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Note 3 - Loans and Allowance for Loan Losses (Details Textual) - USD ($) | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Loans and Leases Receivable, Net of Deferred Income, Total |  | $ 3,216,358,000 |  | $ 2,856,667,000 | $ 2,753,085,000
Impaired Financing Receivable, Interest Income, Accrual Method, Total |  | 1,300,000 |  | 1,300,000 | 1,100,000
Loans and Leases Receivable, Nonaccrual Loans, Interest Income Recognized |  | 100,000 |  | 100,000 | 100,000
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans |  | $ 200,000 |  | 100,000 | 300,000
Minimum Number of Days Past Due at Period End For Loans Modified as Troubled Debt Restructurings (Day) |  | 30 days |  |  |
Commercial Portfolio Segment [Member] |  |  |  |  |
Loans and Leases Receivable, Net of Deferred Income, Total |  | $ 2,793,962,000 |  | 2,441,544,000 | $ 2,360,106,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Loans and Leases Receivable, Net of Deferred Income, Total | [1] | 1,145,423,000 |  | 846,551,000 |
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Grades 1-4 [Member] |  |  |  |  |
Loans and Leases Receivable, Net of Deferred Income, Total |  | 828,706,000 | [2] | $ 521,920,000 |
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | SBA, CARES Act, Paycheck Protection Program [Member] |  |  |  |  |
Loans and Leases Receivable, Net of Deferred Income, Total |  | 365,000,000 |  |  |
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | SBA, CARES Act, Paycheck Protection Program [Member] | Grades 1-4 [Member] |  |  |  |  |
Loans and Leases Receivable, Net of Deferred Income, Total |  | $ 365,000,000 |  |  |
[1] | For December 31, 2020, includes $365 million in loans originated under the Paycheck Protection Program.
[2] | Included in Commercial and Industrial Loans Grades 1 – 4 are $365 million of loans originated under the Paycheck Protection Program.

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- Definition Amount of interest that was recorded on nonaccrual loans that were paid off during the period. + References No definition available. + Details
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- Definition Represents the minimum number of days past due at period end for loans modified as troubled debt restructurings. + References No definition available. + Details
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- Definition Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524 + Details
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- Definition Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18794-111554 + Details
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- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524 + Details
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