Fair Value Measurements (Details 2) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2017	Dec. 31, 2016
Investments in securities that are classified as level 3
Available-for-sale Securities	$ 415,943	$ 363,644
Discounted cash flow methodology [Member] \| Significant Unobservable Inputs (Level 3) \| Weighted Average [Member]
Investments in securities that are classified as level 3
Cumulative Prepayment	2.30%	2.50%
Cumulative Default	12.60%	12.80%
Loss Given Default	94.30%	94.20%
Cure Given Default	60.90%	60.90%
Pooled trust preferred securities \| Significant Unobservable Inputs (Level 3)
Investments in securities that are classified as level 3
Available-for-sale Securities	$ 1,593	$ 1,584
Pooled trust preferred securities \| Discounted cash flow methodology [Member] \| Significant Unobservable Inputs (Level 3) \| Minimum [Member]
Investments in securities that are classified as level 3
Cumulative Prepayment	0.00%	0.00%
Cumulative Default	5.00%	5.00%
Loss Given Default	85.00%	85.00%
Cure Given Default	0.00%	0.00%
Pooled trust preferred securities \| Discounted cash flow methodology [Member] \| Significant Unobservable Inputs (Level 3) \| Maximum [Member]
Investments in securities that are classified as level 3
Cumulative Prepayment	62.00%	62.00%
Cumulative Default	100.00%	100.00%
Loss Given Default	100.00%	100.00%
Cure Given Default	75.00%	75.00%
Collateral dependent impaired loans \| Significant Unobservable Inputs (Level 3)
Investments in securities that are classified as level 3
Fair Value	$ 36,504	$ 33,974
Other real estate owned and other foreclosed assets \| Significant Unobservable Inputs (Level 3)
Investments in securities that are classified as level 3
Fair Value	$ 3,029	$ 4,173

Fair Value Inputs, Cumulative Default

No definition available.

Name:	indb_FairValueInputsCumulativeDefault
Namespace Prefix:	indb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Inputs, Cure Given Default

+ References

No definition available.

+ Details

Name:	indb_FairValueInputsCureGivenDefault
Namespace Prefix:	indb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair Value Inputs, Loss Given Default

+ References

No definition available.

+ Details

Name:	indb_FairValueInputsLossGivenDefault
Namespace Prefix:	indb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value inputs recurring quantitative information for level 3 instruments.

+ References

No definition available.

+ Details

Name:	indb_FairValueInputsRecurringQuantitativeInformationForLevelThreeInstrumentsAbstract
Namespace Prefix:	indb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

No definition available.

+ Details

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

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

+ Details

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

- Definition

Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsPrepaymentRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_IncomeApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=indb_PooledTrustPreferredSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=indb_ImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=indb_OtherRealEstateOwnedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: