Borrowings - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Short-term advances outstanding from FHLB of boston	$ 15,000,000.0	$ 0	$ 15,000,000.0
Weighted average interest rate			2.14%
FHLB borrowings remaining fair value adjustment	157,000,000	68,000,000	$ 157,000,000
Borrowings under PPP loan	$ 85,400,000	0	$ 85,400,000
Percentage of debt instrument interest rate stated	0.35%		0.35%
Unused borrowing capacity based upon collateral pledged		$ 779,000,000.0
Minimum
Debt Instrument [Line Items]
Percentage of carrying value, secured blanket lien on qualified collateral		60.00%
Maximum
Debt Instrument [Line Items]
Percentage of carrying value, secured blanket lien on qualified collateral		70.00%
Commercial Real Estate And Commercial And Industrial Loans \| Line of Credit
Debt Instrument [Line Items]
Collateral pledged amount	$ 734,300,000	$ 652,300,000	$ 734,300,000
FRB Boston \| Commercial Real Estate And Commercial And Industrial Loans
Debt Instrument [Line Items]
Line of credit unused borrowing capacity	562,400,000	$ 419,600,000	$ 562,400,000
Subordinated Debt
Debt Instrument [Line Items]
Redemption amount	$ 10,000,000.0
Coupon rate	6.00%

FHLB borrowings remaining fair value adjustment.

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- Definition

Percentage of carrying value of residential mortgage loans federal home loan bank secured blanket lien on qualified collateral.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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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.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date.

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The cash outflow from the repayment of long-term borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in case of liquidation of the entity's assets or underlying collateral.

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