Note 4 - Loans and Allowance for Credit Losses - 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, 2020		Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Beginning balance		$ 26,791	[1]	$ 26,791	[1]	$ 25,534
Impact of adoption				8,221
Initial allowance for loans with PCD				1,635
Provision for credit losses				5,550		600
Charge-offs				(190)		(99)
Recoveries				136		429
Ending balance		36,647	[1]	42,143		26,464
Allowance for credit losses		36,647	[1]	26,791	[1]	26,464	$ 42,143	$ 26,791	[1]
Loans, individually evaluated for impairment							4,287	11,530
Allowance for loans, individually evaluated for impairment							1,702	1,163
Loans, collectively evaluated for impairment								2,833,486
Loans	[2]						2,937,366	2,845,016	[3]
Allowance for loans, collectively evaluated for impairment								25,628
Allowance for loans		36,647	[1]	26,791	[1]	26,464	42,143	26,791	[1]
Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0		0
Allowance for credit losses		0		0				0
Loans								0
Allowance for loans		0		0				0
Real Estate [Member]
Loans, individually evaluated for impairment							4,235
Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment							0
Other Collateral [Member]
Loans, individually evaluated for impairment							52
Home Equity Line of Credit [Member]
Beginning balance		728		728
Impact of adoption				114
Initial allowance for loans with PCD				0
Provision for credit losses				(219)
Charge-offs				0
Recoveries				0
Ending balance		842		623
Allowance for credit losses		728		623			623	728
Loans, individually evaluated for impairment							0
Allowance for loans, individually evaluated for impairment							0
Loans							107,121	103,854
Allowance for loans		728		623			623	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		8,562
Impact of adoption				4,488
Initial allowance for loans with PCD				1,502
Provision for credit losses				5,390
Charge-offs				0
Recoveries				2
Ending balance		14,552		19,944
Allowance for credit losses		8,562		19,944			19,944	8,562
Loans, individually evaluated for impairment							3,752
Allowance for loans, individually evaluated for impairment							1,552
Loans							1,275,818	1,220,612
Allowance for loans		8,562		19,944			19,944	8,562
Commercial Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							3,752
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
Impact of adoption				2,946
Initial allowance for loans with PCD				152
Provision for credit losses				5,100
Charge-offs				0
Recoveries				2
Ending balance		8,333		13,435
Allowance for credit losses		5,235		13,435			13,435	5,235
Loans, individually evaluated for impairment							718
Allowance for loans, individually evaluated for impairment							201
Loans							799,284	746,283
Allowance for loans		5,235		13,435			13,435	5,235
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							718
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
Impact of adoption				1,542
Initial allowance for loans with PCD				1,350
Provision for credit losses				290
Charge-offs				0
Recoveries				0
Ending balance		6,219		6,509
Allowance for credit losses		3,327		6,509			6,509	3,327
Loans, individually evaluated for impairment							3,034
Allowance for loans, individually evaluated for impairment							1,351
Loans							476,534	474,329
Allowance for loans		3,327		6,509			6,509	3,327
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							3,034
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
Provision for credit losses						1,300
Charge-offs						0
Recoveries						20
Ending balance						12,001
Allowance for credit losses		11,764		11,764		12,001		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		12,001		11,764
Real Estate Mortgage Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0		0
Allowance for credit losses		0		0				0
Loans								0
Allowance for loans		0		0				0
Commercial and Industrial Portfolio Segment [Member]
Beginning balance		12,822		12,822		11,965
Provision for credit losses						(302)
Charge-offs						(3)
Recoveries						102
Ending balance						11,762
Allowance for credit losses		12,822		12,822		11,762		12,822
Loans, individually evaluated for impairment							20	8,223
Allowance for loans, individually evaluated for impairment							20	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		11,762		12,822
Commercial and Industrial Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0		0
Allowance for credit losses		0		0				0
Loans								0
Allowance for loans		0		0				0
Commercial and Industrial Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							0
Commercial and Industrial Portfolio Segment [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment							0
Commercial and Industrial Portfolio Segment [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment							20
Commercial and Industrial Portfolio Segment [Member] | Term [Member]
Beginning balance		6,782		6,782
Impact of adoption				365
Initial allowance for loans with PCD				0
Provision for credit losses				837
Charge-offs				(3)
Recoveries				9
Ending balance		7,147		7,990
Allowance for credit losses		6,782		7,990			7,990	6,782
Loans, individually evaluated for impairment							20
Allowance for loans, individually evaluated for impairment							20
Loans							535,325	457,298
Allowance for loans		6,782		7,990			7,990	6,782
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							0
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Accounts Receivable and Equipment [Member]
Loans, individually evaluated for impairment							0
Commercial and Industrial Portfolio Segment [Member] | Term [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment							20
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member]
Beginning balance		5,657		5,657
Impact of adoption				(1,528)
Initial allowance for loans with PCD				0
Provision for credit losses				(263)
Charge-offs				0
Recoveries				0
Ending balance		4,129		3,866
Allowance for credit losses		5,657		3,866			3,866	5,657
Loans, individually evaluated for impairment							0
Allowance for loans, individually evaluated for impairment							0
Loans							348,543	381,502
Allowance for loans		5,657		3,866			3,866	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							0
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Other Collateral [Member]
Loans, individually evaluated for impairment							0
Construction and Development [Member]
Beginning balance		2,105		2,105		1,760
Impact of adoption				3,056
Initial allowance for loans with PCD				0
Provision for credit losses				24		(79)
Charge-offs				0		0
Recoveries				0		203
Ending balance		5,161		5,185		1,884
Allowance for credit losses		2,105		5,185		1,884	5,185	2,105
Loans, individually evaluated for impairment							0
Allowance for loans, individually evaluated for impairment							0
Loans							246,040	255,816
Allowance for loans		2,105		5,185		1,884	5,185	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		752
Provision for credit losses						(90)
Charge-offs						0
Recoveries						0
Ending balance						662
Allowance for credit losses		786		786		662		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		662		786
Undevelopment Land Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0		0
Allowance for credit losses		0		0				0
Loans								0
Allowance for loans		0		0				0
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Beginning balance		1,319		1,319
Allowance for credit losses		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	[4]							213,822
Allowance for loans, collectively evaluated for impairment								1,319
Allowance for loans		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
Allowance for credit losses		0		0				0
Loans								0
Allowance for loans		0		0				0
Consumer Portfolio Segment [Member]
Beginning balance		100		100		376
Impact of adoption				264
Initial allowance for loans with PCD				34
Provision for credit losses				(138)		(229)
Charge-offs				(177)		(96)
Recoveries				115		104
Ending balance		398		198		155
Allowance for credit losses		100		198		155	198	100
Loans, individually evaluated for impairment							32	0
Allowance for loans, individually evaluated for impairment							32	0
Loans, collectively evaluated for impairment								47,467
Loans							44,939	47,467
Allowance for loans, collectively evaluated for impairment								100
Allowance for loans		100		198		$ 155	198	100
Consumer Portfolio Segment [Member] | Financial Asset Acquired with Credit Deterioration [Member]
Beginning balance		0		0
Allowance for credit losses		0		0				0
Loans								0
Allowance for loans		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							32
Total Commercial and Industrial Portfolio Segment [Member]
Beginning balance		12,439		12,439
Impact of adoption				(1,163)
Initial allowance for loans with PCD				0
Provision for credit losses				574
Charge-offs				(3)
Recoveries				9
Ending balance		11,276		11,856
Allowance for credit losses		12,439		11,856			11,856	12,439
Loans							883,868	838,800
Allowance for loans		12,439		11,856			11,856	12,439
Residential Real Estate Portfolio Segment [Member]
Beginning balance		2,474		2,474
Impact of adoption				1,516
Initial allowance for loans with PCD				99
Provision for credit losses				32
Charge-offs				(10)
Recoveries				10
Ending balance		4,089		4,121
Allowance for credit losses		2,474		4,121			4,121	2,474
Loans, individually evaluated for impairment							483
Allowance for loans, individually evaluated for impairment							98
Loans							353,955	352,601
Allowance for loans		2,474		4,121			4,121	2,474
Residential Real Estate Portfolio Segment [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							483
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
Impact of adoption				429
Initial allowance for loans with PCD				0
Provision for credit losses				43
Charge-offs				0
Recoveries				0
Ending balance		1,376		1,419
Allowance for credit losses		947		1,419			1,419	947
Loans, individually evaluated for impairment							63
Allowance for loans, individually evaluated for impairment							0
Loans							134,734	134,995
Allowance for loans		947		1,419			1,419	947
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							63
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
Impact of adoption				1,087
Initial allowance for loans with PCD				99
Provision for credit losses				(11)
Charge-offs				(10)
Recoveries				10
Ending balance		2,713		2,702
Allowance for credit losses		1,527		2,702			2,702	1,527
Loans, individually evaluated for impairment							420
Allowance for loans, individually evaluated for impairment							98
Loans							219,221	217,606
Allowance for loans		1,527		2,702			2,702	1,527
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Real Estate [Member]
Loans, individually evaluated for impairment							420
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		237
Impact of adoption				(4)
Initial allowance for loans with PCD				0
Provision for credit losses				(74)
Charge-offs				0
Recoveries				0
Ending balance		233		159
Allowance for credit losses		237		159			159	237
Loans, individually evaluated for impairment							0
Allowance for loans, individually evaluated for impairment							0
Loans							15,476	16,003
Allowance for loans		237		159			159	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
Ending balance		96
Allowance for credit losses		146		146				146
Allowance for loans		146		146				146
Commercial Portfolio Segment [Member] | Credit Card Receivable [Member]
Beginning balance		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				57
Allowance for credit losses		146		57			57	146
Loans, individually evaluated for impairment							0
Allowance for loans, individually evaluated for impairment							0
Loans							10,149	9,863
Allowance for loans		$ 146		$ 57			57	$ 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 for 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.

[4] Consists of land acquired for development by the borrower, but for which no development has yet taken place.