517
Securities available for sale, gross unrealized holding gains	6
Securities available for sale, gross unrealized holding losses	11
Securities available for sale, at fair value	3,512
Negotiable Certificates of Deposit [Member]
Securities available for sale, amortized cost	3,172	3,172
Securities available for sale, gross unrealized holding gains	20	44
Securities available for sale, gross unrealized holding losses	0	0
Securities available for sale, at fair value	3,192	3,216
Equity Securities [Member]
Securities available for sale, amortized cost	1,010	1,010
Securities available for sale, gross unrealized holding gains	0	0
Securities available for sale, gross unrealized holding losses	75	74
Securities available for sale, at fair value	$ 935	$ 936