Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Impaired Loans and Associated Reserves (Details) - USD ($) $ in Thousands		Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019
Principal balance		$ 6,158		$ 5,757
Total recorded investment		5,671	[1]	5,289	[1]	$ 6,337
Impaired loans with no valuation allowance		4,557	[1]	4,174	[1]	5,212
Recorded investment for which there is a related allowance		1,114	[1]	1,115	[1]	1,125
Related allowance		110		110		132
Recorded investment for which there is no related allowance		4,557	[1]	4,174	[1]	$ 5,212
Consumer Real Estate Portfolio Segment [Member] | Equity Lines [Member]
Principal balance		100	[2]	100
Total recorded investment		100	[1],[2]	100
Impaired loans with no valuation allowance		100	[1],[2]	100
Recorded investment for which there is a related allowance			[1],[2]
Related allowance			[2]
Recorded investment for which there is no related allowance		100	[1],[2]	100
Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member]
Principal balance	[2]	23		221
Total recorded investment	[1],[2]	22		221
Impaired loans with no valuation allowance	[1],[2]	22		221
Recorded investment for which there is a related allowance	[1],[2]
Related allowance	[2]
Recorded investment for which there is no related allowance	[1],[2]	22		221
Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member]
Principal balance	[2]	488		441
Total recorded investment	[1],[2]	486		438
Impaired loans with no valuation allowance	[1],[2]	289		241
Recorded investment for which there is a related allowance	[1],[2]	197		197
Related allowance	[2]	2		2
Recorded investment for which there is no related allowance	[1],[2]	289		241
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member]
Principal balance	[2]	921		929
Total recorded investment	[1],[2]	885		895
Impaired loans with no valuation allowance	[1],[2]	885		895
Recorded investment for which there is a related allowance	[1],[2]
Related allowance	[2]
Recorded investment for which there is no related allowance	[1],[2]	885		895
Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Principal balance	[2]			278
Total recorded investment	[1],[2]			278
Impaired loans with no valuation allowance	[1],[2]			278
Recorded investment for which there is a related allowance	[1],[2]			0
Related allowance	[2]			0
Recorded investment for which there is no related allowance	[1],[2]			278
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member]
Principal balance	[2]	3,705		2,867
Total recorded investment	[1],[2]	3,257		2,435
Impaired loans with no valuation allowance	[1],[2]	3,257		2,435
Recorded investment for which there is a related allowance	[1],[2]	0		0
Related allowance	[2]	0		0
Recorded investment for which there is no related allowance	[1],[2]	3,257		2,435
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member]
Principal balance	[2]	917		917
Total recorded investment	[1],[2]	917		918
Impaired loans with no valuation allowance	[1],[2]
Recorded investment for which there is a related allowance	[1],[2]	917		918
Related allowance	[2]	108		108
Recorded investment for which there is no related allowance	[1],[2]
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member]
Principal balance	[2]	4		4
Total recorded investment	[1],[2]	4		4
Impaired loans with no valuation allowance	[1],[2]	4		4
Recorded investment for which there is a related allowance	[1],[2]
Related allowance	[2]	0
Recorded investment for which there is no related allowance	[1],[2]	$ 4		$ 4

[1] Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.

[2] Only classes with impaired loans are shown.