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Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) | 3 Months Ended | 6 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020 | Jul. 01, 2020 | Dec. 31, 2019 | Oct. 01, 2019 | Dec. 31, 2006
Stock Issued During Period, Value, New Issues | $ 106,000 | $ 55,000 | $ 281,000 | $ 161,000 |  |  |  |  |
Goodwill, Ending Balance | $ 59,946,000 |  | $ 59,946,000 |  | $ 60,506,000 |  |  |  |
Valley Ridge Financial Corp. [Member] |  |  |  |  |  |  |  |  |
Goodwill, Ending Balance |  |  |  |  |  |  |  |  | $ 13,700,000
County Bank Corp ("County") [Member] |  |  |  |  |  |  |  |  |
Goodwill, Ending Balance |  |  |  |  |  |  | $ 38,900,000 | $ 38,866,000 |
Community Shores Bank Corp ("Community Shores") [Member] |  |  |  |  |  |  |  |  |
Goodwill, Ending Balance |  |  |  |  | $ 7,300,000 | $ 7,353,000 |  |  |
Directors' Stock Purchase Plan [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  |  | 8,929 |  |  |  |  |  |
Stock Issued During Period, Value, New Issues |  |  | $ 247,000 |  |  |  |  |  |
Employee Stock Purchase Plan [Member] |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, New Issues (in shares) |  |  | 2,957 |  |  |  |  |  |
Stock Issued During Period, Value, New Issues |  |  | $ 66,000 |  |  |  |  |  |

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