Derivatives and Hedging Activities (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Summary of net amortization income recognized
Net amortization income	$ 61	$ 61

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