XML 79 R70.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

LOANS, Troubled Debt Restructuring (TDR) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) Loan | Dec. 31, 2018 USD ($) Loan
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 248 | 218
TDRs, amount | $ 6,982,000 | $ 5,525,000
Loans modified in TDR during the year, number | Loan | 73 | 52
Loans modified in TDR during the year, amount | $ 2,798,000 | $ 1,035,000
Maximum [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
Threshold balance of TDR loans collectively included in general loan loss allocation and qualitative review | $ 500,000 |
Nonaccrual [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 80 | 62
TDRs, amount | $ 3,609,000 | $ 2,388,000
Accruing [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 168 | 156
TDRs, amount | $ 3,373,000 | $ 3,137,000
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 106 | 92
TDRs, amount | $ 4,530,000 | $ 3,755,000
Loans modified in TDR during the year, number | Loan | 22 | 9
Loans modified in TDR during the year, amount | $ 1,519,000 | $ 470,000
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Nonaccrual [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 59 | 46
TDRs, amount | $ 2,638,000 | $ 1,986,000
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | Accruing [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 47 | 46
TDRs, amount | $ 1,892,000 | $ 1,769,000
Commercial Portfolio Segment [Member] | Minimum [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
Threshold balance of loan individually evaluated for impairment | $ 500,000 |
Commercial Portfolio Segment [Member] | Business Lending [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 11 | 6
TDRs, amount | $ 882,000 | $ 327,000
Loans modified in TDR during the year, number | Loan | 6 | 2
Loans modified in TDR during the year, amount | $ 685,000 | $ 103,000
Commercial Portfolio Segment [Member] | Business Lending [Member] | Nonaccrual [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 8 | 4
TDRs, amount | $ 681,000 | $ 162,000
Commercial Portfolio Segment [Member] | Business Lending [Member] | Accruing [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 3 | 2
TDRs, amount | $ 201,000 | $ 165,000
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 84 | 77
TDRs, amount | $ 941,000 | $ 857,000
Loans modified in TDR during the year, number | Loan | 33 | 32
Loans modified in TDR during the year, amount | $ 364,000 | $ 320,000
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Nonaccrual [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 0 | 0
TDRs, amount | $ 0 | $ 0
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | Accruing [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 84 | 77
TDRs, amount | $ 941,000 | $ 857,000
Consumer Portfolio Segment [Member] | Consumer Direct [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 23 | 22
TDRs, amount | $ 101,000 | $ 71,000
Loans modified in TDR during the year, number | Loan | 6 | 6
Loans modified in TDR during the year, amount | $ 49,000 | $ 24,000
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Nonaccrual [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 0 | 0
TDRs, amount | $ 0 | $ 0
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | Accruing [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 23 | 22
TDRs, amount | $ 101,000 | $ 71,000
Consumer Portfolio Segment [Member] | Home Equity [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 24 | 21
TDRs, amount | $ 528,000 | $ 515,000
Loans modified in TDR during the year, number | Loan | 6 | 3
Loans modified in TDR during the year, amount | $ 181,000 | $ 118,000
Consumer Portfolio Segment [Member] | Home Equity [Member] | Nonaccrual [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 13 | 12
TDRs, amount | $ 290,000 | $ 240,000
Consumer Portfolio Segment [Member] | Home Equity [Member] | Accruing [Member] |  |
Troubled Debt Restructurings (TDRs) [Abstract] |  |
TDRs, number | Loan | 11 | 9
TDRs, amount | $ 238,000 | $ 275,000

X
- Definition The threshold balance of financing receivable that is individually evaluated for impairment. + References No definition available. + Details
Name: | cbu_FinancingReceivableIndividuallyEvaluatedForImpairmentThresholdBalance
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Threshold balance of financing receivables classified as a troubled debt restructuring that are collectively evaluated for impairment. + References No definition available. + Details
Name: | cbu_FinancingReceivableModificationsCollectivelyEvaluatedForImpairmentThresholdBalance
Namespace Prefix: | cbu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References No definition available. + Details
Name: | cbu_FinancingReceivableModificationsNumberOfContracts
Namespace Prefix: | cbu_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of financing receivable modified as troubled debt restructuring. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554 + Details
Name: | us-gaap_FinancingReceivableModificationsRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=cbu_NonaccrualTdrsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=cbu_AccruingTdrsMember
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_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
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_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: |