<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>527</ContextCount>
  <ElementCount>336</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>53</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0110 - Statement - Consolidated Statements of Financial Condition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/BalanceSheet</Role>
      <ShortName>Consolidated Statements of Financial Condition</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0111 - Statement - Consolidated Statements of Financial Condition (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/StatementOfFinancialConditionParenthetical</Role>
      <ShortName>Consolidated Statements of Financial Condition (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0120 - Statement - Consolidated Statements of Operations (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/StatementOfOperations</Role>
      <ShortName>Consolidated Statements of Operations (Unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0130 - Statement - Consolidated Statements of Comprehensive Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/StatementOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0140 - Statement - Consolidated Statements of Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/StatementOfShareholdersEquity</Role>
      <ShortName>Consolidated Statements of Shareholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0150 - Statement - Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/CashFlowSatement</Role>
      <ShortName>Consolidated Statements of Cash Flows (Unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0201 - Disclosure - Nature of Banking Activities and Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/NatureOfBankingActivitiesAndSignificantAccountingPolicies</Role>
      <ShortName>Nature of Banking Activities and Significant Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0202 - Disclosure - Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/Securities</Role>
      <ShortName>Securities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0203 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonConveredLoans</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0204 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFDICSharedLossAgreementCoveredLoans</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0205 - Disclosure - FDIC Agreements and FDIC Indemnification Asset</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FdicAgreementsAndFdicIndemnificationAsset</Role>
      <ShortName>FDIC Agreements and FDIC Indemnification Asset</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0206 - Disclosure - Other Intangibles</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/OtherIntangibles</Role>
      <ShortName>Other Intangibles</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0207 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/Deposits</Role>
      <ShortName>Deposits</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0208 - Disclosure - Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/AccumulatedOtherComprehensiveIncome</Role>
      <ShortName>Accumulated Other Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0209 - Disclosure - Fair Values of Assets and Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FairValuesOfAssetsAndLiabilities</Role>
      <ShortName>Fair Values of Assets and Liabilities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0210 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/EarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0211 - Disclosure - Defined Benefit Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DefinedBenefitPlan</Role>
      <ShortName>Defined Benefit Plan</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0212 - Disclosure - Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/Contingencies</Role>
      <ShortName>Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>0401 - Disclosure - Nature of Banking Activities and Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/NatureOfBankingActivitiesAndSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Nature of Banking Activities and Significant Accounting Policies (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>0502 - Disclosure - Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/SecuritiesTables</Role>
      <ShortName>Securities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>0503 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansTables</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>0504 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFdicSharedLossAgreementCoveredLoansTables</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>0505 - Disclosure - FDIC Agreements and FDIC Indemnification Asset (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FDICAgreementsAndFDICIndemnificationAssetTables</Role>
      <ShortName>FDIC Agreements and FDIC Indemnification Asset (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>0506 - Disclosure - Other Intangibles (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/OtherIntangiblesTables</Role>
      <ShortName>Other Intangibles (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>0507 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>0508 - Disclosure - Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/AccumulatedOtherComprehensiveIncomeTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>0509 - Disclosure - Fair Values of Assets and Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FairValuesOfAssetsAndLiabilitiesTables</Role>
      <ShortName>Fair Values of Assets and Liabilities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>0510 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/EarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>0511 - Disclosure - Defined Benefit Plan (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DefinedBenefitPlanTables</Role>
      <ShortName>Defined Benefit Plan (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>0601 - Disclosure - Nature of Banking Activities and Significant Accounting Policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/NatureOfBankingActivitiesAndSignificantAccountingPoliciesDetails</Role>
      <ShortName>Nature of Banking Activities and Significant Accounting Policies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>0602 - Disclosure - Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/SecuritiesDetails</Role>
      <ShortName>Securities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>06021 - Disclosure - Securities (Details 1)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/SecuritiesDetails1</Role>
      <ShortName>Securities (Details 1)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>06022 - Disclosure - Securities (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/SecuritiesDetails2</Role>
      <ShortName>Securities (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>06023 - Disclosure - Securities (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/SecuritiesDetails3</Role>
      <ShortName>Securities (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>06024 - Disclosure - Securities (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/SecuritiesDetailsTextual</Role>
      <ShortName>Securities (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>06030 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>060301 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 1)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails1</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 1)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>060302 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFDICSharedLossAgreementNonCoveredLoansDetails2</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>060303 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails3</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>060304 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails4</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>060305 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 5)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails5</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 5)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>060306 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 6)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails6</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 6)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>060307 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 7)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails8</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 7)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>060308 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 8)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails7</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 8)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>060309 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 9)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetails9</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details 9)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>060310 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansNotCoveredByFdicSharedLossAgreementNonCoveredLoansDetailsTextual</Role>
      <ShortName>Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>0604 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFdicSharedLossAgreementCoveredLoansDetails</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>06041 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details 1)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFdicSharedLossAgreementCoveredLoansDetails1</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details 1)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>06042 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFdicSharedLossAgreementCoveredLoansDetails2</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>06043 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFdicSharedLossAgreementCoveredLoansDetails3</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>06044 - Disclosure - Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/LoansCoveredByFdicSharedLossAgreementCoveredLoansDetailsTextual</Role>
      <ShortName>Loans Covered by FDIC Shared Loss Agreement (Covered Loans) (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>0605 - Disclosure - FDIC Agreements and FDIC Indemnification Asset (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FDICAgreementsAndFDICIndemnificationAssetDetails</Role>
      <ShortName>FDIC Agreements and FDIC Indemnification Asset (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>06051 - Disclosure - FDIC Agreements and FDIC Indemnification Asset (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FDICAgreementsAndFDICIndemnificationAssetDetailsTextual</Role>
      <ShortName>FDIC Agreements and FDIC Indemnification Asset (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>0606 - Disclosure - Other Intangibles (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/OtherIntangiblesDetails</Role>
      <ShortName>Other Intangibles (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>06061 - Disclosure - Other Intangibles (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/OtherIntangiblesDetailsTextual</Role>
      <ShortName>Other Intangibles (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>0607 - Disclosure - Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DepositsDetails</Role>
      <ShortName>Deposits (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>0608 - Disclosure - Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/AccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>0609 - Disclosure - Fair Values of Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FairValuesOfAssetsAndLiabilitiesDetails</Role>
      <ShortName>Fair Values of Assets and Liabilities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>06091 - Disclosure - Fair Values of Assets and Liabilities (Details 1)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FairValuesOfAssetsAndLiabilitiesDetails1</Role>
      <ShortName>Fair Values of Assets and Liabilities (Details 1)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>06092 - Disclosure - Fair Values of Assets and Liabilities (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FairValuesOfAssetsAndLiabilitiesDetails2</Role>
      <ShortName>Fair Values of Assets and Liabilities (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>06093 - Disclosure - Fair Values of Assets and Liabilities (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/FairValuesOfAssetsAndLiabilitiesDetailsTextual</Role>
      <ShortName>Fair Values of Assets and Liabilities (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>0610 - Disclosure - Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/EarningsPerShareDetails</Role>
      <ShortName>Earnings Per Share (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>06101 - Disclosure - Earnings Per Share (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/EarningsPerShareDetailsTextual</Role>
      <ShortName>Earnings Per Share (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>0611 - Disclosure - Defined Benefit Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DefinedBenefitPlanDetails</Role>
      <ShortName>Defined Benefit Plan (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>06111 - Disclosure - Defined Benefit Plan (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cbtrustcorp.com/role/DefinedBenefitPlanDetailsTextual</Role>
      <ShortName>Defined Benefit Plan (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Element btc_LoansAndLeasesPercentageOfCoveredLoans had a mix of decimals attribute values: 0 2 4.</Log>
    <Log type="Info">Element btc_PercentOfNonCoveredLoans had a mix of decimals attribute values: 0 4.</Log>
    <Log type="Info">Element us-gaap_FinancingReceivableAllowanceForCreditLosses had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">'Monetary' elements on report '060310 - Disclosure - Loans Not Covered by FDIC Shared Loss Agreement (Non-Covered Loans) (Details Textual)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 0110 - Statement - Consolidated Statements of Financial Condition</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Sep. 30, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 0111 - Statement - Consolidated Statements of Financial Condition (Parenthetical)</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 0120 - Statement - Consolidated Statements of Operations (Unaudited)</Log>
    <Log type="Info">	Process Flow-Through: Removing column '12 Months Ended
Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 0130 - Statement - Consolidated Statements of Comprehensive Income (Unaudited)</Log>
    <Log type="Info">	Process Flow-Through: Removing column '12 Months Ended
Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 0150 - Statement - Consolidated Statements of Cash Flows (Unaudited)</Log>
    <Log type="Info">	Process Flow-Through: Removing column '12 Months Ended
Dec. 31, 2011'</Log>
  </Logs>
  <InputFiles>
    <File>btc-20120930.xml</File>
    <File>btc-20120930.xsd</File>
    <File>btc-20120930_cal.xml</File>
    <File>btc-20120930_def.xml</File>
    <File>btc-20120930_lab.xml</File>
    <File>btc-20120930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
