Loans and Allowance for Credit Losses - Schedule of Non-Accrual Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	$ 39,758	$ 35,995
Non-Accrual Loans Without ACL	13	16,562
Total Nonaccrual Loans	39,771	52,557
Commercial Portfolio Segment \| Commercial and industrial
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	4	4
Non-Accrual Loans Without ACL	8	464
Total Nonaccrual Loans	12	468
Commercial Portfolio Segment \| Commercial real estate
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	23,258	13,969
Non-Accrual Loans Without ACL	0	16,087
Total Nonaccrual Loans	23,258	30,056
Commercial Portfolio Segment \| Commercial construction
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	0	0
Non-Accrual Loans Without ACL	0	0
Total Nonaccrual Loans	0	0
Commercial Portfolio Segment \| Business banking
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	2,864	4,572
Non-Accrual Loans Without ACL	5	11
Total Nonaccrual Loans	2,869	4,583
Residential Real Estate \| Residential real estate
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	6,789	8,725
Non-Accrual Loans Without ACL	0	0
Total Nonaccrual Loans	6,789	8,725
Consumer Portfolio Segment \| Consumer home equity
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	6,715	8,532
Non-Accrual Loans Without ACL	0	0
Total Nonaccrual Loans	6,715	8,532
Consumer Portfolio Segment \| Other Consumer
Financing Receivable, Past Due [Line Items]
Non-Accrual Loans With ACL	128	193
Non-Accrual Loans Without ACL	0	0
Total Nonaccrual Loans	$ 128	$ 193

Financing Receivable, Nonaccrual, With Allowance

No definition available.

Name:	ebc_FinancingReceivableNonaccrualWithAllowance
Namespace Prefix:	ebc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

+ Details

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

- Definition

Amortized cost of financing receivable on nonaccrual status. Excludes net investment in lease.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (3)
-Publisher SEC

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (2)
-Publisher SEC

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-16

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-14

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 80
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-80

+ Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialAndIndustrialSectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ebc_BusinessBankingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ebc_OtherConsumerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: