<?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>HtmlAndXml</ReportFormat>
  <ContextCount>204</ContextCount>
  <ElementCount>321</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>70</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>101 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DocumentDocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <XmlFileName>R1.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>103 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/StatementOfFinancialPositionClassified</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <XmlFileName>R2.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>104 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <XmlFileName>R3.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>105 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/StatementOfIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <XmlFileName>R4.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>106 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/StatementOfOtherComprehensiveIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <XmlFileName>R5.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>107 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/StatementOfCashFlowsIndirect</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <XmlFileName>R6.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>108 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/StatementOfCashFlowsIndirectParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)</ShortName>
      <XmlFileName>R7.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>109 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlock</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <XmlFileName>R8.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>110 - Disclosure - Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsInvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock</Role>
      <ShortName>Financial Instruments</ShortName>
      <XmlFileName>R9.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>111 - Disclosure - Fair Value Measurement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock</Role>
      <ShortName>Fair Value Measurement</ShortName>
      <XmlFileName>R10.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>112 - Disclosure - Goodwill and Other Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsGoodwillAndIntangibleAssetsDisclosureTextBlock</Role>
      <ShortName>Goodwill and Other Intangible Assets</ShortName>
      <XmlFileName>R11.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>113 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <XmlFileName>R12.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>114 - Disclosure - Wind-Down Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsRestructuringAndRelatedActivitiesDisclosureTextBlock</Role>
      <ShortName>Wind-Down Expenses</ShortName>
      <XmlFileName>R13.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>115 - Disclosure - Loan Payable</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</Role>
      <ShortName>Loan Payable</ShortName>
      <XmlFileName>R14.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>116 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <XmlFileName>R15.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>117 - Disclosure - Warrant Liability</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsWarrantLiabilityTextBlock</Role>
      <ShortName>Warrant Liability</ShortName>
      <XmlFileName>R16.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>118 - Disclosure - Common Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock</Role>
      <ShortName>Common Stock</ShortName>
      <XmlFileName>R17.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>119 - Disclosure - Accumulated Other Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsAccumulatedOtherComprehensiveIncomeLossTextBlock</Role>
      <ShortName>Accumulated Other Comprehensive Loss</ShortName>
      <XmlFileName>R18.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>120 - Disclosure - California Institute for Regenerative Medicine Loan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsCollaborativeArrangementDisclosureTextBlock</Role>
      <ShortName>California Institute for Regenerative Medicine Loan</ShortName>
      <XmlFileName>R19.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>121 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsSubsequentEventsTextBlock</Role>
      <ShortName>Subsequent Events</ShortName>
      <XmlFileName>R20.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>122 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlockPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <XmlFileName>R21.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>123 - Disclosure - Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlockTables</Role>
      <ShortName>Summary of Significant Accounting Policies (Tables)</ShortName>
      <XmlFileName>R22.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>124 - Disclosure - Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsInvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlockTables</Role>
      <ShortName>Financial Instruments (Tables)</ShortName>
      <XmlFileName>R23.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>125 - Disclosure - Fair Value Measurement (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</Role>
      <ShortName>Fair Value Measurement (Tables)</ShortName>
      <XmlFileName>R24.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>126 - Disclosure - Goodwill and Other Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsGoodwillAndIntangibleAssetsDisclosureTextBlockTables</Role>
      <ShortName>Goodwill and Other Intangible Assets (Tables)</ShortName>
      <XmlFileName>R25.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>127 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <XmlFileName>R26.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>128 - Disclosure - Wind-Down Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsRestructuringAndRelatedActivitiesDisclosureTextBlockTables</Role>
      <ShortName>Wind-Down Expenses (Tables)</ShortName>
      <XmlFileName>R27.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>129 - Disclosure - Loan Payable (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</Role>
      <ShortName>Loan Payable (Tables)</ShortName>
      <XmlFileName>R28.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>130 - Disclosure - Warrant Liability (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsWarrantLiabilityTextBlockTables</Role>
      <ShortName>Warrant Liability (Tables)</ShortName>
      <XmlFileName>R29.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>131 - Disclosure - Accumulated Other Comprehensive Loss (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/NotesToFinancialStatementsAccumulatedOtherComprehensiveIncomeLossTextBlockTables</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Tables)</ShortName>
      <XmlFileName>R30.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>132 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformation</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <XmlFileName>R31.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>133 - Disclosure - Summary of Significant Accounting Policies - Basic and Dilutive Net loss Per Share Computations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesBasicAndDilutiveNetLossPerShareComputations</Role>
      <ShortName>Summary of Significant Accounting Policies - Basic and Dilutive Net loss Per Share Computations (Detail)</ShortName>
      <XmlFileName>R32.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>134 - Disclosure - Summary of Significant Accounting Policies - Outstanding Options, Warrants and Restricted Stock Units (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesOutstandingOptionsWarrantsAndRestrictedStockUnits</Role>
      <ShortName>Summary of Significant Accounting Policies - Outstanding Options, Warrants and Restricted Stock Units (Detail)</ShortName>
      <XmlFileName>R33.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>135 - Disclosure - Financial Instruments - Available for Sale Securities Held in Investment Portfolio (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureFinancialInstrumentsAvailableForSaleSecuritiesHeldInInvestmentPortfolio</Role>
      <ShortName>Financial Instruments - Available for Sale Securities Held in Investment Portfolio (Detail)</ShortName>
      <XmlFileName>R34.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>136 - Disclosure - Financial Instruments - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureFinancialInstrumentsAdditionalInformation</Role>
      <ShortName>Financial Instruments - Additional Information (Detail)</ShortName>
      <XmlFileName>R35.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>137 - Disclosure - Fair Value Measurement - Financial Assets and Liabilities Measured at Fair Value (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureFairValueMeasurementFinancialAssetsAndLiabilitiesMeasuredAtFairValue</Role>
      <ShortName>Fair Value Measurement - Financial Assets and Liabilities Measured at Fair Value (Detail)</ShortName>
      <XmlFileName>R36.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>138 - Disclosure - Fair Value Measurement - Roll Forward for Financial Assets and Liabilities Measured at Fair Value Using Significant Other Observable Inputs (Level 2) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureFairValueMeasurementRollForwardForFinancialAssetsAndLiabilitiesMeasuredAtFairValueUsingSignificantOtherObservableInputsLevel2</Role>
      <ShortName>Fair Value Measurement - Roll Forward for Financial Assets and Liabilities Measured at Fair Value Using Significant Other Observable Inputs (Level 2) (Detail)</ShortName>
      <XmlFileName>R37.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>139 - Disclosure - Fair Value Measurement - Roll Forward for Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureFairValueMeasurementRollForwardForLiabilitiesMeasuredAtFairValueUsingSignificantUnobservableInputsLevel3</Role>
      <ShortName>Fair Value Measurement - Roll Forward for Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Detail)</ShortName>
      <XmlFileName>R38.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>140 - Disclosure - Goodwill and Other Intangible Assets - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsAdditionalInformation</Role>
      <ShortName>Goodwill and Other Intangible Assets - Additional Information (Detail)</ShortName>
      <XmlFileName>R39.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>141 - Disclosure - Goodwill and Other Intangible Assets - Purchase Price Allocated (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsPurchasePriceAllocated</Role>
      <ShortName>Goodwill and Other Intangible Assets - Purchase Price Allocated (Detail)</ShortName>
      <XmlFileName>R40.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>142 - Disclosure - Goodwill and Other Intangible Assets - Changes in Goodwill (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsChangesInGoodwill</Role>
      <ShortName>Goodwill and Other Intangible Assets - Changes in Goodwill (Detail)</ShortName>
      <XmlFileName>R41.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>143 - Disclosure - Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsComponentsOfOtherIntangibleAssets</Role>
      <ShortName>Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail)</ShortName>
      <XmlFileName>R42.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>144 - Disclosure - Goodwill and Other Intangible Assets - Expected Future Annual Amortization Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsExpectedFutureAnnualAmortizationExpense</Role>
      <ShortName>Goodwill and Other Intangible Assets - Expected Future Annual Amortization Expense (Detail)</ShortName>
      <XmlFileName>R43.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>145 - Disclosure - Stock-Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformation</Role>
      <ShortName>Stock-Based Compensation - Additional Information (Detail)</ShortName>
      <XmlFileName>R44.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>146 - Disclosure - Stock-Based Compensation - Stock-Based Compensation Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationStockBasedCompensationExpense</Role>
      <ShortName>Stock-Based Compensation - Stock-Based Compensation Expense (Detail)</ShortName>
      <XmlFileName>R45.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>147 - Disclosure - Stock-Based Compensation - Stock Option Activity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationStockOptionActivity</Role>
      <ShortName>Stock-Based Compensation - Stock Option Activity (Detail)</ShortName>
      <XmlFileName>R46.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>148 - Disclosure - Stock-Based Compensation - Summary of Changes in Unvested Options (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationSummaryOfChangesInUnvestedOptions</Role>
      <ShortName>Stock-Based Compensation - Summary of Changes in Unvested Options (Detail)</ShortName>
      <XmlFileName>R47.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>149 - Disclosure - Stock-Based Compensation - Summary of Changes in Unvested Restricted Stock Units (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationSummaryOfChangesInUnvestedRestrictedStockUnits</Role>
      <ShortName>Stock-Based Compensation - Summary of Changes in Unvested Restricted Stock Units (Detail)</ShortName>
      <XmlFileName>R48.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>150 - Disclosure - Stock-Based Compensation - Summary of Changes in Unvested Restricted Stock Units (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationSummaryOfChangesInUnvestedRestrictedStockUnitsParenthetical</Role>
      <ShortName>Stock-Based Compensation - Summary of Changes in Unvested Restricted Stock Units (Parenthetical) (Detail)</ShortName>
      <XmlFileName>R49.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>151 - Disclosure - Stock-Based Compensation - Summary of Changes in SARs (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureStockBasedCompensationSummaryOfChangesInSARs</Role>
      <ShortName>Stock-Based Compensation - Summary of Changes in SARs (Detail)</ShortName>
      <XmlFileName>R50.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>152 - Disclosure - Wind-Down Expenses - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWindDownExpensesAdditionalInformation</Role>
      <ShortName>Wind-Down Expenses - Additional Information (Detail)</ShortName>
      <XmlFileName>R51.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>153 - Disclosure - Wind-Down Expenses - Summary of Changes to Wind-Down Reserve (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWindDownExpensesSummaryOfChangesToWindDownReserve</Role>
      <ShortName>Wind-Down Expenses - Summary of Changes to Wind-Down Reserve (Detail)</ShortName>
      <XmlFileName>R52.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>154 - Disclosure - Loan Payable - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureLoanPayableAdditionalInformation</Role>
      <ShortName>Loan Payable - Additional Information (Detail)</ShortName>
      <XmlFileName>R53.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>155 - Disclosure - Disclosure - Loan Payable - Assumptions used for Black-Scholes Option Pricing Model (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureDisclosureLoanPayableAssumptionsUsedForBlackScholesOptionPricingModel</Role>
      <ShortName>Disclosure - Loan Payable - Assumptions used for Black-Scholes Option Pricing Model (Detail)</ShortName>
      <XmlFileName>R54.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>156 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformation</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <XmlFileName>R55.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>157 - Disclosure - Warrant Liability - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWarrantLiabilityAdditionalInformation</Role>
      <ShortName>Warrant Liability - Additional Information (Detail)</ShortName>
      <XmlFileName>R56.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>158 - Disclosure - Warrant Liability - Assumptions used for Black-Scholes Option Pricing Model (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWarrantLiabilityAssumptionsUsedForBlackScholesOptionPricingModel</Role>
      <ShortName>Warrant Liability - Assumptions used for Black-Scholes Option Pricing Model (Detail)</ShortName>
      <XmlFileName>R57.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>159 - Disclosure - Warrant Liability - Assumptions used for Black-Scholes Option Pricing Model1 (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWarrantLiabilityAssumptionsUsedForBlackScholesOptionPricingModel1</Role>
      <ShortName>Warrant Liability - Assumptions used for Black-Scholes Option Pricing Model1 (Detail)</ShortName>
      <XmlFileName>R58.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>160 - Disclosure - Warrant Liability - Assumptions used for Monte Carlo Simulation Model (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWarrantLiabilityAssumptionsUsedForMonteCarloSimulationModel</Role>
      <ShortName>Warrant Liability - Assumptions used for Monte Carlo Simulation Model (Detail)</ShortName>
      <XmlFileName>R59.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>161 - Disclosure - Warrant Liability - Summary of Changes in Fair Value of Warrant Liability (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWarrantLiabilitySummaryOfChangesInFairValueOfWarrantLiability</Role>
      <ShortName>Warrant Liability - Summary of Changes in Fair Value of Warrant Liability (Detail)</ShortName>
      <XmlFileName>R60.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>162 - Disclosure - Warrant Liability - Summary of Outstanding Warrants and Fair Value of Warrant Liability (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureWarrantLiabilitySummaryOfOutstandingWarrantsAndFairValueOfWarrantLiability</Role>
      <ShortName>Warrant Liability - Summary of Outstanding Warrants and Fair Value of Warrant Liability (Detail)</ShortName>
      <XmlFileName>R61.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>163 - Disclosure - Common Stock - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureCommonStockAdditionalInformation</Role>
      <ShortName>Common Stock - Additional Information (Detail)</ShortName>
      <XmlFileName>R62.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>164 - Disclosure - Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive Loss by Component (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureAccumulatedOtherComprehensiveLossSummaryOfChangesInAccumulatedOtherComprehensiveLossByComponent</Role>
      <ShortName>Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive Loss by Component (Detail)</ShortName>
      <XmlFileName>R63.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>165 - Disclosure - California Institute for Regenerative Medicine Loan - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureCaliforniaInstituteForRegenerativeMedicineLoanAdditionalInformation</Role>
      <ShortName>California Institute for Regenerative Medicine Loan - Additional Information (Detail)</ShortName>
      <XmlFileName>R64.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>166 - Disclosure - Subsequent Events - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://stemcellsinc.com/taxonomy/role/DisclosureSubsequentEventsAdditionalInformation</Role>
      <ShortName>Subsequent Events - Additional Information (Detail)</ShortName>
      <XmlFileName>R65.xml</XmlFileName>
    </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 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights had a mix of decimals attribute values: 2 4.</Log>
    <Log type="Info">Element us-gaap_ProceedsFromIssuanceOfCommonStock had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">'Monetary' elements on report '163 - Disclosure - Common Stock - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 103 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 104 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 105 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</Log>
    <Log type="Info">Process Flow-Through: 106 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</Log>
    <Log type="Info">Process Flow-Through: 107 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</Log>
    <Log type="Info">Process Flow-Through: 108 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)</Log>
  </Logs>
  <InputFiles>
    <File>stem-20130630.xml</File>
    <File>stem-20130630.xsd</File>
    <File>stem-20130630_cal.xml</File>
    <File>stem-20130630_def.xml</File>
    <File>stem-20130630_lab.xml</File>
    <File>stem-20130630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
