Note 9 - Fair Value Measurement - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Estimated fair value	$ 158,002	$ 159,320
Reported Value Measurement [Member]
Cash and cash equivalents	175,531	46,942
Estimated fair value	158,002	159,320
Loans, net	737,650	616,036
FHLB stock	3,667	3,517
Accrued interest receivable	5,421	3,398
Deposits	977,529	747,324
Repurchase agreements	15,159	16,013
FHLB advances	10,000
Junior subordinated deferrable interest debentures	10,310	10,310
Accrued interest payable	71	96
Reported Value Measurement [Member] | Interest Rate Swap [Member]
Interest rate swaps	43
Estimate of Fair Value Measurement [Member]
Cash and cash equivalents	175,531	46,942
Estimated fair value	158,002	159,320
Loans, net	769,605	626,795
Accrued interest receivable	5,421	3,398
Deposits	979,110	747,332
Repurchase agreements	15,159	16,013
FHLB advances	9,992
Junior subordinated deferrable interest debentures	7,249	7,661
Accrued interest payable	71	96
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member]
Interest rate swaps	43
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	175,531	46,942
Accrued interest receivable	8	15
Deposits	938,651	709,130
Accrued interest payable	8	13
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Estimated fair value	158,002	159,320
Accrued interest receivable	564	574
Deposits	40,459	38,202
Repurchase agreements	15,159	16,013
FHLB advances	9,992
Accrued interest payable	48	60
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Interest rate swaps	43
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Loans, net	769,605	626,795
Accrued interest receivable	4,849	2,809
Junior subordinated deferrable interest debentures	7,249	7,661
Accrued interest payable	$ 15	$ 23