Note 2 - Securities - Debt Securities by Maturity (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Due in 2019, weighted average yield	1.92%
Due in 2019, amortized cost	$ 3,487,000
Due in 2019, fair value	$ 3,488,000
Due in 2020 through 2024, weighted average yield	2.31%
Due in 2020 through 2024, amortized cost	$ 67,321,000
Due in 2020 through 2024, fair value	$ 67,802,000
Due in 2025 through 2029, weighted average yield	2.70%
Due in 2025 through 2029, amortized cost	$ 113,584,000
Due in 2025 through 2029, fair value	$ 115,696,000
Due in 2030 and beyond, weighted average yield	3.11%
Due in 2030 and beyond, amortized cost	$ 112,686,000
Due in 2030 and beyond, fair value	$ 115,076,000
Weighted average yield	2.78%
Amortized cost	$ 340,141,000	$ 347,795,000
Fair value	$ 345,533,000	337,366,000
Collateralized Mortgage Backed Securities [Member]
No single maturity, weighted average yield	2.87%
No single maturity, amortized cost	$ 42,563,000
No single maturity, fair value	42,971,000
Amortized cost	42,563,000	44,263,000
Fair value	$ 42,971,000	43,658,000
Other Debt and Equity Securities [Member]
No single maturity, weighted average yield	4.50%
No single maturity, amortized cost	$ 500,000
No single maturity, fair value	500,000
Amortized cost	500,000	500,000
Fair value	$ 500,000	$ 500,000