Allowance for Credit Losses and Credit Quality of Loans (Policies)	12 Months Ended
	Dec. 31, 2023
Allowance for Credit Losses and Credit Quality of Loans [Abstract]
Allowance for Credit Losses	As described in Note 2, the Company’s adoption of ASU 2022-02 resulted in an insignificant change to its methodology for estimating the allowance for credit losses on TDRs. The decrease in allowance for credit loss on TDR loans relating to the adoption of ASU 2022-02 was $0.6 million. The allowance for credit losses totaled $114.4 million at December 31, 2023, compared to $100.8 million at December 31, 2022. The allowance for credit losses as a percentage of loans was 1.19% at December 31, 2023, compared to 1.24% at December 31, 2022. The allowance for credit losses calculation incorporated a 6-quarter forecast period to account for forecast economic conditions under each scenario utilized in the measurement. For periods beyond the 6-quarter forecast, the model reverts to long-term economic conditions over a 4-quarter reversion period on a straight-line basis. The Company considers a baseline, upside and downside economic forecast in measuring the allowance. The quantitative model as of December 31, 2023 incorporated a baseline economic outlook along with an alternative downside scenario sourced from a reputable third-party to accommodate other potential economic conditions in the model. At December 31, 2023, the weightings were 70% and 30% for the baseline and downside economic forecasts, respectively. The baseline outlook reflected an unemployment rate environment starting at 3.8% and increasing slightly during the forecast period to 4.1%. Northeast GDP’s annualized growth (on a quarterly basis) was expected to start the first quarter of 2024 at approximately 3.7% before decreasing to a low of 2.9% in the third quarter of 2024 and then increasing to 3.8% by the end of the forecast period. Other utilized economic variable forecasts are mixed compared to the prior year, with retail sales improving, business output mixed and housing starts down. Key assumptions in the baseline economic outlook included currently being in a full employment economy, continued tapering of the Federal Reserve balance sheet and the Federal Open Market Committee (“FOMC”) beginning to cut rates in the second quarter of 2024. The alternative downside scenario assumed deteriorated economic conditions from the baseline outlook. Under this scenario, northeast unemployment increases to a peak of 7.0% in the first quarter of 2025. These scenarios and their respective weightings are evaluated at each measurement date and reflect management’s expectations as of December 31, 2023. Additional qualitative adjustments were made for factors not incorporated in the forecasts or the model, such as loss rate expectations for certain loan pools, considerations for inflation and recent trends in asset value indices. Additional monitoring for industry concentrations, loan growth and policy exceptions was also conducted. The quantitative model as of December 31, 2022 incorporated a baseline economic outlook along with an alternative downside scenario sourced from a reputable third-party to accommodate other potential economic conditions in the model. At December 31, 2022, the weightings were 50% and 50% for the baseline and downside economic forecasts, respectively. The baseline outlook reflected an unemployment rate environment initially around pre-coronavirus (“COVID-19”) levels at 3.9% that increases slightly during the forecast period to 4.0%. Northeast GDP’s annualized growth (on a quarterly basis) was expected to start the first quarter of 2023 at approximately 3.9% and hovering around 4.6% by the end of the forecast period. Other utilized economic variables have generally deteriorated in their respective forecasts, with retail sales and housing starts forecasts declining from the prior year. Key assumptions in the baseline economic outlook included a full employment economy being realized in the near future, continued tapering of the Federal Reserve balance sheet, an increasing yield on ten-year treasury securities and a gradual decline in global oil prices. The alternative downside scenario assumed deteriorated economic and pandemic related conditions from the baseline outlook. Under this scenario, northeast unemployment rises from 3.9% in the fourth quarter of 2022 to a peak of 6.9% in the first quarter of 2024. These scenarios and their respective weightings are evaluated at each measurement date and reflect management’s expectations as of December 31, 2022. Additional qualitative adjustments were made for factors not incorporated in the forecasts or the model, such as loss rate expectations for certain loan pools, considerations for inflation and recent trends in asset value indices. Additional monitoring for industry concentrations, loan growth and policy exceptions was also conducted. The quantitative model as of December 31, 2021 incorporated a baseline economic outlook along with alternative upside and downside scenarios sourced from a reputable third-party to accommodate other potential economic conditions in the model. The baseline outlook reflected an unemployment rate environment initially above pre-COVID-19 levels at 4.8% but falling below pre-COVID-19 levels by the end of the forecast period to 3.5%. Northeast GDP’s annualized growth (on a quarterly basis) was expected to start the first quarter of 2022 at approximately 9% and hover around 5% by the middle and end of the forecast period. The alternative downside scenario assumed deteriorated economic and pandemic related conditions from the baseline outlook. Under this scenario, northeast unemployment rose from 5.7% in the fourth quarter of 2021 to a peak of 8% in the first quarter of 2023, remaining around or above 7% for the entire forecast period. The alternative upside scenario incorporated a more optimistic outlook than the baseline scenario, with a swift return to full employment by the second quarter of 2022 and with northeast unemployment moving down to 3.1% by the end of the forecast period. These scenarios and their respective weightings are evaluated at each measurement date and reflect management’s expectations as of December 31, 2021. At December 31, 2021, the weightings were 60%, 10% and 30% for the baseline, upside and downside economic forecasts, respectively. Additional adjustments were made for COVID-19 related factors not incorporated in the forecasts, such as the mitigating impact of unprecedented stimulus in the second and third quarters of 2020, including direct payments to individuals, increased unemployment benefits, the Company’s loan deferral and modification initiatives and various government sponsored loan programs. The Company also continued to monitor the level of criticized and classified loans in the fourth quarter of 2021 compared to the level contemplated by the model during similar, historical economic conditions, and an adjustment was made to estimate potential additional losses above modeled losses. Additionally, qualitative adjustments were made for Moody’s baseline economic forecast to include impacts of the Build Back Better Act not passing by December 31, 2021 and to address potential economic deterioration due to Omicron, as well as isolated model limitations related to modeled outputs given abnormally high retail sales and business output growth rates in historical periods. The Company made a policy election to report AIR in the other assets line item on the consolidated balance sheets. AIR on loans totaled $34.1 million at December 31, 2023 and $25.0 million at December 31, 2022 and there was no estimated allowance for credit losses related to AIR at December 31, 2023 and 2022 as it is excluded from amortized cost. Credit Quality Indicators The Company has developed an internal loan grading system to evaluate and quantify the Company’s loan portfolio with respect to quality and risk. The system focuses on, among other things, financial strength of borrowers, experience and depth of borrower’s management, primary and secondary sources of repayment, payment history, nature of the business and outlook on particular industries. The internal grading system enables the Company to monitor the quality of the entire loan portfolio on a consistent basis and provide management with an early warning system, which facilitates recognition and response to problem loans and potential problem loans. Commercial Grading System For Commercial and Industrial (“C&I”) and Commercial Real Estate (“CRE”) loans, the Company uses a grading system that relies on quantifiable and measurable characteristics when available. This includes comparison of financial strength to available industry averages, comparison of transaction factors (loan terms and conditions) to loan policy and comparison of credit history to stated repayment terms and industry averages. Some grading factors are necessarily more subjective such as economic and industry factors, regulatory environment and management. C&I and CRE loans are graded Doubtful, Substandard, Special Mention and Pass. Doubtful A Doubtful loan has a high probability of total or substantial loss, but because of specific pending events that may strengthen the asset, its classification as a loss is deferred. Doubtful borrowers are usually in default, lack adequate liquidity or capital and lack the resources necessary to remain an operating entity. Pending events can include mergers, acquisitions, liquidations, capital injections, the perfection of liens on additional collateral, the valuation of collateral and refinancing. Generally, pending events should be resolved within a relatively short period and the ratings will be adjusted based on the new information. Nonaccrual treatment is required for Doubtful assets because of the high probability of loss. Substandard Substandard loans have a high probability of payment default or they have other well-defined weaknesses. They require more intensive supervision by bank management. Substandard loans are generally characterized by current or expected unprofitable operations, inadequate debt service coverage, inadequate liquidity or marginal capitalization. Repayment may depend on collateral or other credit risk mitigants. For some Substandard loans, the likelihood of full collection of interest and principal may be in doubt and those loans should be placed on nonaccrual. Although Substandard assets in the aggregate will have a distinct potential for loss, an individual asset’s loss potential does not have to be distinct for the asset to be rated Substandard. Special Mention Special Mention loans have potential weaknesses that may, if not checked or corrected, weaken the asset or inadequately protect the Company’s position at some future date. These loans pose elevated risk, but their weakness does not yet justify a Substandard classification. Borrowers may be experiencing adverse operating trends (i.e., declining revenues or margins) or may be struggling with an ill-proportioned balance sheet (i.e., increasing inventory without an increase in sales, high leverage and/or tight liquidity). Adverse economic or market conditions, such as interest rate increases or the entry of a new competitor, may also support a Special Mention rating. Although a Special Mention loan has a higher probability of default than a Pass asset, its default is not imminent. Pass Loans graded as Pass encompass all loans not graded as Doubtful, Substandard or Special Mention. Pass loans are in compliance with loan covenants and payments are generally made as agreed. Pass loans range from superior quality to fair quality. Pass loans also include any portion of a government guaranteed loan, including Paycheck Protection Program loans. Consumer and Residential Grading System Consumer and Residential loans are graded as either Nonperforming or Performing. Nonperforming Nonperforming loans are loans that are (1) over 90 days past due and interest is still accruing or (2) on nonaccrual status. Performing All loans not meeting any of the above criteria are considered Performing.
Loan Modifications to Borrowers Experiencing Financial Difficulties	Loan Modifications to Borrowers Experiencing Financial Difficulties As discussed in Note 2, the Company’s January 1, 2023 adoption of ASU 2022-02 eliminates the recognition and measurement of TDRs. Upon adoption of this guidance, the Company no longer recognizes an allowance for credit losses for the economic concession granted to a borrower for changes in the timing and amount of contractual cash flows when a loan is restructured. The adoption of ASU 2022-02 resulted in a change to reporting for loan modifications to borrowers experiencing financial difficulties. With the adoption of ASU 2022-02 these modifications required enhanced reporting on the type of modifications granted and the financial magnitude of the concessions granted. When the Company modifies a loan with financial difficulty, such modifications generally include one or a combination of the following: an extension of the maturity date at a stated rate of interest lower than the current market rate for new debt with similar risk; a change in scheduled payment amount; or principal forgiveness.