XML 66 R54.htm IDEA: XBRL DOCUMENT
v3.24.3

COMMITMENTS, CONTINGENT LIABILITIES AND RESTRICTIONS (Details) $ in Thousands |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Feb. 05, 2024 USD ($) | Nov. 16, 2023 | Sep. 30, 2024 USD ($) | Jun. 30, 2024 USD ($) | Sep. 30, 2023 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Commitments and contingencies |  |  |  |  |  |  |  |  |
Contract amount of commitments and contingencies |  |  | $ 1,760,519 |  |  | $ 1,760,519 |  | $ 1,555,901 |
Basis points |  | 0.134% |  |  |  |  |  |  |
Uninsured deposits |  |  |  |  |  |  |  |  | $ 5,000,000
Expense related to special assessment |  |  |  |  |  |  |  | 1,500 |
FDIC special assessment for a net increase (decrease) |  |  |  |  |  | (200) |  |  |
FDIC insurance expense |  |  | 2,000 |  | $ 1,900 | 6,500 | $ 5,900 |  |
Investment in tax credits |  |  | $ 10,000 |  |  | $ 10,000 |  |  |
Investment, Proportional Amortization Method, Elected, Statement of Financial Position [Extensible Enumeration] |  |  | Other Assets |  |  | Other Assets |  |  |
Unfunded commitments |  |  | $ 9,600 |  |  | $ 9,600 |  |  |
Loss contingency accrual, payments | $ 5,800 |  |  |  |  |  |  |  |
Litigation accrual |  |  |  |  |  |  |  | 5,800 |
Settlement fund |  |  |  | $ 5,800 |  |  |  |  |
Minimum |  |  |  |  |  |  |  |  |
Commitments and contingencies |  |  |  |  |  |  |  |  |
Number of quarterly assessment periods |  |  |  |  |  | 8 |  |  |
Maximum |  |  |  |  |  |  |  |  |
Commitments and contingencies |  |  |  |  |  |  |  |  |
Number of quarterly assessment periods |  |  |  |  |  | 10 |  |  |
Commitments to extend credit |  |  |  |  |  |  |  |  |
Commitments and contingencies |  |  |  |  |  |  |  |  |
Contract amount of commitments and contingencies |  |  | 1,682,414 |  |  | $ 1,682,414 |  | 1,494,549 |
Standby letters of credit |  |  |  |  |  |  |  |  |
Commitments and contingencies |  |  |  |  |  |  |  |  |
Contract amount of commitments and contingencies |  |  | $ 78,105 |  |  | $ 78,105 |  | $ 61,352 |

X
- Definition The amount of expense related to FDIC special assessment. + References No definition available. + Details
Name: | cbu_FederalDepositInsuranceCorporationExpenseRelatedToSpecialAssessment
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) to accrued expense in relation to Federal Deposit Insurance Corporation due to expected increase (decrease) based on Special assessment. + References No definition available. + Details
Name: | cbu_FederalDepositInsuranceCorporationSpecialAssessmentIncreaseDecreaseInAccrualAmount
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the increase in number of quarterly assessment periods. + References No definition available. + Details
Name: | cbu_NumberOfQuarterlyAssessmentPeriods
Namespace Prefix: | cbu_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Uninsured deposit annul interest rate of Federal Deposit Insurance Corporation (FDIC). + References No definition available. + Details
Name: | cbu_UninsuredDepositAnnulInterestRateOfFederalDepositInsuranceCorporation
Namespace Prefix: | cbu_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment that generates income tax credit and other income tax benefit under tax credit program elected to be accounted for using proportional amortization method. Includes, but is not limited to, investment under program not meeting condition for accounting under proportional amortization method. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-1A + Details
Name: | us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of expense for Federal Deposit Insurance Corporation (FDIC) insurance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(14)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_FederalDepositInsuranceCorporationPremiumExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Indicates line item in statement of financial position that includes investment that generates income tax credit and other income tax benefit under tax credit program elected to be accounted for using proportional amortization method. Includes, but is not limited to, investment under tax credit program not meeting condition for accounting under proportional amortization method. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-1A + Details
Name: | us-gaap_InvestmentProportionalAmortizationMethodElectedStatementOfFinancialPositionExtensibleEnumeration
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of loss contingency liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-1 Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-10 + Details
Name: | us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of cash outflow reducing loss contingency liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-1 + Details
Name: | us-gaap_LossContingencyAccrualPayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of damages paid to the plaintiff in the legal matter. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-4 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483076/450-20-50-9 + Details
Name: | us-gaap_LossContingencyDamagesPaidValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_LossContingencyEstimateAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of commitment and contingent commitment, including amount of delayed equity contribution, for investment that generates income tax credit and other income tax benefit under tax credit program elected to be accounted for using proportional amortization method. Includes, but is not limited to, commitment and contingent commitment related to investment under tax credit program not meeting condition for accounting under proportional amortization method. + References Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 740 -SubTopic 323 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478156/740-323-50-2 + Details
Name: | us-gaap_QualifiedAffordableHousingProjectInvestmentsCommitment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of uninsured time deposit liability in excess of Federal Deposit Insurance Corporation (FDIC) insurance limit or similar state deposit insurance regime in United States of America (US). Excludes time deposit that is otherwise uninsured. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph f -Subparagraph (1) -Publisher SEC + Details
Name: | us-gaap_TimeDepositLiabilityAboveUsInsuranceLimit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommitmentsToExtendCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |