Note 3 - Available-for-sale Securities - Investment Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized cost, due within 5 years	$ 7,504	$ 7,823
Amortized cost, due after 5 years through 10 years	29,745	30,226
Amortized cost, due after 10 years	9,932	10,811
Available-for-sale securities, amortized cost	47,181	48,860
Fair value, due within 5 years	7,241	7,961
Fair value, due after 5 years through 10 years	27,407	29,497
Fair value, due after 10 years	10,182	10,859
Fair value, total	44,830	48,317
Corporate Debt Securities [Member]
Amortized cost, due within 5 years	4,017	4,018
Amortized cost, due after 5 years through 10 years	14,000	14,000
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	18,017	18,018
Fair value, due within 5 years	3,739	4,151
Fair value, due after 5 years through 10 years	11,756	13,162
Fair value, due after 10 years
Fair value, total	15,495	17,313
Subordinated Notes [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	9,025	9,022
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	9,025	9,022
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	8,947	9,204
Fair value, due after 10 years
Fair value, total	8,947	9,204
SBA Loan Pools [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	4,805	5,157
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	4,805	5,157
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	4,770	5,115
Fair value, due after 10 years
Fair value, total	4,770	5,115
Available-for-sale Securities with Single Maturity Dates [Member]
Amortized cost, due within 5 years	4,017	4,018
Amortized cost, due after 5 years through 10 years	27,830	28,179
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	31,847	32,197
Fair value, due within 5 years	3,739	4,151
Fair value, due after 5 years through 10 years	25,473	27,481
Fair value, due after 10 years
Fair value, total	29,212	31,632
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Amortized cost, due within 5 years	3,487	3,805
Amortized cost, due after 5 years through 10 years	1,915	2,047
Amortized cost, due after 10 years	9,932	10,811
Available-for-sale securities, amortized cost	15,334	16,663
Fair value, due within 5 years	3,502	3,810
Fair value, due after 5 years through 10 years	1,934	2,016
Fair value, due after 10 years	10,182	10,859
Fair value, total	$ 15,618	$ 16,685