XML 66 R53.htm IDEA: XBRL DOCUMENT
v3.20.2

LOANS, Carrying Amounts of Loans Purchased and Sold (Details) $ in Thousands | 6 Months Ended
--- | ---
Jun. 30, 2020 USD ($)
Carrying Amounts of Loans Purchased and Sold [Abstract] |
Purchases | $ 339,692
Sales | 15,599
Commercial Portfolio Segment [Member] | Business Lending [Member] |
Carrying Amounts of Loans Purchased and Sold [Abstract] |
Purchases | 253,469
Sales | 0
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] |
Carrying Amounts of Loans Purchased and Sold [Abstract] |
Purchases | 26,733
Sales | 15,599
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] |
Carrying Amounts of Loans Purchased and Sold [Abstract] |
Purchases | 13,926
Sales | 0
Consumer Portfolio Segment [Member] | Consumer Direct [Member] |
Carrying Amounts of Loans Purchased and Sold [Abstract] |
Purchases | 6,022
Sales | 0
Consumer Portfolio Segment [Member] | Home Equity [Member] |
Carrying Amounts of Loans Purchased and Sold [Abstract] |
Purchases | 39,542
Sales | $ 0

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

X
- Definition Amount of increase from purchase of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 11 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919244-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableSignificantPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of decrease from sale and reclassification to held-for-sale of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 11 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919244-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableSignificantSales
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbu_ConsumerInstallmentIndirectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbu_ConsumerInstallmentDirectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbu_HomeEquityReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |