XML 64 R52.htm IDEA: XBRL DOCUMENT
v3.25.2

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands | Jun. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | $ 5,250 | $ 6,518
Nonaccrual | 8,237 | 8,954
Loans Past Due 90 Days or More and Still Accruing | 0 | 23
Commercial and industrial |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 70 | 76
Nonaccrual | 879 | 1,534
Loans Past Due 90 Days or More and Still Accruing | 0 | 23
Commercial Mortgages | Construction |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 0 | 0
Nonaccrual | 0 | 0
Loans Past Due 90 Days or More and Still Accruing | 0 | 0
Commercial Mortgages | Owner occupied commercial real estate |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 1,298 | 1,362
Nonaccrual | 1,307 | 1,377
Loans Past Due 90 Days or More and Still Accruing | 0 | 0
Commercial Mortgages | Non-owner occupied commercial real estate |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 293 | 2,619
Nonaccrual | 2,460 | 3,582
Loans Past Due 90 Days or More and Still Accruing | 0 | 0
Residential Mortgages |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 1,837 | 1,372
Nonaccrual | 1,837 | 1,372
Loans Past Due 90 Days or More and Still Accruing | 0 | 0
Consumer Loans | Home equity lines and loans |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 1,012 | 613
Nonaccrual | 1,012 | 613
Loans Past Due 90 Days or More and Still Accruing | 0 | 0
Consumer Loans | Indirect consumer |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 701 | 474
Nonaccrual | 703 | 474
Loans Past Due 90 Days or More and Still Accruing | 0 | 0
Consumer Loans | Direct consumer |  |
Financing Receivable, Impaired [Line Items] |  |
Nonaccrual with No Allowance for Credit Losses | 39 | 2
Nonaccrual | 39 | 2
Loans Past Due 90 Days or More and Still Accruing | $ 0 | $ 0

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FinancingReceivableImpairedLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_FinancingReceivableNonaccrualNoAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost of financing receivable 90 days or more past due and still accruing. Excludes net investment in lease. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-7 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 80 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-80 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost of financing receivable on nonaccrual status. Excludes net investment in lease. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph a -Subparagraph (3) -Publisher SEC Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph a -Subparagraph (2) -Publisher SEC Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=chmg_HomeEquityLinesAndLoansMember
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: |