XML 71 R59.htm IDEA: XBRL DOCUMENT
v3.19.1

FAIR VALUE, Financial Assets and Liabilities Accounted for at Fair Value On a Recurring Basis (Details) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | $ 2,922,943 |
Equity securities | 464 | $ 432
Commitments to Originate Real Estate Loans for Sale [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 20 |
U.S. Treasury and Agency Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 2,034,972 | 2,023,753
Obligations of State and Political Subdivisions [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 433,159 | 459,154
Government Agency Mortgage-Backed Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 386,543 | 382,477
Corporate Debt Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 2,553 | 2,546
Government Agency Collateralized Mortgage Obligations [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 65,716 | 68,119
Recurring [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 2,922,943 | 2,936,049
Equity securities | 464 | 432
Mortgage loans held for sale | 212 | 83
Total | 2,923,763 | 2,936,615
Recurring [Member] | Commitments to Originate Real Estate Loans for Sale [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 20 |
Recurring [Member] | Forward Sales Commitments [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative liability | (6) |
Recurring [Member] | Interest Rate Swap Agreements [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 835 | 793
Derivative liability | (705) | (742)
Recurring [Member] | U.S. Treasury and Agency Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 2,034,972 | 2,023,753
Recurring [Member] | Obligations of State and Political Subdivisions [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 433,159 | 459,154
Recurring [Member] | Government Agency Mortgage-Backed Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 386,543 | 382,477
Recurring [Member] | Corporate Debt Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 2,553 | 2,546
Recurring [Member] | Government Agency Collateralized Mortgage Obligations [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 65,716 | 68,119
Recurring [Member] | Level 1 [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 1,913,361 | 1,896,931
Equity securities | 464 | 432
Mortgage loans held for sale | 0 | 0
Total | 1,913,825 | 1,897,363
Recurring [Member] | Level 1 [Member] | Commitments to Originate Real Estate Loans for Sale [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 0 |
Recurring [Member] | Level 1 [Member] | Forward Sales Commitments [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative liability | 0 |
Recurring [Member] | Level 1 [Member] | Interest Rate Swap Agreements [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 0 | 0
Derivative liability | 0 | 0
Recurring [Member] | Level 1 [Member] | U.S. Treasury and Agency Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 1,913,361 | 1,896,931
Recurring [Member] | Level 1 [Member] | Obligations of State and Political Subdivisions [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 1 [Member] | Government Agency Mortgage-Backed Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 1 [Member] | Corporate Debt Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 1 [Member] | Government Agency Collateralized Mortgage Obligations [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 2 [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 1,009,582 | 1,039,118
Equity securities | 0 | 0
Mortgage loans held for sale | 212 | 83
Total | 1,009,918 | 1,039,252
Mortgage loans held for sale, at principal value | 200 | 100
Recurring [Member] | Level 2 [Member] | Commitments to Originate Real Estate Loans for Sale [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 0 |
Recurring [Member] | Level 2 [Member] | Forward Sales Commitments [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative liability | (6) |
Recurring [Member] | Level 2 [Member] | Interest Rate Swap Agreements [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 835 | 793
Derivative liability | (705) | (742)
Recurring [Member] | Level 2 [Member] | U.S. Treasury and Agency Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 121,611 | 126,822
Recurring [Member] | Level 2 [Member] | Obligations of State and Political Subdivisions [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 433,159 | 459,154
Recurring [Member] | Level 2 [Member] | Government Agency Mortgage-Backed Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 386,543 | 382,477
Recurring [Member] | Level 2 [Member] | Corporate Debt Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 2,553 | 2,546
Recurring [Member] | Level 2 [Member] | Government Agency Collateralized Mortgage Obligations [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 65,716 | 68,119
Recurring [Member] | Level 3 [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Equity securities | 0 | 0
Mortgage loans held for sale | 0 | 0
Total | 20 | 0
Recurring [Member] | Level 3 [Member] | Commitments to Originate Real Estate Loans for Sale [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 20 |
Recurring [Member] | Level 3 [Member] | Forward Sales Commitments [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative liability | 0 |
Recurring [Member] | Level 3 [Member] | Interest Rate Swap Agreements [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Derivative asset | 0 | 0
Derivative liability | 0 | 0
Recurring [Member] | Level 3 [Member] | U.S. Treasury and Agency Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 3 [Member] | Obligations of State and Political Subdivisions [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 3 [Member] | Government Agency Mortgage-Backed Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 3 [Member] | Corporate Debt Securities [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | 0 | 0
Recurring [Member] | Level 3 [Member] | Government Agency Collateralized Mortgage Obligations [Member] |  |
Available-for-sale investment securities [Abstract] |  |
Available-for-sale investment securities | $ 0 | $ 0

X
- Definition Principal amount of mortgage loans held for sale. + References No definition available. + Details
Name: | cbu_LoansHeldForSaleMortgagesPrincipalAmount
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
Name: | us-gaap_DerivativeAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 + Details
Name: | us-gaap_DerivativeLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740 + Details
Name: | us-gaap_EquitySecuritiesFvNi
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of asset after deduction of liability. + References No definition available. + Details
Name: | us-gaap_FairValueNetAssetLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of mortgage loans held-for-sale. + References No definition available. + Details
Name: | us-gaap_MortgagesHeldForSaleFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_LoanOriginationCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

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

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForwardContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |