XML 57 R45.htm IDEA: XBRL DOCUMENT
v3.20.2

LOANS AND ALLOWANCE FOR LOAN LOSSES - Credit Quality Indicator (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | $ 1,543,528 | $ 1,312,903
Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 441,216 | 428,037
Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 1,054,875 | 826,396
Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 10,121 | 18,534
Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 29,872 | 29,701
Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 7,444 | 10,235
Commercial and agricultural: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 406,013 | 230,922
Commercial mortgages: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 692,935 | 650,570
Commercial mortgages: | Construction |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 54,523 | 44,082
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 | 51,126 | 40,304
Commercial mortgages: | Construction | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 610 | 168
Commercial mortgages: | Construction | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 2,787 | 3,610
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 | 638,412 | 606,488
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 | 610,687 | 577,266
Commercial mortgages: | Commercial mortgages | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 6,732 | 12,451
Commercial mortgages: | Commercial mortgages | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 18,755 | 12,356
Commercial mortgages: | Commercial mortgages | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 2,238 | 4,415
Residential mortgages |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 227,984 | 188,874
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 227,984 | 188,874
Residential mortgages | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 226,242 | 186,719
Residential mortgages | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 1,742 | 2,155
Residential mortgages | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 226,242 | 186,719
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 | 1,742 | 2,155
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 | 216,596 | 242,537
Consumer loans: | Home equity lines and loans |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 81,770 | 92,065
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 81,770 | 92,065
Consumer loans: | Home equity lines and loans | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 80,753 | 91,424
Consumer loans: | Home equity lines and loans | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 1,017 | 641
Consumer loans: | Home equity lines and loans | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 80,753 | 91,424
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 | 1,017 | 641
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 | 121,720 | 135,366
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 121,721 | 135,366
Consumer loans: | Indirect consumer loans | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 121,117 | 134,795
Consumer loans: | Indirect consumer loans | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 604 | 571
Consumer loans: | Indirect consumer loans | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 121,116 | 134,795
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 | 604 | 571
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 | 13,106 | 15,106
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 13,105 | 15,106
Consumer loans: | Direct consumer loans | Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 13,104 | 15,099
Consumer loans: | Direct consumer loans | Non-Performing |  |
Residential and consumer finance receivable [Abstract] |  |
Residential and consumer loans receivable | 1 | 7
Consumer loans: | Direct consumer loans | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 13,105 | 15,099
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 | 1 | 7
Consumer loans: | Direct consumer loans | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial and industrial | Commercial and agricultural: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 405,329 | 230,648
Commercial and industrial | Commercial and agricultural: | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Commercial and industrial | Commercial and agricultural: | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 392,378 | 208,552
Commercial and industrial | Commercial and agricultural: | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 2,779 | 5,915
Commercial and industrial | Commercial and agricultural: | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 4,966 | 10,361
Commercial and industrial | Commercial and agricultural: | Doubtful |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 5,206 | 5,820
Agricultural | Commercial and agricultural: |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 684 | 274
Agricultural | Commercial and agricultural: | Not Rated |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Agricultural | Commercial and agricultural: | Pass |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 684 | 274
Agricultural | Commercial and agricultural: | Special Mention |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Agricultural | Commercial and agricultural: | Substandard |  |
Finance receivable by credit quality indicator [Abstract] |  |
Total ending loans balance | 0 | 0
Agricultural | Commercial and agricultural: | 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_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: |

X
- Details
Name: | us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_CommercialAndIndustrialSectorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_AgriculturalSectorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |