Note 1 - Summary of Significant Accounting Policies - Impact of Adoption of Accounting Policy (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Jan. 01, 2020		Dec. 31, 2019
Allowance for credit losses on loans		$ 50,714	$ 51,920	$ 42,143	$ 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		843	895	623	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		27,127	26,379	19,945	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		20,062	19,396	13,436	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		7,065	6,983	6,509	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		2,983	3,614	3,866	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		11,452	12,584	11,856	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		5,001	5,207	4,121	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		1,709	1,818	1,419	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		3,292	3,389	2,702	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		5,527	6,119	5,185	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		395	340	197	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		$ 235	$ 261	$ 159	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.