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Note 1 - Summary of Significant Accounting Policies (Details Textual) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Jan. 01, 2018 USD ($)
Participating Interest In Loans, Losses or Charge-offs | $ 0 |  |  |
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total | $ 4,000,000.0 |  |  |
Financing Receivable, Number of Payment Deferrals | 750 |  |  |
Financing Receivable, Deferred Payments, Remained Active | $ 3,200,000 |  |  |
Loans and Leases Receivable, Gross, Total | 1,069,668,000 | $ 802,048,000 |  |
Interest and Fee Income, Loans and Leases, Total | 46,874,000 | 26,777,000 | $ 20,033,000 |
Financing Receivable, Deferred Payments | 148,000,000 |  |  |
Cash Pass-through Reserve, Federal Home Loan Bank | $ 0 | 13,231,000 |  |
Number of Reportable Segments | 1 |  |  |
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total | $ 11,028,000 | 1,478,000 |  |
Retained Earnings (Accumulated Deficit), Ending Balance | 37,490,000 | $ 28,051,000 |  |
Accounting Standards Update 2016-01 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] |  |  |  |
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total |  |  |  | $ (244,000)
Retained Earnings (Accumulated Deficit), Ending Balance |  |  |  | $ 244,000
PPP Loans [Member] | SBA CARES Act Paycheck Protection Program [Member] |  |  |  |
Financing Receivable, Unamortized Loan Fee | 5,000,000.0 |  |  |
Financing Receivable, Unamortized Loan Cost | 199,000 |  |  |
Financing Receivable, Unamortized Loan Fee (Cost) | 4,800,000 |  |  |
Interest and Fee Income, Loans and Leases, Total | 3,000,000.0 |  |  |
Financing Receivable, Amount Forgiven | 23,400,000 |  |  |
PPP Loans [Member] | SBA CARES Act Paycheck Protection Program [Member] | Community Shores Bank Corporation [Member] |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables | $ 37,000,000 |  |  |
Maximum [Member] |  |  |  |
Financing Receivable, Number of Payment Deferrals, Remained Active | 40 |  |  |
Maximum [Member] | Land Improvements [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 15 years |  |  |
Maximum [Member] | Building [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 39 years |  |  |
Maximum [Member] | Furniture and Fixtures [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 7 years |  |  |
Minimum [Member] | Land Improvements [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 7 years |  |  |
Minimum [Member] | Building [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 5 years |  |  |
Minimum [Member] | Furniture and Fixtures [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 3 years |  |  |
Minimum [Member] | PPP Loans [Member] | SBA CARES Act Paycheck Protection Program [Member] |  |  |  |
Loans and Leases Receivable, Gross, Total | $ 126,000,000 |  |  |

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