XML 19 R42.htm IDEA: XBRL DOCUMENT v2.4.1.9
FAIR VALUE, Quantitative Information (Details) (USD $)
 3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Impaired loan valuation allowance $ 1,581,000us-gaap_ImpairedFinancingReceivableRelatedAllowance   $ 1,235,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
Increase (decrease) in provision for loan losses 390,000us-gaap_ProvisionForLoanAndLeaseLosses 639,000us-gaap_ProvisionForLoanAndLeaseLosses  
Write down of OREO 390,000us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs 573,000us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs  
Impaired Loans [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Carrying amount of impaired loans 4,700,000us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember		   4,900,000us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember
Impaired loan valuation allowance 1,600,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember		   1,200,000us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember
Increase (decrease) in provision for loan losses (653,000)us-gaap_ProvisionForLoanAndLeaseLosses
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember		   232,000us-gaap_ProvisionForLoanAndLeaseLosses
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember
Other Real Estate Owned [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Net carrying amount of OREO 2,500,000chmg_OtherRealEstateOwnedCarryingValueNet
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember		   3,100,000chmg_OtherRealEstateOwnedCarryingValueNet
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
Outstanding balance of OREO     3,100,000us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
Other real estate owned valuation allowance 0us-gaap_RealEstateOwnedValuationAllowanceComponent
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember		   2,000us-gaap_RealEstateOwnedValuationAllowanceComponent
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
Write down of OREO 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember		    
Non-recurring [Member] | Other Real Estate Owned [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Outstanding balance of OREO 2,506,000us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember		   3,065,000us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Non-recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Real Estate Owned [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Outstanding balance of OREO 0us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember		   0us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Non-recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Real Estate Owned [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Outstanding balance of OREO 0us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember		   0us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Non-recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Real Estate Owned [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Outstanding balance of OREO 2,506,000us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember		   3,065,000us-gaap_OtherRealEstateAndForeclosedAssets
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Non-recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Third Party Appraisals [Member] | Impaired Loans [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Fair Value 2,993,000us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_ValuationTechniqueAxis
= us-gaap_MarketApproachValuationTechniqueMember		   3,645,000us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByAssetClassAxis
= chmg_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_ValuationTechniqueAxis
= us-gaap_MarketApproachValuationTechniqueMember
Unobservable Input 1 Management discount based on underlying collateral characteristics and market conditions   Management discount based on underlying collateral characteristics and market conditions
Non-recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Third Party Appraisals [Member] | Other Real Estate Owned [Member]      
Information related to Level 3 non-recurring fair value measurement [Abstract]      
Fair Value $ 2,506,000us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_ValuationTechniqueAxis
= us-gaap_MarketApproachValuationTechniqueMember		   $ 3,065,000us-gaap_AssetsFairValueDisclosureNonrecurring
/ us-gaap_FairValueByAssetClassAxis
= chmg_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_ValuationTechniqueAxis
= us-gaap_MarketApproachValuationTechniqueMember
Unobservable Input 1 Estimated holding period   Estimated holding period
Unobservable Input 2 Estimated closing costs   Estimated closing costs