Note 8 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2021		Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Beginning Balance		$ 145,110	[1]	$ 148,273	$ 166,538	$ 123,224
Provision/(reversal) for possible credit losses		(6,600)		25,000	(18,710)	50,000
Charge-offs		(7,712)		(5,106)	(16,850)	(6,427)
Recoveries		(458)		(1,513)	(1,838)	(2,883)
Net (charge-offs)/recoveries		(7,254)		(3,593)	(15,012)	(3,544)
Ending Balance		131,256		169,680	131,256	169,680
Recoveries		458		1,513	1,838	2,883
Reserve for impaired loans				7,525		7,525
Reserve for non-impaired loans				162,155		162,155
Reserve for off-balance sheet credit commitments				4,663		4,663
Commitments to Extend Credit [Member]
Beginning Balance		10,450	[1]		5,880
Provision/(reversal) for possible credit losses		(2,400)			(3,848)
Ending Balance		8,050			8,050
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	[1]				(1,560)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				6,018
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance	[1]				164,978
Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				11,898
Commercial Portfolio Segment [Member]
Beginning Balance		42,034	[1]	67,799	68,742	57,021
Provision/(reversal) for possible credit losses		5,590		18,213	18,216	29,104
Charge-offs		(7,712)		(5,106)	(16,850)	(6,427)
Recoveries		(155)		(1,350)	(1,425)	(2,558)
Net (charge-offs)/recoveries		(7,557)		(3,756)	(15,425)	(3,869)
Ending Balance		40,067		82,256	40,067	82,256
Recoveries		155		1,350	1,425	2,558
Reserve for impaired loans				6,895		6,895
Reserve for non-impaired loans				75,361		75,361
Reserve for off-balance sheet credit commitments				3,581		3,581
Commercial Portfolio Segment [Member] | Commitments to Extend Credit [Member]
Beginning Balance		8,163	[1]		4,802
Provision/(reversal) for possible credit losses		(3,775)			(3,650)
Ending Balance		4,388			4,388
Commercial Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	[1]				(31,466)
Commercial Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				3,236
Commercial Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance	[1]				37,276
Commercial Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				8,038
Real Estate Construction Portfolio Segment [Member]
Beginning Balance		6,992	[1]	23,222	30,854	19,474
Provision/(reversal) for possible credit losses		(873)		3,478	(428)	7,226
Charge-offs		0		0	0	0
Recoveries		0		0	0	0
Net (charge-offs)/recoveries		0		0	0	0
Ending Balance		6,119		26,700	6,119	26,700
Recoveries		0		0	(0)	0
Reserve for impaired loans				0		0
Reserve for non-impaired loans				26,700		26,700
Reserve for off-balance sheet credit commitments				666		666
Real Estate Construction Portfolio Segment [Member] | Commitments to Extend Credit [Member]
Beginning Balance		2,251	[1]		690
Provision/(reversal) for possible credit losses		1,330			(244)
Ending Balance		3,581			3,581
Real Estate Construction Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	[1]				(24,307)
Real Estate Construction Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				3,135
Real Estate Construction Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance	[1]				6,547
Real Estate Construction Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				3,825
Commercial Real Estate Portfolio Segment [Member]
Beginning Balance		65,347	[1]	39,886	49,205	33,602
Provision/(reversal) for possible credit losses		(7,416)		1,151	(26,362)	7,280
Charge-offs		0		0	0	0
Recoveries		(95)		(95)	(190)	(250)
Net (charge-offs)/recoveries		95		95	190	250
Ending Balance		58,026		41,132	58,026	41,132
Recoveries		95		95	190	250
Reserve for impaired loans				323		323
Reserve for non-impaired loans				40,809		40,809
Reserve for off-balance sheet credit commitments				117		117
Commercial Real Estate Portfolio Segment [Member] | Commitments to Extend Credit [Member]
Beginning Balance		36	[1]		101
Provision/(reversal) for possible credit losses		45			46
Ending Balance		81			81
Commercial Real Estate Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	[1]				34,993
Commercial Real Estate Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				(66)
Commercial Real Estate Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance	[1]				84,198
Commercial Real Estate Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				35
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Beginning Balance		30,734	[1]	17,366	17,737	13,108
Provision/(reversal) for possible credit losses		(3,899)		2,158	(10,128)	6,409
Charge-offs		0		0	0	0
Recoveries		(208)		(68)	(223)	(75)
Net (charge-offs)/recoveries		208		68	223	75
Ending Balance		27,043		19,592	27,043	19,592
Recoveries		208		68	223	75
Reserve for impaired loans				307		307
Reserve for non-impaired loans				19,285		19,285
Reserve for off-balance sheet credit commitments				297		297
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Commitments to Extend Credit [Member]
Beginning Balance		0	[1]		284
Provision/(reversal) for possible credit losses		0			0
Ending Balance		0			0
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	[1]				19,211
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				(284)
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance	[1]				36,948
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				0
Installment and Other Loans [Member ]
Beginning Balance		3	[1]	0	0	19
Provision/(reversal) for possible credit losses		(2)		0	(8)	(19)
Charge-offs		0		0	0	0
Recoveries		0		0	0	0
Net (charge-offs)/recoveries		0		0	0	0
Ending Balance		1		0	1	0
Recoveries		0		0	(0)	0
Reserve for impaired loans				0		0
Reserve for non-impaired loans				0		0
Reserve for off-balance sheet credit commitments				$ 2		$ 2
Installment and Other Loans [Member ] | Commitments to Extend Credit [Member]
Beginning Balance		0	[1]		3
Provision/(reversal) for possible credit losses		0			0
Ending Balance		$ 0			0
Installment and Other Loans [Member ] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning Balance	[1]				9
Installment and Other Loans [Member ] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				(3)
Installment and Other Loans [Member ] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance	[1]				9
Installment and Other Loans [Member ] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member] | Commitments to Extend Credit [Member]
Beginning Balance	[1]				$ 0

[1] Balance sheet amounts previously reported for the impact of the initial adoption of CECL on January 1, 2021 have been corrected. The correction decreased the allowance for loan losses by $2.2 million and increased the allowance for unfunded credit commitments by $5.5 million.