TRANSACTIONS WITH RELATED PARTIES Related Parties Textual (Details) - USD ($)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Nonaccrual/TDR Loans, with related parties	$ 0	$ 0
Loans and Leases Receivable, Related Parties, Additions		0
Related Party Deposit Liabilities	22,300,000	22,900,000
Loans and Leases Receivable, Related Parties, Additions	57,983,000	$ 45,308,000
Related Party [Domain]
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties, Additions	$ 10.6

Leases with related parties

No definition available.

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Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Nonaccrual/TDR Loans, with related parties

+ References

No definition available.

+ Details

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Namespace Prefix:	indb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the amount of new advances made to related parties in the form of loan and lease receivables.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(e))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of deposits held by the entity for a related party (entity, shareholder, employee).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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