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Fair Value Measurements (Narrative) (Details)
 3 Months Ended 12 Months Ended 3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Fair Value Inputs, Prepayment Rate 1.00%us-gaap_FairValueInputsPrepaymentRate 1.00%us-gaap_FairValueInputsPrepaymentRate  
Annual prepayments maturity 100.00%chco_AnnualPrepaymentsMaturityPercentage 100.00%chco_AnnualPrepaymentsMaturityPercentage  
Additional basis points 1.50%chco_AdditionalBasisPointsAnnualDefaultsFromBanks 1.50%chco_AdditionalBasisPointsAnnualDefaultsFromBanks  
Maximum [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Collateral discount 30.00%chco_UnobservableInputsFairValueMeasurementCollateralDiscountPercent
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		   30.00%chco_UnobservableInputsFairValueMeasurementCollateralDiscountPercent
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Minimum [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Collateral discount 20.00%chco_UnobservableInputsFairValueMeasurementCollateralDiscountPercent
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		   20.00%chco_UnobservableInputsFairValueMeasurementCollateralDiscountPercent
/ us-gaap_RangeAxis
= us-gaap_MinimumMember