XML 56 R44.htm IDEA: XBRL DOCUMENT
v3.21.1

LOANS AND ALLOWANCE FOR LOAN LOSSES - Credit Quality Indicator (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | $ 1,585,984 | $ 1,541,498
Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 451,361 | 448,787
Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 1,079,053 | 1,036,759
Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 24,734 | 26,630
Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 28,450 | 26,813
Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 2,386 | 2,509
Commercial and agricultural: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 400,719 | 370,252
Commercial and agricultural: | Commercial and industrial |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 400,281 | 369,968
Commercial and agricultural: | Commercial and industrial | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial and agricultural: | Commercial and industrial | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 390,138 | 360,500
Commercial and agricultural: | Commercial and industrial | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 3,232 | 2,999
Commercial and agricultural: | Commercial and industrial | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 5,652 | 5,092
Commercial and agricultural: | Commercial and industrial | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 1,259 | 1,377
Commercial and agricultural: | Agricultural |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 438 | 284
Commercial and agricultural: | Agricultural | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial and agricultural: | Agricultural | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 438 | 284
Commercial and agricultural: | Agricultural | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial and agricultural: | Agricultural | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial and agricultural: | Agricultural | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial mortgages: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 731,438 | 719,145
Commercial mortgages: | Construction |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 58,525 | 62,164
Commercial mortgages: | Construction | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial mortgages: | Construction | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 57,131 | 59,885
Commercial mortgages: | Construction | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial mortgages: | Construction | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 1,394 | 2,279
Commercial mortgages: | Construction | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial mortgages: | Commercial mortgages |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 672,913 | 656,981
Commercial mortgages: | Commercial mortgages | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial mortgages: | Commercial mortgages | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 631,346 | 616,090
Commercial mortgages: | Commercial mortgages | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 21,502 | 23,631
Commercial mortgages: | Commercial mortgages | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 18,938 | 16,128
Commercial mortgages: | Commercial mortgages | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 1,127 | 1,132
Residential mortgages |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 245,843 | 240,013
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 245,843 | 240,013
Residential mortgages | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 244,589 | 238,381
Residential mortgages | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 1,254 | 1,632
Residential mortgages | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 244,589 | 238,381
Residential mortgages | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Residential mortgages | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Residential mortgages | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 1,254 | 1,632
Residential mortgages | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 207,984 | 212,088
Consumer loans: | Home equity lines and loans |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 75,081 | 78,761
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 75,081 | 78,761
Consumer loans: | Home equity lines and loans | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 74,408 | 77,602
Consumer loans: | Home equity lines and loans | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 673 | 1,159
Consumer loans: | Home equity lines and loans | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 74,408 | 77,602
Consumer loans: | Home equity lines and loans | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Home equity lines and loans | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Home equity lines and loans | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 673 | 1,159
Consumer loans: | Home equity lines and loans | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Indirect consumer loans |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 121,197 | 120,853
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 121,197 | 120,853
Consumer loans: | Indirect consumer loans | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 120,676 | 120,334
Consumer loans: | Indirect consumer loans | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 521 | 519
Consumer loans: | Indirect consumer loans | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 120,676 | 120,334
Consumer loans: | Indirect consumer loans | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Indirect consumer loans | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Indirect consumer loans | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 521 | 519
Consumer loans: | Indirect consumer loans | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Direct consumer loans |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 11,706 | 12,474
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 11,706 | 12,474
Consumer loans: | Direct consumer loans | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 11,688 | 12,470
Consumer loans: | Direct consumer loans | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 18 | 4
Consumer loans: | Direct consumer loans | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 11,688 | 12,470
Consumer loans: | Direct consumer loans | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Direct consumer loans | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Consumer loans: | Direct consumer loans | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 18 | 4
Consumer loans: | Direct consumer loans | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | $ 0 | $ 0

X
- Definition Financing Receivable, after Interest Receivable on Loans, before Allowance on Credit Loss + References No definition available. + Details
Name: | chmg_FinancingReceivableAfterInterestReceivableOnLoansBeforeAllowanceOnCreditLoss
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

X
- Definition The amount of finance receivable related to residential and consumer loans receivable.. + References No definition available. + Details
Name: | chmg_ResidentialAndConsumerLoansReceivable
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=chmg_NotRatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_DoubtfulMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

X
- Details
Name: | us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_NonperformingFinancingReceivableMember
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=us-gaap_HomeEquityLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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