Note 3 - Available-for-sale Securities - Investment Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized cost, due within 5 years	$ 7,823	$ 8,326
Amortized cost, due after 5 years through 10 years	30,226	19,168
Amortized cost, due after 10 years	10,811	13,116
Available-for-sale securities, amortized cost	48,860	40,610
Fair value, due within 5 years	7,961	8,329
Fair value, due after 5 years through 10 years	29,497	18,631
Fair value, due after 10 years	10,859	12,536
Fair value, total	48,317	39,496
Corporate Debt Securities [Member]
Amortized cost, due within 5 years	4,018
Amortized cost, due after 5 years through 10 years	14,000	9,000
Amortized cost, due after 10 years		5,000
Available-for-sale securities, amortized cost	18,018	14,000
Fair value, due within 5 years	4,151
Fair value, due after 5 years through 10 years	13,162	8,537
Fair value, due after 10 years		4,437
Fair value, total	17,313	12,974
Subordinated Notes [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	9,022	4,500
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	9,022	4,500
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	9,204	4,564
Fair value, due after 10 years
Fair value, total	9,204	4,564
SBA Loan Pools [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	5,157
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	5,157
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	5,115
Fair value, due after 10 years
Fair value, total	5,115
Available-for-sale Securities with Single Maturity Dates [Member]
Amortized cost, due within 5 years	4,018	1,484
Amortized cost, due after 5 years through 10 years	28,179	13,500
Amortized cost, due after 10 years		5,000
Available-for-sale securities, amortized cost	32,197	19,984
Fair value, due within 5 years	4,151	1,485
Fair value, due after 5 years through 10 years	27,481	13,101
Fair value, due after 10 years		4,437
Fair value, total	31,632	19,023
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Amortized cost, due within 5 years	3,805	6,842
Amortized cost, due after 5 years through 10 years	2,047	5,668
Amortized cost, due after 10 years	10,811	8,116
Available-for-sale securities, amortized cost	16,663	20,626
Fair value, due within 5 years	3,810	6,844
Fair value, due after 5 years through 10 years	2,016	5,530
Fair value, due after 10 years	10,859	8,099
Fair value, total	$ 16,685	20,473
US Treasury Securities [Member]
Amortized cost, due within 5 years		1,484
Amortized cost, due after 5 years through 10 years
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost		1,484
Fair value, due within 5 years		1,485
Fair value, due after 5 years through 10 years
Fair value, due after 10 years
Fair value, total		$ 1,485