Note 2 - Investment Securities (Details) - Unrealized Loss Positions of Available-for-sale Securities - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Note 2 - Investment Securities (Details) - Unrealized Loss Positions of Available-for-sale Securities [Line Items]
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, fair value	$ 10,155	$ 13,130
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, unrealized loss	(81)	(148)
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, fair value	6,327	8,519
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, unrealized loss	(95)	(148)
Securities available-for-sale in a continuous unrealized loss position, fair value	16,482	21,649
Securities available-for-sale in a continuous unrealized loss position, unrealized loss	(176)	(296)
US Government Agencies Debt Securities [Member]
Note 2 - Investment Securities (Details) - Unrealized Loss Positions of Available-for-sale Securities [Line Items]
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, fair value	6,850	8,878
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, unrealized loss	(50)	(106)
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, fair value	3,284	5,275
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, unrealized loss	(49)	(85)
Securities available-for-sale in a continuous unrealized loss position, fair value	10,134	14,153
Securities available-for-sale in a continuous unrealized loss position, unrealized loss	(99)	(191)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Note 2 - Investment Securities (Details) - Unrealized Loss Positions of Available-for-sale Securities [Line Items]
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, fair value	1,562	3,447
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, unrealized loss	(5)	(32)
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, fair value	2,504	2,718
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, unrealized loss	(40)	(58)
Securities available-for-sale in a continuous unrealized loss position, fair value	4,066	6,165
Securities available-for-sale in a continuous unrealized loss position, unrealized loss	(45)	(90)
US States and Political Subdivisions Debt Securities [Member]
Note 2 - Investment Securities (Details) - Unrealized Loss Positions of Available-for-sale Securities [Line Items]
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, fair value	1,743	805
Securities available-for-sale in a continuous unrealized loss position, less than 12 months, unrealized loss	(26)	(10)
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, fair value	539	526
Securities available-for-sale in a continuous unrealized loss position, 12 months or more, unrealized loss	(6)	(5)
Securities available-for-sale in a continuous unrealized loss position, fair value	2,282	1,331
Securities available-for-sale in a continuous unrealized loss position, unrealized loss	$ (32)	$ (15)