XML 73 R57.htm IDEA: XBRL DOCUMENT
v3.20.4

ACQUISITIONS - Summary of Loans Acquired (Details) - USD ($) $ in Thousands | Jun. 12, 2020 | Jul. 12, 2019
--- | --- | ---
Kinderhook Bank Corp [Member] |  |
Summary of loans acquired [Abstract] |  |
Contractually required principal and interest at acquisition |  | $ 649,734
Contractual cash flows not expected to be collected |  | (9,648)
Expected cash flows at acquisition |  | 640,086
Interest component of expected cash flows |  | (160,209)
Fair value of acquired loans |  | 479,877
Kinderhook Bank Corp [Member] | Acquired Impaired Loans [Member] |  |
Summary of loans acquired [Abstract] |  |
Contractually required principal and interest at acquisition |  | 13,350
Contractual cash flows not expected to be collected |  | (4,176)
Expected cash flows at acquisition |  | 9,174
Interest component of expected cash flows |  | (551)
Fair value of acquired loans |  | 8,623
Kinderhook Bank Corp [Member] | Acquired Non Impaired Loans [Member] |  |
Summary of loans acquired [Abstract] |  |
Contractually required principal and interest at acquisition |  | 636,384
Contractual cash flows not expected to be collected |  | (5,472)
Expected cash flows at acquisition |  | 630,912
Interest component of expected cash flows |  | (159,658)
Fair value of acquired loans |  | $ 471,254
Steuben Trust Corporation [Member] | Acquired Deteriorated |  |
Summary of loans acquired [Abstract] |  |
Par value of loans at acquisition | $ 35,906 |
Allowance for credit losses at acquisition | (668) |
Non-credit discount at acquisition | 103 |
Fair value of acquired loans | 35,341 |
Steuben Trust Corporation [Member] | Non-PCD Loans |  |
Summary of loans acquired [Abstract] |  |
Contractually required principal and interest at acquisition | 400,738 |
Contractual cash flows not expected to be collected | (2,994) |
Expected cash flows at acquisition | 397,744 |
Interest component of expected cash flows | (94,068) |
Fair value of acquired loans | $ 303,676 |

X
- Definition The acquirer's estimate, at acquisition, of the amount and timing of undiscounted principal, interest, and other cash flows not expected to be collected. + References No definition available. + Details
Name: | cbu_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAcquiredDuringPeriodContractualCashFlowsNotExpectedToBeCollected
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Allowance for credit losses at acquisition at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | cbu_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionAllowanceForCreditLosses
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Par value of loans at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | cbu_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionAtParValue
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Non-credit (discount) premium at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | cbu_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionNonCreditDiscountPremium
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The investor's estimate, at acquisition, of the amount and timing of the interest component of expected cash flows for loans acquired in transfer not accounted for as debt securities. + References No definition available. + Details
Name: | cbu_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodInterestComponentOfCashFlows
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Fair value at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash flows expected to be collected at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodCashFlowsExpectedToBeCollectedAtAcquisition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of contractually required payments receivable at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodContractuallyRequiredPaymentsReceivableAtAcquisition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cbu_KinderhookBankCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cbu_SteubenTrustCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredAndNoCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |