v3.25.4

Securities - Narrative (Details) - USD ($)	12 Months Ended
Securities - Narrative (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, allowance for credit loss, excluding accrued interest	$ 0	$ 0
Debt securities, available-for-sale, accrued interest, after allowance for credit loss	$ 11,900,000	$ 8,900,000
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Debt securities, available-for-sale, accrued interest writeoff	$ 0	$ 0
Debt securities, held-to-maturity, allowance for credit loss, excluding accrued interest	0	0
Debt securities, held-to-maturity, accrued interest, after allowance for credit loss	$ 3,600,000	$ 900,000
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Debt securities, held-to-maturity, accrued interest, writeoff	$ 0	$ 0
Debt securities, available-for-sale and held-to-maturity, fair value	4,401,543,000	4,393,322,000
Federal Home Loan Bank of Boston
Debt Securities, Available-for-sale [Line Items]
Deposit liabilities, collateral issued, financial instruments	200,000,000	1,000,000,000.0
Other Purposes Required By Law
Debt Securities, Available-for-sale [Line Items]
Deposit liabilities, collateral issued, financial instruments	692,900,000	687,900,000
Federal Reserve Discount Window
Debt Securities, Available-for-sale [Line Items]
Deposit liabilities, collateral issued, financial instruments	414,200,000	794,800,000
Callable Securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale and held-to-maturity, fair value	$ 385,500,000	$ 196,400,000

Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Eastern Bankshares, Inc. 10-K