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- Definition

Performance Bonus Expense - Executive Plan

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No definition available.

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- Definition

Self funded medical plan expenses during period.

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Self Funded Medical Plan, Maximum Amount Paid Per Family

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Employee Annual Salary

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No definition available.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

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Amount of cost for defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Percentage employer matches of the employee's percentage contribution matched.

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Percentage of employer's matching contributions to a defined contribution plan that vests in a given year.

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Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Employees contribution	100.00%
Corporation matching contribution, percent	100.00%
Employee contribution, percent	5.00%
Defined Contribution Plan Disclosure [Line Items]
Performance bonus expense	$ 1,485	$ 796	$ 1,072
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	(109)
Plan expenses	965	885	805
Corporation self-funded medical plan	100
Medical expenses	2,895	2,281	3,026
Defined Benefit Plan Disclosure [Line Items]
Performance Bonus Expense - Executive Plan	103	53	252
Other Postretirement Benefits Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Plan expenses	529	345	251
Restricted Stock \| Isabella Bank Corporation Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	95	$ 253	$ 147
Unrecognized compensation expense	$ 88
Unrecognized compensation expense, period for recognition	2 years 4 months 17 days
Minimum [Member] \| Restricted Stock \| Isabella Bank Corporation Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award as a percentage of salary	25.00%
Maximum [Member] \| Restricted Stock \| Isabella Bank Corporation Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award as a percentage of salary	40.00%
Safe Harbor 401(k) [Member]
Defined Contribution Plan Disclosure [Line Items]
Vesting percentage	100.00%
Equity Collective Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment allocation in securities	50.00%
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment allocation in securities	50.00%