Note 3 - Securities - Securities Available-for-sale With Unrealized Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Less than 12 Months - Fair Value		$ 10,545
Less than 12 Months - Unrealized Loss		(44)
12 Months or More - Fair Value	27,870	71,298
12 Months or More - Unrealized Loss	(294)	(2,759)
Fair Value	27,870	81,843
Unrealized Loss	(294)	(2,803)
US Government-sponsored Enterprises Debt Securities [Member]
Less than 12 Months - Fair Value		1,981
Less than 12 Months - Unrealized Loss		(1)
12 Months or More - Fair Value	1,991	8,679
12 Months or More - Unrealized Loss	(16)	(214)
Fair Value	1,991	10,660
Unrealized Loss	(16)	(215)
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Less than 12 Months - Fair Value		8,564
Less than 12 Months - Unrealized Loss		(43)
12 Months or More - Fair Value	25,879	62,619
12 Months or More - Unrealized Loss	(278)	(2,545)
Fair Value	25,879	71,183
Unrealized Loss	$ (278)	$ (2,588)