Allowance for Loan Losses - Interest Income Lost on Nonaccrual Loans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Income that would have been recognized if non-accrual loans had been current	$ 1,946	$ 1,893	$ 2,106
Less income recognized	472	244	833
Reduction in interest income	$ 1,474	$ 1,649	$ 1,273

Reflects the net amount of additional interest income (less interest recognized) that would have been recorded if nonaccrual loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

No definition available.

Name:	ebtc_LoansAndLeasesReceivableInterestLossOnNonaccrualLoansNet
Namespace Prefix:	ebtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration