Note 4 - Allowance for Loan Losses and Reserve for Unfunded Lending Commitments - Changes in Allowance for Loan Losses and Reserve for Unfunded Lending Commitments (Details) - USD ($)		3 Months Ended				9 Months Ended			12 Months Ended
		Sep. 30, 2021		Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020	Dec. 31, 2020
Balance, beginning of period						$ 21,403,000		$ 13,152,000	$ 13,152,000
Provision for Loan and Lease Losses, Total		$ 482,000		$ (1,400,000)	$ 2,619,000	(870,000)		8,331,000	8,916,000
Charge-offs						(70,000)		(675,000)	(1,006,000)
Recoveries						167,000		280,000	341,000
Balance, end of period		20,630,000			21,088,000	20,630,000		21,088,000	21,403,000
Individually evaluated for impairment		10,000				10,000			30,000
Collectively evaluated for impairment		19,896,000				19,896,000			20,534,000
Loans and Leases Receivable, Allowance, Ending Balance		20,630,000			21,088,000	20,630,000		21,088,000	21,403,000
Individually evaluated for impairment		2,217,000				2,217,000			2,852,000
Collectively evaluated for impairment		1,915,043,000				1,915,043,000			1,982,003,000
Loans and Leases Receivable, Net of Deferred Income, Total		1,940,332,000				1,940,332,000			2,015,056,000
Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						839,000
Balance, end of period		724,000				724,000			839,000
Loans and Leases Receivable, Allowance, Ending Balance		724,000				724,000			839,000
Loans and Leases Receivable, Net of Deferred Income, Total		23,072,000				23,072,000			30,201,000
Unfunded Loan Commitment [Member]
Balance, beginning of period						304,000		329,000	329,000
Provision for (recovery of) loan losses						23,000		10,000	(25,000)
Balance, end of period		327,000			$ 339,000	327,000		339,000	304,000
Commercial Portfolio Segment [Member]
Balance, beginning of period						3,373,000	[1]	2,657,000	2,657,000
Provision for Loan and Lease Losses, Total						(440,000)			1,156,000
Charge-offs						0	[1]		(505,000)
Recoveries						27,000	[1]		65,000
Balance, end of period	[1]	2,960,000				2,960,000			3,373,000
Individually evaluated for impairment		9,000	[1]			9,000	[1]		29,000
Collectively evaluated for impairment		2,930,000	[1]			2,930,000	[1]		3,318,000
Loans and Leases Receivable, Allowance, Ending Balance	[1]	2,960,000				2,960,000			3,373,000
Individually evaluated for impairment		16,000	[1]			16,000	[1]		57,000
Collectively evaluated for impairment		319,837,000	[1]			319,837,000	[1]		490,736,000
Loans and Leases Receivable, Net of Deferred Income, Total		320,278,000	[1]			320,278,000	[1]		491,256,000
Commercial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						26,000
Balance, end of period		21,000	[1]			21,000	[1]		26,000
Loans and Leases Receivable, Allowance, Ending Balance		21,000	[1]			21,000	[1]		26,000
Loans and Leases Receivable, Net of Deferred Income, Total		425,000	[1]			425,000	[1]		463,000
Construction and Land Development [Member]
Balance, beginning of period						1,927,000		1,161,000	1,161,000
Provision for Loan and Lease Losses, Total						(551,000)			764,000
Charge-offs						0			0
Recoveries						0			2,000
Balance, end of period		1,376,000				1,376,000			1,927,000
Individually evaluated for impairment		0				0			0
Collectively evaluated for impairment		1,376,000				1,376,000			1,927,000
Loans and Leases Receivable, Allowance, Ending Balance		1,376,000				1,376,000			1,927,000
Individually evaluated for impairment		0				0			0
Collectively evaluated for impairment		119,967,000				119,967,000			139,833,000
Loans and Leases Receivable, Net of Deferred Income, Total		120,193,000				120,193,000			140,071,000
Construction and Land Development [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						0
Balance, end of period		0				0			0
Loans and Leases Receivable, Allowance, Ending Balance		0				0			0
Loans and Leases Receivable, Net of Deferred Income, Total		226,000				226,000			238,000
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate [Member]
Balance, beginning of period						4,340,000		2,474,000	2,474,000
Provision for Loan and Lease Losses, Total						166,000			1,871,000
Charge-offs						(3,000)			(17,000)
Recoveries						6,000			12,000
Balance, end of period		4,509,000				4,509,000			4,340,000
Individually evaluated for impairment		0				0			0
Collectively evaluated for impairment		4,311,000				4,311,000			4,138,000
Loans and Leases Receivable, Allowance, Ending Balance		4,509,000				4,509,000			4,340,000
Individually evaluated for impairment		14,000				14,000			286,000
Collectively evaluated for impairment		394,875,000				394,875,000			360,579,000
Loans and Leases Receivable, Net of Deferred Income, Total		404,029,000				404,029,000			373,680,000
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						202,000
Balance, end of period		198,000				198,000			202,000
Loans and Leases Receivable, Allowance, Ending Balance		198,000				198,000			202,000
Loans and Leases Receivable, Net of Deferred Income, Total		9,140,000				9,140,000			12,815,000
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied Commercial Real Estate [Member]
Balance, beginning of period						7,626,000		3,781,000	3,781,000
Provision for Loan and Lease Losses, Total						259,000			3,960,000
Charge-offs						0			(165,000)
Recoveries						6,000			50,000
Balance, end of period		7,891,000				7,891,000			7,626,000
Individually evaluated for impairment		0				0			0
Collectively evaluated for impairment		7,465,000				7,465,000			7,185,000
Loans and Leases Receivable, Allowance, Ending Balance		7,891,000				7,891,000			7,626,000
Individually evaluated for impairment		1,027,000				1,027,000			1,270,000
Collectively evaluated for impairment		704,158,000				704,158,000			616,498,000
Loans and Leases Receivable, Net of Deferred Income, Total		713,339,000				713,339,000			627,569,000
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied Commercial Real Estate [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						441,000
Balance, end of period		426,000				426,000			441,000
Loans and Leases Receivable, Allowance, Ending Balance		426,000				426,000			441,000
Loans and Leases Receivable, Net of Deferred Income, Total		8,154,000				8,154,000			9,801,000
Residential Portfolio Segment [Member]
Balance, beginning of period						4,067,000		3,023,000	3,023,000
Provision for Loan and Lease Losses, Total						(281,000)			1,076,000
Charge-offs						(17,000)			(117,000)
Recoveries						71,000			85,000
Balance, end of period		3,840,000				3,840,000			4,067,000
Individually evaluated for impairment		1,000				1,000			1,000
Collectively evaluated for impairment		3,760,000				3,760,000			3,896,000
Loans and Leases Receivable, Allowance, Ending Balance		3,840,000				3,840,000			4,067,000
Individually evaluated for impairment		1,160,000				1,160,000			1,239,000
Collectively evaluated for impairment		369,394,000				369,394,000			365,967,000
Loans and Leases Receivable, Net of Deferred Income, Total		375,668,000				375,668,000			374,018,000
Residential Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						170,000
Balance, end of period		79,000				79,000			170,000
Loans and Leases Receivable, Allowance, Ending Balance		79,000				79,000			170,000
Loans and Leases Receivable, Net of Deferred Income, Total		5,114,000				5,114,000			6,812,000
Residential Portfolio Segment [Member] | Non-owner Occupied Commercial Real Estate [Member]
Loans and Leases Receivable, Net of Deferred Income, Total		713,339,000				713,339,000			627,569,000
Consumer Portfolio Segment [Member]
Balance, beginning of period						70,000		$ 56,000	56,000
Provision for Loan and Lease Losses, Total						(23,000)			89,000
Charge-offs						(50,000)			(202,000)
Recoveries						57,000			127,000
Balance, end of period		54,000				54,000			70,000
Individually evaluated for impairment		0				0			0
Collectively evaluated for impairment		54,000				54,000			70,000
Loans and Leases Receivable, Allowance, Ending Balance		54,000				54,000			70,000
Individually evaluated for impairment		0				0			0
Collectively evaluated for impairment		6,812,000				6,812,000			8,390,000
Loans and Leases Receivable, Net of Deferred Income, Total		6,825,000				6,825,000			8,462,000
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Balance, beginning of period						0
Balance, end of period		0				0			0
Loans and Leases Receivable, Allowance, Ending Balance		0				0			0
Loans and Leases Receivable, Net of Deferred Income, Total		$ 13,000				$ 13,000			$ 72,000

[1] Includes PPP loans, which are guaranteed by the SBA and have no related allowance.