Note 1 - Significant Accounting Policies (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) shares	Jun. 30, 2021 USD ($) shares	Jun. 30, 2022 USD ($) shares	Jun. 30, 2021 USD ($) shares	Mar. 31, 2022 USD ($)	Jan. 01, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Aug. 08, 2020 USD ($)
Number of Unconsolidated Business Trusts Formed to Issue Trust Preferred Securities	5		5
Financing Receivable, before Allowance for Credit Loss, Total	$ 3,723,800,000		$ 3,723,800,000				$ 3,453,459,000
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance	0		0
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Total	2,200,000		$ 2,200,000
Interest Income on Commercial and Mortgage Loans Discontinued Period (Day)			90 days
Maximum Delinquency Period for Consumer and Credit Card Loans to be Charged Off (Day)			120 days
Mortgages Held-for-sale, Fair Value Disclosure	13,300,000		$ 13,300,000				16,700,000
Servicing Asset, Total	1,370,000,000		1,370,000,000				1,340,000,000
Financing Receivable, Allowance for Credit Loss, Ending Balance	35,974,000	$ 35,913,000	35,974,000	$ 35,913,000	$ 35,153,000		35,363,000		$ 38,695,000	$ 37,967,000
Retained Earnings (Accumulated Deficit), Total	$ 188,452,000		$ 188,452,000				174,536,000
Core Deposits [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)			10 years
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss, Ending Balance						$ (400,000)	$ (400,000)
Retained Earnings (Accumulated Deficit), Total						300,000
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Other Assets [Member]
Deferred Income Tax Assets, Net						$ 100,000
Restricted Stock [Member]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights (in shares) | shares	325,000	262,000	325,000	262,000
Share-Based Payment Arrangement, Option [Member]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights (in shares) | shares	1,000	3,000	1,000	3,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares	6,000	7,000	6,000	7,000
SBA, CARES Act, Paycheck Protection Program [Member]
Number of Loans Originated Under the Paycheck Protection Program											2,200
Financing Receivable, before Allowance for Credit Loss, Total											$ 553,000,000
Financing Receivable, Not Yet Forgiven, Number of Loans	12		12
Financing Receivable, Not Yet Forgiven	$ 700,000		$ 700,000
Amortization of Deferred Loan Origination Fees, Net			$ 100,000
SBA, CARES Act, Paycheck Protection Program, Round Two [Member]
Number of Loans Originated Under the Paycheck Protection Program								1,200
Financing Receivable, before Allowance for Credit Loss, Total								$ 209,000,000
Financing Receivable, Not Yet Forgiven, Number of Loans	9		9
Financing Receivable, Not Yet Forgiven	$ 2,200,000		$ 2,200,000
Amortization of Deferred Loan Origination Fees, Net			$ 900,000