v3.26.1
Derivative Financial Instruments - Schedule of Company's derivative financial instruments included in OCI as follows (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
(Loss) gain in OCI on derivatives $ (1,894) $ (432) $ (6,096) $ 5,973
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test) 0 0 0 0
(Loss) gain recognized in other income for foreign currency exchange contracts: (187) 148 (319) (66)
Income Statement Location [Axis]: us-gaap:InterestIncomeExpenseNet        
Derivative Instruments, Gain (Loss) [Line Items]        
Loss reclassified from OCI into interest income (effective portion) (2,212) (7,981) (4,989) (15,914)
Income Statement Location [Axis]: us-gaap:InterestIncomeExpenseNet | Net Investment Hedging        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test) 0 0 0 0
Income Statement Location [Axis]: us-gaap:InterestIncomeExpenseNet | Interest rate swaps        
Derivative Instruments, Gain (Loss) [Line Items]        
Customer-related positions: (123) (95) (246) (167)
Income Statement Location [Axis]: us-gaap:InterestIncomeExpenseNet | Risk participation agreements        
Derivative Instruments, Gain (Loss) [Line Items]        
Customer-related positions: 0 0 (1) 0
Income Statement Location [Axis]: ebc:OtherNonoperatingIncomeLossNet        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test) 0 0 0 0
Income Statement Location [Axis]: ebc:OtherNonoperatingIncomeLossNet | Foreign currency exchange contracts - matched customer book        
Derivative Instruments, Gain (Loss) [Line Items]        
(Loss) gain recognized in other income for foreign currency exchange contracts: (61) 270 (64) 214
Income Statement Location [Axis]: ebc:OtherNonoperatingIncomeLossNet | Foreign currency exchange contracts - foreign currency loan        
Derivative Instruments, Gain (Loss) [Line Items]        
(Loss) gain recognized in other income for foreign currency exchange contracts: $ (3) $ (27) $ (8) $ (113)