Note 4 - 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					9 Months Ended
		Jan. 01, 2020		Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Beginning balance		$ 26,791	[1]	$ 47,708		$ 26,791	[1]	$ 26,416	$ 26,791	[1]	$ 25,534
Impact of adoption		8,200		0					8,221
Initial allowance for loans with PCD				0					1,635
Provision for credit losses				4,418	$ 5,500	5,500		400	15,518		1,000
Charge-offs				(1,698)				(230)	(1,970)		(490)
Recoveries				73				291	306		833
Ending balance		36,647	[1]	50,501	47,708			26,877	50,501		26,877
Allowance for credit losses		36,647	[1]	47,708	47,708	26,791	[1]	26,877	26,791	[1]	25,534	$ 50,501	$ 26,791	[1]
Loans, individually evaluated for impairment												12,376	11,530
Allowance for loans, individually evaluated for impairment												2,009	1,163
Loans, collectively evaluated for impairment													2,833,486
Loans	[2]											3,472,481	2,845,016	[3]
Allowance for loans, collectively evaluated for impairment													25,628
Allowance for loans		36,647	[1]	47,708	47,708	26,791	[1]	26,877	26,791	[1]	25,534	50,501	26,791	[1]
Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0				0			0
Allowance for credit losses		0				0			0				0
Loans													0
Allowance for loans		0				0			0				0
Real Estate [Member]
Loans, individually evaluated for impairment												12,274
Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment												97
Other Collateral [Member]
Loans, individually evaluated for impairment												5
Home Equity Line of Credit [Member]
Beginning balance		728		832		728			728
Impact of adoption				0					114
Initial allowance for loans with PCD				0					0
Provision for credit losses				106					96
Charge-offs				0					0
Recoveries				0					0
Ending balance		842		938	832				938
Allowance for credit losses		728		938	832	728			938			938	728
Loans, individually evaluated for impairment												0
Allowance for loans, individually evaluated for impairment												0
Loans												97,150	103,854
Allowance for loans		728		938	832	728			938			938	728
Home Equity Line of Credit [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												0
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		25,545		8,562			8,562
Impact of adoption				0					4,488
Initial allowance for loans with PCD				0					1,502
Provision for credit losses				1,116					12,106
Charge-offs				(1,494)					(1,494)
Recoveries				2					5
Ending balance		14,552		25,169	25,545				25,169
Allowance for credit losses		8,562		25,169	25,545	8,562			25,169			25,169	8,562
Loans, individually evaluated for impairment												11,711
Allowance for loans, individually evaluated for impairment												1,991
Loans												1,321,153	1,220,612
Allowance for loans		8,562		25,169	25,545	8,562			25,169			25,169	8,562
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												11,711
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		18,839		5,235			5,235
Impact of adoption				0					2,946
Initial allowance for loans with PCD				0					152
Provision for credit losses				(558)					9,945
Charge-offs				(143)					(143)
Recoveries				2					5
Ending balance		8,333		18,140	18,839				18,140
Allowance for credit losses		5,235		18,140	18,839	5,235			18,140			18,140	5,235
Loans, individually evaluated for impairment												10,218
Allowance for loans, individually evaluated for impairment												1,991
Loans												828,328	746,283
Allowance for loans		5,235		18,140	18,839	5,235			18,140			18,140	5,235
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												10,218
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		6,706		3,327			3,327
Impact of adoption				0					1,542
Initial allowance for loans with PCD				0					1,350
Provision for credit losses				1,674					2,161
Charge-offs				(1,351)					(1,351)
Recoveries				0					0
Ending balance		6,219		7,029	6,706				7,029
Allowance for credit losses		3,327		7,029	6,706	3,327			7,029			7,029	3,327
Loans, individually evaluated for impairment												1,493
Allowance for loans, individually evaluated for impairment												0
Loans												492,825	474,329
Allowance for loans		3,327		7,029	6,706	3,327			7,029			7,029	3,327
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												1,493
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		12,030	11,764		10,681
Provision for credit losses								269			1,579
Charge-offs								0			(13)
Recoveries								46			98
Ending balance								12,345			12,345
Allowance for credit losses		11,764				11,764		12,345	11,764		10,681		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		12,345	11,764		10,681		11,764
Real Estate Mortgage Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0				0			0
Allowance for credit losses		0				0			0				0
Loans													0
Allowance for loans		0				0			0				0
Commercial and Industrial Portfolio Segment [Member]
Beginning balance		12,822				12,822		11,858	12,822		11,965
Provision for credit losses								32			(178)
Charge-offs								(91)			(94)
Recoveries								154			260
Ending balance								11,953			11,953
Allowance for credit losses		12,822				12,822		11,953	12,822		11,965		12,822
Loans, individually evaluated for impairment												115	8,223
Allowance for loans, individually evaluated for impairment												18	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		11,953	12,822		11,965		12,822
Commercial and Industrial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0				0			0
Allowance for credit losses		0				0			0				0
Loans													0
Allowance for loans		0				0			0				0
Commercial and Industrial Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												18
Commercial and Industrial Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment												97
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		7,339		6,782			6,782
Impact of adoption				0					365
Initial allowance for loans with PCD				0					0
Provision for credit losses				1,605					1,790
Charge-offs				(1)					(1)
Recoveries				1					8
Ending balance				8,944	7,339				8,944
Allowance for credit losses		6,782		8,944	7,339	6,782			6,782			8,944	6,782
Loans, individually evaluated for impairment												27
Allowance for loans, individually evaluated for impairment												18
Loans												1,136,450
Allowance for loans		6,782		8,944	7,339	6,782			6,782			8,944	6,782
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												18
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment												9
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		3,242		5,657			5,657
Impact of adoption				0					(1,528)
Initial allowance for loans with PCD				0					0
Provision for credit losses				179					(708)
Charge-offs				0					0
Recoveries				0					0
Ending balance		4,129		3,421	3,242				3,421
Allowance for credit losses		5,657		3,421	3,242	5,657			3,421			3,421	5,657
Loans, individually evaluated for impairment												88
Allowance for loans, individually evaluated for impairment												0
Loans												237,456	381,502
Allowance for loans		5,657		3,421	3,242	5,657			3,421			3,421	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			1,319
Allowance for credit losses		1,319				1,319			1,319				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				1,319
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0				0			0
Allowance for credit losses		0				0			0				0
Loans													0
Allowance for loans		0				0			0				0
Construction and Development [Member]
Beginning balance		2,105		5,608		2,105		1,810	2,105		1,760
Impact of adoption				0					3,056
Initial allowance for loans with PCD				0					0
Provision for credit losses				420				(108)	867		(261)
Charge-offs				0				0	0		0
Recoveries				0				0	0		203
Ending balance		5,161		6,028	5,608			1,702	6,028		1,702
Allowance for credit losses		2,105		6,028	5,608	2,105		1,702	6,028		1,760	6,028	2,105
Loans, individually evaluated for impairment												0
Allowance for loans, individually evaluated for impairment												0
Loans												257,875	255,816
Allowance for loans		2,105		6,028	5,608	2,105		1,702	6,028		1,760	6,028	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
Undevelopment Land Portfolio Segment [Member]
Beginning balance		786				786		601	786		752
Provision for credit losses								195			44
Charge-offs								0			0
Recoveries								0			0
Ending balance								796			796
Allowance for credit losses		786				786		796	786		752		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		796	786		752		786
Undevelopment Land Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0				0			0
Allowance for credit losses		0				0			0				0
Loans													0
Allowance for loans		0				0			0				0
Consumer Portfolio Segment [Member]
Beginning balance		100		362		100		117	100		376
Impact of adoption				0					264
Initial allowance for loans with PCD				0					34
Provision for credit losses				57				12	54		(184)
Charge-offs				(140)				(139)	(394)		(383)
Recoveries				57				91	278		272
Ending balance		398		336	362			81	336		81
Allowance for credit losses		100		336	362	100		81	336		376	336	100
Loans, individually evaluated for impairment												5	0
Allowance for loans, individually evaluated for impairment												0	0
Loans, collectively evaluated for impairment													47,467
Loans												44,161	47,467
Allowance for loans, collectively evaluated for impairment													100
Allowance for loans		100		336	362	100		$ 81	336		$ 376	336	100
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0				0			0
Allowance for credit losses		0				0			0				0
Loans													0
Allowance for loans		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												5
Total Commercial and Industrial Portfolio Segment [Member]
Beginning balance		12,439		10,581		12,439			12,439
Impact of adoption				0					(1,163)
Initial allowance for loans with PCD				0					0
Provision for credit losses				1,784					1,082
Charge-offs				(1)					(1)
Recoveries				1					8
Ending balance		11,276		12,365	10,581				12,365
Allowance for credit losses		12,439		12,365	10,581	12,439			12,365			12,365	12,439
Loans												1,373,906	838,800
Allowance for loans		12,439		12,365	10,581	12,439			12,365			12,365	12,439
Residential Real Estate Portfolio Segment [Member]
Beginning balance		2,474		4,442		2,474			2,474
Impact of adoption				0					1,516
Initial allowance for loans with PCD				0					99
Provision for credit losses				882					1,251
Charge-offs				(63)					(81)
Recoveries				13					15
Ending balance		4,089		5,274	4,442				5,274
Allowance for credit losses		2,474		5,274	4,442	2,474			5,274			5,274	2,474
Loans, individually evaluated for impairment												545
Allowance for loans, individually evaluated for impairment												0
Loans												355,133	352,601
Allowance for loans		2,474		5,274	4,442	2,474			5,274			5,274	2,474
Residential Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												545
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		1,594		947			947
Impact of adoption				0					429
Initial allowance for loans with PCD				0					0
Provision for credit losses				418					636
Charge-offs				(2)					(2)
Recoveries				0					0
Ending balance		1,376		2,010	1,594				2,010
Allowance for credit losses		947		2,010	1,594	947			2,010			2,010	947
Loans, individually evaluated for impairment												102
Allowance for loans, individually evaluated for impairment												0
Loans												143,149	134,995
Allowance for loans		947		2,010	1,594	947			2,010			2,010	947
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												102
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		2,848		1,527			1,527
Impact of adoption				0					1,087
Initial allowance for loans with PCD				0					99
Provision for credit losses				464					615
Charge-offs				(61)					(79)
Recoveries				13					15
Ending balance		2,713		3,264	2,848				3,264
Allowance for credit losses		1,527		3,264	2,848	1,527			3,264			3,264	1,527
Loans, individually evaluated for impairment												443
Allowance for loans, individually evaluated for impairment												0
Loans												211,984	217,606
Allowance for loans		1,527		3,264	2,848	1,527			3,264			3,264	1,527
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment												443
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
Finance Leases Portfolio Segment [Member]
Beginning balance		237		223		237			237
Impact of adoption				0					(4)
Initial allowance for loans with PCD				0					0
Provision for credit losses				34					24
Charge-offs				0					0
Recoveries				0					0
Ending balance		233		257	223				257
Allowance for credit losses		237		257	223	237			257			257	237
Loans, individually evaluated for impairment												0
Allowance for loans, individually evaluated for impairment												0
Loans												13,981	16,003
Allowance for loans		237		257	223	237			257			257	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
Allowance for credit losses		146				146			146				146
Allowance for loans		146				146			146				146
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member]
Beginning balance		146		115		146			146
Impact of adoption				0					(50)
Initial allowance for loans with PCD				0					0
Provision for credit losses				19					38
Charge-offs				0					0
Recoveries				0					0
Ending balance				134	115				134
Allowance for credit losses		146		134	115	146			146			134	146
Loans, individually evaluated for impairment												0
Allowance for loans, individually evaluated for impairment												0
Loans												9,122	9,863
Allowance for loans		$ 146		$ 134	$ 115	$ 146			$ 146			134	$ 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

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