Note 5 - Fair Value Measurements - Assets Measured on a Recurring Basis (Details) - USD ($)	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Total debt securities	$ 171,958,000	$ 171,958,000	$ 170,199,000
Equity securities in financial institutions	779,000		818,000
Investment securities available for sale, at fair value	171,958,000	171,958,000	170,199,000
Subordinated Debt Securities [Member]
Total debt securities		31,308,000	32,537,000
Investment securities available for sale, at fair value		31,308,000	32,537,000
Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities		8,342,000	10,317,000
Investment securities available for sale, at fair value		$ 8,342,000	10,317,000
Fair Value, Recurring [Member]
Total debt securities	171,958,000		170,199,000
Equity securities in financial institutions	779,000		818,000
Total	172,737,000		171,017,000
Investment securities available for sale, at fair value	171,958,000		170,199,000
Fair Value, Recurring [Member] | Subordinated Debt Securities [Member]
Total debt securities	31,308,000		32,537,000
Investment securities available for sale, at fair value	31,308,000		32,537,000
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	132,308,000		127,345,000
Investment securities available for sale, at fair value	132,308,000		127,345,000
Fair Value, Recurring [Member] | Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	8,342,000		10,317,000
Investment securities available for sale, at fair value	8,342,000		10,317,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total debt securities	0		0
Equity securities in financial institutions	779,000		818,000
Total	779,000		818,000
Investment securities available for sale, at fair value	0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Subordinated Debt Securities [Member]
Total debt securities	0		0
Investment securities available for sale, at fair value	0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	0		0
Investment securities available for sale, at fair value	0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	0		0
Investment securities available for sale, at fair value	0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total debt securities	162,128,000		157,999,000
Equity securities in financial institutions	0		0
Total	162,128,000		157,999,000
Investment securities available for sale, at fair value	162,128,000		157,999,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Subordinated Debt Securities [Member]
Total debt securities	21,478,000		20,337,000
Investment securities available for sale, at fair value	21,478,000		20,337,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	132,308,000		127,345,000
Investment securities available for sale, at fair value	132,308,000		127,345,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	8,342,000		10,317,000
Investment securities available for sale, at fair value	8,342,000		10,317,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total debt securities	9,830,000		12,200,000
Equity securities in financial institutions	0		0
Total	9,830,000		12,200,000
Investment securities available for sale, at fair value	9,830,000		12,200,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Subordinated Debt Securities [Member]
Total debt securities	9,830,000		12,200,000
Investment securities available for sale, at fair value	9,830,000		12,200,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	0		0
Investment securities available for sale, at fair value	0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	0		0
Investment securities available for sale, at fair value	$ 0		$ 0