Note 5 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Restructurings By Class (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2014
Number of contracts		13	10	4
Pre-modification outstanding principal balance		$ 4,213	$ 1,387	$ 3,042
Post-modification outstanding principal balance	[1]	$ 4,213	$ 1,387	$ 3,043
Real Estate Construction Portfolio Segment[Member] | Construction Loans [Member]
Number of contracts		2
Pre-modification outstanding principal balance		$ 2,882
Post-modification outstanding principal balance	[1]	$ 2,882
Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member]
Number of contracts		1	1
Pre-modification outstanding principal balance		$ 22	$ 8
Post-modification outstanding principal balance	[1]	$ 22	$ 8
Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member]
Number of contracts		8
Pre-modification outstanding principal balance		$ 594
Post-modification outstanding principal balance	[1]	$ 594
Commercial Real Estate Portfolio Segment [Member]
Number of contracts					2
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Number of contracts			1	2
Pre-modification outstanding principal balance			$ 132	$ 3,008
Post-modification outstanding principal balance	[1]		$ 132	$ 3,008
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member]
Number of contracts		2
Pre-modification outstanding principal balance		$ 715
Post-modification outstanding principal balance	[1]	$ 715
Commercial Non Real Estate Segment [Member]
Number of contracts			4	1
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member]
Number of contracts			4	1
Pre-modification outstanding principal balance			$ 1,221	$ 29
Post-modification outstanding principal balance	[1]		$ 1,221	$ 30
Commercial Non Real Estate Segment [Member] | Automobile Loan [Member]
Number of contracts			4	1
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member]
Number of contracts			4	1
Pre-modification outstanding principal balance			$ 26	$ 5
Post-modification outstanding principal balance	[1]		$ 26	$ 5

[1] Post-modification outstanding recorded investment considers amounts immediately following the modification. Amounts do not reflect balances at the end of the period.