XML 96 R79.htm IDEA: XBRL DOCUMENT
v3.25.0.1

PREMISES AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Property, Plant and Equipment [Line Items] |  |
Depreciation | $ 1,814 | $ 2,001
Discontinued Operations, Held-for-Sale | Ithaca Station |  |
Property, Plant and Equipment [Line Items] |  |
Property, plant and equipment, disposal group’s carrying value | 700 |
Disposal group, appraised value less selling costs | $ 1,300 |

X
- Definition Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Appraised Value + References No definition available. + Details
Name: | chmg_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentAppraisedValue
Namespace Prefix: | chmg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-1 + Details
Name: | us-gaap_Depreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount classified as property, plant and equipment attributable to disposal group held for sale or disposed of. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 10 -SubTopic 20 -Topic 205 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483475/205-20-45-10 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 205 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5B -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483499/205-20-50-5B Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 360 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-3 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 205 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483475/205-20-45-11 + Details
Name: | us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A + Details
Name: | us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsHeldforsaleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=chmg_IthacaStationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |