BENEFIT PLANS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
BENEFIT PLANS [Abstract]
Maximum matching contribution, percent (in hundredths)	3.00%
Employee matching contribution, percentage (in hundredths)	0.00%	0.00%	0.00%
Maximum contribution of employees' eligible wages (in hundredths)	6.00%
Employee stock ownership plan (ESOP), contributions (in hundredths)	3.00%	0.00%	0.00%
401(k) and employee stock ownership plans amount expensed	$ 1.0	$ 0	$ 0
Performance-based compensation expense	4.0	1.1	0.6
Health care and life insurance expense	$ 4.9	$ 5.0	$ 4.7

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

No definition available.

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

- Definition

Percentage of employees' contribution to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	ibcp_EmployeeMatchingContributionPercentage
Namespace Prefix:	ibcp_
Data Type:	num:percentItemType
Balance Type:	na
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_EmployeeStockOwnershipPlanESOPContributionsToESOP
Namespace Prefix:	ibcp_
Data Type:	num: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

- Details

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

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ 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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration