Note 3 - Available-for-sale Securities - Investment Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Amortized cost, due within 5 years	$ 15,727	$ 8,326
Amortized cost, due after 5 years through 10 years	28,157	19,168
Amortized cost, due after 10 years	7,155	13,116
Available-for-sale securities, amortized cost	51,039	40,610
Fair value, due within 5 years	15,819	8,329
Fair value, due after 5 years through 10 years	27,005	18,631
Fair value, due after 10 years	7,233	12,536
Available-for-sale securities	50,057	39,496
Corporate Debt Securities [Member]
Amortized cost, due within 5 years	4,019
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	18,019	14,000
Fair value, due within 5 years	4,081
Fair value, due after 5 years through 10 years	12,782	8,537
Fair value, due after 10 years		4,437
Available-for-sale securities	16,863	12,974
Subordinated Notes [Member]
Amortized cost, due within 5 years	1,407
Amortized cost, due after 5 years through 10 years	6,611	4,500
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	8,018	4,500
Fair value, due within 5 years	1,426
Fair value, due after 5 years through 10 years	6,766	4,564
Fair value, due after 10 years
Available-for-sale securities	8,192	4,564
SBA Loan Pools [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	5,369
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	5,369
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	5,320
Fair value, due after 10 years
Available-for-sale securities	5,320
US Treasury Securities [Member]
Amortized cost, due within 5 years	1,496	1,484
Amortized cost, due after 5 years through 10 years
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	1,496	1,484
Fair value, due within 5 years	1,499	1,485
Fair value, due after 5 years through 10 years
Fair value, due after 10 years
Available-for-sale securities	1,499	1,485
Available-for-sale Securities with Single Maturity Dates [Member]
Amortized cost, due within 5 years	6,922	1,484
Amortized cost, due after 5 years through 10 years	25,980	13,500
Amortized cost, due after 10 years		5,000
Available-for-sale securities, amortized cost	32,902	19,984
Fair value, due within 5 years	7,006	1,485
Fair value, due after 5 years through 10 years	24,868	13,101
Fair value, due after 10 years		4,437
Available-for-sale securities	31,874	19,023
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Amortized cost, due within 5 years	8,805	6,842
Amortized cost, due after 5 years through 10 years	2,177	5,668
Amortized cost, due after 10 years	7,155	8,116
Available-for-sale securities, amortized cost	18,137	20,626
Fair value, due within 5 years	8,813	6,844
Fair value, due after 5 years through 10 years	2,137	5,530
Fair value, due after 10 years	7,233	8,099
Available-for-sale securities	$ 18,183	$ 20,473