XML 69 R56.htm IDEA: XBRL DOCUMENT
v3.21.1

FAIR VALUE - Assets and Liabilities Measured on Nonrecurring Basis (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Unpaid principal value of business lending loans held for sale | $ 800 |
Valuation allowance | 3,560 | $ 3,874
Mortgage Servicing Rights [Member] |  |
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Valuation allowance | 100 | 200
Significant Unobservable Inputs, Level 3 [Member] |  |
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Impaired loans | 21,647 | 25,063
Business loans held for sale | 848 |
Other real estate owned | 824 | 883
Mortgage servicing rights | 807 | 682
Non-recurring [Member] |  |
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Impaired loans | 21,647 | 25,063
Business loans held for sale | 848 | 0
Other real estate owned | 824 | 883
Mortgage servicing rights | 807 | 682
Total | 24,126 | 26,628
Non-recurring [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member] |  |
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Impaired loans | 0 | 0
Business loans held for sale | 0 | 0
Other real estate owned | 0 | 0
Mortgage servicing rights | 0 | 0
Total | 0 | 0
Non-recurring [Member] | Significant Observable Inputs, Level 2 [Member] |  |
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Impaired loans | 0 | 0
Business loans held for sale | 0 | 0
Other real estate owned | 0 | 0
Mortgage servicing rights | 0 | 0
Total | 0 | 0
Non-recurring [Member] | Significant Unobservable Inputs, Level 3 [Member] |  |
Assets and Liabilities Measured on Nonrecurring Basis [Abstract] |  |
Impaired loans | 21,647 | 25,063
Business loans held for sale | 848 | 0
Other real estate owned | 824 | 883
Mortgage servicing rights | 807 | 682
Total | $ 24,126 | $ 26,628

X
- Definition Amount of unpaid principal balance of business lending loans held for sale. + References No definition available. + Details
Name: | cbu_BusinessLendingLoansHeldForSaleUnpaidPrincipalBalance
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of business loans held-for-sale including, but not limited to, mortgage loans and finance receivables. + References No definition available. + Details
Name: | cbu_BusinessLoansHeldForSaleFairValueDisclosure
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This is the amount of impaired loans carried at fair value. + References No definition available. + Details
Name: | cbu_ImpairedLoansFairValueDisclosure
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10(4)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
Name: | us-gaap_OtherRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=7516967&loc=d3e66267-113978 + Details
Name: | us-gaap_ServicingAssetAtAmortizedValueFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=cbu_MortgageServicingRightsMember
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: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
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: |