Derivatives and Hedging Activities (FV of Derivative Financial Instruments and Classification on Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair value of derivative financial instruments as well as their classification on the balance sheet
Total	$ 23,072	$ 22,390
Total	160,270	225,824
Other Assets [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	23,305	22,688
Total	23,305	22,688
Other Liabilities [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	23,040	22,380
Total	26,313	27,950
Interest rate derivatives
Fair value of derivative financial instruments as well as their classification on the balance sheet
Total	3,273	5,570
Interest rate derivatives \| Derivatives designated as hedges: [Member] \| Other Liabilities [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Interest rate derivatives	3,273	5,570
Loan level derivatives
Fair value of derivative financial instruments as well as their classification on the balance sheet
Total	22,470	18,383
Total	22,465	18,380
Loan level derivatives \| Derivatives not designated as hedges: [Member] \| Other Assets [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Loan level derivatives	22,470	18,383
Loan level derivatives \| Derivatives not designated as hedges: [Member] \| Other Liabilities [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Loan level derivatives	22,465	18,380
Foreign exchange contracts
Fair value of derivative financial instruments as well as their classification on the balance sheet
Total	602	4,007
Total	574	3,984
Foreign exchange contracts \| Derivatives not designated as hedges: [Member] \| Other Assets [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Foreign exchange contracts	602	4,007
Foreign exchange contracts \| Derivatives not designated as hedges: [Member] \| Other Liabilities [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Foreign exchange contracts	574	3,984
Mortgage Derivatives \| Derivatives not designated as hedges: [Member] \| Other Assets [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Interest rate lock commitments	233	295
Forward TBA mortgage contracts	0	0
Forward sales agreements	0	3
Mortgage Derivatives \| Derivatives not designated as hedges: [Member] \| Other Liabilities [Member]
Fair value of derivative financial instruments as well as their classification on the balance sheet
Interest rate lock commitments	0	0
Forward TBA mortgage contracts	0	16
Forward sales agreements	$ 1	$ 0

Derivative Instrument Not Designated as a Hedge, Forward Sales Agreements, Asset at Fair Value

No definition available.

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

- Definition

Derivative Instrument Not Designated as a Hedge, Forward Sales Agreements, Liabilities at Fair Value

+ References

No definition available.

+ Details

Name:	indb_DerivativeInstrumentNotDesignatedasaHedgeForwardSalesAgreementsLiabilitiesatFairValue
Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Derivative Instrument Not Designated as a Hedge, Forward TBA Mortgage Contracts, Asset at Fair Value

+ References

No definition available.

+ Details

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

- Definition

Derivative Instrument Not Designated as a Hedge, Forward TBA Mortgage Contracts, Liability at Fair Value

+ References

No definition available.

+ Details

Name:	indb_DerivativeInstrumentNotDesignatedasaHedgeForwardTBAMortgageContractsLiabilityatFairValue
Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Derivative Instrument Not Designated as a Hedge, Interest Rate Lock Commitments, Asset at Fair Value

+ References

No definition available.

+ Details

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

- Definition

Derivative Instrument Not Designated as a Hedge, Interest Rate Lock Commitments, Liabilities at Fair Value

+ References

No definition available.

+ Details

Name:	indb_DerivativeInstrumentNotDesignatedasaHedgeInterestRateLockCommitmentsLiabilitiesatFairValue
Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226000-175313

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=51814546&loc=SL51823488-111719

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=51814546&loc=SL51823488-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeNetAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

+ Details

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

+ References

+ Details

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all foreign currency derivative assets not designated as hedging instruments.

+ References

+ Details

Name:	us-gaap_ForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all foreign currency derivative liabilities not designated as hedging instruments.

+ References

+ Details

Name:	us-gaap_ForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all derivative assets not designated as hedging instruments.

+ References

+ Details

Name:	us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all derivative liabilities not designated as hedging instruments.

+ References

+ Details

Name:	us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611

+ Details

Name:	us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=indb_LoanLevelSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateLockCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: