Note 8 - Fair Value Disclosure - Assets and Liabilities Reported Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities	$ 169,124	$ 194,675
Marketable Equity Securities	2,287	2,710
Available-for-Sale	171,411	197,385
Fair Value, Recurring [Member]
Debt Securities	169,124	194,675
Marketable Equity Securities	2,287	2,710
Available-for-Sale	171,411	197,385
US Government Agencies Debt Securities [Member]
Debt Securities	8,008	48,056
US States and Political Subdivisions Debt Securities [Member]
Debt Securities	24,884	25,843
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Debt Securities	136,232	120,776
Equity Securities - Mutual Funds [Member]
Marketable Equity Securities	1,013	997
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member]
Debt Securities	8,008	48,056
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member]
Debt Securities	24,884	25,843
Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Recurring [Member]
Debt Securities	136,232	120,776
Fair Value, Inputs, Level 1 [Member] | Equity Securities - Mutual Funds [Member] | Fair Value, Recurring [Member]
Marketable Equity Securities	1,013	997
Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other [Member] | Fair Value, Recurring [Member]
Marketable Equity Securities	$ 1,274	$ 1,713