Note 7 - Fair Value - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Securities - available-for-sale	$ 141,871,000	$ 113,041,000
Securities - equity investments	13,000	15,000
Fair Value, Inputs, Level 1 [Member]
Securities - available-for-sale
Securities - equity investments	13,000	15,000
Fair Value, Inputs, Level 2 [Member]
Securities - available-for-sale	139,865,000	111,035,000
Securities - equity investments
Fair Value, Inputs, Level 3 [Member]
Securities - available-for-sale	2,006,000	2,006,000
Securities - equity investments
US Government-sponsored Enterprises Debt Securities [Member]
Securities - available-for-sale	6,059,000	3,007,000
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities - available-for-sale
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities - available-for-sale	6,059,000	3,007,000
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities - available-for-sale
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities - available-for-sale	20,045,000	16,581,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 1 [Member]
Securities - available-for-sale
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 2 [Member]
Securities - available-for-sale	20,045,000	16,581,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 3 [Member]
Securities - available-for-sale
Collateralized Mortgage Obligations [Member]
Securities - available-for-sale	22,676,000	15,911,000
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Securities - available-for-sale
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities - available-for-sale	22,676,000	15,911,000
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities - available-for-sale
US States and Political Subdivisions Debt Securities [Member]
Securities - available-for-sale	69,243,000	55,577,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities - available-for-sale
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities - available-for-sale	69,243,000	55,577,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities - available-for-sale
Corporate Debt Securities [Member]
Securities - available-for-sale	23,848,000	21,965,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities - available-for-sale
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities - available-for-sale	21,842,000	19,959,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities - available-for-sale	$ 2,006,000	$ 2,006,000