Revenue Recognition Contract with Customer, Asset (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Investment Management Income Receivable	$ 5,292	$ 4,636

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