Note 3 - Loans and Allowance for Credit Losses on Loans - Allowance for Loan Losses by Portfolio Segment and Based on Impairment Evaluation Method (Details) - USD ($) $ in Thousands			3 Months Ended
	Jan. 01, 2020		Mar. 31, 2021	Mar. 31, 2020		Dec. 31, 2020
Beginning balance	$ 26,791	[1]	$ 51,920	$ 26,791	[1]
Provision for credit losses			(1,200)	5,550
Charge-offs			(122)	(174)
Recoveries			116	120
Ending balance	36,647	[1]	50,714	42,143
Impact of adoption				8,221
Initial allowance for loans with PCD				1,635
Provision for credit losses			(1,200)	5,550
Recoveries			116	120
Loans, individually evaluated for impairment			12,928			$ 12,531
Allowance for loans, individually evaluated for impairment			3,065			3,066
Real Estate [Member]
Loans, individually evaluated for impairment			12,877			12,432
Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			51			95
Other Collateral [Member]
Loans, individually evaluated for impairment			0			4
Home Equity Line of Credit [Member]
Beginning balance	728		895	728
Provision for credit losses			(52)	(219)
Charge-offs			0	0
Recoveries			0	0
Ending balance	842		843	623
Impact of adoption				114
Initial allowance for loans with PCD				0
Provision for credit losses			(52)	(219)
Recoveries			0	0
Loans, individually evaluated for impairment			274			221
Allowance for loans, individually evaluated for impairment			0			0
Home Equity Line of Credit [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			274			221
Home Equity Line of Credit [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Home Equity Line of Credit [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial Real Estate Portfolio Segment [Member]
Beginning balance	8,562		26,379	8,562
Provision for credit losses			717	5,390
Charge-offs			0	0
Recoveries			31	3
Ending balance	14,552		27,127	19,945
Impact of adoption				4,488
Initial allowance for loans with PCD				1,502
Provision for credit losses			717	5,390
Recoveries			31	3
Loans, individually evaluated for impairment			11,359			11,681
Allowance for loans, individually evaluated for impairment			3,050			3,050
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			11,359			11,681
Commercial Real Estate Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Commercial Real Estate Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member]
Beginning balance	5,235		19,396	5,235
Provision for credit losses			635	5,100
Charge-offs			0	0
Recoveries			31	3
Ending balance	8,333		20,062	13,436
Impact of adoption				2,946
Initial allowance for loans with PCD				152
Provision for credit losses			635	5,100
Recoveries			31	3
Loans, individually evaluated for impairment			10,305			10,278
Allowance for loans, individually evaluated for impairment			3,037			3,037
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			10,305			10,278
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Beginning balance	3,327		6,983	3,327
Provision for credit losses			82	290
Charge-offs			0	0
Recoveries			0	0
Ending balance	6,219		7,065	6,509
Impact of adoption				1,542
Initial allowance for loans with PCD				1,350
Provision for credit losses			82	290
Recoveries			0	0
Loans, individually evaluated for impairment			1,054			1,403
Allowance for loans, individually evaluated for impairment			13			13
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			1,054			1,403
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial and Industrial Portfolio Segment [Member]
Loans, individually evaluated for impairment			378			111
Allowance for loans, individually evaluated for impairment			15			16
Commercial and Industrial Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			327			16
Commercial and Industrial Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			51			95
Commercial and Industrial Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial and Industrial Portfolio Segment [Member] | Term [Member]
Beginning balance	6,782		8,970	6,782
Provision for credit losses			(452)	837
Charge-offs			(55)	0
Recoveries			6	6
Ending balance			8,469	7,990
Impact of adoption				365
Initial allowance for loans with PCD				0
Provision for credit losses			(452)	837
Recoveries			6	6
Loans, individually evaluated for impairment			378			23
Allowance for loans, individually evaluated for impairment			15			16
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			327			16
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			51			7
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member]
Beginning balance	5,657		3,614	5,657
Provision for credit losses			(631)	(263)
Charge-offs			0	0
Recoveries			0	0
Ending balance	4,129		2,983	3,866
Impact of adoption				(1,528)
Initial allowance for loans with PCD				0
Provision for credit losses			(631)	(263)
Recoveries			0	0
Loans, individually evaluated for impairment			0			88
Allowance for loans, individually evaluated for impairment			0			0
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			0			0
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			88
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Total Commercial and Industrial Portfolio Segment [Member]
Beginning balance	12,439		12,584	12,439
Provision for credit losses			(1,083)	574
Charge-offs			(55)	0
Recoveries			6	6
Ending balance	11,276		11,452	11,856
Impact of adoption				(1,163)
Initial allowance for loans with PCD				0
Provision for credit losses			(1,083)	574
Recoveries			6	6
Residential Real Estate Portfolio Segment [Member]
Beginning balance	2,474		5,207	2,474
Provision for credit losses			(204)	32
Charge-offs			(3)	0
Recoveries			1	0
Ending balance	4,089		5,001	4,121
Impact of adoption				1,516
Initial allowance for loans with PCD				99
Provision for credit losses			(204)	32
Recoveries			1	0
Loans, individually evaluated for impairment			910			514
Allowance for loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			910			514
Residential Real Estate Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member]
Beginning balance	947		1,818	947
Provision for credit losses			(110)	43
Charge-offs			0	0
Recoveries			1	0
Ending balance	1,376		1,709	1,419
Impact of adoption				429
Initial allowance for loans with PCD				0
Provision for credit losses			(110)	43
Recoveries			1	0
Loans, individually evaluated for impairment			100			101
Allowance for loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			100			101
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Beginning balance	1,527		3,389	1,527
Provision for credit losses			(94)	(11)
Charge-offs			(3)	0
Recoveries			0	0
Ending balance	2,713		3,292	2,702
Impact of adoption				1,087
Initial allowance for loans with PCD				99
Provision for credit losses			(94)	(11)
Recoveries			0	0
Loans, individually evaluated for impairment			810			413
Allowance for loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			810			413
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Construction and Development [Member]
Beginning balance	2,105		6,119	2,105
Provision for credit losses			(592)	24
Charge-offs			0	0
Recoveries			0	0
Ending balance	5,161		5,527	5,185
Impact of adoption				3,056
Initial allowance for loans with PCD				0
Provision for credit losses			(592)	24
Recoveries			0	0
Loans, individually evaluated for impairment			0			0
Allowance for loans, individually evaluated for impairment			0			0
Construction and Development [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			0			0
Construction and Development [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Construction and Development [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Consumer Portfolio Segment [Member]
Beginning balance	100		340	100
Provision for credit losses			41	(138)
Charge-offs			(64)	(174)
Recoveries			78	111
Ending balance	398		395	197
Impact of adoption				264
Initial allowance for loans with PCD				34
Provision for credit losses			41	(138)
Recoveries			78	111
Loans, individually evaluated for impairment			7			4
Allowance for loans, individually evaluated for impairment			0			0
Consumer Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			7			0
Consumer Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Consumer Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			4
Finance Leases Portfolio Segment [Member]
Beginning balance	237		261	237
Provision for credit losses			(26)	(74)
Charge-offs			0	0
Recoveries			0	0
Ending balance	233		235	159
Impact of adoption				(4)
Initial allowance for loans with PCD				0
Provision for credit losses			(26)	(74)
Recoveries			0	0
Loans, individually evaluated for impairment			0			0
Allowance for loans, individually evaluated for impairment			0			0
Finance Leases Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			0			0
Finance Leases Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Finance Leases Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			0			0
Commercial Portfolio Segment [Member]
Beginning balance	146			146
Ending balance	96
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member]
Beginning balance	$ 146		135	146
Provision for credit losses			(1)	(39)
Charge-offs			0	0
Recoveries			0	0
Ending balance			134	57
Impact of adoption				(50)
Initial allowance for loans with PCD				0
Provision for credit losses			(1)	(39)
Recoveries			0	$ 0
Loans, individually evaluated for impairment			0			0
Allowance for loans, individually evaluated for impairment			0			0
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member] | Real Estate [Member]
Loans, individually evaluated for impairment			0			0
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment			0			0
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment			$ 0			$ 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.