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Consolidated Entities [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Financial Instrument Performance Status [Domain] Financial Instrument Performance Status [Domain] Banking Regulation, Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Total Risk-Based Capital Ratio, Capital Adequacy, Minimum Doubtful Doubtful [Member] Other comprehensive income: Other Comprehensive Income (Loss), Net of Tax [Abstract] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Banking Regulation, Tier One Risk-Based Capital, Actual Banking Regulation, Tier 1 Risk-Based Capital, Actual Consolidated Entities [Domain] Consolidated Entities [Domain] Debt Securities, Held-to-maturity Debt Securities, Held-to-Maturity [Table Text 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Purchased under Agreement to Resell, and Security Borrowed, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Gross Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, before Offset Summary of Derivative Financial Instruments Schedule of Derivative Instruments [Table Text Block] Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Issuance of restricted stock, net of repurchase for tax withholdings Proceeds Payments From Common Stock Issued Under Stock Compensation Plans Proceeds Payments from Common Stock Issued under Stock Compensation Plans Entity Address, City or Town Entity Address, City or Town Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned FHLBB Federal Home Loan Bank Stock Financing Receivable Allowance [Domain] 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 Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount AOCI, Derivative Qualifying as Hedge, Excluded Component AOCI, Derivative Qualifying as Hedge, Excluded Component [Member] AOCI, Derivative Qualifying as Hedge, Excluded Component Observable Market Data (Level 2) Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] 90 Days or Greater Past Due Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Due in one year or less Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value Dividend income Dividend Income, Operating Proceeds from the sale of mortgage loans Proceeds from Sale, Loan, Mortgage, Held-for-Sale Concentration Risk Type [Axis] Concentration Risk Type [Axis] Net decrease in fair value, tax (expense) benefit Net decrease in fair value, after-tax amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] (Credit) provision for loan losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Loans Only Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Loans Only Cash collateral Cash Collateral for Borrowed Securities Liabilities assumed in Northway Financial, Inc. acquisition Noncash or Part Noncash Acquisition, Value of Liabilities Assumed Gain on sale of mortgage loans, net of origination costs Gain on sale of mortgage loans Gain (Loss) on Sale of Mortgage Loans Net gain on postretirement plans, tax (expense) benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Banking Regulation, Regulatory Capital Requirement, Compliance [Table] Banking Regulation, Regulatory Capital Requirement, Compliance [Table] Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Net unrealized gains, tax (expense) benefit Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, Tax Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, Tax Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Less: allowance for credit losses on loans Beginning balance Ending balance Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Document Period End Date Document Period End Date Furniture, equipment and data processing Equipment And Software Expense This element represents furniture and equipment expense including depreciation, repairs, rentals, and service contract costs. This item also includes equipment purchases which do not qualify for capitalization in accordance with accounting policy. In addition, this item includes the amount charged to expense for amortization of capitalized computer software costs as well as amounts incurred for software development activities that were not capitalized. Subsidiaries Subsidiaries [Member] Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan Debt Securities, Available-for-sale, Realized Loss Debt Securities, Available-for-Sale, Realized Loss Financial Instruments [Table] Financial Instruments [Table] Financial Instruments [Table] Recoveries of previously charged-off loans Proceeds, Financing Receivable, Previously Written off, Recovery Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Repurchase Agreements Securities Sold under Agreements to Repurchase Securities Sold under Agreements to Repurchase Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company CMO issued or guaranteed by U.S. government-sponsored enterprises Collateralized Mortgage Obligations Issued By United States Government Sponsored Enterprises [Member] Collateralized Mortgage Obligations Issued By United States Government Sponsored Enterprises [Member] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] EPS Earnings Per Share [Text Block] Per Share Data Earnings Per Share [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Due in one year or less Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Year One Total liabilities Liabilities Trading Symbol Trading Symbol Purchase of premises and equipment Payments to Acquire Property, Plant, and Equipment Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Company Selected Measure Name Company Selected Measure Name Unrealized holding gains, pre-tax amount OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment and Tax Purchase of available-for-sale debt securities Payments to Acquire Debt Securities, Available-for-Sale Customer Loan Swap Dealer Bank [Member] Customer Loan Swap Dealer Bank [Member] Customer Loan Swap Dealer Bank [Member] Risk participation agreements Loan Participations and Assignments [Member] Interest on deposits Interest Expense, Deposits Customer Repurchase Agreements Customer Repurchase Agreements [Member] Customer Repurchase Agreements [Member] Due after one year through five years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Axis] 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 Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Non-Accrual Loans Financing Receivable, Nonaccrual Financing Receivable, Nonaccrual Legal Proceedings [Table] Legal Proceedings [Table] Legal Proceedings [Table] FHLB advances, general debt obligations, pledged collateral Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Loans and Leases Receivable, Excluded Accrued Interest from Amortized Cost Loans and Leases Receivable, Excluded Accrued Interest from Amortized Cost Loans and Leases Receivable, Excluded Accrued Interest from Amortized Cost Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Banking Regulation, Tier One Leverage Capital, Actual Banking Regulation, Tier 1 Leverage Capital, Actual Deferred income tax expense (benefit) Deferred Income Taxes and Tax Credits Cash dividends declared, not paid Dividends Payable Entities [Table] Entities [Table] Commitments to Extend Credit [Member] Commitments to Extend Credit [Member] Other Investments, Amortized Cost Other Investments, Amortized Cost Other Investments, Amortized Cost Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Amount Offset Against Collateral Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Unrealized gain (loss) on loans held for sale Unrealized gain (loss) on loans held for sale Unrealized gain (loss) on loans held for sale Dilutive effect of stock-based awards (shares) Weighted Average Number of Shares Outstanding, Diluted, Adjustment Mortgage-related securities Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Amortized Cost Award Timing Predetermined Award Timing Predetermined [Flag] Schedule of of Comprehensive Income (Loss) Comprehensive Income (Loss) [Table Text Block] Interest Income Interest and Dividend Income, Operating [Abstract] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Readily Available Market Prices (Level 1) Fair Value, Inputs, Level 1 [Member] Proceeds from maturities of held-to-maturity securities Proceeds from Sale and Maturity of Held-to-Maturity Securities Debt Securities, Available-for-sale [Abstract] Debt Securities, Available-for-Sale [Abstract] Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Portfolio Segment [Axis] Class of Financing Receivable [Axis] Long-term Debt, Fair Value Long-Term Debt, Fair Value Antidilutive Securities [Axis] Antidilutive Securities [Axis] Subtotal Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Concentration Risk Type [Domain] Concentration Risk Type [Domain] Offsetting Assets [Table] Offsetting Assets [Table] Due in one year or less 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] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments INVESTMENTS Investment in Debt and Equity Securities and Other Trading Assets [Text Block] Expiration Date Trading Arrangement Expiration Date Hedging Relationship [Axis] Hedging Relationship [Axis] Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets [Table Text Block] Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items] Unrealized Gains Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain Derivative Asset, Not Offset, Policy Election Deduction Derivative Asset, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Acquired PCD loans Financing Receivable, Excluding Accrued Interest, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] Antidilutive Security, Excluded EPS Calculation [Table] Antidilutive Security, Excluded EPS Calculation [Table] Common stock, no par value (dollars per share) Common Stock, No Par Value Time deposits Deposits, Fair Value Disclosure Assets acquired in Northway Financial, Inc. acquisition, excluding cash received Noncash or Part Noncash Acquisition, Value of Assets Acquired Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] BORROWINGS Debt Disclosure [Text Block] Contractual Obligation, Fiscal Year Maturity Contractual Obligation, Fiscal Year Maturity [Table Text Block] REPURCHASE AGREEMENTS Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block] Customer loan swaps Customer Loan Swaps [Member] Customer Loan Swaps [Member] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Available-for-sale, Fair Value Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract] Cash dividends declared Dividends, Common Stock, Cash Total shareholders’ equity Beginning Balance Ending Balance Stockholders' Equity Attributable to Parent Equity, Attributable to Parent Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Gross Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, before Offset Offsetting Assets [Line Items] Offsetting Assets [Line Items] ASSETS Assets [Abstract] Other investments Other Investments Available-for-sale securities, book value Amortized Cost, Total Available-for-sale securities, book value Debt Securities, Available-for-Sale, Amortized Cost Credit Risk Exposure Indicators by Portfolio Segment Financing Receivable Credit Quality Indicators [Table Text Block] Consulting and professional fees Professional Fees Insider Trading Policies and Procedures [Line Items] Nonperforming Financial Instruments [Member] Nonperforming Financial Instruments [Member] Performance Shares Performance Shares [Member] Commercial Real Estate Commercial Real Estate Portfolio Segment [Member] Financing Receivable, Troubled Debt Restructuring [Domain] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Cash Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Other interest income Interest Income Federal Funds Sold And Other Short Term Investments Interest income on federal funds sold. Federal funds sold represent the excess federal funds held by one commercial bank which it lends to another commercial bank, usually at an agreed-upon (federal funds) rate of interest. Such loans are made for legal reserve requirement purposes of the borrowing bank and generally are of short-duration (overnight). Also include interest income on other investments not otherwise specified in the taxonomy that will be realized in a short period of time, usually less than one year or the normal operating cycle, whichever is longer. Antidilutive Stock options (shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Entity Central Index Key Entity Central Index Key Net interest income after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Equity [Abstract] Equity [Abstract] 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] Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Banking Regulation, Excess Tier One Leverage Capital Ratio, Actual Banking Regulation, Excess Tier 1 Leverage Capital Ratio, Actual Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Banking Regulation, Total Risk-Based Capital Ratio, Well Capitalized, Minimum Banking Regulation, Total Risk-Based Capital Ratio, Well Capitalized, Minimum All Individuals All Individuals [Member] Carrying Amount of Hedged Assets/(Liabilities) Hedged Asset, Fair Value Hedge Cash dividends paid on common stock Payments of Dividends Deferred tax assets, unrealized losses on available for sale securities Deferred Tax Asset, Debt Securities, Available-for-Sale, Unrealized Loss Performing Financial Instruments [Member] Performing Financial Instruments [Member] Less: reclassification adjustment for amortization of securities transferred from AFS to HTM, tax (expense) benefit OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), Tax Statement [Line Items] Statement [Line Items] Total assets Assets Total interest expense Interest Expense, Operating Beneficial Interest, Portfolio Layer Method, Amortized Cost Beneficial Interest, Portfolio Layer Method, Amortized Cost HTM debt securities, excluding accrued interest from amortized cost Debt Securities, Held-to-Maturity, Excluded Accrued Interest from Amortized Cost Debt Securities, Held-to-Maturity, Excluded Accrued Interest from Amortized Cost Industry Sector [Axis] Industry Sector [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Accounting Standards Update and Change in Accounting Principle [Abstract] Accounting Standards Update and Change in Accounting Principle [Abstract] Assets Sold under Agreements to Repurchase [Line Items] Assets Sold under Agreements to Repurchase [Line Items] Provision for acquired non-PCD loans Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Excluding Loans Acquired Through Business Combination Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Excluding Loans Acquired Through Business Combination Asset Sold under Agreement to Repurchase [Table] Asset Sold under Agreement to Repurchase [Table] Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax 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] Mortgage-related securities Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Fair Value Net occupancy costs Occupancy, Net PEO PEO [Member] Beginning Balance (in shares) Ending Balance (in shares) Shares, Outstanding Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed Goodwill Goodwill Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Derivative Liability, Not Offset, Policy Election Deduction Derivative Liability, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Change in fair value hedges presented within residential real estate loans and other assets Change in fair value hedges presented within residential real estate loans and other assets Change in fair value hedges presented within residential real estate loans and other assets Retained Earnings Retained Earnings [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock, outstanding (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Carrying Amounts and Estimated Fair Value for Financial Instrument Assets and Liabilities Fair Value, by Balance Sheet Grouping [Table Text Block] Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Subordinated corporate bonds Corporate Debt Securities [Member] Diluted earnings per share Diluted EPS (in dollars per share) Earnings Per Share, Diluted Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Value Of Trust Preferred Securities Included In Tier One Capital Value Of Trust Preferred Securities Included In Tier One Capital Value of trust preferred securities included in Tier I Capital. Amortization of core deposit intangible assets Amortization of core deposit intangible assets Intangible Asset, Finite-Lived, Amortization Expense Repayments of Federal Home Loan Bank long-term advances Proceeds from Federal Home Loan Bank long-term advances Proceeds from Federal Home Loan Bank long-term advances 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 Offsetting Assets Offsetting Assets [Table Text Block] Revenue from Contract with Customer, Excluding Assessed Tax Revenue from Contract with Customer, Excluding Assessed Tax Banking Regulation, Tier One Leverage Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Tier One Leverage Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Tier 1 Leverage Capital Ratio, Capital Adequacy, Minimum Schedule of Cash Flow Hedging Instruments, Location Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Financial assets: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Common stock repurchased Stock Repurchased During Period, Value Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] MBS issued or guaranteed by U.S. government-sponsored enterprises MBS issued or guaranteed by U.S. government-sponsored enterprises Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] Service charges on deposit accounts Deposit Account [Member] Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Common stock issued for Northway Financial, Inc. acquisition Stock Issued Contract with Customer, Sales Channel [Axis] Contract with Customer, Sales Channel [Axis] Derivative, Gain (Loss) on Derivative, Net Derivative, Gain (Loss) on Derivative, Net Banking Regulation, Tier One Risk-Based Capital Ratio, Capital Adequacy, Minimum Banking Regulation, Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Cash Flow Hedges: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Collateral Held [Axis] Collateral Held [Axis] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Financing Receivable, Excluding Accrued Interest, Revolving Financing Receivable, Excluding Accrued Interest, Revolving Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Summary of Activity in Allowance for Loan Losses Financing Receivable, Allowance for Credit Loss [Table Text Block] Common stock, issued (in shares) Common Stock, Shares, Issued Entity Information [Line Items] Entity Information [Line Items] Forward delivery commitments Forward Contracts [Member] AFS debt securities, allowance Debt Securities, Available-for-Sale, Allowance for Credit Loss Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss OTHER COMPREHENSIVE INCOME (LOSS) Comprehensive Income (Loss) Note [Text Block] Product and Service [Domain] Product and Service [Domain] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Non-Interest Expense Noninterest Expense [Abstract] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Termination Date Trading Arrangement Termination Date Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Net gain on postretirement plans, net of tax Net gain on postretirement plans, net of tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Derivative Asset, Fair Value, Amount Offset Against Collateral Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Obligations of U.S. government-sponsored enterprises US Government-sponsored Enterprises Debt Securities [Member] Fair Value as of Grant Date Award Grant Date Fair Value Common Equity Tier I Risk Based Capital Ratio Common Equity Tier I Risk Based Capital Ratio Common Equity Tier I To Total Risk Weighted Assets Capital Ratio Total Collateral -Dependent Non-Accrual Loans Collateral Pledged [Member] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash Security Sold under Agreement to Repurchase, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Collateral, Right to Reclaim Securities Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Security Not Offset Northway Financial, Inc "NFI" Northway Financial, Inc "NFI" [Member] Northway Financial, Inc "NFI" Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Collateralized Mortgage Obligations CMO issued or guaranteed by U.S. government-sponsored enterprises Collateralized Mortgage Obligations [Member] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Subtotal Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Fair Value Net Unamortized fair Value Mark (Discount) on Loans Net Unamortized fair Value Mark (Discount) on Loans Net Unamortized fair Value Mark (Discount) on Loans Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Investments: Marketable Securities [Abstract] All Award Types Award Type [Domain] FAIR VALUE MEASUREMENT AND DISCLOSURE Fair Value Disclosures [Text Block] Company Determined Fair Value (Level 3) Fair Value, Inputs, Level 3 [Member] Held-to-maturity, Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date [Abstract] Asset Pledged as Collateral Asset Pledged as Collateral [Member] Net increase (decrease) in derivative collateral received from counterparties Increase (Decrease) In Derivative Collateral Received From Counterparties Increase (Decrease) In Derivative Collateral Received From Counterparties Geographical [Axis] Geographical [Axis] Other Other Investment Other Investment Interest checking Interest-Bearing Domestic Deposit, Checking Other assets Other Assets 30-59 Days Past Due Financial Asset, 30 to 59 Days Past Due [Member] Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Liability Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Liability Offset Legal Entity [Axis] Legal Entity [Axis] Banking Regulation, Total Capital, Actual Banking Regulation, Total Capital, Actual Non-Interest Income Noninterest Income [Abstract] Total cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Derivative, Collateral, Right to Reclaim Cash Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Gross charge-offs for the six months ended Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] Non-NEOs Non-NEOs [Member] 46203 Maturity Overnight [Member] Schedule of Borrowed Funds Outstanding Schedule of Debt [Table Text Block] Derivative liability, fair value, net Derivative Liability, Subject to Master Netting Arrangement, before Offset of Collateral Customer [Domain] Customer [Domain] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Due after five years through ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Common stock repurchases Common stock repurchases Payments for Repurchase of Common Stock Statistical Measurement [Axis] Statistical Measurement [Axis] Payment to Acquire Life Insurance Policy, Investing Activities Proceeds from BOLI death benefit Proceeds from BOLI death benefit Award Type Award Type [Axis] Net decrease in fair value, pre-tax amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Interest rate contracts Interest Rate Contract [Member] Subsidiary One Subsidiary One [Member] Subsidiary One [Member] Transferred Securities Transferred Securities [Member] Transferred Securities Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Real Estate Real Estate [Member] Retained earnings Retained Earnings (Accumulated Deficit) Commercial real estate - owner-occupied Commercial Real Estate portfolio Segment, Owner-Occupied [Member] Commercial Real Estate portfolio Segment, Owner-Occupied Consumer Consumer Portfolio Segment [Member] Product and Service [Axis] Product and Service [Axis] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Common Stock Common Stock [Member] Available-for-sale securities, at fair value (amortized cost of $937,123 and $972,686, respectively) Fair value, total Debt Securities, Available-for-Sale Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] 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 Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Derivative Contract [Domain] Derivative Contract Type [Domain] Derivative Contract [Domain] Total Past Due Financial Asset, Past Due [Member] Proceeds from sale of Federal Home Loan Bank stock Proceeds from sale of Federal Home Loan Bank and Federal Reserve Bank stock Proceeds from sale of Federal Home Loan Bank and Federal Reserve Bank stock Total liabilities and shareholders’ equity Liabilities and Equity Employee Stock Option Share-Based Payment Arrangement, Option [Member] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Asset Class [Axis] Asset Class [Axis] Products And Services, Fiduciary Services Income [Member] Products And Services, Fiduciary Services Income [Member] Products And Services, Fiduciary Services Income [Member] Trading securities Debt Securities, Trading Debt Securities, Trading Tabular List, Table Tabular List [Table Text Block] Summary of Amortized Costs and Estimated Fair Values of Available-For-Sale Securities Unrealized Gain (Loss) on Investments [Table Text Block] Purchase of held-to-maturity securities Payments to Acquire Held-to-Maturity Securities Loans And Leases Receivable Impaired Interest Income Foregone Loans And Leases Receivable Impaired Interest Income Foregone Foregone interest. Name Awards Close in Time to MNPI Disclosures, Individual Name Due after five years through ten years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 5 through 10 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] Residential Building Operators Industry Sector Residential Building Operators Industry Sector [Member] Residential Building Operators Industry Sector Financing Receivable, Troubled Debt Restructuring [Axis] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Adjustment to Compensation: Adjustment to Compensation [Axis] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activity Hedging Designation [Axis] Hedging Designation [Axis] 60-89 Days Past Due Financial Asset, 60 to 89 Days Past Due [Member] Name Measure Name Pay vs Performance Disclosure [Line Items] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Non-interest checking Demand Deposit Accounts Debt Instrument [Line Items] Debt Instrument [Line Items] Interest and fees on loans Interest and Fee Income, Financing Receivable Termination value Provision Breach, Settlement Obligation, Termination Value Provision Breach, Settlement Obligation, Termination Value Revenue Not from Contract with Customer Revenue Not from Contract with Customer Interest receivable Interest Receivable Name Trading Arrangement, Individual Name Interest on junior subordinated debentures Interest Expense, Subordinated Notes and Debentures Company Selected Measure Amount Company Selected Measure Amount Securities Sold under Agreements to Repurchase, Gross Security Sold under Agreement to Repurchase, Subject to Master Netting Arrangement, before Offset Accounts and Financing Receivables [Table] Accounts and Financing Receivables [Table] Nontaxable interest on investments Interest Income, Securities, State and Municipal Non-PEO NEO Non-PEO NEO [Member] Total non-interest expense Noninterest Expense (Credit) provision for loan losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), General, Loans Only Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), General, Loans Only Award Timing Method Award Timing Method [Text Block] Non-Residential Building Operators Industry Sector Non-Residential Building Operators Industry Sector [Member] Non-Residential Building Operators Industry Sector [Member] Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Notional Amount Derivative Liability, Notional Amount Debt Securities, Held-to-maturity, Maturity, without Single Maturity Date, Fair Value Debt Securities, Held-to-Maturity, Maturity, without Single Maturity Date, Fair Value Net Income Net Income Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Cash Equivalent, Certificate of Deposit, Carrying Value Cash Equivalent, Certificate of Deposit, Carrying Value Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Restatement Determination Date: Restatement Determination Date [Axis] Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Net increase in loans Payments for (Proceeds from) Loans and Leases, Excluding Loans Previously Charged Off Payments for (Proceeds from) Loans and Leases, Excluding Loans Previously Charged Off Less: reclassification adjustment for amortization of securities transferred from AFS to HTM, after-tax amount Less: reclassification adjustment for amortization of securities transferred from AFS to HTM, after-tax amount OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), after Tax Brokered deposits Interest-Bearing Domestic Deposit, Brokered Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Due after ten years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 10 Statistical Measurement [Domain] Statistical Measurement [Domain] Document Fiscal Year Focus Document Fiscal Year Focus Derivative Liability, Fair Value, Gross Asset Derivative Liability, Subject to Master Netting Arrangement, Asset Offset Merger and acquisition costs Business Combination, Acquisition-Related Cost, Expense Financing Receivable, Nonaccrual, With Allowance Financing Receivable, Nonaccrual, With Allowance Financing Receivable, Nonaccrual, With Allowance Customer [Axis] Customer [Axis] Total deposits Deposits Common stock, no par value: authorized 40,000,000 shares, issued and outstanding 16,896,273 and 16,924,310 on June 30, 2026 and December 31, 2025, respectively Common Stock, Value, Issued Subsidiary Three Subsidiary Three [Member] Subsidiary Three Restatement Determination Date Restatement Determination Date Other expenses Other Noninterest Expense Amendment Flag Amendment Flag Finance lease payments Finance Lease, Principal Payments FRB Federal Reserve Bank Stock Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Standby Letters of Credit [Member] Standby Letters of Credit [Member] Originations of mortgage loans held for sale Payment for Origination, Loan, Mortgage, Held-for-Sale Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] AOCI, Derivative Qualifying as Hedge, Included Component AOCI, Derivative Qualifying as Hedge, Included Component [Member] AOCI, Derivative Qualifying as Hedge, Included Component General Business Assets General Business Assets [Member] General Business Assets Common stock issued for acquisition of Northway Financial, Inc. Stock Issued During Period, Value, Acquisitions Net gain on postretirement plans, pre-tax amount Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax 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 PEO Total Compensation Amount PEO Total Compensation Amount Financial assets: Assets, Fair Value Disclosure [Abstract] Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, without Single Maturity Date Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, without Single Maturity Date Weighted average number of common shares outstanding Weighted-average common shares outstanding for basic EPS Weighted Average Number of Shares Outstanding, Basic Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] AFS Debt Securities: OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax [Abstract] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Interest-bearing deposits in other banks Interest-Bearing Deposits in Banks and Other Financial Institutions Due after five years through ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Purchase accounting accretion, net Purchase Accounting Accretion During Period Purchase Accounting Accretion Total non-interest income Noninterest Income Noninterest Income Revenue Revenue from Contract with Customer, Including Assessed Tax Subsidiary Four Subsidiary Four [Member] Subsidiary Four Available-for-sale, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] LOANS AND ALLOWANCE FOR LOAN LOSSES Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Certificates of deposit Time Deposits Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Net income available to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Interest on borrowings Interest Expense, Borrowings, Excluding Subordinated Notes and Debentures Interest Expense, Borrowings, Excluding Subordinated Notes and Debentures Other industry exposures Number of Portfolio Concentration Industries Number of Portfolio Concentration Industries Banking and Thrift, Other Disclosures [Abstract] Banking and Thrift, Other Disclosure [Abstract] Net loans Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Loan Concentration Risk Loan Concentration Risk [Member] Loan Concentration Risk [Member] Accounting Standards Adopted New Accounting Pronouncements, Policy [Policy Text Block] BALANCE SHEET OFFSETTING Offsetting [Text Block] Offsetting Amount of gain (loss) recognized in OCI on derivative Net decrease in fair value, tax (expense) benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Other comprehensive income, pre-tax amount Other Comprehensive Income (Loss), before Tax Long-term Debt Long-Term Debt 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 Unrealized holdings gains, tax (expense) benefit OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment, Tax Net cash provided by 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] Derivative, Collateral, Obligation to Return Cash Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Due after five years through ten years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Security Exchange Name Security Exchange Name Products And Services, Brokerage and Insurance Commissions [Member] Products And Services, Brokerage and Insurance Commissions [Member] Products And Services, Brokerage and Insurance Commissions [Member] Loans outstanding Financing Receivable, before Allowance for Credit Loss Brokerage and insurance commissions Brokerage Fees And Insurance Income Brokerage Fees and Insurance Income. Due after one year through five years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year One through Five Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 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] Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Banking Regulation, Tier One Risk-Based Capital Ratio, Capital Adequacy, Minimum Tier One Risk Based Capital Required For Capital Adequacy With Buffer To Risk Weighted Assets Tier One Risk Based Capital Required For Capital Adequacy With Buffer To Risk Weighted Assets Geographical [Domain] Geographical [Domain] 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] Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value 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: Amounts reclassified from AOCI Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Schedule of Investments [Table] Schedule of Investments [Table] Due in one year or less Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Net change in unrealized gains on available-for-sale securities, net of tax Net unrealized gains, after-tax amount OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Defined Benefit Postretirement Plans(1) Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Debt Securities Total AFS debt securities Debt Securities [Member] Asset Class [Domain] Asset Class [Domain] Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Diluted weighted average number of common shares outstanding Weighted-average common and potential common shares for diluted EPS (shares) Weighted Average Number of Shares Outstanding, Diluted Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Mortgage Loans in Process of Foreclosure, Amount Mortgage Loans in Process of Foreclosure, Amount Loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Underlying Security Market Price Change Underlying Security Market Price Change, Percent Net unamortized loan origination costs Net unamortized loan origination costs Net unamortized loan origination costs DERIVATIVES AND HEDGING Derivative Instruments and Hedging Activities Disclosure [Text Block] Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss Debt Securities, Held-to-Maturity, Amortized Cost, Unamortized Unrealized Loss Debt Securities, Held-to-Maturity, Amortized Cost, Unamortized Unrealized Loss Debt Securities, Held-to-Maturity, Amortized Cost, Unamortized Unrealized Loss Short-term borrowings Total short-term borrowings Short-Term Debt Derivative Liability, Fair Value, Gross Liability Derivative Liability, Subject to Master Netting Arrangement, before Offset Financial Asset, Closed Portfolio, Portfolio Layer Method, Amortized Cost Financial Asset, Closed Portfolio, Portfolio Layer Method, Amortized Cost Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Subsidiary Two Subsidiary Two [Member] Subsidiary Two [Member] Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease) Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease) Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring Basis [Table] Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Other real estate owned and collection costs, net Foreclosed Real Estate Expense (Recoveries) Foreclosed Real Estate Expense (Recoveries) Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Commercial Loans Commercial Loan [Member] Notional Amount Derivative Asset, Notional Amount Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year, Writeoff Accrued interest and other liabilities Accrued Interest Payable And Other Liabilities Accrued interest payable and other liabilities. Collateral Held [Domain] Collateral Held [Domain] All Executive Categories All Executive Categories [Member] Fixed rate mortgage interest rate lock commitments Interest Rate Lock Commitments [Member] Interest Rate Lock Commitments [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums Total Loan Portfolio Total Loan Portfolio [Member] Total Loan Portfolio [Member] Savings and money market Savings and Money Market Deposits Savings and Money Market Deposits Analysis of Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Proceeds from maturities of available-for-sale debt securities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Minimum Minimum [Member] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Liabilities Liabilities [Abstract] Location, Statement of Income, Balance [Axis] Location, Statement of Income, Balance [Axis] 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] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Other income Noninterest Income, Other Operating Income Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Common stock, authorized (in shares) Common Stock, Shares Authorized Long-term borrowings Long-term Debt, Excluding Subordinating Debt Long-term Debt, Excluding Subordinating Debt Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Debt Securities, Available-for-sale, Realized Gain Debt Securities, Available-for-Sale, Realized Gain Due after ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Exercise Price Award Exercise Price Fair Value, Measurements, Recurring Fair Value, Recurring [Member] Document Quarterly Report Document Quarterly Report Cash Surrender Value, Fair Value Disclosure Cash Surrender Value, Fair Value Disclosure Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Obligations of states and political subdivisions US States and Political Subdivisions Debt Securities [Member] Special Mention [Member] Special Mention [Member] REGULATORY CAPITAL REQUIREMENTS Regulatory Capital Requirements under Banking Regulations [Text Block] Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year, Writeoff Proceeds from sales of available-for-sale debt securities Proceeds from Sale of Debt Securities, Available-for-Sale Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Equity Component [Domain] Equity Component [Domain] Loans receivable, net of allowance Loans Receivable, Fair Value Disclosure Adoption Date Trading Arrangement Adoption Date Retail Loans Retail Loan [Member] Retail Loan Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Interest rate contracts Interest Rate Contract Four [Member] Interest Rate Contract Four Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Asset Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Asset Offset Taxable interest on investments Interest Income, Securities, US Treasury and Other US Government Held-to-maturity securities, fair value Fair value, total Debt Securities, Held-to-Maturity, Fair Value Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Loans Loans Receivable [Member] Commercial Commercial Commercial Portfolio Segment [Member] Business Combination [Domain] Business Combination [Domain] FHLBB and Correspondent Bank Overnight Borrowings FHLBB and Correspondent Bank Overnight Borrowings FHLBB and Correspondent Bank Overnight Borrowings COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] All Adjustments to Compensation All Adjustments to Compensation [Member] Business Combination [Axis] Business Combination [Axis] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Residential real estate Residential real estate Residential Portfolio Segment [Member] Substandard [Member] Substandard [Member] Substandard [Member] Income Statement [Abstract] Income Statement [Abstract] Shareholders’ Equity Equity, Attributable to Parent [Abstract] Document Transition Report Document Transition Report Deferred tax assets Deferred Income Tax Assets, Net Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Home equity Home Equity Portfolio Segment [Member] Home Equity Portfolio Segment [Member] City Area Code City Area Code Junior subordinated debentures Debt Instrument, Fair Value Disclosure Debit card income Debit Card [Member] Name Forgone Recovery, Individual Name Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Entity [Domain] Entity [Domain] Total interest income Interest and Dividend Income, Operating Unrealized holdings gains, after-tax amount OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment, after Tax OCI, Debt Securities, Available-for-Sale, Gain (Loss), before Adjustment, after Tax Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Loans 90 Days Past Due and Accruing Financing Receivable, 90 Days or More Past Due, Still Accruing Subordinated Debt and Junior Subordinated Debt Subordinated Debt and Junior Subordinated Debt [Member] Subordinated Debt and Junior Subordinated Debt [Member] Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] (Increase) decrease in other assets Increase (Decrease) in Other Operating Assets Net increase (decrease) in deposits Increase (Decrease) in Deposits Derivative Asset, Fair Value, Gross Liability Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Measurement Basis [Axis] Measurement Basis [Axis] Commercial real estate - non-owner-occupied Commercial Real Estate Portfolio Segment, Non Owner-Occupied [Member] Commercial Real Estate Portfolio Segment, Non Owner-Occupied Total investments Investments Banking Regulation, Tier One Risk-Based Capital Ratio, Actual Banking Regulation, Tier 1 Risk-Based Capital Ratio, Actual Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Common equity tier I capital Common equity tier I capital Common equity tier I capital Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Net Unrealized Gains (Losses) on Debt Securities(1) AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Mortgage banking income, net Fees and Commissions, Mortgage Banking and Servicing Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Net decrease in fair value, tax (expense) benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax Interest rate contracts Interest Rate Contract Three [Member] Interest Rate Contract Three Financial liabilities: Liabilities, Fair Value Disclosure [Abstract] Cash Flow Hedging Cash Flow Hedging [Member] Net (repayments) proceeds from borrowings less than 90 days Proceeds from (Repayments of) Short-Term Debt, Maturing in Three Months or Less FHLBB and Correspondent Bank Overnight Borrowings FHLBB and Correspondent Bank Overnight Borrowings [Member] FHLBB and Correspondent Bank Overnight Borrowings [Member] Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Composition of Loan Portfolio, Excluding Residential Loans Held for Sale Loan Portfolio [Table Text Block] Loan Portfolio Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Premises and equipment, net Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Financial Instruments [Domain] Financial Instruments [Domain] Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Fair Value Derivative Asset Offsetting [Abstract] Offsetting [Abstract] Underlying Securities Award Underlying Securities Amount REVENUE FROM CONTRACTS WITH CUSTOMERS Revenue from Contract with Customer [Text Block] Derivative Asset, Statement of Financial Position [Extensible Enumeration] Derivative Asset, Statement of Financial Position [Extensible Enumeration] Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Collateral, Obligation to Return Cash Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Common stock issued for acquisition of Northway Financial, Inc. (in shares) Stock Issued During Period, Shares, Acquisitions Customer Loan Swaps Commercial Customer [Member] Customer Loan Swaps Commercial Customer [Member] Customer Loan Swaps Commercial Customer [Member] Net unrealized gains, pre-tax amount OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax Provision for credit losses Provision for Loan, Lease, and Other Losses Off-Balance Sheet, Credit Loss, Liability Off-Balance-Sheet, Credit Loss, Liability Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Less: effective portion reclassified into interest expense, tax (expense) benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Current Fiscal Year End Date Current Fiscal Year End Date Held-to-maturity securities, at amortized cost (fair value of $432,640 and $457,821, respectively) Held-to-maturity securities, at amortized cost Amortized Cost Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] Derivative [Line Items] Derivative [Line Items] Common stock repurchased (in shares) Stock Repurchased During Period, Shares Exercise of stock options and issuance of vested share awards, net of repurchase for tax withholdings and tax benefit (shares) Stock Issued During Period Shares Stock Options Exercised And Issuance Of Restricted Shares Stock Issued During Period, Shares, Stock Options Exercised and Issuance of Restricted Shares Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Cash dividends declared per share Cash dividends declared, per share (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Net unrealized loss on debt securities, net of tax AOCI, Debt Securities, Available-for-Sale, Adjustment, after Tax Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Corporate Bond Securities [Member] Corporate Bond Securities [Member] Less: effective portion reclassified into interest expense, pre-tax amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Measure: Measure [Axis] Postretirement Plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment and Tax [Abstract] Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing [Axis] Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Not Offset, Policy Election Deduction Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Equity Components [Axis] Equity Components [Axis] Entity Interactive Data Current Entity Interactive Data Current Available-for-sale Securities Available-for-Sale Securities [Member] Due after one year through five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Entity Small Business Entity Small Business Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Banking Regulation, Tier One Leverage Capital Ratio, Well Capitalized, Minimum Banking Regulation, Tier 1 Leverage Capital Ratio, Well Capitalized, Minimum Net interest income Net interest income Interest Income (Expense), Operating MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Document Type Document Type Due after ten years Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Regulatory assessments Regulatory Assessments Regulatory assessments. Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Local Phone Number Local Phone Number Pledged Status [Domain] Pledged Status [Domain] Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Commitments and Contingencies (Note 7) Commitments and Contingencies Depreciation and amortization expense Depreciation, Depletion and Amortization, Excluding Amortization Of Intangible Assets Depreciation, Depletion and Amortization, Excluding Amortization Of Intangible Assets Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Estimated amount to be reclassified as an increase to interest expense Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Expense, Estimated Net Amount to be Transferred Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Expense, Estimated Net Amount to be Transferred Income from fiduciary services Fiduciary and Trust [Member] Executive Category: Executive Category [Axis] Other comprehensive income, tax (expense) benefit Other Comprehensive Income (Loss), Tax LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity [Abstract] Other Commitments [Table] Other Commitments [Table] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Less: effective portion reclassified into interest expense, after-tax amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Supplemental information Supplemental Cash Flow Information [Abstract] Schedule Of Contractual And Notional Amounts Of Financial Instruments Table Schedule Of Contractual And Notional Amounts Of Financial Instruments Table [Table Text Block] Schedule of Contractual and Notional Amounts of Financial Instruments PEO Name PEO Name Products And Services, Debt Card Income [Member] Products And Services, Debt Card Income [Member] Products And Services, Debt Card Income [Member] Net Unrealized Gains (Losses) on Cash Flow Hedges(1) Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Financial liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Income taxes paid Income Tax Paid, before Refund Received Cash received in acquisition of Northway Financial, Inc. Cash Acquired from Acquisition Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Cash and due from banks Cash and Due from Banks Loan Aging Analysis by Portfolio Segment Financing Receivable, Past Due [Table Text Block] Current Financial Asset, Not Past Due [Member] Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Other Commitments [Line Items] Other Commitments [Line Items] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Bank-owned life insurance Bank Owned Life Insurance Income Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] BASIS OF PRESENTATION Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Measurement Frequency [Domain] Measurement Frequency [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Issuance of vested share awards, net of repurchase for tax withholdings Stock Issued During Period Value Stock Options Exercised And Issuance Of Restricted Shares Stock Issued During Period, Value, Stock Options Exercised And Issuance Of Restricted Shares Interest Expense Interest Expense, Operating and Nonoperating [Abstract] Salaries and employee benefits Labor and Related Expense Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral Security Sold under Agreement to Repurchase, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Short-term Debt [Member] Short-Term Debt [Member] Basic earnings per share Basic EPS (in dollars per share) Earnings Per Share, Basic Insider Trading Arrangements [Line Items] Short-term Debt, Fair Value Short-Term Debt, Fair Value Bank-owned life insurance Bank Owned Life Insurance Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Contractual Amounts Of Financial Instrument Contractual Amounts Of Financial Instrument Contractual Amounts of Financial Instrument Fair Value Measurement [Domain] Fair Value Measurement [Domain] Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] Cover [Abstract] Less: reclassification adjustment for amortization of securities transferred from AFS to HTM, pre-tax amount OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax Loans and Leases Receivable Disclosure [Abstract] Loans and Leases Receivable Disclosure [Abstract] Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Concentration risk (percentage) Concentration Risk, Percentage Equity Awards Adjustments Equity Awards Adjustments [Member] Hedging Relationship [Domain] Hedging Relationship [Domain] Financial Instruments [Line Items] Financial Instruments [Line Items] Financial Instruments [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Industry Sector [Domain] Industry Sector [Domain] Decrease in other liabilities Increase (Decrease) in Other Operating Liabilities Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan, Writeoff Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan, Writeoff Pass [Member] Pass [Member] Schedule of Loan Balances by Portfolio Segment Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Cumulative Fair Value Hedging Adjustment in the Carrying Amount of the Hedged Assets/(Liabilities) Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Schedule of Realized Gain (Loss) Schedule of Realized Gain (Loss) [Table Text Block] Hedging Designation [Domain] Hedging Designation [Domain] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Purchase of Federal Home Loan Bank and Federal Reserve Bank stock Payments for Federal Home Loan Bank Stock Payments for Federal Home Loan Bank Stock Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net decrease in fair value, pre-tax amount Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Entity Filer Category Entity Filer Category Debt Securities, Available-for-sale, Unrealized Loss Position, Total Debt Securities, Available-for-Sale, Unrealized Loss Position Legal Proceedings [Line Items] Legal Proceedings [Line Items] Legal Proceedings [Line Items] Offsetting Liabilities Offsetting Liabilities [Table Text Block] Financing Receivable, Nonaccrual [Line Items] Financing Receivable, Nonaccrual [Line Items] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Deposits: Deposits [Abstract] Securities Sold under Agreements to Repurchase, Asset Security Sold under Agreement to Repurchase, Subject to Master Netting Arrangement, Asset Offset Products And Services, Other Income [Member] Products And Services, Other Income [Member] Products And Services, Other Income [Member] Contract with Customer, Sales Channel [Domain] Contract with Customer, Sales Channel [Domain] Fair Value Derivative Liability Derivative Liability Entity Address, Address Line One Entity Address, Address Line One Held-to-maturity, Fair Value Debt Securities, Held-to-Maturity, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Income Tax Expense Income Tax Expense (Benefit) Fair Value Hedging Fair Value Hedging [Member] Charge-offs Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Core deposit intangible assets Other Intangible Assets, Net RECENT ACCOUNTING PRONOUNCEMENTS Accounting Standards Update and Change in Accounting Principle [Text Block] Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Statement [Table] Statement [Table] Banking Regulation, Tier One Risk-Based Capital Ratio, Well Capitalized, Minimum Banking Regulation, Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Financing Receivable, Nonaccrual Financing Receivable, Nonaccrual [Table Text Block] Products And Services, Deposit Accounts Service Charges [Member] Products And Services, Deposit Accounts Service Charges [Member] Products And Services, Deposit Accounts Service Charges [Member] Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned, Not Offset, Policy Election Deduction Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Derivative Asset, Fair Value, Gross Asset Derivative Asset, Subject to Master Netting Arrangement, before Offset Debit card expense Debit Card Expense Debit Card Expense Loans held for sale Loan, Held-for-Sale, Fair Value Disclosure Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract]