Note 12 - Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available-for-sale debt securities, at fair value	$ 302,638	$ 272,839
Equity securities, at fair value	934	920
Derivative liabilities	14
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale debt securities, at fair value	149,798	117,763
Collateralized Mortgage Backed Securities [Member]
Available-for-sale debt securities, at fair value	18,793	18,485
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Available-for-sale debt securities, at fair value	23,765	25,075
Corporate Debt Securities [Member]
Available-for-sale debt securities, at fair value	9,584	7,182
Asset-backed Securities [Member]
Available-for-sale debt securities, at fair value	6,802	5,621
Negotiable Certificates of Deposit [Member]
Available-for-sale debt securities, at fair value	696	696
Fair Value, Recurring [Member]
Available-for-sale debt securities, at fair value	302,638	272,839
Equity securities, at fair value	934	920
Total assets	303,572	273,759
Derivative liabilities	14
Total liabilities	14
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Equity securities, at fair value	934	920
Total assets	934	920
Derivative liabilities
Total liabilities
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	294,958	267,689
Equity securities, at fair value
Total assets	294,958	267,689
Derivative liabilities	14
Total liabilities	14
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value	7,680	5,150
Equity securities, at fair value
Total assets	7,680	5,150
Derivative liabilities
Total liabilities
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale debt securities, at fair value	149,798	117,763
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	149,798	117,763
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Residential Mortgage [Member]
Available-for-sale debt securities, at fair value	79,211	80,294
Fair Value, Recurring [Member] | Residential Mortgage [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Residential Mortgage [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	79,211	80,294
Fair Value, Recurring [Member] | Residential Mortgage [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Commercial Loan [Member]
Available-for-sale debt securities, at fair value	13,989	17,723
Fair Value, Recurring [Member] | Commercial Loan [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Commercial Loan [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	13,989	17,723
Fair Value, Recurring [Member] | Commercial Loan [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]
Available-for-sale debt securities, at fair value	18,793	18,485
Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	18,793	18,485
Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Available-for-sale debt securities, at fair value	23,765	25,075
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	23,765	25,075
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Available-for-sale debt securities, at fair value	9,584	7,182
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	1,904	2,032
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value	7,680	5,150
Fair Value, Recurring [Member] | Asset-backed Securities [Member]
Available-for-sale debt securities, at fair value	6,802	5,621
Fair Value, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	6,802	5,621
Fair Value, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Negotiable Certificates of Deposit [Member]
Available-for-sale debt securities, at fair value	696	696
Fair Value, Recurring [Member] | Negotiable Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale debt securities, at fair value
Fair Value, Recurring [Member] | Negotiable Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale debt securities, at fair value	696	696
Fair Value, Recurring [Member] | Negotiable Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale debt securities, at fair value