XML 86 R69.htm IDEA: XBRL DOCUMENT v3.24.0.1

LOANS AND ALLOWANCE FOR CREDIT LOSSES - Collateral Dependent (Details) - USD ($) $ in Thousands	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	$ 8,035		$ 7,482
Related Allowance	22,517	[1]	19,659	[1]	$ 21,025
Commercial and Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	2,067		2,112
Related Allowance	5,055		3,373		3,591
Commercial Mortgages
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	5,968		4,383
Related Allowance	12,026		$ 11,576		$ 13,556
Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	6,347
Related Allowance	267
Commercial Real Estate And Business Assets | Commercial and Agricultural | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	353
Related Allowance	214
Commercial Real Estate And Business Assets | Commercial and Agricultural | Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	26
Related Allowance	26
Commercial Real Estate and Residential Real Estate | Commercial Mortgages | Construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	2,209
Related Allowance	0
Commercial Real Estate and Residential Real Estate | Commercial Mortgages | Commercial mortgages, other
Financing Receivable, Allowance for Credit Loss [Line Items]
Amortized Cost Basis	3,759
Related Allowance	$ 27
[1] Effective January 1, 2023, the allowance calculation is based upon Current Expected Credit loss methodology. Prior to January 1, 2023, the allowance calculation was based upon incurred loss methodology. Refer to Note 1 for further discussion.

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

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/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

Reference 1: 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

Reference 2: 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

+ 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_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=chmg_CommercialRealEstateAndBusinessAssetsMember
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_AgriculturalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=chmg_CommercialRealEstateAndResidentialRealEstateMember
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: