Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Trading Arrangement: Trading Arrangement [Axis] Maximum Maximum [Member] Loans held for sale Financing Receivable, Held-for-Sale Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Title of 12(b) Security Title of 12(b) Security Reported Value Measurement Carrying Value Reported Value Measurement [Member] Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-Sale [Table] Amortized Cost Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss Fair Value Debt Securities, Available-for-Sale and Held-to-Maturity, Fair Value Total noninterest income (loss) out-of-scope of ASC 606 Revenue Not from Contract with Customer, Excluding Interest Income Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Adjustment to Compensation, Amount Adjustment to Compensation Amount Pledged Status [Axis] Pledged Status [Axis] Non-Accrual Loans Without ACL Financing Receivable, Nonaccrual, No Allowance Financial Instrument [Axis] Financial Instrument [Axis] Forward commitments to sell loans Forward commitments to sell loans [Member] Forward commitments to sell loans Liabilities Financial Liabilities Fair Value Disclosure [Abstract] Segment Reporting [Abstract] Segment Reporting [Abstract] Revenue from External Customers by Products and Services [Table] Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Table] Schedule of of the Company's Investments in Low Income Housing Projects Accounted for Using the Proportional Amortization Method Investment Program, Proportional Amortization Method, Elected [Table Text Block] Investment Program, Proportional Amortization Method, Elected Employee Benefits Retirement Benefits [Text Block] Leases Lessee, Finance Leases [Text Block] Derivative Instrument [Axis] Derivative Instrument [Axis] Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract] Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract] Before reclassifications Other Comprehensive Income (Loss) before Reclassifications, Tax Mortgage servicing rights Servicing Asset at Fair Value, Amount Measurement Frequency [Axis] Measurement Frequency [Axis] Risk participation agreements Risk participation agreements Risk Participation Agreements [Member] Risk participation agreements [member]. Financing receivable, accrued interest, before allowance for credit loss Financing Receivable, Accrued Interest, before Allowance for Credit Loss Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Doubtful Doubtful [Member] Leases [Abstract] Leases [Abstract] Interest Rate Reduction Contractual Interest Rate Reduction [Member] Schedule of Debt Securities, Held-to-Maturity Debt Securities, Held-to-Maturity [Table Text Block] Prior Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year, Writeoff Total Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Options granted in period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Gross Unrealized Losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract] Prior Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Non-vested stock at beginning of year (in shares) Non-vested stock at end of year (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Abstract] Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value Schedule of the modifications which occurred during the periods and the change in the recorded investment subsequent to the modifications occurring Financing Receivable, Modified [Table Text Block] Current period gross charge-offs Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Share-Based Payment Arrangement, Activity Share-Based Payment Arrangement, Activity [Table Text Block] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Commercial construction Construction Loans [Member] Number of reportable segments Number of Reportable Segments Available-for-sale debt securities, amortized cost Amortized Cost Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Entity Address, City or Town Entity Address, City or Town Fair Value Derivative, Fair Value, Net Shares granted (in shares) Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Money market investment Deposits, Money Market Deposits Federal Home Loan Bank stock, at cost FHLB stock Federal Home Loan Bank Stock Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Receivables [Abstract] Receivables [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Financing receivable, excluding accrued interest, year one, originated, current fiscal year, writeoff Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year, Writeoff Net increase in operating lease right-of-use assets and operating lease liabilities relating to lease remeasurements/modifications Net Increase (Decrease) In Operating Lease Right-Of-Use Assets And Operating Lease Liabilities Relating To Lease Remeasurements And Modifications Net Increase (Decrease) In Operating Lease Right-Of-Use Assets And Operating Lease Liabilities Relating To Lease Remeasurements And Modifications Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Federal Home Loan Bank Branch [Axis] Federal Home Loan Bank Branch [Axis] Significant Other Observable Inputs (Level 2) Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] 90 or More Days Past Due 90 or More Days Past Due Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Loans 90 days or more past due and still accruing Financial Asset, Equal to or Greater than 90 Days Past Due, Accruing [Member] Financial Asset, Equal to or Greater than 90 Days Past Due, Accruing Issuance of restricted stock awards (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Before reclassifications OCI, before Reclassifications, before Tax, Attributable to Parent Current Rate Paid Derivative, Average Variable Interest Rate Nature Of Transaction [Axis] Nature Of Transaction [Axis] Low income housing tax credit and other tax credit investments Low Income Housing Tax Credit And Other Tax Credit Investments [Member] Low income housing tax credit and other tax credit investments [Member]. Number of loans in process of foreclosure Mortgage Loans In Process Of Foreclosure, Number Mortgage Loans In Process Of Foreclosure, Number Savings accounts Deposits, Savings Deposits State and municipal bonds and obligations Municipal Bonds [Member] Use of Estimates Use of Estimates, Policy [Policy Text Block] Mortgage banking income (loss) Gain (Loss) on Sale of Mortgage Loans Total other comprehensive (loss) income Other comprehensive income, net of tax Net current-period other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Schedule of Fair Value of Available for Sale Securities by Contractual Maturities Disclosure Of Contractual Maturities Of Available For Sale Securities [Table Text Block] Disclosure of contractual maturities of available for sale securities. Due after one year to five years, Fair value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Allowance for loan losses Allowance for loan losses Financing receivable, allowance for credit loss, excluding accrued interest Beginning balance Ending balance Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] Fair value assets and liabilities measured on recurring basis [Line Items]. Document Period End Date Document Period End Date Revolving Loans Converted to Term Loans Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan Gross realized losses from sales of AFS securities Debt Securities, Available-for-Sale, Realized Loss Due after ten years, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Disclosure of Leases [Line Items] Lessee, Lease, Description [Line Items] Total other comprehensive loss Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Tax credit period of benefits Tax Credit Period Of Benefits Tax credit period of benefits. Accumulated other comprehensive loss, net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Non-accrual Non-Accrual [Member] Non-Accrual % of Total Portfolio Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Earnings (Loss) Per Share (“EPS”) Earnings Per Share [Text Block] Earnings Per Share [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Line Items] Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Line Items] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Schedule of Revenue from External Customers by Products and Services Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Table Text Block] Total liabilities Liabilities Trading Symbol Trading Symbol Interest Rate Reduction Financing Receivable, Modified, Weighted-Average Interest Rate Decrease from Modification Available for sale (amortized cost $4,400,498 and $4,143,163, respectively) Fair Value Fair Value Securities available for sale: Debt Securities, Available-for-Sale, Excluding Accrued Interest Schedule of Interest Rate Derivatives Schedule of Interest Rate Derivatives [Table Text Block] Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Company Selected Measure Name Company Selected Measure Name Purchases of securities available for sale Payments to Acquire Debt Securities, Available-for-Sale Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Less: reclassification adjustments Reclassification from AOCI, Current Period, before Tax, Attributable to Parent Lines of credit, exposure Exposure To Credit Risk Of Loans Or Receivables Maximum exposure to credit risk of loans or receivables. Interest on deposits Interest Expense, Deposits Due after one year to five years, Fair value Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Schedule of Derivatives Not Designated as Hedging Instruments Derivatives Not Designated as Hedging Instruments [Table Text Block] Financing receivable, excluding accrued interest, year one, originated, current fiscal year Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year Credit Facility [Domain] Credit Facility [Domain] Operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Total Non-Accrual Loans Financing Receivable, Nonaccrual Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] U.S. Treasury securities US Treasury Securities [Member] Financing Receivable, Troubled Debt Restructuring [Line Items] Financing Receivable, Modified [Line Items] Commitments to extend credit Commitments to Extend Credit [Member] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Investment advisory fees Investment Advisory Fees [Member] Investment Advisory Fees Common stock equivalents (in shares) Weighted Average Number of Shares Outstanding, Diluted, Adjustment Customer-related positions: Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments Financing receivable, modified, commitment to lend Financing Receivable, Modified, Commitment to Lend Maximum length of time hedged in cash flow hedge Cash Flow Hedge, Hedging Exposure, Maximum Period Award Timing Predetermined Award Timing Predetermined [Flag] Interest-only period Financing Receivable, Modified, Interest Only Period Financing Receivable, Modified, Interest Only Period Schedule of Comprehensive Income Comprehensive Income (Loss) [Table Text Block] Interest and dividend income: Interest and Dividend Income, Operating [Abstract] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Share-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Quoted Prices in Active Markets for Identical Assets (Level 1) Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Debt Securities [Abstract] Debt Securities [Abstract] ESOP shares committed to be released Employee Stock Ownership Plan (ESOP), Value, Committed-to-be-Released Shares Employee Stock Ownership Plan (ESOP), Value, Committed-to-be-Released Shares Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Government-sponsored residential mortgage-backed securities Residential Mortgage-Backed Securities [Member] Customer-related positions Individually Immaterial Counterparties [Member] Plan Name [Domain] Plan Name [Domain] Federal Home Loan Bank Branch [Domain] Federal Home Loan Bank Branch [Domain] Right-of-use assets Operating Lease, Right-of-Use Asset Premises and equipment Property, Plant and Equipment, Including Assets Held-for-sale, Not Part of Disposal Group Property, Plant and Equipment, Including Assets Held-for-sale, Not Part of Disposal Group Offsetting Assets [Table] Offsetting Assets [Table] Due in one year or less, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Derivative Liability, Statement of Financial Position [Extensible Enumeration] Derivative Liability, Statement of Financial Position [Extensible Enumeration] Interest rate swap cash flow hedges amount expected to reclassified from other comprehensive income to income statement in the next twelve months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Balance Sheet Offsetting Disclosure Of Balance Sheet Offsetting [Text Block] Disclosure Of Balance Sheet Offsetting. Securities Investment in Debt and Equity Securities and Other Trading Assets [Text Block] Financing receivable, collateral dependent loans Financing Receivable, Collateral Dependent Loans Financing Receivable, Collateral Dependent Loans Expiration Date Trading Arrangement Expiration Date Hedging Relationship [Axis] Hedging Relationship [Axis] Unrealized Gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain Schedule of The Fair Value Of Assets And Liabilities Measured At Fair Value On A Nonrecurring Basis Summary Of The Fair Value Of Assets And Liabilities Measured At Fair Value On A Nonrecurring Basis [Table Text Block] Summary of the fair value of assets and liabilities measured at fair value on a nonrecurring basis. Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments Derivative Asset, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Net Amount Derivative Asset, Subject to Master Netting Arrangement, after Offset and Deduction Total Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] Non-performing Loan Rate (%) Non Performing Loan Percentage Non performing loan percentage. Earnings per common share: Earnings Per Share Reconciliation [Abstract] Customer Related Interest Rate Swap Derivatives Customer Related Interest Rate Swap Derivatives [Member] Commercial real estate Commercial Real Estate [Member] Investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Derivative Assets Derivative Asset [Abstract] Operating loss tax benefits period Operating Loss Period Of Tax Benefits Operating loss period of tax benefits. Interest rate swaps Interest rate swaps Interest Rate Swap [Member] Contractual obligation Contractual Obligation Loans, net of allowance for loan losses Financing Receivable, after Allowance for Credit Loss PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Employee Stock Ownership Plan expense Employee Stock Ownership Plan (ESOP), Compensation Expense Dividends to common shareholders Dividends, Common Stock, Cash Total shareholders’ equity Beginning Balance Ending balance Equity, Attributable to Parent Offsetting Assets [Line Items] Offsetting Assets [Line Items] ASSETS Assets [Abstract] Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] Debt Securities, Held-to-Maturity, Allowance for Credit Loss [Line Items] Other-than-Insignificant Delay in Repayment Payment Deferral [Member] Schedule of details the internal risk-rating categories for the Company's commercial and industrial, commercial real estate, commercial construction and business banking portfolios Financing Receivable Credit Quality Indicators [Table Text Block] Fair Value, Nonrecurring Fair Value, Nonrecurring [Member] Professional services Professional Fees Insider Trading Policies and Procedures [Line Items] PSU Performance Shares [Member] Deferred income tax expense (benefit) Deferred Income Tax Expense (Benefit) Business Banking Business Banking Segment [Member] Business Banking Segment Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Antidilutive securities (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Mortgage Derivative Mortgage Derivative [Member] Mortgage Derivative Entity Central Index Key Entity Central Index Key Net interest income after provision for allowance for loan losses Interest Income (Expense), after Provision for Loan Loss Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Payment of lease payments Payment Of Lease Payments Payment of lease payments. Current and accruing Financial Asset, Not Past Due, Accruing [Member] Financial Asset, Not Past Due, Accruing Pledging Purpose [Axis] Pledging Purpose [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Schedule of Company's Tax Provision and Applicable Tax Rates Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Financing Receivable, Troubled Debt Restructuring [Table] Financing Receivable, Modified [Table] RSA Restricted Stock [Member] Accumulated Other Comprehensive Loss Total AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Dividends declared and paid to common shareholders Payments of Dividends Period for recognition for unrecognized compensation expense related to unvested awards Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Statement [Line Items] Statement [Line Items] Increase in cash surrender value of bank-owned life insurance Increase (Decrease) in Insurance Settlements Receivable Total assets Assets Term Extension Extended Maturity [Member] Total interest expense Interest Expense, Operating Service charges on deposit accounts Service Charges On Deposit Accounts Service charges on deposit accounts. Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Pre Tax Amount Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent [Abstract] Schedule of The Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Summary Of The Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis [Table Text Block] Summary of the balances of assets and liabilities measured at fair value on a recurring basis. Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Before reclassifications Other comprehensive income before reclassifications OCI, before Reclassifications, Net of Tax, Attributable to Parent Occupancy and equipment Occupancy, Net PEO PEO [Member] Total borrowed funds Debt, long-term and short-term, combined amount Debt, Long-Term and Short-Term, Combined Amount Prepaid pension expense Increase (Decrease) in Prepaid Expense Borrowed funds: Securities Borrowed [Abstract] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Number of holdings Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Derivative designated as hedging instruments, Interest rate swaps, Other liabilities Derivative Instruments in Hedges, Liabilities, at Fair Value Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments Derivative Liability, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Retained Earnings Retained Earnings [Member] Loss on lease right-of-use assets, net Operating Lease, Impairment Loss Due in one year or less, Amortized Cost Debt Securities, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Debt Securities, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Change in actuarial net loss Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Schedule of Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Changes in lines of credit,resrticted to commercial exposure Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Corporate bonds Corporate Debt Securities [Member] Diluted earnings (loss) per share (in dollars per share) Diluted (in dollars per share) Earnings Per Share, Diluted Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] FDIC insurance Federal Deposit Insurance Corporation Premium Expense Amortization of intangible assets Intangible Asset, Finite-Lived, Amortization Expense Financing receivable, excluding accrued interest, year four, originated, three years before current fiscal year Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Share-Based Payment Arrangement [Abstract] Less: reclassification adjustments Reclassification from AOCI, Current Period, Tax Total noninterest income in-scope of ASC 606 Revenue from Contract with Customer, Excluding Assessed Tax Mortgage loans partially or wholly-owned by others and serviced by the Company Participating Mortgage Loans, Mortgage Obligations, Amount Repurchased common stock Stock Repurchased During Period, Value Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Government-sponsored residential mortgage-backed securities Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] Unallocated common shares held by the Employee Stock Ownership Plan Unearned ESOP Shares Schedule of the Company's loan participations Schedule of Participating Mortgage Loans [Table Text Block] Investments In Affordable Housing Projects [Table] Equity Method Investment [Table] Non-taxable interest and dividends on securities Nontaxable Interest And Dividends On Available For Sale Securities Non-taxable interest and dividends on available for sale securities. Interest Rate Futures Interest Rate Futures [Member] Interest Rate Futures Loans Insured or Guaranteed by Government Authorities [Domain] Loans Insured or Guaranteed by Government Authorities [Domain] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Service cost Defined Benefit Plan, Service Cost Taxable interest and dividends on securities Taxable Interest And Dividends On Available For Sale Securities Taxable interest and dividends on available for sale securities. Revolving Loans Financing Receivable, Excluding Accrued Interest, Revolving Schedule of Financing Receivable, Allowance for Credit Loss Financing Receivable, Allowance for Credit Loss [Table Text Block] Common stock issued (in shares) Common Stock, Shares, Issued Due in one year or less, Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Year One Corporate Structure and Nature of Operations; Basis of Presentation Business Description and Basis of Presentation [Text Block] Forward Contracts Forward Contracts [Member] 12 Months or Longer Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Other Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Product and Service [Domain] Product and Service [Domain] Due after one year to five years, Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year One through Five Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Noninterest expense: Noninterest Expense [Abstract] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Federal Home Loan Bank of Boston Federal Home Loan Bank of Boston [Member] Termination Date Trading Arrangement Termination Date Fair Value Assets And Liabilities Measured On Recurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Purpose [Domain] Purpose [Domain] Purpose [Domain]. Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Award expiration period Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period Fair Value as of Grant Date Award Grant Date Fair Value Schedule of Government-Sponsored Residential Mortgage-Backed Securities with Gross Unrealized Losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Unearned discounts and deferred fees, net Unearned discounts and deferred fees, net Financing Receivable, Unamortized Loan Cost (Fee) and Purchase Premium (Discount) Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Income from investments for employee retirement benefits Income (Losses) From Investments For Employee Retirement Benefits Income from investments for employee retirement benefits Less than 12 Months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Less: amortization of actuarial net loss Accumulated Defined Benefit Plans Adjustment, Amortization Of Actuarial Loss, Attributable To Parent [Member] Accumulated Defined Benefit Plans Adjustment, Amortization Of Actuarial Loss, Attributable To Parent Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Investment in mutual funds Alternative Investment Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Renewable Energy Program Renewable Energy Program [Member] Debt securities, available-for-sale, accrued interest writeoff Debt Securities, Available-for-Sale, Accrued Interest Writeoff Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Vesting period Vesting Period (Approximate from date of grant) Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Award Type [Domain] Award Type [Domain] Fair Value of Assets and Liabilities Fair Value Disclosures [Text Block] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Asset Pledged as Collateral Asset Pledged as Collateral [Member] Operating lease remaining lease term Lessee, Operating Lease, Term of Contract Summary of Derivative Instruments [Abstract] Summary of Derivative Instruments [Abstract] Other-than-Insignificant Delay in Repayment Financing Receivable, Modified, Weighted Average Number Of Payments Deferred Financing Receivable, Modified, Weighted Average Number Of Payments Deferred Cash and cash equivalents Cash, Cash Equivalents, and Short-Term Investments Debt securities, held-to-maturity, allowance for credit loss, excluding accrued interest Allowance for Credit Losses Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest Interest checking accounts Interest-Bearing Domestic Deposit, Checking Schedule of Derivative Financial Instruments On The Consolidated Income Statements Schedule Of The Net Impact Of Derivative Instruments On Statement Of Income And Comprehensive Income Loss [Table Text Block] schedule of the net impact of derivative instruments on statement of income and comprehensive income loss. Other assets Other Assets 30-59 Days Past Due 30-59 Days Past Due Financial Asset, 30 to 59 Days Past Due [Member] Due after one year to five years, Fair value Debt Securities, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Debt Securities, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five 30-89 days past due and accruing Financial Asset, 30 to 89 Days Past Due, Accruing [Member] Financial Asset, 30 to 89 Days Past Due, Accruing Disclosure of Leases [Table] Lessee, Lease, Description [Table] Noninterest income (loss): Noninterest Income [Abstract] Cash, cash equivalents, and restricted cash at beginning of period Cash, cash equivalents, and restricted cash at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Gross Amounts Not Offset in the Consolidated Balance Sheet, Collateral Pledged (Received) Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Non-NEOs Non-NEOs [Member] Financing Receivable, Allowance for Credit Loss [Roll Forward] Financing Receivable, Allowance for Credit Loss [Roll Forward] Net decrease in time deposits Increase (Decrease) in Time Deposits Leases Lessee, Operating Leases [Text Block] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Due after five to ten years, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Combination - Interest Rate Reduction & Other-than-Insignificant Delay in Repayment Payment Deferral And Interest Rate Reduction [Member] Payment Deferral And Interest Rate Reduction Loss Unlikely to be Collected Financing Receivable [Member] Schedule of Share-based Compensation Expense Under the 2021 Plan and the Related Tax Benefit Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block] Payments for repurchase of common stock Payments for Repurchase of Common Stock Statistical Measurement [Axis] Statistical Measurement [Axis] Federal Home Loan Bank advances FHLB advances Long-Term Federal Home Loan Bank Advances (Loss) gain in OCI on derivatives Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Award Type [Axis] Award Type [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Net increase (decrease) in demand, savings, interest checking, and money market investment deposit accounts Increase (Decrease) in Demand Deposits Retained earnings Retained Earnings (Accumulated Deficit) Consumer Portfolio Segment Consumer Portfolio Segment [Member] Product and Service [Axis] Product and Service [Axis] Fair value of interest rate swap liabilities that are net in a net liability position Credit Risk Derivatives, at Fair Value, Net Net change in fair value of cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Common Stock Common Stock [Member] Operating lease cost Operating Lease, Cost Number of additional commitments to lend Financing Receivable, Modified, Number Of Additional Commitments To Lend Financing Receivable, Modified, Number Of Additional Commitments To Lend Debt securities, held-to-maturity, accrued interest, writeoff Debt Securities, Held-to-Maturity, Accrued Interest, Writeoff Financing receivable, excluding accrued interest, year five, originated, four years before current fiscal year, writeoff Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year, Writeoff Derivative Contract [Domain] Derivative Contract [Domain] Total Past Due Financial Asset, Past Due [Member] Losses on sales of securities available for sale, net Loss on sale of securities available for sale, net Net losses from sales of AFS securities Debt Securities, Available-for-Sale, Realized Gain (Loss) Total liabilities and shareholders’ equity Liabilities and Equity Variable lease cost Variable Lease, Cost Goodwill and other intangibles, net Intangible Asset, Including Goodwill, after Accumulated Amortization Share-based Payment Arrangement, Option Share-Based Payment Arrangement, Option [Member] (Loss) gain recognized in other income for foreign currency exchange contracts: Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Tabular List, Table Tabular List [Table Text Block] Additional paid in capital Additional Paid in Capital Service charges on deposit accounts Service Charge On Deposit Accounts [Member] Service Charge On Deposit Accounts Purchases of securities held to maturity Payments to Acquire Held-to-Maturity Securities Credit Derivatives Contract Type [Axis] Credit Derivatives Contract Type [Axis] Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Schedule of Components of Net Pension Expense Schedule of Defined Benefit Plans Disclosures [Table Text Block] Adjustment to Compensation: Adjustment to Compensation [Axis] Receive Fixed Swap Rate Derivative, Average Fixed Interest Rate Nature Of Transaction [Domain] Nature Of Transaction [Domain] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Interest paid on deposits and borrowings Interest Paid, Excluding Capitalized Interest, Operating Activity Hedging Designation [Axis] Hedging Designation [Axis] 60-89 Days Past Due 60-89 Days Past Due Financial Asset, 60 to 89 Days Past Due [Member] Credit exposure to settled variation margin in excess of customer related interest rate swap Credit Exposure To Interest Swap In Excess Of Termination Values Credit exposure to settled variation margin in excess of customer related interest rate swap. 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Schedule of the age analysis of past due loans to borrowers experiencing financial difficulty Financing Receivable, Modified, Past Due [Table Text Block] Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Standby letters of credit Standby Letters of Credit [Member] Schedule of Debt Securities, Available-for-Sale Debt Securities, Available-for-Sale [Table Text Block] Loans originated for sale, net of repayments Payment for Origination, Loan, Mortgage, Held-for-Sale Federal Home Loan Bank Advances Federal Home Loan Bank Advances [Member] Purchased banking premises and equipment Payments to Acquire Other Property, Plant, and Equipment Schedule of Other Information Related to Leases Assets and Liabilities, Lessee [Table Text Block] Assets and Liabilities, Lessee Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Entity Address, State or Province Entity Address, State or Province Due in one year or less, Fair value Debt Securities, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Debt Securities, Fair Value, Maturity, Allocated and Single Maturity Date, Year One PEO Total Compensation Amount PEO Total Compensation Amount Current recorded investment included in other assets Investment, Proportional Amortization Method, Elected, Amount Assets Assets, Fair Value Disclosure [Abstract] Notional Amount Total Notional Derivative, Notional Amount Average number of common shares outstanding used to calculate basic earnings (loss) per common share (in shares) Weighted Average Number of Shares Outstanding, Basic Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Unfunded Loan Commitment Unfunded Loan Commitment [Member] Due after five to ten years, Fair value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Total noninterest income (loss) Noninterest Income Purchases of Federal Home Loan Bank stock Payments to Acquire Federal Home Loan Bank Stock Certificates of deposit Time Deposits Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Due after ten years, Fair value Debt Securities, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Debt Securities, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness test) Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), after Adjustments and Tax Debt Securities, Held-to-Maturity [Table] Debt Securities, Held-to-Maturity [Table] Tax credit investment Affordable Housing Investment, Tax Credits Affordable Housing Investment, Tax Credits Net loans Financing receivable, excluding accrued interest, after allowance for credit loss Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Matched commercial customer book Foreign currency exchange contracts - matched customer book Foreign Exchange Currency Contracts Matched Book Customer [Member] Foreign Exchange Currency Contracts Matched Book Customer Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Average number of common shares outstanding (in shares) Weighted Average Number of Shares Issued, Basic Interest on federal funds sold and other short-term investments Interest On Federal Funds Sold And Other Short Term Investments Interest on federal funds sold and other short-term investments. Due after five to ten years, Amortized Cost Debt Securities, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year Five through Ten Debt Securities, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year Five through Ten Net increase (decrease) in borrowed funds Proceeds From Repayments Of Borrowed Funds Proceeds from (repayments) of borrowed funds. Federal Reserve Discount Window Federal Reserve Discount Window [Member] Federal Reserve Discount Window Financing receivable, excluding accrued interest, year three, originated, two years before current fiscal year Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Change in: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Gross Amounts Not Offset in the Consolidated Balance Sheet, Collateral Pledged (Received) Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Due after five to ten years, Fair value Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Security Exchange Name Security Exchange Name Tax benefit Income Tax Expense (Benefit), Gain (Loss) On Sale Of Securities Income Tax Expense (Benefit), Gain (Loss) On Sale Of Securities Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost Excluding Accrued Interest, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date Total Liabilities, Fair Value Disclosure Loans modified during the prior 12 months which had subsequently defaulted Financing Receivable, Excluding Accrued Interest, Modified, Subsequent Default Number of Positions Number of Interest Rate Derivatives Held Number of shares authorized (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized 12 Months or Longer Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Interest rate swap income Interest Rate Swap Income Losses Interest rate swap income (losses). Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Interest on borrowings Interest Expense, Borrowings Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Derivative not designated as hedging instruments, Interest rate swaps, Other liabilities Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Less: reclassification adjustments Less: Amounts reclassified from accumulated other comprehensive loss Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Due in one year or less, Fair value Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Derivatives not designated as hedging instruments, Other liabilities Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value Non-cash activities Noncash Investing and Financing Items [Abstract] Contributions to other equity investments Payments to Acquire Other Investments Defined benefit pension plans: Defined Benefit Pension Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Residential real estate Residential Mortgage [Member] Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Average number of common shares outstanding used to calculate diluted earnings (loss) per common share (in shares) Weighted Average Number of Shares Outstanding, Diluted Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Mortgage loans in process of foreclosure, amount Mortgage Loans in Process of Foreclosure, Amount Other consumer Other Consumer Other Consumer [Member] Other consumer. Total Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Underlying Security Market Price Change Underlying Security Market Price Change, Percent Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Contributions to low income housing tax credit investments Contributions To Low Income Housing Tax Credit Investments Contributions to low income housing tax credit investments. 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Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Other comprehensive (loss) income, net of tax: After Tax Amount Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unallocated Common Stock Held by ESOP Deferred Compensation, Share-Based Payments [Member] Technology and data processing Information Technology and Data Processing Schedule of Earnings (Loss) Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Less: Average unallocated ESOP shares (in shares) Weighted Average Number of Shares, Employee Stock Ownership Plan Shares Not Committed to be Released Segment Reporting Segment Reporting [Text Block] Proceeds from maturities and principal paydowns of securities available for sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Minimum Minimum [Member] Income Statement Location [Axis] Location, Statement of Income, Balance [Axis] Amortization expense included in income tax expense Investment Program, Proportional Amortization Method, Applied, Amortization Expense Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Advance from FHLBB Advance from Federal Home Loan Bank Other liabilities Other Liabilities Disclosure Of Financial Instruments Indicated [Line Items] Securities Borrowed, Allowance for Credit Loss [Line Items] Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Proceeds from sale of Federal Home Loan Bank stock Proceeds from Sale of Federal Home Loan Bank Stock Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Purpose [Axis] Purpose [Axis] Purpose [Axis]. 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