<?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>140</ContextCount>
  <ElementCount>230</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>41</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/BalanceSheet</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0015 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/BalanceSheetParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0020 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/StatementOfIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/CashFlows</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1010 - Disclosure - The Company and Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureTheCompanyAndSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>The Company and Summary of Significant Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1020 - Disclosure - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureFairValueOfFinancialInstruments</Role>
      <ShortName>Fair Value of Financial Instruments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1030 - Disclosure - Sale of I/O Technology</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureSaleOfIOTechnology</Role>
      <ShortName>Sale of I/O Technology</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>1040 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>1050 - Disclosure - Business Segments and Significant Customers</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureBusinessSegmentsAndSignificantCustomers</Role>
      <ShortName>Business Segments and Significant Customers</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>1060 - Disclosure - Income Tax Provision</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureIncomeTaxProvision</Role>
      <ShortName>Income Tax Provision</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>1070 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>1080 - Disclosure - Stockholder's Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockholdersEquity</Role>
      <ShortName>Stockholder's Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>1090 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2010 - Disclosure - The Company and Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureTheCompanyAndSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>The Company and Summary of Significant Accounting Policies (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>3010 - Disclosure - The Company and Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureTheCompanyAndSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>The Company and Summary of Significant Accounting Policies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>3020 - Disclosure - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureFairValueOfFinancialInstrumentsTables</Role>
      <ShortName>Fair Value of Financial Instruments (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>3050 - Disclosure - Business Segments and Significant Customers (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureBusinessSegmentsAndSignificantCustomersTables</Role>
      <ShortName>Business Segments and Significant Customers (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>3070 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>4010 - Disclosure - The Company and Summary of Significant Accounting Policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureTheCompanyAndSummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>The Company and Summary of Significant Accounting Policies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>4011 - Disclosure - The Company and Summary of Significant Accounting Policies (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureTheCompanyAndSummaryOfSignificantAccountingPoliciesDetails2</Role>
      <ShortName>The Company and Summary of Significant Accounting Policies (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>4020 - Disclosure - Fair Value of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureFairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>4021 - Disclosure - Fair Value of Financial Instruments (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureFairValueOfFinancialInstrumentsDetails2</Role>
      <ShortName>Fair Value of Financial Instruments (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>4022 - Disclosure - Fair Value of Financial Instruments (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureFairValueOfFinancialInstrumentsDetails3</Role>
      <ShortName>Fair Value of Financial Instruments (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>4030 - Disclosure - Sale of I/O Technology (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureSaleOfIOTechnologyDetails</Role>
      <ShortName>Sale of I/O Technology (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>4040 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>4050 - Disclosure - Business Segments and Significant Customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureBusinessSegmentsAndSignificantCustomersDetails</Role>
      <ShortName>Business Segments and Significant Customers (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>4051 - Disclosure - Business Segments and Significant Customers (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureBusinessSegmentsAndSignificantCustomersDetails2</Role>
      <ShortName>Business Segments and Significant Customers (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>4070 - Disclosure - Stock-Based Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockBasedCompensationDetails</Role>
      <ShortName>Stock-Based Compensation (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>4071 - Disclosure - Stock-Based Compensation (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockBasedCompensationDetails2</Role>
      <ShortName>Stock-Based Compensation (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>4072 - Disclosure - Stock-Based Compensation (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockBasedCompensationDetails3</Role>
      <ShortName>Stock-Based Compensation (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>4080 - Disclosure - Stockholder's Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureStockholdersEquityDetails</Role>
      <ShortName>Stockholder's Equity (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>4090 - Disclosure - Related Party Transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.mosys.com/role/DisclosureRelatedPartyTransactionsDetails</Role>
      <ShortName>Related Party Transactions (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 mosy_SignificantAcquisitionsAndDisposalsAmountOfHoldBack had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">'Monetary' elements on report '4011 - Disclosure - The Company and Summary of Significant Accounting Policies (Details 2)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '4030 - Disclosure - Sale of I/O Technology (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '4070 - Disclosure - Stock-Based Compensation (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Shares' elements on report '4072 - Disclosure - Stock-Based Compensation (Details 3)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '4072 - Disclosure - Stock-Based Compensation (Details 3)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Shares' elements on report '4080 - Disclosure - Stockholder's Equity (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 0010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Sep. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 0015 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 0020 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</Log>
    <Log type="Info">Process Flow-Through: 0030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</Log>
  </Logs>
  <InputFiles>
    <File>mosy-20130930.xml</File>
    <File>mosy-20130930.xsd</File>
    <File>mosy-20130930_cal.xml</File>
    <File>mosy-20130930_def.xml</File>
    <File>mosy-20130930_lab.xml</File>
    <File>mosy-20130930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
