<?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>51</ContextCount>
  <ElementCount>186</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>16</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>4</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - Statements Of Consolidated Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/StatementStatementsOfConsolidatedIncome</Role>
      <ShortName>Statements Of Consolidated Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - Statements Of Consolidated Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/StatementStatementsOfConsolidatedComprehensiveIncome</Role>
      <ShortName>Statements Of Consolidated Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00305 - Statement - Statements Of Consolidated Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/StatementStatementsOfConsolidatedComprehensiveIncomeParenthetical</Role>
      <ShortName>Statements Of Consolidated Comprehensive Income (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00400 - Statement - Statements Of Consolidated Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/StatementStatementsOfConsolidatedCashFlows</Role>
      <ShortName>Statements Of Consolidated Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Principal Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosurePrincipalAccountingPolicies</Role>
      <ShortName>Principal Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Goodwill And Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureGoodwillAndIntangibleAssets</Role>
      <ShortName>Goodwill And Intangible Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureSegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Fair-Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureFairValueMeasurements</Role>
      <ShortName>Fair-Value Measurements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Employee Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureEmployeeBenefitPlans</Role>
      <ShortName>Employee Benefit Plans</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Share-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureShareBasedCompensation</Role>
      <ShortName>Share-Based Compensation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Commitments And Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments And Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>20102 - Disclosure - Principal Accounting Policies (Policy)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosurePrincipalAccountingPoliciesPolicy</Role>
      <ShortName>Principal Accounting Policies (Policy)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>30103 - Disclosure - Principal Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosurePrincipalAccountingPoliciesTables</Role>
      <ShortName>Principal Accounting Policies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Goodwill And Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureGoodwillAndIntangibleAssetsTables</Role>
      <ShortName>Goodwill And Intangible Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureSegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Fair-Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair-Value Measurements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>30503 - Disclosure - Employee Benefit Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureEmployeeBenefitPlansTables</Role>
      <ShortName>Employee Benefit Plans (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Share-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureShareBasedCompensationTables</Role>
      <ShortName>Share-Based Compensation (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Principal Accounting Policies (Calculation Of Diluted Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosurePrincipalAccountingPoliciesCalculationOfDilutedEarningsPerShareDetails</Role>
      <ShortName>Principal Accounting Policies (Calculation Of Diluted Earnings Per Share) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Goodwill And Intangible Assets (Schedule Of Changes In Gross Carrying Amounts Of Goodwill) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureGoodwillAndIntangibleAssetsScheduleOfChangesInGrossCarryingAmountsOfGoodwillDetails</Role>
      <ShortName>Goodwill And Intangible Assets (Schedule Of Changes In Gross Carrying Amounts Of Goodwill) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>40202 - Disclosure - Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureGoodwillAndIntangibleAssetsScheduleOfIntangibleAssetsDetails</Role>
      <ShortName>Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>40203 - Disclosure - Goodwill And Intangible Assets (Schedule Of Estimated Amortization Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureGoodwillAndIntangibleAssetsScheduleOfEstimatedAmortizationExpenseDetails</Role>
      <ShortName>Goodwill And Intangible Assets (Schedule Of Estimated Amortization Expense) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Segment Reporting (Operating Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureSegmentReportingOperatingIncomeLossDetails</Role>
      <ShortName>Segment Reporting (Operating Income (Loss)) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Fair-Value Measurements (Summary Of Valuation Of Financial Instruments At Fair-Value) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureFairValueMeasurementsSummaryOfValuationOfFinancialInstrumentsAtFairValueDetails</Role>
      <ShortName>Fair-Value Measurements (Summary Of Valuation Of Financial Instruments At Fair-Value) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>40402 - Disclosure - Fair-Value Measurements (Changes In Fair Value Of Auction-Rate Security) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureFairValueMeasurementsChangesInFairValueOfAuctionRateSecurityDetails</Role>
      <ShortName>Fair-Value Measurements (Changes In Fair Value Of Auction-Rate Security) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Employee Benefit Plans (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureEmployeeBenefitPlansNarrativeDetails</Role>
      <ShortName>Employee Benefit Plans (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>40502 - Disclosure - Employee Benefit Plans (Components Of Net Periodic Benefit Expense (Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureEmployeeBenefitPlansComponentsOfNetPeriodicBenefitExpenseIncomeDetails</Role>
      <ShortName>Employee Benefit Plans (Components Of Net Periodic Benefit Expense (Income) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Share-Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureShareBasedCompensationNarrativeDetails</Role>
      <ShortName>Share-Based Compensation (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>40602 - Disclosure - Share-Based Compensation (Share-Based Compensation Arrangement Expenses Recognized) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureShareBasedCompensationShareBasedCompensationArrangementExpensesRecognizedDetails</Role>
      <ShortName>Share-Based Compensation (Share-Based Compensation Arrangement Expenses Recognized) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureIncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Commitments And Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.con-way.com/2020-02-20/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments And Contingencies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">'Monetary' elements on report '40202 - Disclosure - Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40501 - Disclosure - Employee Benefit Plans (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40701 - Disclosure - Income Taxes (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 00100 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 00105 - Statement - Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 00200 - Statement - Statements Of Consolidated Income</Log>
    <Log type="Info">Process Flow-Through: 00300 - Statement - Statements Of Consolidated Comprehensive Income</Log>
    <Log type="Info">Process Flow-Through: 00305 - Statement - Statements Of Consolidated Comprehensive Income (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 00400 - Statement - Statements Of Consolidated Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>cnw-20120331.xml</File>
    <File>cnw-20120331.xsd</File>
    <File>cnw-20120331_cal.xml</File>
    <File>cnw-20120331_def.xml</File>
    <File>cnw-20120331_lab.xml</File>
    <File>cnw-20120331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
