XML 60 R48.htm IDEA: XBRL DOCUMENT
v3.25.2

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Allowances by Impairment (Details) - USD ($) $ in Thousands | Jun. 30, 2025 | Mar. 31, 2025 | Dec. 31, 2024 | Jun. 30, 2024 | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | --- | --- | --- | --- | ---
Allowance for credit losses |  |  |  |  |  |
Individually analyzed | $ 858 |  | $ 1,552 |  |  |
Collectively analyzed | 21,807 |  | 19,836 |  |  |
Total ending allowance balance | 22,665 | $ 22,522 | 21,388 | $ 21,031 | $ 20,471 | $ 22,517
Amortized cost basis of loans: |  |  |  |  |  |
Individually analyzed | 4,981 |  | 6,471 |  |  |
Collectively analyzed | 2,127,433 |  | 2,064,948 |  |  |
Total loans, net of deferred loan fees and costs | 2,132,414 |  | 2,071,419 |  |  |
Commercial and Industrial |  |  |  |  |  |
Allowance for credit losses |  |  |  |  |  |
Individually analyzed | 700 |  | 1,446 |  |  |
Collectively analyzed | 3,824 |  | 3,074 |  |  |
Total ending allowance balance | 4,524 | 5,153 | 4,520 | 4,894 | 4,516 | 5,055
Amortized cost basis of loans: |  |  |  |  |  |
Individually analyzed | 861 |  | 1,512 |  |  |
Collectively analyzed | 293,613 |  | 298,009 |  |  |
Total loans, net of deferred loan fees and costs | 294,474 |  | 299,521 |  |  |
Commercial Mortgages |  |  |  |  |  |
Allowance for credit losses |  |  |  |  |  |
Individually analyzed | 158 |  | 106 |  |  |
Collectively analyzed | 12,556 |  | 11,108 |  |  |
Total ending allowance balance | 12,714 | 12,089 | 11,214 | 10,530 | 10,367 | 12,026
Amortized cost basis of loans: |  |  |  |  |  |
Individually analyzed | 3,767 |  | 4,959 |  |  |
Collectively analyzed | 1,293,758 |  | 1,212,045 |  |  |
Total loans, net of deferred loan fees and costs | 1,297,525 |  | 1,217,004 |  |  |
Residential Mortgages |  |  |  |  |  |
Allowance for credit losses |  |  |  |  |  |
Individually analyzed | 0 |  | 0 |  |  |
Collectively analyzed | 2,597 |  | 2,259 |  |  |
Total ending allowance balance | 2,597 | 2,473 | 2,259 | 2,106 | 2,062 | 2,194
Amortized cost basis of loans: |  |  |  |  |  |
Individually analyzed | 0 |  | 0 |  |  |
Collectively analyzed | 278,221 |  | 274,979 |  |  |
Total loans, net of deferred loan fees and costs | 278,221 |  | 274,979 |  |  |
Consumer Loans |  |  |  |  |  |
Allowance for credit losses |  |  |  |  |  |
Individually analyzed | 0 |  | 0 |  |  |
Collectively analyzed | 2,830 |  | 3,395 |  |  |
Total ending allowance balance | 2,830 | $ 2,807 | 3,395 | $ 3,501 | $ 3,526 | $ 3,242
Amortized cost basis of loans: |  |  |  |  |  |
Individually analyzed | 353 |  | 0 |  |  |
Collectively analyzed | 261,841 |  | 279,915 |  |  |
Total loans, net of deferred loan fees and costs | $ 262,194 |  | $ 279,915 |  |  |

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

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

X
- Definition Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of allowance for credit loss on financing receivable evaluated on collective basis. Excludes financing receivable evaluated on individual basis. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.5.a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11B -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-11B Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 30 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479391/326-20-30-2 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of allowance for credit loss on financing receivable evaluated on individual basis. Excludes financing receivable evaluated on collective basis. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.5.a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11B -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-11B Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 30 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479391/326-20-30-2 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of financing receivable collectively evaluated for credit loss. Excludes financing receivable individually evaluated for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.5.a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11C -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-11C + Details
Name: | us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-5 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable individually evaluated for credit loss. Excludes financing receivable collectively evaluated for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.5.a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11C -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-11C + Details
Name: | us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_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: |