Note 2 - Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Less than 12 months, fair value	$ 31,421	$ 27,562
Less than 12 months, unrealized loss	(437)	(182)
12 months or more, fair value	50,394	43,661
12 months or more, unrealized loss	(1,570)	(1,073)
Total, fair value	81,815	71,223
Total, unrealized loss	(2,007)	(1,255)
US Treasury and Government [Member]
Less than 12 months, fair value
Less than 12 months, unrealized loss
12 months or more, fair value	4,445	4,472
12 months or more, unrealized loss	(87)	(69)
Total, fair value	4,445	4,472
Total, unrealized loss	(87)	(69)
US Government Agencies Debt Securities [Member]
Less than 12 months, fair value	2,472	3,447
Less than 12 months, unrealized loss	(30)	(42)
12 months or more, fair value	10,337	8,975
12 months or more, unrealized loss	(269)	(170)
Total, fair value	12,809	12,422
Total, unrealized loss	(299)	(212)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Less than 12 months, fair value	19,483	9,659
Less than 12 months, unrealized loss	(297)	(48)
12 months or more, fair value	7,693	6,581
12 months or more, unrealized loss	(193)	(105)
Total, fair value	27,176	16,240
Total, unrealized loss	(490)	(153)
Collateralized Mortgage Obligations [Member]
Less than 12 months, fair value	1,443	954
Less than 12 months, unrealized loss	(5)	(16)
12 months or more, fair value	15,388	19,147
12 months or more, unrealized loss	(805)	(692)
Total, fair value	16,831	20,101
Total, unrealized loss	(810)	(708)
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months, fair value	7,061	10,510
Less than 12 months, unrealized loss	(67)	(60)
12 months or more, fair value	10,083	3,487
12 months or more, unrealized loss	(157)	(36)
Total, fair value	17,144	13,997
Total, unrealized loss	(224)	(96)
Corporate Debt Securities [Member]
Less than 12 months, fair value	962	2,992
Less than 12 months, unrealized loss	(38)	(16)
12 months or more, fair value	2,448	999
12 months or more, unrealized loss	(59)	(1)
Total, fair value	3,410	3,991
Total, unrealized loss	$ (97)	$ (17)