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
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Beginning balance		$ 35,363,000	$ 37,967,000
Provision for credit losses		100,000	300,000
Charge-offs		(205,000)	(52,000)
Recoveries		295,000	480,000
Ending balance		35,153,000	38,695,000
Ending balance: individually evaluated for impairment			487,000
Ending balance: collectively evaluated for impairment			38,208,000
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]
Beginning balance		(400,000)
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Beginning balance		10,782,000	9,424,000
Provision for credit losses		(742,000)	583,000
Charge-offs		(170,000)	0
Recoveries		114,000	104,000
Ending balance		8,413,000	10,111,000
Ending balance: individually evaluated for impairment			62,000
Ending balance: collectively evaluated for impairment			10,049,000
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]
Beginning balance		(1,571,000)
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Beginning balance		420,000	679,000
Provision for credit losses		106,000	40,000
Charge-offs		(29,000)	(15,000)
Recoveries		1,000	16,000
Ending balance		455,000	720,000
Ending balance: individually evaluated for impairment			0
Ending balance: collectively evaluated for impairment			720,000
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]
Beginning balance		(43,000)
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Beginning balance		6,045,000	8,246,000
Provision for credit losses		286,000	(181,000)
Charge-offs		0	0
Recoveries		32,000	239,000
Ending balance		5,803,000	8,304,000
Ending balance: individually evaluated for impairment			47,000
Ending balance: collectively evaluated for impairment			8,257,000
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]
Beginning balance		(560,000)
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Beginning balance		13,301,000	13,611,000
Provision for credit losses		(445,000)	140,000
Charge-offs		0	0
Recoveries		0	0
Ending balance		10,322,000	13,751,000
Ending balance: individually evaluated for impairment			7,000
Ending balance: collectively evaluated for impairment			13,744,000
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]
Beginning balance		(2,534,000)
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Beginning balance		1,695,000	1,819,000
Provision for credit losses		194,000	6,000
Charge-offs		0	0
Recoveries		8,000	0
Ending balance		1,276,000	1,825,000
Ending balance: individually evaluated for impairment			0
Ending balance: collectively evaluated for impairment			1,825,000
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]
Beginning balance		(621,000)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Beginning balance		2,449,000	3,240,000
Provision for credit losses		593,000	(337,000)
Charge-offs		(2,000)	(33,000)
Recoveries		127,000	83,000
Ending balance		8,562,000	2,953,000
Ending balance: individually evaluated for impairment			141,000
Ending balance: collectively evaluated for impairment			2,812,000
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]
Beginning balance		5,395,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Beginning balance		626,000	889,000
Provision for credit losses		(33,000)	(82,000)
Charge-offs		(4,000)	(4,000)
Recoveries		13,000	38,000
Ending balance		191,000	841,000
Ending balance: individually evaluated for impairment			230,000
Ending balance: collectively evaluated for impairment			611,000
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]
Beginning balance		(411,000)
Unallocated Financing Receivables [Member]
Beginning balance		45,000	59,000
Provision for credit losses		141,000	131,000
Charge-offs		0	0
Recoveries		0	0
Ending balance		131,000	190,000
Ending balance: individually evaluated for impairment			0
Ending balance: collectively evaluated for impairment			$ 190,000
Unallocated Financing Receivables [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Beginning balance		$ (55,000)

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