Note 1 - Significant Accounting Policies (Details Textual)	3 Months Ended
	Mar. 31, 2022 USD ($) shares	Mar. 31, 2021 USD ($) shares	Jan. 01, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Aug. 08, 2020 USD ($)
Number of Unconsolidated Business Trusts Formed to Issue Trust Preferred Securities	5
Financing Receivable, before Allowance for Credit Loss, Total	$ 3,555,790,000			$ 3,453,459,000
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance	0
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Total	$ 3,000,000.0
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	$ 15,200,000			16,700,000
Servicing Asset, Total	1,360,000,000			1,340,000,000
Financing Receivable, Allowance for Credit Loss, Ending Balance	35,153,000	$ 38,695,000		35,363,000		$ 37,967,000
Retained Earnings (Accumulated Deficit), Total	$ 181,532,000			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	335,000	262,000
Share-Based Payment Arrangement, Option [Member]
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights (in shares) | shares	8,000	3,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares		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	6
Financing Receivable, Not Yet Forgiven	$ 900,000
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					$ 208,000,000
Financing Receivable, Not Yet Forgiven, Number of Loans	38
Financing Receivable, Not Yet Forgiven	$ 11,300,000
Amortization of Deferred Loan Origination Fees, Net	$ 800,000