SHARE BASED COMPENSATION AND BENEFIT PLANS - Narrative (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share Based Compensation [Abstract]
Number of additional shares approved for grant (in shares)	300
Shares issued on deferral basis, credited percentage of current value	90.00%
Share-based payment arrangement, nonvested award, cost not yet recognized, amount	$ 2,800
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition	1 year 10 months 6 days
Defined contribution plan, employer matching contribution, percent of match	50.00%	50.00%	50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay	8.00%	8.00%	8.00%
Maximum matching contribution, percent	6.00%	6.00%	6.00%
Employee stock ownership plan contributions	2.00%	2.00%	2.00%
401(k) and employee stock ownership plans, amount expensed	$ 3,400	$ 3,300	$ 3,100
Performance-based compensation expense	11,600	12,900	8,000
Health care and life insurance expense	6,700	7,100	7,200
Long-Term Incentive Plan
Share Based Compensation [Abstract]
Total compensation expense recognized	2,500	2,100	1,900
Tax benefit relating to compensation expense recognized	$ 500	$ 400	$ 400
Restricted Stock \| Long-Term Incentive Plan
Share Based Compensation [Abstract]
Vesting period	3 years	3 years	3 years
Performance Shares \| Long-Term Incentive Plan
Share Based Compensation [Abstract]
Vesting period	3 years	3 years
Performance feature comparison period	3 years
Non-Employee Directors
Share Based Compensation [Abstract]
Number of additional shares approved for grant (in shares)	50
Total compensation expense recognized	$ 300	$ 200	$ 400
Tax benefit relating to compensation expense recognized	$ 60	$ 50	$ 80
Executive Officer \| Restricted Stock \| Long-Term Incentive Plan
Share Based Compensation [Abstract]
Number of restricted stock units issued to executive officers (in shares)	50	90	80
Executive Officer \| Performance Shares \| Long-Term Incentive Plan
Share Based Compensation [Abstract]
Number of restricted stock units issued to executive officers (in shares)	20	20	20
Director
Share Based Compensation [Abstract]
Shares issues as retainer fees (in shares)	10	10	20

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

No definition available.

Name:	ibcp_DefinedContributionPlanMaximumAnnualContributionsEmployerPercent
Namespace Prefix:	ibcp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Expenditures for employee health care and life insurance benefits as provided for compensation.

+ References

No definition available.

+ Details

Name:	ibcp_EmployeeCompensationBenefitHealthCareAndLifeInsuranceExpense
Namespace Prefix:	ibcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the percentage of contributions during the period made by the entity to the Employee Stock Ownership Plan (ESOP).

+ References

No definition available.

+ Details

Name:	ibcp_EmployeeStockOwnershipPlanContributions
Namespace Prefix:	ibcp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the expense recognized during the period arising from compensation arrangements for performance programs with employees, directors and certain consultants qualifying for treatment as employees.

+ References

No definition available.

+ Details

Name:	ibcp_IncentiveBasedCompensationExpense
Namespace Prefix:	ibcp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Performance Shares, Performance Feature Period of Comparison

+ References

No definition available.

+ Details

Name:	ibcp_PerformanceSharesPerformanceFeaturePeriodOfComparison
Namespace Prefix:	ibcp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share issued to directors in place of quarterly cash retainer's fees during the period.

+ References

No definition available.

+ Details

Name:	ibcp_SharesIssuedInPlaceOfRetainerFees
Namespace Prefix:	ibcp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The credited percentage of the current value of shares issued on a deferred basis.

+ References

No definition available.

+ Details

Name:	ibcp_SharesIssuedOnDeferralBasisCreditedPercentageOfCurrentValue
Namespace Prefix:	ibcp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of new stock units or restricted shares issued during the period.

+ References

No definition available.

+ Details

Name:	ibcp_StockUnitsOrRestrictedSharesIssuedDuringPeriod
Namespace Prefix:	ibcp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479983/718-10-S45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479830/718-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480794/715-70-50-1

+ Details

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of additional shares authorized for issuance under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-4

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=ibcp_LongTermIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=ibcp_NonEmployeeDirectorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_ExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: