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Restricted Stock Plan (Details) - Restricted Stock - Isabella Bank Corporation Restricted Stock Plan $ in Thousands | 3 Months Ended
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Mar. 31, 2021 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Expense | $ 4
Minimum [Member] |
Share-based Payment Arrangement [Abstract] |
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Employee Annual Salary | 2500.00%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Employee Annual Salary | 2500.00%
Maximum [Member] |
Share-based Payment Arrangement [Abstract] |
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Employee Annual Salary | 4000.00%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Employee Annual Salary | 4000.00%

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