Note 8 - Fair Value Measurements - Assets Measured at Fair Value on Recurring and Nonrecurring Basis (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Securities available for sale	$ 255,028,000	$ 261,841,000
Equity securities	1,800,000	1,700,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure	0
Other Consumer Loan [Member]
Impaired loans	49,000
Fair Value, Recurring [Member]
Securities available for sale	255,028,000	261,841,000
Equity securities	1,823,000	1,715,000
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale	74,656,000	91,257,000
Fair Value, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale	43,797,000	32,992,000
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale	63,985,000	74,504,000
Fair Value, Recurring [Member] | Municipal Notes [Member]
Securities available for sale	72,590,000	63,088,000
Fair Value, Nonrecurring [Member]
Impaired loans	3,077,000	3,737,000
Loans held for sale	5,897,000	2,849,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure		3,142,000
Fair Value, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans	1,972,000	2,181,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure		33,000
Fair Value, Nonrecurring [Member] | Land Segment [Member]
Impaired loans	89,000	152,000
Fair Value, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans	689,000	422,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure		3,109,000
Fair Value, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans	255,000	426,000
Fair Value, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans	23,000	35,000
Fair Value, Nonrecurring [Member] | Residential Construction [Member]
Impaired loans		521,000
Fair Value, Inputs, Level 1 [Member] | Other Consumer Loan [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Securities available for sale
Equity securities	1,823,000	1,715,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Municipal Notes [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Impaired loans
Loans held for sale
Real Estate Acquired through Foreclosure, Fair Value Disclosure
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans
Real Estate Acquired through Foreclosure, Fair Value Disclosure
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member] | Land Segment [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans
Real Estate Acquired through Foreclosure, Fair Value Disclosure
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member] | Residential Construction [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Other Consumer Loan [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Securities available for sale	255,028,000	261,841,000
Equity securities
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale	74,656,000	91,257,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale	43,797,000	32,992,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale	63,985,000	74,504,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Municipal Notes [Member]
Securities available for sale	72,590,000	63,088,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Impaired loans
Loans held for sale	5,897,000	2,849,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans
Real Estate Acquired through Foreclosure, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member] | Land Segment [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans
Real Estate Acquired through Foreclosure, Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member] | Residential Construction [Member]
Impaired loans
Fair Value, Inputs, Level 3 [Member] | Other Consumer Loan [Member]
Impaired loans	49,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Securities available for sale
Equity securities
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Municipal Notes [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Impaired loans	3,077,000	3,737,000
Loans held for sale
Real Estate Acquired through Foreclosure, Fair Value Disclosure		3,142,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans	1,972,000	2,181,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure		33,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Land Segment [Member]
Impaired loans	89,000	152,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans	689,000	422,000
Real Estate Acquired through Foreclosure, Fair Value Disclosure		3,109,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans	255,000	426,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans	$ 23,000	35,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member] | Residential Construction [Member]
Impaired loans		$ 521,000