<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>153</ContextCount>
  <ElementCount>318</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>35</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Cover Page</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/CoverPage</Role>
      <ShortName>Cover Page</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedBalanceSheets</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1001501 - Statement - Unaudited Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Unaudited Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1002000 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedStatementsOfIncome</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003000 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1004000 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERSEQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedStatementsOfStockholdersequity</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERSEQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1004501 - Statement - Unaudited Condensed Consolidated Statements of Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedStatementsOfStockholdersEquityParenthetical</Role>
      <ShortName>Unaudited Condensed Consolidated Statements of Stockholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1005000 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/UnauditedCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Nature of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/NatureOfOperations</Role>
      <ShortName>Nature of Operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPolicies</Role>
      <ShortName>Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - Revenue Recognition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RevenueRecognition</Role>
      <ShortName>Revenue Recognition</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - Restructuring and Related Charges</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RestructuringAndRelatedCharges</Role>
      <ShortName>Restructuring and Related Charges</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2105100 - Disclosure - Marketable Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/MarketableSecurities</Role>
      <ShortName>Marketable Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - Fair Value Measurement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/FairValueMeasurement</Role>
      <ShortName>Fair Value Measurement</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2107100 - Disclosure - Accounts Payable and Accrued Expenses Accounts Payable and Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/AccountsPayableAndAccruedExpensesAccountsPayableAndAccruedExpenses</Role>
      <ShortName>Accounts Payable and Accrued Expenses Accounts Payable and Accrued Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2108100 - Disclosure - Long-Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/LongTermDebt</Role>
      <ShortName>Long-Term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Other Long-Term Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherLongTermLiabilities</Role>
      <ShortName>Other Long-Term Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - Equity Awards</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/EquityAwards</Role>
      <ShortName>Equity Awards</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2112100 - Disclosure - Other Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherInvestments</Role>
      <ShortName>Other Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2113100 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2114100 - Disclosure - Litigation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/Litigation</Role>
      <ShortName>Litigation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2115100 - Disclosure - Regulation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/Regulation</Role>
      <ShortName>Regulation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2202201 - Disclosure - Significant Accounting Policies  (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesPolicies</Role>
      <ShortName>Significant Accounting Policies  (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/SignificantAccountingPolicies</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2302302 - Disclosure - Significant Accounting Policies  (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesTables</Role>
      <ShortName>Significant Accounting Policies  (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/SignificantAccountingPolicies</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2303301 - Disclosure - Revenue Recognition (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RevenueRecognitionTables</Role>
      <ShortName>Revenue Recognition (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/RevenueRecognition</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2304301 - Disclosure - Restructuring and Related Charges (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RestructuringAndRelatedChargesTables</Role>
      <ShortName>Restructuring and Related Charges (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/RestructuringAndRelatedCharges</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2305301 - Disclosure - Marketable Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/MarketableSecuritiesTables</Role>
      <ShortName>Marketable Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/MarketableSecurities</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2306301 - Disclosure - Fair Value Measurement (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/FairValueMeasurementTables</Role>
      <ShortName>Fair Value Measurement (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/FairValueMeasurement</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2307301 - Disclosure - Accounts Payable and Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/AccountsPayableAndAccruedExpensesTables</Role>
      <ShortName>Accounts Payable and Accrued Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/AccountsPayableAndAccruedExpensesAccountsPayableAndAccruedExpenses</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2309301 - Disclosure - Other Long-Term Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherLongTermLiabilitiesTables</Role>
      <ShortName>Other Long-Term Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/OtherLongTermLiabilities</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2310301 - Disclosure - Equity Awards (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/EquityAwardsTables</Role>
      <ShortName>Equity Awards (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/EquityAwards</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2312301 - Disclosure - Other Investments Other Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherInvestmentsOtherInvestmentsTables</Role>
      <ShortName>Other Investments Other Investments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2313301 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/SegmentReporting</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2401401 - Disclosure - Nature of Operations  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/NatureOfOperationsAdditionalInformationDetails</Role>
      <ShortName>Nature of Operations  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2402403 - Disclosure - Significant Accounting Policies  - Impact of Adoption on Balance Sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesImpactOfAdoptionOnBalanceSheetDetails</Role>
      <ShortName>Significant Accounting Policies  - Impact of Adoption on Balance Sheet (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2402404 - Disclosure - Significant Accounting Policies  - Restricted Cash (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesRestrictedCashDetails</Role>
      <ShortName>Significant Accounting Policies  - Restricted Cash (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2402405 - Disclosure - Significant Accounting Policies  - Tuition Receivable (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesTuitionReceivableDetails</Role>
      <ShortName>Significant Accounting Policies  - Tuition Receivable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2402406 - Disclosure - Significant Accounting Policies  - Doubtful Accounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesDoubtfulAccountsDetails</Role>
      <ShortName>Significant Accounting Policies  - Doubtful Accounts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2402407 - Disclosure - Significant Accounting Policies  - Net Income (Loss) Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesNetIncomeLossPerShareDetails</Role>
      <ShortName>Significant Accounting Policies  - Net Income (Loss) Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2402408 - Disclosure - Significant Accounting Policies  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SignificantAccountingPoliciesAdditionalInformationDetails</Role>
      <ShortName>Significant Accounting Policies  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2403402 - Disclosure - Revenue Recognition  - Disaggregation of Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RevenueRecognitionDisaggregationOfRevenueDetails</Role>
      <ShortName>Revenue Recognition  - Disaggregation of Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2403403 - Disclosure - Revenue Recognition  - Graduation Fund (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RevenueRecognitionGraduationFundDetails</Role>
      <ShortName>Revenue Recognition  - Graduation Fund (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2403404 - Disclosure - Revenue Recognition  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RevenueRecognitionAdditionalInformationDetails</Role>
      <ShortName>Revenue Recognition  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2404402 - Disclosure - Restructuring and Related Charges  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RestructuringAndRelatedChargesAdditionalInformationDetails</Role>
      <ShortName>Restructuring and Related Charges  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2404403 - Disclosure - Restructuring and Related Charges  - Restructuring liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RestructuringAndRelatedChargesRestructuringLiabilityDetails</Role>
      <ShortName>Restructuring and Related Charges  - Restructuring liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2405402 - Disclosure - Marketable Securities  - Available-For-Sale Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/MarketableSecuritiesAvailableForSaleSecuritiesDetails</Role>
      <ShortName>Marketable Securities  - Available-For-Sale Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2405403 - Disclosure - Marketable Securities  - Maturities of Marketable Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/MarketableSecuritiesMaturitiesOfMarketableSecuritiesDetails</Role>
      <ShortName>Marketable Securities  - Maturities of Marketable Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2405404 - Disclosure - Marketable Securities  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/MarketableSecuritiesAdditionalInformationDetails</Role>
      <ShortName>Marketable Securities  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/FairValueMeasurementAssetsAndLiabilitiesMeasuredAtFairValueDetails</Role>
      <ShortName>Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2406403 - Disclosure - Fair Value Measurement  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/FairValueMeasurementAdditionalInformationDetails</Role>
      <ShortName>Fair Value Measurement  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2406404 - Disclosure - Fair Value Measurement  - Change in Fair Value of Level 3 Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/FairValueMeasurementChangeInFairValueOfLevel3LiabilityDetails</Role>
      <ShortName>Fair Value Measurement  - Change in Fair Value of Level 3 Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2407402 - Disclosure - Accounts Payable and Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/AccountsPayableAndAccruedExpensesDetails</Role>
      <ShortName>Accounts Payable and Accrued Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/AccountsPayableAndAccruedExpensesTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2408401 - Disclosure - Long-Term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/LongTermDebtDetails</Role>
      <ShortName>Long-Term Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/LongTermDebt</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2409402 - Disclosure - Other Long-Term Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherLongTermLiabilitiesDetails</Role>
      <ShortName>Other Long-Term Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/OtherLongTermLiabilitiesTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - Other Long-Term Liabilities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherLongTermLiabilitiesAdditionalInformationDetails</Role>
      <ShortName>Other Long-Term Liabilities - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2410402 - Disclosure - Equity Awards  - Stock-based compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/EquityAwardsStockBasedCompensationDetails</Role>
      <ShortName>Equity Awards  - Stock-based compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2410403 - Disclosure - Equity Awards  - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/EquityAwardsAdditionalInformationDetails</Role>
      <ShortName>Equity Awards  - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2411401 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/IncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/IncomeTaxes</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2412402 - Disclosure - Other Investments - Equity Method Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/OtherInvestmentsEquityMethodInvestmentsDetails</Role>
      <ShortName>Other Investments - Equity Method Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2413402 - Disclosure - Segment Reporting - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SegmentReportingAdditionalInformationDetails</Role>
      <ShortName>Segment Reporting - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2413403 - Disclosure - Segment Reporting - Financial Information by Reportable Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/SegmentReportingFinancialInformationByReportableSegmentDetails</Role>
      <ShortName>Segment Reporting - Financial Information by Reportable Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="stra-20200331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2415401 - Disclosure - Regulation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.strategiceducation.com/role/RegulationDetails</Role>
      <ShortName>Regulation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.strategiceducation.com/role/Regulation</ParentRole>
      <Position>63</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" original="stra-20200331x10q.htm">stra-20200331x10q.htm</File>
    <File>stra-20200331.xsd</File>
    <File>stra-20200331_cal.xml</File>
    <File>stra-20200331_def.xml</File>
    <File>stra-20200331_lab.xml</File>
    <File>stra-20200331_pre.xml</File>
    <File>stra-20200331xex311.htm</File>
    <File>stra-20200331xex312.htm</File>
    <File>stra-20200331xex321.htm</File>
    <File>stra-20200331xex322.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/us-gaap/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
