Note 1 - Summary of Significant Accounting Policies - Impact of Adoption of Accounting Policy (Details) - USD ($) $ in Thousands		Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020		Dec. 31, 2019
Allowance for credit losses on loans		$ 56,533	$ 59,424	$ 51,920	$ 50,501	$ 47,708	$ 36,647	[1]	$ 26,791	[1]
Total allowance for credit losses on off-balance sheet exposures							3,850		350
Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans	[1]						9,856
Total allowance for credit losses on off-balance sheet exposures							3,500
Home Equity Line of Credit [Member]
Allowance for credit losses on loans		1,057	1,230	895	938	832	842		728
Home Equity Line of Credit [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							114
Commercial Real Estate Portfolio Segment [Member]
Allowance for credit losses on loans		26,489	29,295	26,379	25,169	25,545	14,552		8,562
Commercial Real Estate Portfolio Segment [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							5,990
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member]
Allowance for credit losses on loans		16,171	19,747	19,396	18,140	18,839	8,333		5,235
Commercial Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							3,098
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Allowance for credit losses on loans		10,318	9,548	6,983	7,029	6,706	6,219		3,327
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							2,892
Commercial and Industrial Portfolio Segment [Member] | Term, Excluding PPP [Member]
Allowance for credit losses on loans							7,147		6,782
Commercial and Industrial Portfolio Segment [Member] | Term, Excluding PPP [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							365
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member]
Allowance for credit losses on loans		4,912	5,240	3,614	3,421	3,242	4,129		5,657
Commercial and Industrial Portfolio Segment [Member] | Lines of Credit [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							(1,528)
Total Commercial and Industrial Portfolio Segment [Member]
Allowance for credit losses on loans		14,678	14,988	12,584	12,365	10,581	11,276		12,439
Total Commercial and Industrial Portfolio Segment [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							(1,163)
Residential Real Estate Portfolio Segment [Member]
Allowance for credit losses on loans		7,987	7,772	5,207	5,274	4,442	4,089		2,474
Residential Real Estate Portfolio Segment [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							1,615
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member]
Allowance for credit losses on loans		3,530	3,422	1,818	2,010	1,594	1,376		947
Residential Real Estate Portfolio Segment [Member] | Non-owner Occupied [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							429
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Allowance for credit losses on loans		4,457	4,350	3,389	3,264	2,848	2,713		1,527
Residential Real Estate Portfolio Segment [Member] | Owner Occupied [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							1,186
Construction and Development [Member]
Allowance for credit losses on loans		5,238	5,193	6,119	6,028	5,608	5,161		2,105
Construction and Development [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							3,056
Consumer Portfolio Segment [Member]
Allowance for credit losses on loans		727	572	340	336	362	398		100
Consumer Portfolio Segment [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							298
Finance Leases Portfolio Segment [Member]
Allowance for credit losses on loans		$ 194	$ 232	$ 261	$ 257	$ 223	233		237
Finance Leases Portfolio Segment [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							(4)
Commercial Portfolio Segment [Member]
Allowance for credit losses on loans							96		$ 146
Commercial Portfolio Segment [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses on loans							$ (50)

[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.