REVENUE RECOGNITION CONTRACT WITH CUSTOMER (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Investment Management Income Receivable	$ 4,636	$ 2,341

Fees earned from investment management wealth and advisory services but not yet received as of the end of the reporting period.

No definition available.

Name:	indb_InvestmentManagementIncomeReceivable
Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant