RESTRICTIONS ON CASH AND DUE FROM BANKS (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
RESTRICTIONS ON CASH AND DUE FROM BANKS [Abstract]
Average reserve balances maintained	$ 9.6	$ 5.2
Reserve balances related to investment security transactions and merchant payment processing operations	$ 0.1	$ 0.7

Bank is required to maintain reserve balances in the form of vault cash and non-interest earning balances with the FRB. The amount refers to average reserve balances to be maintained.

No definition available.

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