Derivatives and Hedging Activities (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary of net amortization income recognized
NET AMORTIZATION INCOME	$ 61	$ 61	$ 183	$ 183

The amount of expense charged against earnings by an entity to record deferred gains and losses on hedge instruments.

No definition available.

Name:	indb_AmortizationOfDeferredHedgeGainsLosses
Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration