Note 5 - Loans - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Evaluation Method (Details) - USD ($) $ in Thousands				3 Months Ended														12 Months Ended
		Jan. 01, 2020		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Beginning balance		$ 26,791	[1]				$ 26,791	[1]					$ 25,534				$ 24,885	$ 26,791	[1]	$ 25,534		$ 24,885
Impact of adoption		8,200																8,221
Initial allowance for loans with PCD																		1,635
Provision for credit losses				$ 1,400	$ 4,418	$ 5,550	5,550		$ 0		$ 400	$ 0	600	$ 0	$ 735	$ 1,235	735	16,918		1,000		2,705
Charge-offs																		(2,101)		(684)		(3,012)
Recoveries																		456		941		956
Ending balance		36,647	[1]	51,920					26,791	[1]				25,534				51,920		26,791	[1]	25,534
Allowance for credit losses		36,647	[1]	51,920			26,791	[1]	26,791	[1]			25,534	25,534			24,885	26,791	[1]	25,534		24,885	$ 51,920	$ 26,791	[1]
Loans, individually evaluated for impairment																							12,531	11,530
Allowance for loans, individually evaluated for impairment																							3,066	1,163
Loans, collectively evaluated for impairment																								2,833,486
Loans	[2]																						3,531,596	2,845,016
Allowance for loans, collectively evaluated for impairment																								25,628
Allowance for loans		36,647	[1]	51,920			26,791	[1]	26,791	[1]			25,534	25,534			24,885	26,791	[1]	25,534		24,885	51,920	26,791	[1]
Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0					0											0
Ending balance									0											0
Allowance for credit losses		0					0		0									0		0				0
Loans																								0
Allowance for loans		0					0		0									0		0				0
Real Estate [Member]
Loans, individually evaluated for impairment																							12,432
Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							95
Other Collateral [Member]
Loans, individually evaluated for impairment																							4
Home Equity Line of Credit [Member]
Beginning balance		728					728											728
Impact of adoption																		114
Initial allowance for loans with PCD																		0
Provision for credit losses																		53
Charge-offs																		0
Recoveries																		0
Ending balance		842		895					728									895		728
Allowance for credit losses		728		895			728		728									895		728			895	728
Loans, individually evaluated for impairment																							221
Allowance for loans, individually evaluated for impairment																							0
Loans																							95,366	103,854
Allowance for loans		728		895			728		728									895		728			895	728
Home Equity Line of Credit [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							221
Home Equity Line of Credit [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Home Equity Line of Credit [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Commercial Real Estate Portfolio Segment [Member]
Beginning balance		8,562					8,562											8,562
Impact of adoption																		4,488
Initial allowance for loans with PCD																		1,502
Provision for credit losses																		13,309
Charge-offs																		(1,494)
Recoveries																		12
Ending balance		14,552		26,379					8,562									26,379		8,562
Allowance for credit losses		8,562		26,379			8,562		8,562									26,379		8,562			26,379	8,562
Loans, individually evaluated for impairment																							11,681
Allowance for loans, individually evaluated for impairment																							3,050
Loans																							1,342,142	1,220,612
Allowance for loans		8,562		26,379			8,562		8,562									26,379		8,562			26,379	8,562
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							11,681
Commercial Real Estate Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Commercial Real Estate Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member]
Beginning balance		5,235					5,235											5,235
Impact of adoption																		2,946
Initial allowance for loans with PCD																		152
Provision for credit losses																		11,194
Charge-offs																		(143)
Recoveries																		12
Ending balance		8,333		19,396					5,235									19,396		5,235
Allowance for credit losses		5,235		19,396			5,235		5,235									19,396		5,235			19,396	5,235
Loans, individually evaluated for impairment																							10,278
Allowance for loans, individually evaluated for impairment																							3,037
Loans																							833,470	746,283
Allowance for loans		5,235		19,396			5,235		5,235									19,396		5,235			19,396	5,235
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							10,278
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Beginning balance		3,327					3,327											3,327
Impact of adoption																		1,542
Initial allowance for loans with PCD																		1,350
Provision for credit losses																		2,115
Charge-offs																		(1,351)
Recoveries																		0
Ending balance		6,219		6,983					3,327									6,983		3,327
Allowance for credit losses		3,327		6,983			3,327		3,327									6,983		3,327			6,983	3,327
Loans, individually evaluated for impairment																							1,403
Allowance for loans, individually evaluated for impairment																							13
Loans																							508,672	474,329
Allowance for loans		3,327		6,983			3,327		3,327									6,983		3,327			6,983	3,327
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							1,403
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Real Estate Mortgage Portfolio Segment [Member]
Beginning balance		11,764					11,764						10,681				11,012	11,764		10,681		11,012
Provision for credit losses																				1,021		(261)
Charge-offs																				(38)		(132)
Recoveries																				100		62
Ending balance									11,764					10,681						11,764		10,681
Allowance for credit losses		11,764					11,764		11,764				10,681	10,681			11,012	11,764		11,764		11,012		11,764
Loans, individually evaluated for impairment																								3,307
Allowance for loans, individually evaluated for impairment																								13
Loans, collectively evaluated for impairment																								1,663,549
Loans																								1,666,856
Allowance for loans, collectively evaluated for impairment																								11,751
Allowance for loans		11,764					11,764		11,764				10,681	10,681			11,012	11,764		11,764		11,012		11,764
Real Estate Mortgage Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0					0											0
Ending balance									0											0
Allowance for credit losses		0					0		0									0		0				0
Loans																								0
Allowance for loans		0					0		0									0		0				0
Commercial and Industrial Portfolio Segment [Member]
Beginning balance		12,822					12,822						11,965				11,276	12,822		11,965		11,276
Provision for credit losses																				684		2,539
Charge-offs																				(94)		(2,404)
Recoveries																				267		554
Ending balance									12,822					11,965						12,822		11,965
Allowance for credit losses		12,822					12,822		12,822				11,965	11,965			11,276	12,822		12,822		11,276		12,822
Loans, individually evaluated for impairment																							111	8,223
Allowance for loans, individually evaluated for impairment																							16	1,150
Loans, collectively evaluated for impairment																								862,288
Loans																								870,511
Allowance for loans, collectively evaluated for impairment																								11,672
Allowance for loans		12,822					12,822		12,822				11,965	11,965			11,276	12,822		12,822		11,276		12,822
Commercial and Industrial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0					0											0
Ending balance									0											0
Allowance for credit losses		0					0		0									0		0				0
Loans																								0
Allowance for loans		0					0		0									0		0				0
Commercial and Industrial Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							16
Commercial and Industrial Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							95
Commercial and Industrial Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Commercial and Industrial Portfolio Segment [Member] | Term [Member]
Beginning balance		6,782					6,782											6,782
Impact of adoption																		365
Initial allowance for loans with PCD																		0
Provision for credit losses																		1,832
Charge-offs																		(18)
Recoveries																		9
Ending balance				8,970					6,782									8,970		6,782
Allowance for credit losses		6,782		8,970			6,782		6,782									8,970		6,782			8,970	6,782
Loans, individually evaluated for impairment																							23
Allowance for loans, individually evaluated for impairment																							16
Loans																							525,776
Allowance for loans		6,782		8,970			6,782		6,782									8,970		6,782			8,970	6,782
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							16
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							7
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member]
Beginning balance		5,657					5,657											5,657
Impact of adoption																		(1,528)
Initial allowance for loans with PCD																		0
Provision for credit losses																		(515)
Charge-offs																		0
Recoveries																		0
Ending balance		4,129		3,614					5,657									3,614		5,657
Allowance for credit losses		5,657		3,614			5,657		5,657									3,614		5,657			3,614	5,657
Loans, individually evaluated for impairment																							88
Allowance for loans, individually evaluated for impairment																							0
Loans																							276,646	381,502
Allowance for loans		5,657		3,614			5,657		5,657									3,614		5,657			3,614	5,657
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							0
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							88
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Beginning balance		1,319					1,319						1,760				1,724	1,319		1,760		1,724
Provision for credit losses																				(644)		36
Charge-offs																				0		0
Recoveries																				203		0
Ending balance									1,319					1,760						1,319		1,760
Allowance for credit losses		1,319					1,319		1,319				1,760	1,760			1,724	1,319		1,319		1,724		1,319
Loans, individually evaluated for impairment																								0
Allowance for loans, individually evaluated for impairment																								0
Loans, collectively evaluated for impairment																								213,822
Loans																								213,822
Allowance for loans, collectively evaluated for impairment																								1,319
Allowance for loans		1,319					1,319		1,319				1,760	1,760			1,724	1,319		1,319		1,724		1,319
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0					0											0
Ending balance									0											0
Allowance for credit losses		0					0		0									0		0				0
Loans																								0
Allowance for loans		0					0		0									0		0				0
Undevelopment Land Portfolio Segment [Member]
Beginning balance		786					786						752				521	786		752		521
Provision for credit losses																				34		231
Charge-offs																				0		0
Recoveries																				0		0
Ending balance									786					752						786		752
Allowance for credit losses		786					786		786				752	752			521	786		786		521		786
Loans, individually evaluated for impairment																								0
Allowance for loans, individually evaluated for impairment																								0
Loans, collectively evaluated for impairment																								46,360
Loans																								46,360
Allowance for loans, collectively evaluated for impairment																								786
Allowance for loans		786					786		786				752	752			521	786		786		521		786
Undevelopment Land Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0					0											0
Ending balance									0											0
Allowance for credit losses		0					0		0									0		0				0
Loans																								0
Allowance for loans		0					0		0									0		0				0
Consumer Portfolio Segment [Member]
Beginning balance		100					100						376				352	100		376		352
Impact of adoption																		264
Initial allowance for loans with PCD																		34
Provision for credit losses																		91		(95)		160
Charge-offs																		(508)		(552)		(476)
Recoveries																		359		371		340
Ending balance		398		340					100					376				340		100		376
Allowance for credit losses		100		340			100		100				376	376			352	340		376		352	340	100
Loans, individually evaluated for impairment																							4	0
Allowance for loans, individually evaluated for impairment																							0	0
Loans, collectively evaluated for impairment																								47,467
Loans																							44,606	47,467
Allowance for loans, collectively evaluated for impairment																								100
Allowance for loans		100		340			100		100				$ 376	$ 376			$ 352	340		376		$ 352	340	100
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0					0											0
Ending balance									0											0
Allowance for credit losses		0					0		0									0		0				0
Loans																								0
Allowance for loans		0					0		0									0		0				0
Consumer Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							0
Consumer Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Consumer Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							4
Total Commercial and Industrial Portfolio Segment [Member]
Beginning balance		12,439					12,439											12,439
Impact of adoption																		(1,163)
Initial allowance for loans with PCD																		0
Provision for credit losses																		1,317
Charge-offs																		(18)
Recoveries																		9
Ending balance		11,276		12,584					12,439									12,584		12,439
Allowance for credit losses		12,439		12,584			12,439		12,439									12,584		12,439			12,584	12,439
Loans																							1,352,608	838,800
Allowance for loans		12,439		12,584			12,439		12,439									12,584		12,439			12,584	12,439
Residential Real Estate Portfolio Segment [Member]
Beginning balance		2,474					2,474											2,474
Impact of adoption																		1,516
Initial allowance for loans with PCD																		99
Provision for credit losses																		1,179
Charge-offs																		(81)
Recoveries																		20
Ending balance		4,089		5,207					2,474									5,207		2,474
Allowance for credit losses		2,474		5,207			2,474		2,474									5,207		2,474			5,207	2,474
Loans, individually evaluated for impairment																							514
Allowance for loans, individually evaluated for impairment																							0
Loans																							380,121	352,601
Allowance for loans		2,474		5,207			2,474		2,474									5,207		2,474			5,207	2,474
Residential Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							514
Residential Real Estate Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Residential Real Estate Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member]
Beginning balance		947					947											947
Impact of adoption																		429
Initial allowance for loans with PCD																		0
Provision for credit losses																		442
Charge-offs																		(2)
Recoveries																		2
Ending balance		1,376		1,818					947									1,818		947
Allowance for credit losses		947		1,818			947		947									1,818		947			1,818	947
Loans, individually evaluated for impairment																							101
Allowance for loans, individually evaluated for impairment																							0
Loans																							140,930	134,995
Allowance for loans		947		1,818			947		947									1,818		947			1,818	947
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							101
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Beginning balance		1,527					1,527											1,527
Impact of adoption																		1,087
Initial allowance for loans with PCD																		99
Provision for credit losses																		737
Charge-offs																		(79)
Recoveries																		18
Ending balance		2,713		3,389					1,527									3,389		1,527
Allowance for credit losses		1,527		3,389			1,527		1,527									3,389		1,527			3,389	1,527
Loans, individually evaluated for impairment																							413
Allowance for loans, individually evaluated for impairment																							0
Loans																							239,191	217,606
Allowance for loans		1,527		3,389			1,527		1,527									3,389		1,527			3,389	1,527
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							413
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Construction and Development [Member]
Beginning balance		2,105					2,105											2,105
Impact of adoption																		3,056
Initial allowance for loans with PCD																		0
Provision for credit losses																		902
Charge-offs																		0
Recoveries																		56
Ending balance		5,161		6,119					2,105									6,119		2,105
Allowance for credit losses		2,105		6,119			2,105		2,105									6,119		2,105			6,119	2,105
Loans, individually evaluated for impairment																							0
Allowance for loans, individually evaluated for impairment																							0
Loans																							291,764	255,816
Allowance for loans		2,105		6,119			2,105		2,105									6,119		2,105			6,119	2,105
Construction and Development [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							0
Construction and Development [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Construction and Development [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Finance Leases Portfolio Segment [Member]
Beginning balance		237					237											237
Impact of adoption																		(4)
Initial allowance for loans with PCD																		0
Provision for credit losses																		28
Charge-offs																		0
Recoveries																		0
Ending balance		233		261					237									261		237
Allowance for credit losses		237		261			237		237									261		237			261	237
Loans, individually evaluated for impairment																							0
Allowance for loans, individually evaluated for impairment																							0
Loans																							14,786	16,003
Allowance for loans		237		261			237		237									261		237			261	237
Finance Leases Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							0
Finance Leases Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Finance Leases Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							0
Commercial Portfolio Segment [Member]
Beginning balance		146					146											146
Ending balance		96							146											146
Allowance for credit losses		146					146		146									146		146				146
Allowance for loans		146					146		146									146		146				146
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member]
Beginning balance		146					146											146
Impact of adoption																		(50)
Initial allowance for loans with PCD																		0
Provision for credit losses																		39
Charge-offs																		0
Recoveries																		0
Ending balance				135					146									135		146
Allowance for credit losses		146		135			146		146									135		146			135	146
Loans, individually evaluated for impairment																							0
Allowance for loans, individually evaluated for impairment																							0
Loans																							10,203	9,863
Allowance for loans		$ 146		$ 135			$ 146		$ 146									$ 135		$ 146			135	$ 146
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member] | Real Estate [Member]
Loans, individually evaluated for impairment																							0
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment																							0
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment																							$ 0

[1] The impact of the ASC 326 adoption on the ACL on loans reflects $8.2 million related to the transition from the incurred loss ACL model to the CECL ACL model and $1.6 million related to the transition from PCI to PCD methodology as defined in the standard.

[2] Total loans are presented inclusive of premiums, discounts and net loan origination fees and costs.