<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.0.8</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>177</ContextCount>
  <ElementCount>295</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>59</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000100 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>010000 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>010100 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>020000 - Statement - Consolidated Statements of Operations and Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveLoss</Role>
      <ShortName>Consolidated Statements of Operations and Comprehensive Loss</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>030000 - Statement - Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/ConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>030100 - Statement - Consolidated Statements of Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/ConsolidatedStatementsOfStockholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>040000 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>060100 - Disclosure - Organization and Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>060200 - Disclosure - Accounts Receivable</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccountsReceivable</Role>
      <ShortName>Accounts Receivable</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>060300 - Disclosure - Prepaid Expenses and Other Current Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/PrepaidExpensesAndOtherCurrentAssets</Role>
      <ShortName>Prepaid Expenses and Other Current Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>060400 - Disclosure - Furniture and Fixtures, Equipment and Leasehold Improvements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/FurnitureAndFixturesEquipmentAndLeaseholdImprovements</Role>
      <ShortName>Furniture and Fixtures, Equipment and Leasehold Improvements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>060500 - Disclosure - Notes Receivable</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://getcosi.com/role/NotesReceivable</Role>
      <ShortName>Notes Receivable</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>060600 - Disclosure - Other Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OtherAssets</Role>
      <ShortName>Other Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>060700 - Disclosure - Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccruedExpenses</Role>
      <ShortName>Accrued Expenses</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>060800 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>060900 - Disclosure - Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockholdersEquity</Role>
      <ShortName>Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>061000 - Disclosure - Stock-Based Employee Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensation</Role>
      <ShortName>Stock-Based Employee Compensation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>061100 - Disclosure - Defined Contribution Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/DefinedContributionPlan</Role>
      <ShortName>Defined Contribution Plan</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>061200 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/CommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>061300 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>070100 - Disclosure - Organization and Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>080100 - Disclosure - Organization and Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>080200 - Disclosure - Accounts Receivable (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccountsReceivableTables</Role>
      <ShortName>Accounts Receivable (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>080300 - Disclosure - Prepaid Expenses and Other Current Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/PrepaidExpensesAndOtherCurrentAssetsTables</Role>
      <ShortName>Prepaid Expenses and Other Current Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>080400 - Disclosure - Furniture and Fixtures, Equipment and Leasehold Improvements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/FurnitureAndFixturesEquipmentAndLeaseholdImprovementsTables</Role>
      <ShortName>Furniture and Fixtures, Equipment and Leasehold Improvements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>080500 - Disclosure - Notes Receivable (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://getcosi.com/role/NotesReceivableTables</Role>
      <ShortName>Notes Receivable (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>080600 - Disclosure - Other Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OtherAssetsTables</Role>
      <ShortName>Other Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>080700 - Disclosure - Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccruedExpensesTables</Role>
      <ShortName>Accrued Expenses (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>080800 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>081000 - Disclosure - Stock-Based Employee Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensationTables</Role>
      <ShortName>Stock-Based Employee Compensation (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>081200 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/CommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>090100 - Disclosure - Organization and Summary of Significant Accounting Policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>090102 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails2</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>090104 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails3</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>090106 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails4</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>090108 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 5)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails5</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 5)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>090110 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 6)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails6</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 6)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>090112 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 7)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails7</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 7)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>090114 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 8)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails8</Role>
      <ShortName>Organization and Summary of Significant Accounting Policies (Details 8)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>090200 - Disclosure - Accounts Receivable (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccountsReceivableDetails</Role>
      <ShortName>Accounts Receivable (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>090202 - Disclosure - Accounts Receivable (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccountsReceivableDetails2</Role>
      <ShortName>Accounts Receivable (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>090300 - Disclosure - Prepaid Expenses and Other Current Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/PrepaidExpensesAndOtherCurrentAssetsDetails</Role>
      <ShortName>Prepaid Expenses and Other Current Assets (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>090400 - Disclosure - Furniture and Fixtures, Equipment and Leasehold Improvements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/FurnitureAndFixturesEquipmentAndLeaseholdImprovementsDetails</Role>
      <ShortName>Furniture and Fixtures, Equipment and Leasehold Improvements (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>090500 - Disclosure - Notes Receivable (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://getcosi.com/role/NotesReceivableDetails</Role>
      <ShortName>Notes Receivable (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>090600 - Disclosure - Other Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/OtherAssetsDetails</Role>
      <ShortName>Other Assets (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>090700 - Disclosure - Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/AccruedExpensesDetails</Role>
      <ShortName>Accrued Expenses (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>090800 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/IncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>090802 - Disclosure - Income Taxes (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/IncomeTaxesDetails2</Role>
      <ShortName>Income Taxes (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>090900 - Disclosure - Stockholders' Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockholdersEquityDetails</Role>
      <ShortName>Stockholders' Equity (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>091000 - Disclosure - Stock-Based Employee Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensationDetails</Role>
      <ShortName>Stock-Based Employee Compensation (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>091002 - Disclosure - Stock-Based Employee Compensation (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensationDetails2</Role>
      <ShortName>Stock-Based Employee Compensation (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>091004 - Disclosure - Stock-Based Employee Compensation (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensationDetails3</Role>
      <ShortName>Stock-Based Employee Compensation (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>091006 - Disclosure - Stock-Based Employee Compensation (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensationDetails4</Role>
      <ShortName>Stock-Based Employee Compensation (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>091008 - Disclosure - Stock-Based Employee Compensation (Details 5)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/StockbasedEmployeeCompensationDetails5</Role>
      <ShortName>Stock-Based Employee Compensation (Details 5)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>091100 - Disclosure - Defined Contribution Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/DefinedContributionPlanDetails</Role>
      <ShortName>Defined Contribution Plan (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>091200 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/CommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>091202 - Disclosure - Commitments and Contingencies (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/CommitmentsAndContingenciesDetails2</Role>
      <ShortName>Commitments and Contingencies (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>091204 - Disclosure - Commitments and Contingencies (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/CommitmentsAndContingenciesDetails3</Role>
      <ShortName>Commitments and Contingencies (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>091206 - Disclosure - Commitments and Contingencies (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/CommitmentsAndContingenciesDetails4</Role>
      <ShortName>Commitments and Contingencies (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>091300 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://getcosi.com/role/SubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (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">Element cosi_PercentageOfSalesContributedToNationalMarketingFund had a mix of decimals attribute values: 2 3.</Log>
    <Log type="Info">Element us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice had a mix of decimals attribute values: 0 2.</Log>
    <Log type="Info">Element us-gaap_StockGrantedDuringPeriodValueSharebasedCompensationForfeited had a mix of decimals attribute values: -5 -4.</Log>
    <Log type="Info">'Monetary' elements on report '090108 - Disclosure - Organization and Summary of Significant Accounting Policies (Details 5)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090200 - Disclosure - Accounts Receivable (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091004 - Disclosure - Stock-Based Employee Compensation (Details 3)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091200 - Disclosure - Commitments and Contingencies (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Shares' elements on report '091300 - Disclosure - Subsequent Events (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 010000 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jan. 02, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 27, 2010'</Log>
    <Log type="Info">Process Flow-Through: 010100 - Statement - Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'May 08, 2013'</Log>
    <Log type="Info">Process Flow-Through: 020000 - Statement - Consolidated Statements of Operations and Comprehensive Loss</Log>
    <Log type="Info">Process Flow-Through: 030100 - Statement - Consolidated Statements of Stockholders' Equity (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 040000 - Statement - Consolidated Statements of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>cosi-20131230.xml</File>
    <File>cosi-20131230.xsd</File>
    <File>cosi-20131230_cal.xml</File>
    <File>cosi-20131230_def.xml</File>
    <File>cosi-20131230_lab.xml</File>
    <File>cosi-20131230_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
