Note 6 - Securities - Available-for-sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Due in one year or less, amortized cost	$ 6,037
Due in one year or less, fair value	6,052
Due from one year through five years. amortized cost	34,921
Due from one year through five years, fair value	35,666
Due from five years through ten years, amortized cost	43,081
Due from five years through ten years, fair value	44,315
Due after ten years, amortized cost	35,564
Due after ten years, fair value	37,430
Sub-total, amortized cost	119,603
Sub-total, fair value	123,463
Total, amortized cost	358,185	$ 368,725
Total, fair value	363,467	363,273
Residential Pass-Through Securities [Member]
Mortgage-backed securities issued or guaranteed by U.S. Government agencies or sponsored agencies, amortized cost	62,051
Mortgage-backed securities issued or guaranteed by U.S. Government agencies or sponsored agencies, fair value	62,245
Total, amortized cost	62,051	54,827
Total, fair value	62,245	53,445
Residential Collateralized Mortgage Obligations [Member]
Mortgage-backed securities issued or guaranteed by U.S. Government agencies or sponsored agencies, amortized cost	127,950
Mortgage-backed securities issued or guaranteed by U.S. Government agencies or sponsored agencies, fair value	127,815
Total, amortized cost	127,950	148,964
Total, fair value	127,815	$ 145,912
Commercial Mortgage-backed Securities [Member]
Mortgage-backed securities issued or guaranteed by U.S. Government agencies or sponsored agencies, amortized cost	48,581
Mortgage-backed securities issued or guaranteed by U.S. Government agencies or sponsored agencies, fair value	$ 49,944