XML 65 R38.htm IDEA: XBRL DOCUMENT v2.4.1.9
LOANS AND ALLOWANCE FOR LOAN LOSSES, RECEIVABLES PAST DUE (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Aging of the recorded investment in loans past due [Abstract]    
Current $ 1,128,004us-gaap_FinancingReceivableRecordedInvestmentCurrent $ 1,103,760us-gaap_FinancingReceivableRecordedInvestmentCurrent
30-89 Days Past Due 4,329chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue 8,731chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
90 Days or more Past Due and accruing 1,476us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing 1,454us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Loans acquired with deteriorated credit quality 2,017us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality 2,631us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
Non-Accrual 10,419us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus [1] 7,778us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus [2]
Total 1,146,245us-gaap_NotesReceivableNet 1,124,354us-gaap_NotesReceivableNet
Commercial and Agricultural [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndAgriculturalPortfolioSegmentMember
620us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndAgriculturalPortfolioSegmentMember
Total 172,227us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndAgriculturalPortfolioSegmentMember
166,820us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndAgriculturalPortfolioSegmentMember
Commercial and Industrial [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 170,397us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
164,109us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
30-89 Days Past Due 317chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
756chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
90 Days or more Past Due and accruing 24us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
620us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
Non-Accrual 331us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
[1] 312us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
[2]
Total 171,069us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
165,797us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_CommercialAndIndustrialMember
Agricultural [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 1,158us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
1,023us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
30-89 Days Past Due 0chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
0chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
90 Days or more Past Due and accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
Non-Accrual 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
[1] 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
[2]
Total 1,158us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
1,023us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_AgriculturalMember
Commercial Mortgages [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Loans acquired with deteriorated credit quality 1,761us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
1,761us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Total 481,488us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
453,719us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstatePortfolioSegmentMember
Construction [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 47,913us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
53,371us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
30-89 Days Past Due 0chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
90 Days or more Past Due and accruing 1,444us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
1,446us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Non-Accrual 148us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
[1] 150us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
[2]
Total 49,505us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
54,967us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Commercial mortgages [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 424,367us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
391,096us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
30-89 Days Past Due 536chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
3,064chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
90 Days or more Past Due and accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
Loans acquired with deteriorated credit quality 1,761us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
1,761us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
Non-Accrual 5,319us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
[1] 2,831us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
[2]
Total 431,983us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
398,752us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateOtherReceivableMember
Residential mortgages [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 193,684us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
191,089us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
30-89 Days Past Due 1,482chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
2,333chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
90 Days or more Past Due and accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Loans acquired with deteriorated credit quality 256us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
250us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Non-Accrual 3,705us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
[1] 3,615us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
[2]
Total 199,127us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
197,287us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialPortfolioSegmentMember
Consumer Loans [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Total 293,403us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
306,528us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
Credit cards [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 1,505us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
1,641us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
30-89 Days Past Due 13chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
5chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
90 Days or more Past Due and accruing 8us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
8us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
Non-Accrual 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
[1] 0us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
[2]
Total 1,526us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
1,654us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerCreditCardFinancingReceivableMember
Home equity lines and loans [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 97,626us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
98,340us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
30-89 Days Past Due 672chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
736chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
90 Days or more Past Due and accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
Non-Accrual 655us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
[1] 515us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
[2]
Total 98,953us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
99,591us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_HomeEquityLinesAndLoansMember
Indirect consumer loans [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 172,573us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
183,103us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
30-89 Days Past Due 1,266chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
1,789chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
90 Days or more Past Due and accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
Non-Accrual 249us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
[1] 325us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
[2]
Total 174,088us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
185,217us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= chmg_IndirectConsumerLoansMember
Direct consumer loans [Member]    
Aging of the recorded investment in loans past due [Abstract]    
Current 18,781us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
19,988us-gaap_FinancingReceivableRecordedInvestmentCurrent
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
30-89 Days Past Due 43chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
48chmg_FinancingReceivableRecordedInvestment30To89DaysPastDue
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
90 Days or more Past Due and accruing 0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
0us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
Loans acquired with deteriorated credit quality 0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
0us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
Non-Accrual 12us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
[1] 30us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
[2]
Total $ 18,836us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
$ 20,066us-gaap_NotesReceivableNet
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerOtherFinancingReceivableMember
[1] Includes all loans on non-accrual status regardless of the number of days such loans were delinquent as of March 31,2015.
[2] Includes all loans on non-accrual status regardless of the number of days such loans were delinquent as of December 31, 2014.