Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
Non-interest checking	$ 858,718	$ 794,583
Interest-bearing checking	492,313	467,988
Savings	205,367	203,236
Money market	1,054,344	1,009,972
CDs $250,000 or less	216,490	220,751
CDs greater than $250,000	85,618	90,200
Deposits	2,912,850	2,786,730
Reciprocal deposits	$ 471,700	$ 419,700

Reciprocal deposits

No definition available.

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Balance Type:	credit
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- Definition

Time Deposits, $250,000 or Less, Excluding Non-reciprocal Brokered Term Deposits

+ References

No definition available.

+ Details

Name:	ebtc_TimeDeposits250000orLessExcludingNonreciprocalBrokeredTermDeposits
Namespace Prefix:	ebtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Time Deposits, More Than $250,000, Excluding Non-reciprocal Brokered Deposits

+ References

No definition available.

+ Details

Name:	ebtc_TimeDepositsMoreThan250000ExcludingNonreciprocalBrokeredDeposits
Namespace Prefix:	ebtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of money in accounts that may bear interest and that the depositor is entitled to withdraw at any time without prior notice.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

+ Details

Name:	us-gaap_Deposits
Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_DepositsAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of deposits in accounts that offer many of the same services as checking accounts although transactions may be somewhat more limited, share some of the characteristics of a money market fund and are insured by the Federal government, also known as money market accounts.

+ References

+ Details

Name:	us-gaap_DepositsMoneyMarketDeposits
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest bearing deposits with no stated maturity, which may include passbook and statement savings accounts and money-market deposit accounts (MMDAs).

+ References

+ Details

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Period Type:	instant

- Definition

The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

+ References

+ Details

Name:	us-gaap_NoninterestBearingDepositLiabilities
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant