Note 3 - Loans and Allowance for Credit Losses - Activity in Allowance for Loan Losses and the Recorded Investments in Loans (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Balance		$ 35,153,000	$ 38,695,000	$ 35,363,000	$ 37,967,000
Provision for credit losses		500,000	(3,100,000)	600,000	(2,800,000)
Charge-offs		(15,000)	(68,000)	(220,000)	(121,000)
Recoveries		336,000	386,000	631,000	867,000
Balance		35,974,000	35,913,000	35,974,000	35,913,000
Ending balance: individually evaluated for impairment			787,000		787,000
Ending balance: collectively evaluated for impairment			35,126,000		35,126,000
Ending balance	[1]					$ 3,413,349,000
Ending balance: individually evaluated for impairment	[1]					19,366,000
Ending balance: collectively evaluated for impairment	[1]					3,393,983,000
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(400,000)
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Balance		8,413,000	10,111,000	10,782,000	9,424,000
Provision for credit losses		150,000	(764,000)	(592,000)	(181,000)
Charge-offs		0	(54,000)	(171,000)	(54,000)
Recoveries		45,000	47,000	160,000	151,000
Balance		8,608,000	9,340,000	8,608,000	9,340,000
Ending balance: individually evaluated for impairment			355,000		355,000
Ending balance: collectively evaluated for impairment			8,985,000		8,985,000
Ending balance	[1]					1,097,309,000
Ending balance: individually evaluated for impairment	[1]					5,010,000
Ending balance: collectively evaluated for impairment	[1]					1,092,299,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(1,571,000)
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Balance		455,000	720,000	420,000	679,000
Provision for credit losses		(10,000)	(243,000)	96,000	(203,000)
Charge-offs		0	0	(29,000)	(15,000)
Recoveries		1,000	2,000	2,000	18,000
Balance		446,000	479,000	446,000	479,000
Ending balance: individually evaluated for impairment			0		0
Ending balance: collectively evaluated for impairment			479,000		479,000
Ending balance						43,239,000
Ending balance: individually evaluated for impairment						0
Ending balance: collectively evaluated for impairment						43,239,000
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(43,000)
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Balance		5,803,000	8,304,000	6,045,000	8,246,000
Provision for credit losses		(251,000)	(696,000)	35,000	(877,000)
Charge-offs		0	(12,000)	0	(12,000)
Recoveries		26,000	105,000	58,000	344,000
Balance		5,578,000	7,701,000	5,578,000	7,701,000
Ending balance: individually evaluated for impairment			117,000		117,000
Ending balance: collectively evaluated for impairment			7,584,000		7,584,000
Ending balance						565,758,000
Ending balance: individually evaluated for impairment						10,435,000
Ending balance: collectively evaluated for impairment						555,323,000
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(560,000)
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Balance		10,322,000	13,751,000	13,301,000	13,611,000
Provision for credit losses		(708,000)	(966,000)	(1,153,000)	(826,000)
Charge-offs		0	0	0	0
Recoveries		0	0	0	0
Balance		9,614,000	12,785,000	9,614,000	12,785,000
Ending balance: individually evaluated for impairment			5,000		5,000
Ending balance: collectively evaluated for impairment			12,780,000		12,780,000
Ending balance						1,027,415,000
Ending balance: individually evaluated for impairment						146,000
Ending balance: collectively evaluated for impairment						1,027,269,000
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(2,534,000)
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Balance		1,276,000	1,825,000	1,695,000	1,819,000
Provision for credit losses		(8,000)	(38,000)	186,000	(32,000)
Charge-offs		0	0	0	0
Recoveries		6,000	0	14,000	0
Balance		1,274,000	1,787,000	1,274,000	1,787,000
Ending balance: individually evaluated for impairment			0		0
Ending balance: collectively evaluated for impairment			1,787,000		1,787,000
Ending balance						176,593,000
Ending balance: individually evaluated for impairment						91,000
Ending balance: collectively evaluated for impairment						176,502,000
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(621,000)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Balance		8,562,000	2,953,000	2,449,000	3,240,000
Provision for credit losses		1,464,000	(263,000)	2,057,000	(600,000)
Charge-offs		0	0	(2,000)	(34,000)
Recoveries		241,000	204,000	368,000	288,000
Balance		10,267,000	2,894,000	10,267,000	2,894,000
Ending balance: individually evaluated for impairment			103,000		103,000
Ending balance: collectively evaluated for impairment			2,791,000		2,791,000
Ending balance						442,547,000
Ending balance: individually evaluated for impairment						2,437,000
Ending balance: collectively evaluated for impairment						440,110,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				5,395,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Balance		191,000	841,000	626,000	889,000
Provision for credit losses		(28,000)	(125,000)	(61,000)	(207,000)
Charge-offs		(15,000)	(2,000)	(18,000)	(6,000)
Recoveries		17,000	28,000	29,000	66,000
Balance		165,000	742,000	165,000	742,000
Ending balance: individually evaluated for impairment			207,000		207,000
Ending balance: collectively evaluated for impairment			535,000		535,000
Ending balance						60,488,000
Ending balance: individually evaluated for impairment						1,247,000
Ending balance: collectively evaluated for impairment						$ 59,241,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				(411,000)
Unallocated Financing Receivables [Member]
Balance		131,000	190,000	45,000	59,000
Provision for credit losses		(109,000)	(5,000)	32,000	126,000
Charge-offs		0	0	0	0
Recoveries		0	0	0	0
Balance		$ 22,000	185,000	22,000	185,000
Ending balance: individually evaluated for impairment			0		0
Ending balance: collectively evaluated for impairment			$ 185,000		$ 185,000
Unallocated Financing Receivables [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Balance				$ (55,000)

[1] Excludes $40.1 million in loans originated under the Paycheck Protection Program.