$CBU
COMMUNITY FINANCIAL SYSTEM, INC. Stock $cbu

$cbu Overview Financials Valuation SEC Filings Company Website

2024 Q1 Form 10-K Financial Statement

#000141057824000095 Filed on February 29, 2024

Income Statement

Concept	2024 Q1	2023 Q4	2023
Revenue	$152.7M		$541.4M
YoY Change	21.27%		22.01%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development	$14.35M		$57.59M
YoY Change	9.28%		6.44%
% of Gross Profit
Depreciation & Amortization	$3.280M	$6.968M	$12.99M
YoY Change	-0.73%	-7.04%	-9.85%
% of Gross Profit
Operating Expenses	$14.35M		$57.59M
YoY Change	9.28%		6.44%
Operating Profit
YoY Change
Interest Expense	$45.67M		$104.1M
YoY Change	207.49%		350.68%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$53.04M	$43.80M	$168.2M
YoY Change	660.69%	-34.93%	-30.0%
Income Tax	$12.17M	$10.09M	$36.31M
% Of Pretax Income	22.95%	23.04%	21.58%
Net Earnings	$40.87M	$33.59M	$131.9M
YoY Change	604.93%	-35.88%	-29.86%
Net Earnings / Revenue	26.77%		24.37%
Basic Earnings Per Share	$0.77		$2.45
Diluted Earnings Per Share	$0.76	$0.63	$2.45
COMMON SHARES
Basic Shares Outstanding	53.33M	53.39M	53.60M
Diluted Shares Outstanding	53.32M		53.73M

Balance Sheet

Concept	2024 Q1	2023 Q4	2023
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$338.4M	$191.0M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$171.0M	$173.4M	$173.4M
YoY Change	7.83%	7.86%	7.86%
Goodwill	$849.8M	$845.4M
YoY Change	0.81%	0.42%
Intangibles	$54.65M	$52.59M
YoY Change	-5.74%	-13.78%
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$15.86B	$15.56B	$15.56B
YoY Change	3.95%	-1.77%	-1.77%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$167.3M	$164.5M	$123.1M
YoY Change	27.76%	22.88%	19.77%
Accrued Expenses			$41.41M
YoY Change			33.19%
Deferred Revenue
YoY Change
Short-Term Debt	$287.2M	$304.6M	$304.6M
YoY Change	-5.7%	-12.13%	-12.13%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$454.6M	$469.1M	$469.1M
YoY Change	4.36%	250.43%	250.43%
LONG-TERM LIABILITIES
Long-Term Debt	$0.00	$0.00	$0.00
YoY Change		-100.0%	-100.0%
Other Long-Term Liabilities
YoY Change
Total Long-Term Liabilities	$0.00	$0.00	$0.00
YoY Change		-100.0%	-100.0%
TOTAL LIABILITIES
Total Short-Term Liabilities	$454.6M	$469.1M	$469.1M
Total Long-Term Liabilities	$0.00	$0.00	$0.00
Total Liabilities	$14.20B	$13.86B	$13.86B
YoY Change	4.26%	-2.98%	-2.98%
SHAREHOLDERS EQUITY
Retained Earnings	$1.206B	$1.189B
YoY Change	6.3%	3.16%
Common Stock
YoY Change
Preferred Stock
YoY Change
Treasury Stock (at cost)	$89.03M	$55.59M
YoY Change	145.08%	109.9%
Treasury Stock Shares
Shareholders Equity	$1.657B	$1.698B	$1.698B
YoY Change
Total Liabilities & Shareholders Equity	$15.86B	$15.56B	$15.56B
YoY Change	3.95%	-1.77%	-1.77%

Cashflow Statement

Concept	2024 Q1	2023 Q4	2023
OPERATING ACTIVITIES
Net Income	$40.87M	$33.59M	$131.9M
YoY Change	604.93%	-35.88%	-29.86%
Depreciation, Depletion And Amortization	$3.280M	$6.968M	$12.99M
YoY Change	-0.73%	-7.04%	-9.85%
Cash From Operating Activities	$79.89M	$44.71M	$228.4M
YoY Change	3.26%	-37.53%	6.44%
INVESTING ACTIVITIES
Capital Expenditures	$2.559M	$4.696M	$18.59M
YoY Change	-37.13%	61.49%	43.82%
Acquisitions	$5.995M		$8.517M
YoY Change	190.88%		1175.0%
Other Investing Activities	-$212.1M	-$292.2M	$354.4M
YoY Change	-135.34%	16.44%	-116.67%
Cash From Investing Activities	-$214.7M	-$296.9M	$335.8M
YoY Change	-136.02%	16.96%	-115.7%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$29.22M
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	282.2M	-12.69M	-583.1M
YoY Change	-140.66%	-108.76%	-324.96%
NET CHANGE
Cash From Operating Activities	79.89M	44.71M	228.4M
Cash From Investing Activities	-214.7M	-296.9M	335.8M
Cash From Financing Activities	282.2M	-12.69M	-583.1M
Net Change In Cash	147.4M	-264.8M	-18.93M
YoY Change	-815.7%	606.35%	-98.86%
FREE CASH FLOW
Cash From Operating Activities	$79.89M	$44.71M	$228.4M
Capital Expenditures	$2.559M	$4.696M	$18.59M
Free Cash Flow	$77.33M	$40.01M	$209.8M
YoY Change	5.5%	-41.72%	4.04%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value
CY2023	dei	Entity Central Index Key EntityCentralIndexKey	0000723188
CY2023	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2023	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2023
CY2023	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2023	dei	Entity Registrant Name EntityRegistrantName	COMMUNITY BANK SYSTEM, INC.
CY2023Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies
CY2022Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies
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CY2023Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OperatingLeaseLiability
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CY2023Q4	us-gaap	Debt Securities Pledging Purpose Extensible Enumeration DebtSecuritiesPledgingPurposeExtensibleEnumeration	http://fasb.org/us-gaap/2023#Deposits
CY2022Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss Statement Of Financial Position Extensible List DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLossStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#InterestReceivable
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CY2023	dei	Amendment Flag AmendmentFlag	false
CY2023	dei	Document Type DocumentType	10-K
CY2023	dei	Document Annual Report DocumentAnnualReport	true
CY2023	dei	Document Period End Date DocumentPeriodEndDate	2023-12-31
CY2023	dei	Document Transition Report DocumentTransitionReport	false
CY2023	dei	Entity File Number EntityFileNumber	001-13695
CY2023	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2023	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	16-1213679
CY2023	dei	Entity Address Address Line1 EntityAddressAddressLine1	5790 Widewaters Parkway
CY2023	dei	Entity Address City Or Town EntityAddressCityOrTown	DeWitt
CY2023	dei	Entity Address State Or Province EntityAddressStateOrProvince	NY
CY2023	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	13214
CY2023	dei	City Area Code CityAreaCode	315
CY2023	dei	Local Phone Number LocalPhoneNumber	445-2282
CY2023	dei	Security12b Title Security12bTitle	Common Stock, $1.00 par value per share
CY2023	dei	Trading Symbol TradingSymbol	CBU
CY2023	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2023	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2023	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2023	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2023	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2023	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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CY2022Q4	cbu	Core Deposit Intangibles Net CoreDepositIntangiblesNet	12304000
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CY2023	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	11203000
CY2022	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	14773000
CY2021	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-8839000
CY2023	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	426082000
CY2022	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	405857000
CY2021	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	383251000
CY2023	cbu	Deposit Service Fees DepositServiceFees	63062000
CY2022	cbu	Deposit Service Fees DepositServiceFees	66850000
CY2021	cbu	Deposit Service Fees DepositServiceFees	59212000
CY2023	cbu	Mortgage Banking MortgageBanking	595000
CY2022	cbu	Mortgage Banking MortgageBanking	390000
CY2021	cbu	Mortgage Banking MortgageBanking	1772000
CY2023	cbu	Other Banking Services OtherBankingServices	6315000
CY2022	cbu	Other Banking Services OtherBankingServices	4644000
CY2021	cbu	Other Banking Services OtherBankingServices	3674000
CY2023	cbu	Employee Benefit Services EmployeeBenefitServices	117961000
CY2022	cbu	Employee Benefit Services EmployeeBenefitServices	115408000
CY2021	cbu	Employee Benefit Services EmployeeBenefitServices	114328000
CY2023	us-gaap	Insurance Services Revenue InsuranceServicesRevenue	47094000
CY2022	us-gaap	Insurance Services Revenue InsuranceServicesRevenue	39810000
CY2021	us-gaap	Insurance Services Revenue InsuranceServicesRevenue	33992000
CY2023	cbu	Wealth Management Services WealthManagementServices	31941000
CY2022	cbu	Wealth Management Services WealthManagementServices	31667000
CY2021	cbu	Wealth Management Services WealthManagementServices	33240000
CY2023	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-52329000
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0
CY2023	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	242000
CY2022	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0
CY2021	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0
CY2023	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-47000
CY2022	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-44000
CY2021	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	17000
CY2023	us-gaap	Noninterest Income NoninterestIncome	214834000
CY2022	us-gaap	Noninterest Income NoninterestIncome	258725000
CY2021	us-gaap	Noninterest Income NoninterestIncome	246235000
CY2023	us-gaap	Labor And Related Expense LaborAndRelatedExpense	281803000
CY2022	us-gaap	Labor And Related Expense LaborAndRelatedExpense	257339000
CY2021	us-gaap	Labor And Related Expense LaborAndRelatedExpense	241501000
CY2023	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	57585000
CY2022	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	54099000
CY2021	us-gaap	Communications And Information Technology CommunicationsAndInformationTechnology	51003000
CY2023	us-gaap	Occupancy Net OccupancyNet	42550000
CY2022	us-gaap	Occupancy Net OccupancyNet	42413000
CY2021	us-gaap	Occupancy Net OccupancyNet	41240000
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14511000
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	15214000
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14051000
CY2023	us-gaap	Professional Fees ProfessionalFees	15921000
CY2022	us-gaap	Professional Fees ProfessionalFees	14018000
CY2021	us-gaap	Professional Fees ProfessionalFees	11723000
CY2023	us-gaap	Business Development BusinessDevelopment	15731000
CY2022	us-gaap	Business Development BusinessDevelopment	13095000
CY2021	us-gaap	Business Development BusinessDevelopment	9319000
CY2023	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	5800000
CY2022	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	0
CY2021	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	-100000
CY2023	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	63000
CY2022	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	5021000
CY2021	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	701000
CY2023	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	3280000
CY2022	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-300000
CY2021	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	200000
CY2023	us-gaap	Restructuring Charges RestructuringCharges	1163000
CY2022	us-gaap	Restructuring Charges RestructuringCharges	0
CY2021	us-gaap	Restructuring Charges RestructuringCharges	0
CY2023	us-gaap	Other Noninterest Expense OtherNoninterestExpense	34278000
CY2022	us-gaap	Other Noninterest Expense OtherNoninterestExpense	23369000
CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	18500000
CY2023	us-gaap	Noninterest Expense NoninterestExpense	472685000
CY2022	us-gaap	Noninterest Expense NoninterestExpense	424268000
CY2021	us-gaap	Noninterest Expense NoninterestExpense	388138000
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	168231000
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	240314000
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	241348000
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	36307000
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52233000
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	51654000
CY2023	us-gaap	Net Income Loss NetIncomeLoss	131924000
CY2022	us-gaap	Net Income Loss NetIncomeLoss	188081000
CY2021	us-gaap	Net Income Loss NetIncomeLoss	189694000
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.45
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.48
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.51
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.45
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.46
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.48
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-4774000
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	21587000
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-17443000
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-1162000
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	5243000
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-4192000
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-3612000
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	16344000
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-13251000
CY2023	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	641000
CY2022	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	678000
CY2021	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	200000
CY2023	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	156000
CY2022	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	165000
CY2021	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	48000
CY2023	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	485000
CY2022	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	513000
CY2021	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	152000
CY2023	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	-4097000
CY2022	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	15831000
CY2021	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	-13403000
CY2023	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	113464000
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-818890000
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	-166007000
CY2023	cbu	Other Comprehensive Income Investment Securities Unrealized Holding Gain Loss Before Adjustment Tax OtherComprehensiveIncomeInvestmentSecuritiesUnrealizedHoldingGainLossBeforeAdjustmentTax	27629000
CY2022	cbu	Other Comprehensive Income Investment Securities Unrealized Holding Gain Loss Before Adjustment Tax OtherComprehensiveIncomeInvestmentSecuritiesUnrealizedHoldingGainLossBeforeAdjustmentTax	-198909000
CY2021	cbu	Other Comprehensive Income Investment Securities Unrealized Holding Gain Loss Before Adjustment Tax OtherComprehensiveIncomeInvestmentSecuritiesUnrealizedHoldingGainLossBeforeAdjustmentTax	-39900000
CY2023	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	85835000
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-619981000
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-126107000
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-52329000
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-12714000
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-39615000
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0
CY2023	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	125450000
CY2022	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	-619981000
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	-126107000
CY2023	cbu	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Including Cumulative Effect Of Change In Accounting Principle OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentIncludingCumulativeEffectOfChangeInAccountingPrinciple	129547000
CY2022	cbu	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Including Cumulative Effect Of Change In Accounting Principle OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentIncludingCumulativeEffectOfChangeInAccountingPrinciple	-635812000
CY2021	cbu	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent Including Cumulative Effect Of Change In Accounting Principle OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentIncludingCumulativeEffectOfChangeInAccountingPrinciple	-112704000
CY2023	us-gaap	Net Income Loss NetIncomeLoss	131924000
CY2022	us-gaap	Net Income Loss NetIncomeLoss	188081000
CY2021	us-gaap	Net Income Loss NetIncomeLoss	189694000
CY2023	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	261471000
CY2022	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-447731000
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	76990000
CY2023Q4	cbu	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Gross Of Tax AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansGrossOfTax	36118000
CY2022Q4	cbu	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Gross Of Tax AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansGrossOfTax	41533000
CY2021Q4	cbu	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Gross Of Tax AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansGrossOfTax	20624000
CY2023Q4	cbu	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax Effect AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTaxEffect	-8914000
CY2022Q4	cbu	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax Effect AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTaxEffect	-10232000
CY2021Q4	cbu	Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax Effect AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTaxEffect	-5154000
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	27204000
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	31301000
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	15470000
CY2023Q4	cbu	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Gross AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentGross	-698990000
CY2022Q4	cbu	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Gross AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentGross	-864783000
CY2021Q4	cbu	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Gross AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentGross	-45893000
CY2023Q4	cbu	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Tax Effect AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentTaxEffect	-169302000
CY2022Q4	cbu	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Tax Effect AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentTaxEffect	-209645000
CY2021Q4	cbu	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Tax Effect AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentTaxEffect	-10736000
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-529688000
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-655138000
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-35157000
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-556892000
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-686439000
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-50627000
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	2104107000
CY2021	us-gaap	Net Income Loss NetIncomeLoss	189694000
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-112704000
CY2021	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.70
CY2021	us-gaap	Dividends Common Stock DividendsCommonStock	91591000
CY2021	cbu	Stock Issued During Period Value Employee Stock Ownership Plan Net Of Impact Of Net Settlement Of Tax Withholding Obligations StockIssuedDuringPeriodValueEmployeeStockOwnershipPlanNetOfImpactOfNetSettlementOfTaxWithholdingObligations	9821000
CY2021	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6334000
CY2021	cbu	Stock Issued During Period Value Deferred Compensation Arrangements StockIssuedDuringPeriodValueDeferredCompensationArrangements	0
CY2021	cbu	Treasury Stock Value Acquired And Issued To Deferred Compensation Arrangements Cost Method TreasuryStockValueAcquiredAndIssuedToDeferredCompensationArrangementsCostMethod	4854000
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	2100807000
CY2022	us-gaap	Net Income Loss NetIncomeLoss	188081000
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-635812000
CY2022	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.74
CY2022	us-gaap	Dividends Common Stock DividendsCommonStock	93915000
CY2022	cbu	Stock Issued During Period Value Employee Stock Ownership Plan Net Of Impact Of Net Settlement Of Tax Withholding Obligations StockIssuedDuringPeriodValueEmployeeStockOwnershipPlanNetOfImpactOfNetSettlementOfTaxWithholdingObligations	1184000
CY2022	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	7738000
CY2022	cbu	Stock Issued During Period Value Deferred Compensation Arrangements StockIssuedDuringPeriodValueDeferredCompensationArrangements	0
CY2022	cbu	Treasury Stock Value Acquired And Issued To Deferred Compensation Arrangements Cost Method TreasuryStockValueAcquiredAndIssuedToDeferredCompensationArrangementsCostMethod	16378000
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	1551705000
CY2023	us-gaap	Net Income Loss NetIncomeLoss	131924000
CY2023	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	129547000
CY2023	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.78
CY2023	us-gaap	Dividends Common Stock DividendsCommonStock	95507000
CY2023	cbu	Stock Issued During Period Value Employee Stock Ownership Plan Net Of Impact Of Net Settlement Of Tax Withholding Obligations StockIssuedDuringPeriodValueEmployeeStockOwnershipPlanNetOfImpactOfNetSettlementOfTaxWithholdingObligations	1015000
CY2023	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	9269000
CY2023	cbu	Stock Issued During Period Value Deferred Compensation Arrangements StockIssuedDuringPeriodValueDeferredCompensationArrangements	0
CY2023	cbu	Treasury Stock Value Acquired And Issued To Deferred Compensation Arrangements Cost Method TreasuryStockValueAcquiredAndIssuedToDeferredCompensationArrangementsCostMethod	30016000
CY2023Q4	us-gaap	Stockholders Equity StockholdersEquity	1697937000
CY2023	us-gaap	Net Income Loss NetIncomeLoss	131924000
CY2022	us-gaap	Net Income Loss NetIncomeLoss	188081000
CY2021	us-gaap	Net Income Loss NetIncomeLoss	189694000
CY2023	us-gaap	Depreciation Depreciation	12991000
CY2022	us-gaap	Depreciation Depreciation	14411000
CY2021	us-gaap	Depreciation Depreciation	15592000
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14511000
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	15214000
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14051000
CY2023	cbu	Accretion Amortization On Investments Loans And Borrowings AccretionAmortizationOnInvestmentsLoansAndBorrowings	-5838000
CY2022	cbu	Accretion Amortization On Investments Loans And Borrowings AccretionAmortizationOnInvestmentsLoansAndBorrowings	18738000
CY2021	cbu	Accretion Amortization On Investments Loans And Borrowings AccretionAmortizationOnInvestmentsLoansAndBorrowings	22501000
CY2023	us-gaap	Share Based Compensation ShareBasedCompensation	9269000
CY2022	us-gaap	Share Based Compensation ShareBasedCompensation	7738000
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	6334000
CY2023	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	242000
CY2022	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0
CY2021	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0
CY2023	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	11203000
CY2022	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	14773000
CY2021	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-8839000
CY2023	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	7503000
CY2022	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-1309000
CY2021	us-gaap	Increase Decrease In Deferred Income Taxes IncreaseDecreaseInDeferredIncomeTaxes	-7989000
CY2023	us-gaap	Amortization Of Mortgage Servicing Rights Ms Rs AmortizationOfMortgageServicingRightsMSRs	849000
CY2022	us-gaap	Amortization Of Mortgage Servicing Rights Ms Rs AmortizationOfMortgageServicingRightsMSRs	801000
CY2021	us-gaap	Amortization Of Mortgage Servicing Rights Ms Rs AmortizationOfMortgageServicingRightsMSRs	519000
CY2023	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-52329000
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0
CY2023	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-47000
CY2022	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-44000
CY2021	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	17000
CY2023	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	2412000
CY2022	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	2147000
CY2021	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	2012000
CY2023	cbu	Net Gain Loss On Sale Of Loans And Other Assets NetGainLossOnSaleOfLoansAndOtherAssets	1490000
CY2022	cbu	Net Gain Loss On Sale Of Loans And Other Assets NetGainLossOnSaleOfLoansAndOtherAssets	655000
CY2021	cbu	Net Gain Loss On Sale Of Loans And Other Assets NetGainLossOnSaleOfLoansAndOtherAssets	328000
CY2023	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-1106000
CY2022	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	6231000
CY2021	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-2064000
CY2023	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	228420000
CY2022	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	214600000
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	202546000
CY2023	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	597823000
CY2022	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	262256000
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	423738000
CY2023	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	208000
CY2022	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	0
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	0
CY2023	us-gaap	Proceeds From Maturities Prepayments And Calls Of Other Investments ProceedsFromMaturitiesPrepaymentsAndCallsOfOtherInvestments	14945000
CY2022	us-gaap	Proceeds From Maturities Prepayments And Calls Of Other Investments ProceedsFromMaturitiesPrepaymentsAndCallsOfOtherInvestments	4683000
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Other Investments ProceedsFromMaturitiesPrepaymentsAndCallsOfOtherInvestments	2946000
CY2023	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	733789000
CY2022	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0
CY2023	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	0
CY2022	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1355475000
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1963884000
CY2023	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	63284000
CY2022	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0
CY2021	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	0
CY2023	cbu	Payments To Acquire Equity And Other Securities PaymentsToAcquireEquityAndOtherSecurities	4796000
CY2022	cbu	Payments To Acquire Equity And Other Securities PaymentsToAcquireEquityAndOtherSecurities	35303000
CY2021	cbu	Payments To Acquire Equity And Other Securities PaymentsToAcquireEquityAndOtherSecurities	353000
CY2023	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	923280000
CY2022	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	1003741000
CY2021	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-49929000
CY2023	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	0
CY2022	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	84988000
CY2021	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	541000
CY2023	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	8517000
CY2022	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	668000
CY2021	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	29329000
CY2023	cbu	Proceeds From Sales Of Premises And Equipment Net ProceedsFromSalesOfPremisesAndEquipmentNet	7473000
CY2022	cbu	Proceeds From Sales Of Premises And Equipment Net ProceedsFromSalesOfPremisesAndEquipmentNet	2432000
CY2021	cbu	Proceeds From Sales Of Premises And Equipment Net ProceedsFromSalesOfPremisesAndEquipmentNet	201000
CY2023	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	18585000
CY2022	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12922000
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	13377000
CY2023	us-gaap	Payments For Proceeds From Real Estate Partnership Investment Net PaymentsForProceedsFromRealEstatePartnershipInvestmentNet	0
CY2022	us-gaap	Payments For Proceeds From Real Estate Partnership Investment Net PaymentsForProceedsFromRealEstatePartnershipInvestmentNet	247000
CY2021	us-gaap	Payments For Proceeds From Real Estate Partnership Investment Net PaymentsForProceedsFromRealEstatePartnershipInvestmentNet	646000
CY2023	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	335776000
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-2138985000
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1530775000
CY2023	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-84187000
CY2022	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-421155000
CY2021	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	1686194000
CY2023	cbu	Net Increase Decrease In Overnight Federal Reserve Bank Borrowings NetIncreaseDecreaseInOvernightFederalReserveBankBorrowings	-715400000
CY2022	cbu	Net Increase Decrease In Overnight Federal Reserve Bank Borrowings NetIncreaseDecreaseInOvernightFederalReserveBankBorrowings	768400000
CY2021	cbu	Net Increase Decrease In Overnight Federal Reserve Bank Borrowings NetIncreaseDecreaseInOvernightFederalReserveBankBorrowings	0
CY2023	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	-42058000
CY2022	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	21932000
CY2021	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	40711000
CY2023	us-gaap	Increase Decrease In Loans From Other Federal Home Loan Banks IncreaseDecreaseInLoansFromOtherFederalHomeLoanBanks	400000000
CY2022	us-gaap	Increase Decrease In Loans From Other Federal Home Loan Banks IncreaseDecreaseInLoansFromOtherFederalHomeLoanBanks	0
CY2021	us-gaap	Increase Decrease In Loans From Other Federal Home Loan Banks IncreaseDecreaseInLoansFromOtherFederalHomeLoanBanks	0
CY2023	cbu	Payments On And Maturities Of Other Federal Home Loan Bank Borrowings PaymentsOnAndMaturitiesOfOtherFederalHomeLoanBankBorrowings	11971000
CY2022	cbu	Payments On And Maturities Of Other Federal Home Loan Bank Borrowings PaymentsOnAndMaturitiesOfOtherFederalHomeLoanBankBorrowings	95000
CY2021	cbu	Payments On And Maturities Of Other Federal Home Loan Bank Borrowings PaymentsOnAndMaturitiesOfOtherFederalHomeLoanBankBorrowings	4769000
CY2023	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	1214000
CY2022	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	0
CY2021	us-gaap	Payment For Contingent Consideration Liability Financing Activities PaymentForContingentConsiderationLiabilityFinancingActivities	0
CY2023	cbu	Repayments Of Subordinated Debt Held By Unconsolidated Subsidiary Trusts RepaymentsOfSubordinatedDebtHeldByUnconsolidatedSubsidiaryTrusts	0
CY2022	cbu	Repayments Of Subordinated Debt Held By Unconsolidated Subsidiary Trusts RepaymentsOfSubordinatedDebtHeldByUnconsolidatedSubsidiaryTrusts	0
CY2021	cbu	Repayments Of Subordinated Debt Held By Unconsolidated Subsidiary Trusts RepaymentsOfSubordinatedDebtHeldByUnconsolidatedSubsidiaryTrusts	77320000
CY2023	cbu	Repayment Of Subordinate Notes Payable RepaymentOfSubordinateNotesPayable	3000000
CY2022	cbu	Repayment Of Subordinate Notes Payable RepaymentOfSubordinateNotesPayable	0
CY2021	cbu	Repayment Of Subordinate Notes Payable RepaymentOfSubordinateNotesPayable	0
CY2023	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	1015000
CY2022	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	1184000
CY2021	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	9821000
CY2023	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	30233000
CY2022	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	16614000
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	5106000
CY2023	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	217000
CY2022	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	236000
CY2021	us-gaap	Employee Stock Ownership Plan Esop Compensation Expense EmployeeStockOwnershipPlanESOPCompensationExpense	252000
CY2023	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	95102000
CY2022	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	93387000
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	91051000
CY2023	cbu	Withholding Taxes Paid On Share Based Compensation WithholdingTaxesPaidOnShareBasedCompensation	1197000
CY2022	cbu	Withholding Taxes Paid On Share Based Compensation WithholdingTaxesPaidOnShareBasedCompensation	1284000
CY2021	cbu	Withholding Taxes Paid On Share Based Compensation WithholdingTaxesPaidOnShareBasedCompensation	1244000
CY2023	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-583130000
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	259217000
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	1557488000
CY2023	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-18934000
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	-1665168000
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	229259000
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	209896000
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1875064000
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1645805000
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	190962000
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	209896000
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1875064000
CY2023	us-gaap	Interest Paid Net InterestPaidNet	100040000
CY2022	us-gaap	Interest Paid Net InterestPaidNet	23402000
CY2021	us-gaap	Interest Paid Net InterestPaidNet	13752000
CY2023	us-gaap	Income Taxes Paid IncomeTaxesPaid	41661000
CY2022	us-gaap	Income Taxes Paid IncomeTaxesPaid	57131000
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	41531000
CY2023Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	24168000
CY2022Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	23762000
CY2021Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	23235000
CY2023	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	1051000
CY2022	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	543000
CY2021	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	520000
CY2023	cbu	Transfer Of Property Plant And Equipment To Other Assets TransferOfPropertyPlantAndEquipmentToOtherAssets	2899000
CY2022	cbu	Transfer Of Property Plant And Equipment To Other Assets TransferOfPropertyPlantAndEquipmentToOtherAssets	5795000
CY2021	cbu	Transfer Of Property Plant And Equipment To Other Assets TransferOfPropertyPlantAndEquipmentToOtherAssets	0
CY2023	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	243000
CY2022	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	490637000
CY2021	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	1339000
CY2023	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	18000
CY2022	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	543541000
CY2021	us-gaap	Liabilities Assumed1 LiabilitiesAssumed1	1164000
CY2023	cbu	Contingent Consideration In Exchange For Acquired Assets ContingentConsiderationInExchangeForAcquiredAssets	1450000
CY2022	cbu	Contingent Consideration In Exchange For Acquired Assets ContingentConsiderationInExchangeForAcquiredAssets	0
CY2021	cbu	Contingent Consideration In Exchange For Acquired Assets ContingentConsiderationInExchangeForAcquiredAssets	2900000
CY2023Q4	cbu	Number Of Significant Consolidated Subsidiaries Owned NumberOfSignificantConsolidatedSubsidiariesOwned	2
CY2023Q4	cbu	Number Of Significant Consolidated Subsidiaries Owned NumberOfSignificantConsolidatedSubsidiariesOwned	5
CY2023Q4	cbu	Number Of Customer Facilities NumberOfCustomerFacilities	193
CY2023	cbu	Number Of Operating Location NumberOfOperatingLocation	12
CY2023	us-gaap	Basis Of Accounting BasisOfAccounting	<p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 10pt 0pt;"><span style="font-style:italic;font-weight:bold;">Basis of Presentation</span></p><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 10pt 0pt;"><span style="white-space:pre-wrap;">The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Critical accounting estimates include the allowance for credit losses, actuarial assumptions associated with the pension, post-retirement and other employee benefit plans and the carrying value of goodwill and other intangible assets, including the impact of acquired loan valuations. The impact of subsequent events on the consolidated financial statements has been considered, see Note U for further detail. </span></p><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 10pt 0pt;">Certain reclassifications have been made to prior years’ balances to conform to the current year presentation.</p>
CY2023	cbu	Number Of Main Components Of Economic Risk NumberOfMainComponentsOfEconomicRisk	3
CY2023Q4	cbu	Number Of Types Of Performance Obligations NumberOfTypesOfPerformanceObligations	2
CY2023Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	41700000
CY2023Q4	us-gaap	Unbilled Contracts Receivable UnbilledContractsReceivable	8100000
CY2023Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	800000
CY2022Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	33300000
CY2022Q4	us-gaap	Unbilled Contracts Receivable UnbilledContractsReceivable	8800000
CY2022Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	1100000
CY2023Q4	us-gaap	Due From Banks DueFromBanks	11500000
CY2022Q4	us-gaap	Due From Banks DueFromBanks	10000000.0
CY2023Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	1200000
CY2022Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	500000
CY2022Q4	cbu	Other Investments And Equity Securities At Cost OtherInvestmentsAndEquitySecuritiesAtCost	82424000
CY2022Q4	cbu	Other Investments And Equity Securities Accumulated Gross Unrealized Gain Before Tax OtherInvestmentsAndEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax	918000
CY2023	us-gaap	Affordable Housing Project Investment Write Down Amount AffordableHousingProjectInvestmentWriteDownAmount	0
CY2023	us-gaap	Advertising Expense AdvertisingExpense	9500000
CY2022	us-gaap	Advertising Expense AdvertisingExpense	8200000
CY2021	us-gaap	Advertising Expense AdvertisingExpense	5200000
CY2022Q4	us-gaap	Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Intangibles BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles	2900000
CY2023	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	687976000
CY2022	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	646375000
CY2023	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	193417000
CY2022	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	191450000
CY2023Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	3301607000
CY2023	us-gaap	Available For Sale Debt Securities Gross Unrealized Gain AvailableForSaleDebtSecuritiesGrossUnrealizedGain	1545000
CY2023	us-gaap	Available For Sale Debt Securities Gross Unrealized Loss AvailableForSaleDebtSecuritiesGrossUnrealizedLoss	383160000
CY2023Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	2919992000
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	4675474000
CY2022	us-gaap	Available For Sale Debt Securities Gross Unrealized Gain AvailableForSaleDebtSecuritiesGrossUnrealizedGain	565000
CY2022	us-gaap	Available For Sale Debt Securities Gross Unrealized Loss AvailableForSaleDebtSecuritiesGrossUnrealizedLoss	524188000
CY2022Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	4151851000
CY2023Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	1172174000
CY2023Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	688000
CY2023Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	51046000
CY2023Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	1121816000
CY2022Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	1079695000
CY2022Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	0
CY2022Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	44900000
CY2022Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	1034795000
CY2023Q4	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	251000
CY2023Q4	cbu	Equity Securities Fv Ni Accumulated Gross Unrealized Gain Before Tax EquitySecuritiesFvNiAccumulatedGrossUnrealizedGainBeforeTax	121000
CY2023Q4	cbu	Equity Securities Fv Ni Accumulated Gross Unrealized Loss Before Tax EquitySecuritiesFvNiAccumulatedGrossUnrealizedLossBeforeTax	0
CY2023Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	372000
CY2022Q4	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	251000
CY2022Q4	cbu	Equity Securities Fv Ni Accumulated Gross Unrealized Gain Before Tax EquitySecuritiesFvNiAccumulatedGrossUnrealizedGainBeforeTax	168000
CY2022Q4	cbu	Equity Securities Fv Ni Accumulated Gross Unrealized Loss Before Tax EquitySecuritiesFvNiAccumulatedGrossUnrealizedLossBeforeTax	0
CY2022Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	419000
CY2023Q4	cbu	Other Investments And Equity Securities At Cost OtherInvestmentsAndEquitySecuritiesAtCost	72275000
CY2023Q4	cbu	Other Investments And Equity Securities Accumulated Gross Unrealized Gain Before Tax OtherInvestmentsAndEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax	871000
CY2023Q4	cbu	Other Investments And Equity Securities Accumulated Gross Unrealized Loss Before Tax OtherInvestmentsAndEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax	0
CY2023Q4	cbu	Other Investment And Equity Securities Fair Value OtherInvestmentAndEquitySecuritiesFairValue	73146000
CY2022Q4	cbu	Other Investments And Equity Securities Accumulated Gross Unrealized Loss Before Tax OtherInvestmentsAndEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax	0
CY2022Q4	cbu	Other Investment And Equity Securities Fair Value OtherInvestmentAndEquitySecuritiesFairValue	83342000
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	72127000
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	933000
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	2720541000
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	382227000
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	2792668000
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	383160000
CY2023Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions Less Than12 Months Fair Value DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionsLessThan12MonthsFairValue	555836000
CY2023Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions Less Than12 Months Accumulated Loss DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionsLessThan12MonthsAccumulatedLoss	16111000
CY2023Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions12 Months Or Longer Fair Value DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositions12MonthsOrLongerFairValue	522743000
CY2023Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions12 Months Or Longer Accumulated Loss DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositions12MonthsOrLongerAccumulatedLoss	34935000
CY2023Q4	cbu	Debt Securities Held To Maturity Unrealized Loss Positions Fair Value DebtSecuritiesHeldToMaturityUnrealizedLossPositionsFairValue	1078579000
CY2023Q4	cbu	Debt Securities Held To Maturity Unrealized Loss Positions Accumulated Loss DebtSecuritiesHeldToMaturityUnrealizedLossPositionsAccumulatedLoss	51046000
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	1955294000
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	188107000
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	2106692000
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	336081000
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	4061986000
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	524188000
CY2022Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions Less Than12 Months Fair Value DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionsLessThan12MonthsFairValue	1034795000
CY2022Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions Less Than12 Months Accumulated Loss DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositionsLessThan12MonthsAccumulatedLoss	44900000
CY2022Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions12 Months Or Longer Fair Value DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositions12MonthsOrLongerFairValue	0
CY2022Q4	cbu	Debt Securities Held To Maturity Continuous Unrealized Loss Positions12 Months Or Longer Accumulated Loss DebtSecuritiesHeldToMaturityContinuousUnrealizedLossPositions12MonthsOrLongerAccumulatedLoss	0
CY2022Q4	cbu	Debt Securities Held To Maturity Unrealized Loss Positions Fair Value DebtSecuritiesHeldToMaturityUnrealizedLossPositionsFairValue	1034795000
CY2022Q4	cbu	Debt Securities Held To Maturity Unrealized Loss Positions Accumulated Loss DebtSecuritiesHeldToMaturityUnrealizedLossPositionsAccumulatedLoss	44900000
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0
CY2023Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0
CY2023Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0
CY2023Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	14400000
CY2022Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	19300000
CY2022Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0
CY2023Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0
CY2023Q4	us-gaap	Accrued Fees And Other Revenue Receivable AccruedFeesAndOtherRevenueReceivable	5000000.0
CY2022Q4	us-gaap	Accrued Fees And Other Revenue Receivable AccruedFeesAndOtherRevenueReceivable	4700000
CY2023Q4	us-gaap	Heldtomaturity Securities Debt Maturities Next Rolling Twelve Months Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCost	0
CY2023Q4	us-gaap	Held To Maturity Securities Debt Maturities Next Rolling Twelve Months Fair Value HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	0
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	16671000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	16566000
CY2023Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Two Through Five Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCost	0
CY2023Q4	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Two Through Five Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	0
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	1583809000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	1441328000
CY2023Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCost	552838000
CY2023Q4	us-gaap	Held To Maturity Securities Debt Maturities Rolling Year Six Through Ten Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	536885000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	579092000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	523830000
CY2023Q4	us-gaap	Heldtomaturity Securities Debt Maturities Rolling After Ten Years Amortized Cost HeldtomaturitySecuritiesDebtMaturitiesRollingAfterTenYearsAmortizedCost	556263000
CY2023Q4	us-gaap	Held To Maturity Securities Debt Maturities Rolling After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue	521350000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	712475000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	580816000
CY2023Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	1109101000
CY2023Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	1058235000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	2892047000
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Single Maturity Date AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate	2562540000
CY2023Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss	1172174000
CY2023Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	1121816000
CY2023Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestBeforeAllowanceForCreditLoss	3301607000
CY2023Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	2919992000
CY2023Q4	us-gaap	Debt Securities DebtSecurities	2140000000
CY2022Q4	us-gaap	Debt Securities DebtSecurities	2180000000
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	9704598000
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	8809394000
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	66669000
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	61059000
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	9637929000
CY2022Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	8748335000
CY2023Q4	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	81600000
CY2022Q4	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	73800000
CY2022Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	12373000
CY2021Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	13773000
CY2023	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	1372000
CY2022	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	2025000
CY2023	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	2053000
CY2022	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	3425000
CY2023Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	11692000
CY2022Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	12373000
CY2022	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0
CY2023	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0
CY2023Q4	cbu	Financing Receivable Recorded Investment Purchased Impaired FinancingReceivableRecordedInvestmentPurchasedImpaired	400000
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff	0
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff	160000
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff	0
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff	0
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff	0
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff	36000
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Revolving Writeoff FinancingReceivableExcludingAccruedInterestRevolvingWriteoff	588000
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Revolving Converted To Term Loan Writeoff FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff	0
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	784000
CY2023Q4	cbu	Individual Business Lending Loans IndividualBusinessLendingLoans	500000
CY2023Q4	cbu	Impaired Financing Receivable With Related Allowance ImpairedFinancingReceivableWithRelatedAllowance	3484000
CY2022Q4	cbu	Impaired Financing Receivable With Related Allowance ImpairedFinancingReceivableWithRelatedAllowance	0
CY2023Q4	cbu	Impaired Financing Receivable Unpaid Principal Balance With No Related Allowance ImpairedFinancingReceivableUnpaidPrincipalBalanceWithNoRelatedAllowance	15750000
CY2022Q4	cbu	Impaired Financing Receivable Unpaid Principal Balance With No Related Allowance ImpairedFinancingReceivableUnpaidPrincipalBalanceWithNoRelatedAllowance	3163000
CY2023Q4	cbu	Impaired Financing Receivable Allowance ImpairedFinancingReceivableAllowance	19234000
CY2022Q4	cbu	Impaired Financing Receivable Allowance ImpairedFinancingReceivableAllowance	3163000
CY2023Q4	cbu	Impaired Financing Receivable Contractual Balance ImpairedFinancingReceivableContractualBalance	19249000
CY2022Q4	cbu	Impaired Financing Receivable Contractual Balance ImpairedFinancingReceivableContractualBalance	4201000
CY2023Q4	cbu	Impaired Financing Receivable Specifically Allocated Allowance ImpairedFinancingReceivableSpecificallyAllocatedAllowance	470000
CY2022Q4	cbu	Impaired Financing Receivable Specifically Allocated Allowance ImpairedFinancingReceivableSpecificallyAllocatedAllowance	0
CY2023	cbu	Impaired Financing Receivable Average Balances ImpairedFinancingReceivableAverageBalances	20200000
CY2022	cbu	Impaired Financing Receivable Average Balances ImpairedFinancingReceivableAverageBalances	12200000
CY2021	cbu	Impaired Financing Receivable Interest Income ImpairedFinancingReceivableInterestIncome	0
CY2022	cbu	Impaired Financing Receivable Interest Income ImpairedFinancingReceivableInterestIncome	0
CY2023	cbu	Amortized Cost Basis Of Each Class Of Financing Receivable AmortizedCostBasisOfEachClassOfFinancingReceivable	<p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt;"><span style="margin-bottom:12pt;visibility:hidden;"></span></p><table style="border-collapse:collapse;font-size:16pt;height:max-content;margin-left:auto;margin-right:auto;padding-left:0pt;padding-right:0pt;width:80%;"><tr style="height:1pt;"><td style="vertical-align:bottom;white-space:nowrap;width:65.32%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><div style="height:1pt;overflow:hidden;overflow-wrap:break-word;position:relative;"><div style="bottom:0pt;position:absolute;width:100%;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-size:1pt;visibility:hidden;"></span></p></div></div></td></tr><tr><td style="vertical-align:bottom;width:65.32%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"> </p></td><td colspan="4" style="vertical-align:bottom;white-space:nowrap;width:30.42%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">Year Ended December 31, 2023</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"> </p></td></tr><tr><td style="vertical-align:bottom;white-space:nowrap;width:65.32%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">Total Class of</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"> </p></td></tr><tr><td style="vertical-align:bottom;white-space:nowrap;width:65.32%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td colspan="2" style="vertical-align:bottom;white-space:nowrap;width:14.3%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">Term</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="font-weight:bold;visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">Financing</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"> </p></td></tr><tr><td style="vertical-align:bottom;width:65.32%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">(000s omitted except for percentages)</p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td colspan="2" style="vertical-align:bottom;white-space:nowrap;width:14.3%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">Extension</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">Receivable</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"> </p></td></tr><tr><td style="vertical-align:bottom;width:65.32%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">CRE - owner occupied</p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">$</p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;">1,367</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;">0.18</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">%</p></td></tr><tr><td style="vertical-align:bottom;width:65.32%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">CRE - non-owner occupied</p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 700</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 0.04</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:center;margin:0pt 0pt 0.05pt 0pt;">%</p></td></tr><tr><td style="vertical-align:bottom;width:65.32%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">Consumer mortgage</p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"> </p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 281</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"> </p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 0.01</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">%</p></td></tr><tr><td style="vertical-align:bottom;width:65.32%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">Home equity</p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"> </p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 31</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"> </p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;border-bottom:1px solid #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 0.01</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">%</p></td></tr><tr><td style="vertical-align:bottom;width:65.32%;background:#cceeff;border-bottom:3px double #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">Total</p></td><td style="vertical-align:bottom;white-space:nowrap;width:2.31%;background:#cceeff;border-bottom:3px double #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"><span style="visibility:hidden;"></span></p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.96%;background:#cceeff;border-bottom:3px double #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">$</p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.33%;background:#cceeff;border-bottom:3px double #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 2,379</p></td><td style="vertical-align:bottom;white-space:nowrap;width:3.12%;background:#cceeff;border-bottom:3px double #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;"> </p></td><td style="vertical-align:bottom;white-space:nowrap;width:12.99%;background:#cceeff;border-bottom:3px double #000000;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:right;margin:0pt 3pt 0.05pt 0pt;"> 0.02</p></td><td style="vertical-align:bottom;white-space:nowrap;width:1.93%;background:#cceeff;margin:0pt;padding:0pt;"><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;margin:0pt 0pt 0.05pt 0pt;">%</p></td></tr></table>
CY2023	us-gaap	Financing Receivable Modification To Total Financing Receivables Excluding Accrued Interest Percent FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent	0.0002
CY2023	us-gaap	Financing Receivable Excluding Accrued Interest Modified Period FinancingReceivableExcludingAccruedInterestModifiedPeriod	2379000
CY2023Q4	cbu	Financing Receivable Modifications Number Of Contracts FinancingReceivableModificationsNumberOfContracts	194
CY2023Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	5629000
CY2022Q4	cbu	Financing Receivable Modifications Number Of Contracts FinancingReceivableModificationsNumberOfContracts	232
CY2022Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	8239000
CY2023	cbu	Credit Loss Renewal Number Of Contracts Integer Duration CreditLossRenewalNumberOfContractsIntegerDuration	24000
CY2023	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	784000
CY2022	cbu	Credit Loss Renewal Number Of Contracts Integer Duration CreditLossRenewalNumberOfContractsIntegerDuration	54000
CY2022	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	3087000
CY2022Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1123000
CY2023	cbu	Off Balance Sheet Credit Loss Liability Charge Offs OffBalanceSheetCreditLossLiabilityChargeOffs	0
CY2023	cbu	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0
CY2023	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-210000
CY2023Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	913000
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	803000
CY2022	cbu	Off Balance Sheet Credit Loss Liability Charge Offs OffBalanceSheetCreditLossLiabilityChargeOffs	0
CY2022	cbu	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0
CY2022	cbu	Off Balance Sheet Credit Loss Liability Pcd Allowance Acquisitions OffBalanceSheetCreditLossLiabilityPcdAllowanceAcquisitions	0
CY2022Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	1123000
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	8965000
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Recovery FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery	6118000
CY2021	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	-8153000
CY2021Q4	cbu	Financing Receivable Allowance For Credit Loss Net FinancingReceivableAllowanceForCreditLossNet	49869000
CY2021	cbu	Off Balance Sheet Credit Loss Liability Charge Offs OffBalanceSheetCreditLossLiabilityChargeOffs	0
CY2021	cbu	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0
CY2021	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-686000
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	803000
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	8965000
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	6118000
CY2021	cbu	Provision For Loan Lease And Other Losses Excluding Acquisition Related Provision For Credit Losses ProvisionForLoanLeaseAndOtherLossesExcludingAcquisitionRelatedProvisionForCreditLosses	-8839000
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	50672000
CY2023Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	31200000
CY2022Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	25100000
CY2023Q4	us-gaap	Other Long Term Debt OtherLongTermDebt	406900000
CY2023Q4	cbu	Federal Home Loan Bank Advances Foreclosures In Progress FederalHomeLoanBankAdvancesForeclosuresInProgress	5800000
CY2022Q4	cbu	Federal Home Loan Bank Advances Foreclosures In Progress FederalHomeLoanBankAdvancesForeclosuresInProgress	3500000
CY2023	us-gaap	Financing Receivable Sale FinancingReceivableSale	6100000
CY2022	us-gaap	Financing Receivable Significant Purchases FinancingReceivableSignificantPurchases	436900000
CY2022	us-gaap	Financing Receivable Sale FinancingReceivableSale	5300000
CY2023Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	308503000
CY2022Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	298205000
CY2023Q4	cbu	Property Plant And Equipment And Operating Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	135085000
CY2022Q4	cbu	Property Plant And Equipment And Operating Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	137427000
CY2023Q4	cbu	Property Plant And Equipment And Operating Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	173418000
CY2022Q4	cbu	Property Plant And Equipment And Operating Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	160778000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	203292000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	150701000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	52591000
CY2022Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	197186000
CY2022Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	136190000
CY2022Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	60996000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	12856000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	10969000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	9662000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	4079000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	3011000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	12014000
CY2023Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	52591000
CY2023Q4	cbu	Federal Reserve Advances General Debt Obligations Disclosures Amount Of Available Unused Funds FederalReserveAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds	1110000000
CY2023Q4	us-gaap	Deferred Tax Liabilities Prepaid Expenses DeferredTaxLiabilitiesPrepaidExpenses	19181000
CY2021Q4	us-gaap	Goodwill Gross GoodwillGross	799109000
CY2022	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	42732000
CY2022Q4	us-gaap	Goodwill Gross GoodwillGross	841841000
CY2023	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	3555000
CY2023Q4	us-gaap	Goodwill Gross GoodwillGross	845396000
CY2022	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0
CY2023Q4	cbu	Principal Balance Of Loans Serviced For Others PrincipalBalanceOfLoansServicedForOthers	532900000
CY2022Q4	cbu	Principal Balance Of Loans Serviced For Others PrincipalBalanceOfLoansServicedForOthers	583100000
CY2023Q4	cbu	Custodial Escrow Balances In Connection With Loans Serviced For Others CustodialEscrowBalancesInConnectionWithLoansServicedForOthers	10200000
CY2022Q4	cbu	Custodial Escrow Balances In Connection With Loans Serviced For Others CustodialEscrowBalancesInConnectionWithLoansServicedForOthers	10500000
CY2023Q4	us-gaap	Noninterest Bearing Domestic Deposit Checking NoninterestBearingDomesticDepositChecking	3638527000
CY2022Q4	us-gaap	Noninterest Bearing Domestic Deposit Checking NoninterestBearingDomesticDepositChecking	4140617000
CY2023Q4	us-gaap	Interest Bearing Domestic Deposit Checking InterestBearingDomesticDepositChecking	2900003000
CY2022Q4	us-gaap	Interest Bearing Domestic Deposit Checking InterestBearingDomesticDepositChecking	3231096000
CY2023Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	2276523000
CY2022Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	2433922000
CY2023Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	2392605000
CY2022Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	2299965000
CY2023Q4	us-gaap	Time Deposits TimeDeposits	1720463000
CY2022Q4	us-gaap	Time Deposits TimeDeposits	906708000
CY2023Q4	us-gaap	Deposits Deposits	12928121000
CY2022Q4	us-gaap	Deposits Deposits	13012308000
CY2023	us-gaap	Interest Expense Domestic Deposit Liabilities Checking InterestExpenseDomesticDepositLiabilitiesChecking	12950000
CY2022	us-gaap	Interest Expense Domestic Deposit Liabilities Checking InterestExpenseDomesticDepositLiabilitiesChecking	3340000
CY2021	us-gaap	Interest Expense Domestic Deposit Liabilities Checking InterestExpenseDomesticDepositLiabilitiesChecking	1142000
CY2023	us-gaap	Interest Expense Domestic Deposit Liabilities Savings InterestExpenseDomesticDepositLiabilitiesSavings	5970000
CY2022	us-gaap	Interest Expense Domestic Deposit Liabilities Savings InterestExpenseDomesticDepositLiabilitiesSavings	671000
CY2021	us-gaap	Interest Expense Domestic Deposit Liabilities Savings InterestExpenseDomesticDepositLiabilitiesSavings	598000
CY2023	us-gaap	Interest Expense Domestic Deposit Liabilities Money Market InterestExpenseDomesticDepositLiabilitiesMoneyMarket	33709000
CY2022	us-gaap	Interest Expense Domestic Deposit Liabilities Money Market InterestExpenseDomesticDepositLiabilitiesMoneyMarket	4019000
CY2021	us-gaap	Interest Expense Domestic Deposit Liabilities Money Market InterestExpenseDomesticDepositLiabilitiesMoneyMarket	1393000
CY2023	us-gaap	Interest Expense Domestic Deposit Liabilities Time Deposit InterestExpenseDomesticDepositLiabilitiesTimeDeposit	32708000
CY2022	us-gaap	Interest Expense Domestic Deposit Liabilities Time Deposit InterestExpenseDomesticDepositLiabilitiesTimeDeposit	7014000
CY2021	us-gaap	Interest Expense Domestic Deposit Liabilities Time Deposit InterestExpenseDomesticDepositLiabilitiesTimeDeposit	8498000
CY2023	us-gaap	Interest Expense Deposits InterestExpenseDeposits	85337000
CY2022	us-gaap	Interest Expense Deposits InterestExpenseDeposits	15044000
CY2021	us-gaap	Interest Expense Deposits InterestExpenseDeposits	11631000
CY2023Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	1379783000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More Next Twelve Months TimeDepositsMaturities250000OrMoreNextTwelveMonths	315497000
CY2023Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	281122000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More Year Two TimeDepositsMaturities250000OrMoreYearTwo	131153000
CY2023Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	26212000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More Year Three TimeDepositsMaturities250000OrMoreYearThree	263000
CY2023Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	17295000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More Year Four TimeDepositsMaturities250000OrMoreYearFour	789000
CY2023Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	16040000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More Year Five TimeDepositsMaturities250000OrMoreYearFive	287000
CY2023Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	11000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More After Year Five TimeDepositsMaturities250000OrMoreAfterYearFive	0
CY2023Q4	us-gaap	Time Deposits TimeDeposits	1720463000
CY2023Q4	cbu	Time Deposits Maturities250000 Or More TimeDepositsMaturities250000OrMore	447989000
CY2023Q4	us-gaap	Debt Instrument Unamortized Discount Premium Net DebtInstrumentUnamortizedDiscountPremiumNet	0
CY2022Q4	us-gaap	Debt Instrument Unamortized Discount Premium Net DebtInstrumentUnamortizedDiscountPremiumNet	249000
CY2023Q4	us-gaap	Junior Subordinated Notes JuniorSubordinatedNotes	0
CY2022Q4	us-gaap	Junior Subordinated Notes JuniorSubordinatedNotes	3249000
CY2023Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	304595000
CY2022Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	346652000
CY2023Q4	cbu	Federal Home Loan Bank Overnight Advance FederalHomeLoanBankOvernightAdvance	53000000
CY2022Q4	cbu	Federal Home Loan Bank Overnight Advance FederalHomeLoanBankOvernightAdvance	768400000
CY2023Q4	us-gaap	Federal Home Loan Bank Advances Discount FederalHomeLoanBankAdvancesDiscount	217000
CY2022Q4	us-gaap	Federal Home Loan Bank Advances Discount FederalHomeLoanBankAdvancesDiscount	319000
CY2023Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	407603000
CY2022Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	19474000
CY2023Q4	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	765198000
CY2022Q4	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	1137775000
CY2023Q4	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	765198000
CY2023Q4	us-gaap	Debt Weighted Average Interest Rate DebtWeightedAverageInterestRate	0.0350
CY2023	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	9349000
CY2022	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	6518000
CY2021	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	0
CY2023	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	3094000
CY2022	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	998000
CY2021	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	841000
CY2023	us-gaap	Interest Expense Loans From Other Federal Home Loan Banks InterestExpenseLoansFromOtherFederalHomeLoanBanks	6285000
CY2022	us-gaap	Interest Expense Loans From Other Federal Home Loan Banks InterestExpenseLoansFromOtherFederalHomeLoanBanks	386000
CY2021	us-gaap	Interest Expense Loans From Other Federal Home Loan Banks InterestExpenseLoansFromOtherFederalHomeLoanBanks	89000
CY2023	us-gaap	Interest Expense Subordinated Notes And Debentures InterestExpenseSubordinatedNotesAndDebentures	38000
CY2022	us-gaap	Interest Expense Subordinated Notes And Debentures InterestExpenseSubordinatedNotesAndDebentures	153000
CY2021	us-gaap	Interest Expense Subordinated Notes And Debentures InterestExpenseSubordinatedNotesAndDebentures	154000
CY2023	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	0
CY2022	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	0
CY2021	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	293000
CY2023	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	18766000
CY2022	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	8055000
CY2021	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	1377000
CY2023	us-gaap	Long Term Debt Weighted Average Interest Rate Over Time LongTermDebtWeightedAverageInterestRateOverTime	0.0297
CY2022	us-gaap	Long Term Debt Weighted Average Interest Rate Over Time LongTermDebtWeightedAverageInterestRateOverTime	0.0161
CY2023Q4	us-gaap	Line Of Credit Facility Current Borrowing Capacity LineOfCreditFacilityCurrentBorrowingCapacity	25000000.0
CY2023Q4	us-gaap	Federal Home Loan Bank Advances General Debt Obligations Disclosures Amount Of Available Unused Funds FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds	1370000000
CY2022Q4	us-gaap	Deferred Tax Liabilities Prepaid Expenses DeferredTaxLiabilitiesPrepaidExpenses	18154000
CY2023Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	79885000
CY2022Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	75378000
CY2023Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	115930000
CY2022Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	149633000
CY2023	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	36617000
CY2022	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	41025000
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	35507000
CY2023	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	7193000
CY2022	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	9899000
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	8158000
CY2023	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-4877000
CY2022	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1163000
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	5493000
CY2023	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-2626000
CY2022	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	146000
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	2496000
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	36307000
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52233000
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	51654000
CY2023Q4	cbu	Deferred Tax Assets Unrealized Gains On Investment Securities DeferredTaxAssetsUnrealizedGainsOnInvestmentSecurities	157456000
CY2022Q4	cbu	Deferred Tax Assets Unrealized Gains On Investment Securities DeferredTaxAssetsUnrealizedGainsOnInvestmentSecurities	191953000
CY2023Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	16398000
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	15346000
CY2023Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	5727000
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	5775000
CY2023Q4	cbu	Deferred Tax Assets Tax Deferred Expense Operating Lease Liabilities DeferredTaxAssetsTaxDeferredExpenseOperatingLeaseLiabilities	10211000
CY2022Q4	cbu	Deferred Tax Assets Tax Deferred Expense Operating Lease Liabilities DeferredTaxAssetsTaxDeferredExpenseOperatingLeaseLiabilities	7552000
CY2023Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	6023000
CY2022Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	4385000
CY2023Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	195815000
CY2022Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	225011000
CY2023Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	39366000
CY2022Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	39454000
CY2023Q4	cbu	Deferred Tax Liabilities Right Of Use Assets DeferredTaxLiabilitiesRightOfUseAssets	9872000
CY2022Q4	cbu	Deferred Tax Liabilities Right Of Use Assets DeferredTaxLiabilitiesRightOfUseAssets	7303000
CY2023Q4	cbu	Deferred Tax Liabilities Deferred Expense Deferred Loan Origination Costs DeferredTaxLiabilitiesDeferredExpenseDeferredLoanOriginationCosts	10777000
CY2022Q4	cbu	Deferred Tax Liabilities Deferred Expense Deferred Loan Origination Costs DeferredTaxLiabilitiesDeferredExpenseDeferredLoanOriginationCosts	9731000
CY2023Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	383000
CY2022Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	96000
CY2023Q4	us-gaap	Deferred Tax Liabilities Mortgage Servicing Rights DeferredTaxLiabilitiesMortgageServicingRights	306000
CY2022Q4	us-gaap	Deferred Tax Liabilities Mortgage Servicing Rights DeferredTaxLiabilitiesMortgageServicingRights	640000
CY2023	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2022	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.017
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.013
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.011
CY2023	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.022
CY2022	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.033
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.036
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost	-0.002
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost	-0.003
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost	-0.009
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.005
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.010
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.010
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.008
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.000
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.002
CY2023	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.216
CY2022	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.217
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.214
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0
CY2022Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0
CY2023Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0
CY2009	cbu	Other Comprehensive Income Loss Negative Postretirement Medical Plan Amendment Net Of Tax OtherComprehensiveIncomeLossNegativePostretirementMedicalPlanAmendmentNetOfTax	3500000
CY2023	cbu	Maximum Percentage Of Pension Gain Loss Not Amortized MaximumPercentageOfPensionGainLossNotAmortized	0.10
CY2011Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized	900000
CY2014Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized	1000000
CY2017Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized	1000000
CY2022Q2	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	600000
CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	600000
CY2023Q4	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Outstanding Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions	1641854
CY2023Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Exercise Price Beginning Balance1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1	54.27
CY2023	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Remaining Contractual Term2 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2	P5Y2M23D
CY2023Q4	us-gaap	Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Exercisable Options ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions	1100927
CY2023Q4	us-gaap	Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Exercise Price1 SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1	50.60
CY2023	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P5Y2M23D
CY2023	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P3Y10M20D
CY2023Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	6900000
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Method Used ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMethodUsed	Black-Scholes option-pricing model
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	14.93
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	17.86
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	18.43
CY2023	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y6M
CY2022	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y6M
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y6M
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0248
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0241
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0248
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.2972
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.2988
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.3009
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0374
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0216
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0128
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	189249000
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53601000
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53896000
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	47820
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	29.71
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	35815
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	34.93
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	51000
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	30.02
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	636
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	35.89
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	31999
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	34.93
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	52588
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	25.36
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	2874
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	34.93
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	575
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	34.93
CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	81138
CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	27.15
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	100000
CY2023	us-gaap	Net Income Loss NetIncomeLoss	131924000
CY2022	us-gaap	Net Income Loss NetIncomeLoss	188081000
CY2021	us-gaap	Net Income Loss NetIncomeLoss	189694000
CY2023	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	-447000
CY2022	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	-533000
CY2021	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	-445000
CY2023	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	131477000
CY2022	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	187548000
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53977000
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.45
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.48
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.51
CY2023	us-gaap	Net Income Loss NetIncomeLoss	131924000
CY2022	us-gaap	Net Income Loss NetIncomeLoss	188081000
CY2021	us-gaap	Net Income Loss NetIncomeLoss	189694000
CY2023	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	-447000
CY2022	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	-533000
CY2021	us-gaap	Amount Of Dilutive Securities Stock Options And Restrictive Stock Units AmountOfDilutiveSecuritiesStockOptionsAndRestrictiveStockUnits	-445000
CY2023	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	131477000
CY2022	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	187548000
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	189249000
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53601000
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53896000
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	53977000
CY2023	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	124000
CY2022	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	312000
CY2021	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	423000
CY2023	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	53725000
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	54208000
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	54400000
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.45
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.46
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.48
CY2023	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.78
CY2022	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.74
CY2021	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.70
CY2023Q4	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	2697000
CY2022Q4	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	2697000
CY2023	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	607161
CY2023Q4	cbu	Treasury Stock Shares Acquired Price Per Share TreasuryStockSharesAcquiredPricePerShare	49.44
CY2021Q4	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	2697000
CY2022	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	250000
CY2022Q4	cbu	Treasury Stock Shares Acquired Price Per Share TreasuryStockSharesAcquiredPricePerShare	65.51
CY2020Q4	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	2680000
CY2021	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	67500
CY2021Q4	cbu	Treasury Stock Shares Acquired Price Per Share TreasuryStockSharesAcquiredPricePerShare	71.91
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CY2022Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Face Amount Liability FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability	1544138000
CY2023Q4	us-gaap	Statutory Accounting Practices Statutory Amount Available For Dividend Payments StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPayments	156900000
CY2022Q4	cbu	Required Capital Conservation Ratio RequiredCapitalConservationRatio	0.0250
CY2023Q4	cbu	Required Capital Conservation Ratio RequiredCapitalConservationRatio	0.0250
CY2023	us-gaap	Loss Contingency Accrual Payments LossContingencyAccrualPayments	5800000
CY2023	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	5800000
CY2023Q4	cbu	Uninsured Deposit Annul Interest Rate Of Federal Deposit Insurance Corporation UninsuredDepositAnnulInterestRateOfFederalDepositInsuranceCorporation	0.00134
CY2022Q4	us-gaap	Time Deposit Liability Above Us Insurance Limit TimeDepositLiabilityAboveUsInsuranceLimit	5000000000.0
CY2023	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1500000
CY2023Q4	us-gaap	Accrued Insurance Current AccruedInsuranceCurrent	9500000
CY2022Q4	us-gaap	Accrued Insurance Current AccruedInsuranceCurrent	5500000
CY2021Q4	us-gaap	Accrued Insurance Current AccruedInsuranceCurrent	4100000
CY2023	cbu	Lessee Operating Lease Option To Terminate Term LesseeOperatingLeaseOptionToTerminateTerm	P1Y
CY2023	us-gaap	Operating Lease Cost OperatingLeaseCost	9358000
CY2022	us-gaap	Operating Lease Cost OperatingLeaseCost	8568000
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	8397000
CY2023	us-gaap	Variable Lease Cost VariableLeaseCost	68000
CY2022	us-gaap	Variable Lease Cost VariableLeaseCost	108000
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	50000
CY2023	us-gaap	Short Term Lease Cost ShortTermLeaseCost	64000
CY2022	us-gaap	Short Term Lease Cost ShortTermLeaseCost	65000
CY2021	us-gaap	Short Term Lease Cost ShortTermLeaseCost	148000
CY2023	us-gaap	Lease Cost LeaseCost	9490000
CY2022	us-gaap	Lease Cost LeaseCost	8741000
CY2021	us-gaap	Lease Cost LeaseCost	8595000
CY2023	us-gaap	Operating Lease Payments OperatingLeasePayments	8584000
CY2022	us-gaap	Operating Lease Payments OperatingLeasePayments	8402000
CY2023	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	19301000
CY2022	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	6758000
CY2023Q4	cbu	Common Equity Tier One Capital Required For Capital Adequacy Plus Capital Conservation Buffer Ratio CommonEquityTierOneCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferRatio	0.070
CY2023Q4	cbu	Tier One Risk Based Capital Required For Capital Adequacy Plus Capital Conservation Buffer To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets	0.085
CY2023Q4	cbu	Capital Required For Capital Adequacy Plus Capital Conservation Buffer To Risk Weighted Assets CapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets	0.105
CY2023Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	1402188000
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CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	30069000
CY2023Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	41409000
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	31091000
CY2023Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P6Y6M
CY2022Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P4Y10M24D
CY2023Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0379
CY2022Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0289
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	9661000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	8590000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	7379000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	5264000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	3854000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	13048000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	47796000
CY2023Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	6387000
CY2023Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	41409000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	8995000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	7579000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	5992000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	4180000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	2547000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	4333000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	33626000
CY2022Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	2535000
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	31091000
CY2023Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0934
CY2023Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	600442000
CY2023Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2023Q4	us-gaap	Tier One Leverage Capital Required To Be Well Capitalized TierOneLeverageCapitalRequiredToBeWellCapitalized	750553000
CY2023Q4	us-gaap	Tier One Leverage Capital Required To Be Well Capitalized To Average Assets TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets	0.0500
CY2023Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	1402042000
CY2023Q4	us-gaap	Common Equity Tier One Capital Ratio CommonEquityTierOneCapitalRatio	0.1475
CY2023Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	427618000
CY2023Q4	cbu	Common Equity Tier1 Capital Required For Capital Adequacy Ratio CommonEquityTier1CapitalRequiredForCapitalAdequacyRatio	0.0450
CY2023Q4	cbu	Common Equity Tier One Capital Required For Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer	665184000
CY2023Q4	cbu	Common Equity Tier One Capital Required For Capital Adequacy Plus Capital Conservation Buffer Ratio CommonEquityTierOneCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferRatio	0.0700
CY2023Q4	us-gaap	Common Equity Tier One Capital Required To Be Well Capitalized CommonEquityTierOneCapitalRequiredToBeWellCapitalized	617671000
CY2023Q4	cbu	Common Equity Tier1 Capital Required To Be Well Capitalized Ratio CommonEquityTier1CapitalRequiredToBeWellCapitalizedRatio	0.0650
CY2023Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	1402188000
CY2023Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1476
CY2023Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	570158000
CY2023Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2023Q4	cbu	Tier One Risk Based Capital Required For Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer	807723000
CY2023Q4	cbu	Tier One Risk Based Capital Required For Capital Adequacy Plus Capital Conservation Buffer To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets	0.0850
CY2023Q4	us-gaap	Tier One Risk Based Capital Required To Be Well Capitalized TierOneRiskBasedCapitalRequiredToBeWellCapitalized	760210000
CY2023Q4	us-gaap	Tier One Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.0800
CY2023Q4	us-gaap	Capital Capital	1468920000
CY2023Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1546
CY2023Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	760210000
CY2023Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2023Q4	cbu	Capital Required For Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer	997776000
CY2023Q4	cbu	Capital Required For Capital Adequacy Plus Capital Conservation Buffer To Risk Weighted Assets CapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets	0.1050
CY2023Q4	us-gaap	Capital Required To Be Well Capitalized CapitalRequiredToBeWellCapitalized	950263000
CY2023Q4	us-gaap	Capital Required To Be Well Capitalized To Risk Weighted Assets CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.1000
CY2022Q4	us-gaap	Tier One Leverage Capital TierOneLeverageCapital	1381598000
CY2022Q4	us-gaap	Tier One Leverage Capital To Average Assets TierOneLeverageCapitalToAverageAssets	0.0879
CY2022Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy TierOneLeverageCapitalRequiredForCapitalAdequacy	628485000
CY2022Q4	us-gaap	Tier One Leverage Capital Required For Capital Adequacy To Average Assets TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets	0.0400
CY2022Q4	us-gaap	Tier One Leverage Capital Required To Be Well Capitalized TierOneLeverageCapitalRequiredToBeWellCapitalized	785606000
CY2022Q4	us-gaap	Tier One Leverage Capital Required To Be Well Capitalized To Average Assets TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets	0.0500
CY2022Q4	us-gaap	Common Equity Tier One Capital CommonEquityTierOneCapital	1381439000
CY2022Q4	us-gaap	Common Equity Tier One Capital Ratio CommonEquityTierOneCapitalRatio	0.1571
CY2022Q4	us-gaap	Common Equity Tier One Capital Required For Capital Adequacy CommonEquityTierOneCapitalRequiredForCapitalAdequacy	395771000
CY2022Q4	cbu	Common Equity Tier1 Capital Required For Capital Adequacy Ratio CommonEquityTier1CapitalRequiredForCapitalAdequacyRatio	0.0450
CY2022Q4	cbu	Common Equity Tier One Capital Required For Capital Adequacy Plus Capital Conservation Buffer CommonEquityTierOneCapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer	615644000
CY2022Q4	cbu	Common Equity Tier One Capital Required For Capital Adequacy Plus Capital Conservation Buffer Ratio CommonEquityTierOneCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferRatio	0.0700
CY2022Q4	us-gaap	Common Equity Tier One Capital Required To Be Well Capitalized CommonEquityTierOneCapitalRequiredToBeWellCapitalized	571669000
CY2022Q4	cbu	Common Equity Tier1 Capital Required To Be Well Capitalized Ratio CommonEquityTier1CapitalRequiredToBeWellCapitalizedRatio	0.0650
CY2022Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	1381598000
CY2022Q4	us-gaap	Tier One Risk Based Capital To Risk Weighted Assets TierOneRiskBasedCapitalToRiskWeightedAssets	0.1571
CY2022Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy TierOneRiskBasedCapitalRequiredForCapitalAdequacy	527695000
CY2022Q4	us-gaap	Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0600
CY2022Q4	cbu	Tier One Risk Based Capital Required For Capital Adequacy Plus Capital Conservation Buffer TierOneRiskBasedCapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer	747568000
CY2022Q4	cbu	Tier One Risk Based Capital Required For Capital Adequacy Plus Capital Conservation Buffer To Risk Weighted Assets TierOneRiskBasedCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets	0.0850
CY2022Q4	us-gaap	Tier One Risk Based Capital Required To Be Well Capitalized TierOneRiskBasedCapitalRequiredToBeWellCapitalized	703593000
CY2022Q4	us-gaap	Tier One Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.0800
CY2022Q4	us-gaap	Capital Capital	1442529000
CY2022Q4	us-gaap	Capital To Risk Weighted Assets CapitalToRiskWeightedAssets	0.1640
CY2022Q4	us-gaap	Capital Required For Capital Adequacy CapitalRequiredForCapitalAdequacy	703593000
CY2022Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	0.0800
CY2022Q4	cbu	Capital Required For Capital Adequacy Plus Capital Conservation Buffer CapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer	923466000
CY2022Q4	cbu	Capital Required For Capital Adequacy Plus Capital Conservation Buffer To Risk Weighted Assets CapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets	0.1050
CY2022Q4	us-gaap	Capital Required To Be Well Capitalized CapitalRequiredToBeWellCapitalized	879491000
CY2022Q4	us-gaap	Capital Required To Be Well Capitalized To Risk Weighted Assets CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets	0.1000
CY2023Q4	cbu	Fair Value Assets Level1 To Level2 Transfers Amount1 FairValueAssetsLevel1ToLevel2TransfersAmount1	0
CY2023Q4	cbu	Mortgages Held For Sale Unpaid Principal Value MortgagesHeldForSaleUnpaidPrincipalValue	400000
CY2022Q4	us-gaap	Mortgages Held For Sale Fair Value Disclosure MortgagesHeldForSaleFairValueDisclosure	0
CY2023	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	437285000
CY2023	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	11203000
CY2023	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-52329000
CY2023	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	242000
CY2023	cbu	Non Interest Income Expenses Other Revenues NonInterestIncomeExpensesOtherRevenues	266921000
CY2023	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14511000
CY2023	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	63000
CY2023	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	3280000
CY2023	us-gaap	Restructuring Charges RestructuringCharges	1163000
CY2023	us-gaap	Litigation Settlement Expense LitigationSettlementExpense	5800000
CY2023	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	447868000
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	168231000
CY2023Q4	us-gaap	Assets Assets	15555753000
CY2023Q4	us-gaap	Goodwill Goodwill	845396000
CY2023Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	52591000
CY2022	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	420630000
CY2022	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	14773000
CY2022	us-gaap	Noninterest Income NoninterestIncome	258725000
CY2022	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	15214000
CY2022	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	5021000
CY2022	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-300000
CY2022	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	404333000
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	240314000
CY2022Q4	us-gaap	Assets Assets	15835651000
CY2022Q4	us-gaap	Goodwill Goodwill	841841000
CY2022Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	60996000
CY2021	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	374412000
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-8839000
CY2021	us-gaap	Noninterest Income NoninterestIncome	246235000
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14051000
CY2021	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	701000
CY2021	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	200000
CY2021	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	373186000
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	241348000
CY2021Q4	us-gaap	Assets Assets	15552657000
CY2021Q4	us-gaap	Goodwill Goodwill	799109000
CY2021Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	65226000
CY2023	dei	Auditor Name AuditorName	PricewaterhouseCoopers LLP
CY2023	dei	Auditor Location AuditorLocation	New York

Files In Submission

Name	View Source	Status
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$CBU
COMMUNITY FINANCIAL SYSTEM, INC. Stock $cbu

2024 Q1 Form 10-K Financial Statement

#000141057824000095 Filed on February 29, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CBU COMMUNITY FINANCIAL SYSTEM, INC. Stock $cbu

2024 Q1 Form 10-K Financial Statement

#000141057824000095 Filed on February 29, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CBU
COMMUNITY FINANCIAL SYSTEM, INC. Stock $cbu