Note 3 - Available-for-sale Securities - Investment Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Amortized cost, due within 5 years	$ 10,667	$ 8,326
Amortized cost, due after 5 years through 10 years	21,211	19,168
Amortized cost, due after 10 years	12,728	13,116
Available-for-sale securities, amortized cost	44,606	40,610
Fair value, due within 5 years	10,687	8,329
Fair value, due after 5 years through 10 years	20,796	18,631
Fair value, due after 10 years	12,356	12,536
Available-for-sale securities	43,839	39,496
Corporate Debt Securities [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	12,000	9,000
Amortized cost, due after 10 years	5,000	5,000
Available-for-sale securities, amortized cost	17,000	14,000
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	11,504	8,537
Fair value, due after 10 years	4,561	4,437
Available-for-sale securities	16,065	12,974
Subordinated Notes [Member]
Amortized cost, due within 5 years
Amortized cost, due after 5 years through 10 years	6,903	4,500
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	6,903	4,500
Fair value, due within 5 years
Fair value, due after 5 years through 10 years	7,029	4,564
Fair value, due after 10 years
Available-for-sale securities	7,029	4,564
US Treasury Securities [Member]
Amortized cost, due within 5 years	1,492	1,484
Amortized cost, due after 5 years through 10 years
Amortized cost, due after 10 years
Available-for-sale securities, amortized cost	1,492	1,484
Fair value, due within 5 years	1,496	1,485
Fair value, due after 5 years through 10 years
Fair value, due after 10 years
Available-for-sale securities	1,496	1,485
Available-for-sale Securities with Single Maturity Dates [Member]
Amortized cost, due within 5 years	1,492	1,484
Amortized cost, due after 5 years through 10 years	18,903	13,500
Amortized cost, due after 10 years	5,000	5,000
Available-for-sale securities, amortized cost	25,395	19,984
Fair value, due within 5 years	1,496	1,485
Fair value, due after 5 years through 10 years	18,533	13,101
Fair value, due after 10 years	4,561	4,437
Available-for-sale securities	24,590	19,023
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Amortized cost, due within 5 years	9,175	6,842
Amortized cost, due after 5 years through 10 years	2,308	5,668
Amortized cost, due after 10 years	7,728	8,116
Available-for-sale securities, amortized cost	19,211	20,626
Fair value, due within 5 years	9,191	6,844
Fair value, due after 5 years through 10 years	2,263	5,530
Fair value, due after 10 years	7,795	8,099
Available-for-sale securities	$ 19,249	$ 20,473