<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.3</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>287</ContextCount>
  <ElementCount>307</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>53</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/StatementCondensedConsolidatedStatementsOfChangesInStockholdersEquityUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Nature of Organization and Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureNatureOfOrganizationAndOperations</Role>
      <ShortName>Nature of Organization and Operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPolicies1</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureProductRevenuesAccountsReceivableAndReservesForProductSales</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Inventory</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureInventory</Role>
      <ShortName>Inventory</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Prepaid and Other Current Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosurePrepaidAndOtherCurrentAssets</Role>
      <ShortName>Prepaid and Other Current Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Development Liability</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureDevelopmentLiability1</Role>
      <ShortName>Development Liability</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureAccruedExpenses</Role>
      <ShortName>Accrued Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Long-term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLongTermDebt</Role>
      <ShortName>Long-term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995585 - Disclosure - License and Collaboration Agreements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLicenseAndCollaborationAgreements</Role>
      <ShortName>License and Collaboration Agreements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Net Loss per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureNetLossPerShare</Role>
      <ShortName>Net Loss per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPolicies1</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureProductRevenuesAccountsReceivableAndReservesForProductSalesTables</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureProductRevenuesAccountsReceivableAndReservesForProductSales</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Inventory (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureInventoryTables</Role>
      <ShortName>Inventory (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureInventory</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Prepaid and Other Current Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosurePrepaidAndOtherCurrentAssetsTables</Role>
      <ShortName>Prepaid and Other Current Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/DisclosurePrepaidAndOtherCurrentAssets</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Development Liability (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureDevelopmentLiabilityTables</Role>
      <ShortName>Development Liability (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/DisclosureDevelopmentLiability1</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureAccruedExpensesTables</Role>
      <ShortName>Accrued Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/DisclosureAccruedExpenses</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Long-term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureLongtermDebtTables</Role>
      <ShortName>Long-term Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLongTermDebt</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeases</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureFairValueMeasurements</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Net Loss per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureNetLossPerShareTables</Role>
      <ShortName>Net Loss per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureNetLossPerShare</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995745 - Disclosure - Nature of Organization and Operations - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureNatureOfOrganizationAndOperationsAdditionalInformationDetail</Role>
      <ShortName>Nature of Organization and Operations - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureProductRevenuesAccountsReceivableAndReservesForProductSalesAdditionalInformationDetail</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995775 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Disaggregation of Product Revenue by Major Source (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureProductRevenuesAccountsReceivableAndReservesForProductSalesScheduleOfDisaggregationOfProductRevenueByMajorSourceDetail</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Disaggregation of Product Revenue by Major Source (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995785 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales - Summary of Product Revenue Allowance and Reserve Categories (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureProductRevenuesAccountsReceivableAndReservesForProductSalesSummaryOfProductRevenueAllowanceAndReserveCategoriesDetail</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales - Summary of Product Revenue Allowance and Reserve Categories (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Customer Accounted for 10% of More of Gross Product Revenues and Accounts Receivable (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureProductRevenuesAccountsReceivableAndReservesForProductSalesScheduleOfCustomerAccountedFor10OfMoreOfGrossProductRevenuesAndAcc</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Customer Accounted for 10% of More of Gross Product Revenues and Accounts Receivable (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Factoring of Accounts Receivable and Associated Fees (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureProductRevenuesAccountsReceivableAndReservesForProductSalesScheduleOfFactoringOfAccountsReceivableAndAssociatedFeesDetails</Role>
      <ShortName>Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Factoring of Accounts Receivable and Associated Fees (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Inventory - Schedule of Inventory (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureInventoryScheduleOfInventoryDetail</Role>
      <ShortName>Inventory - Schedule of Inventory (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995835 - Disclosure - Inventory - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureInventoryAdditionalInformationDetail</Role>
      <ShortName>Inventory - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995865 - Disclosure - Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosurePrepaidAndOtherCurrentAssetsSummaryOfPrepaidAndOtherCurrentAssetsDetail</Role>
      <ShortName>Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995875 - Disclosure - Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosurePrepaidAndOtherCurrentAssetsSummaryOfPrepaidAndOtherCurrentAssetsParentheticalDetail</Role>
      <ShortName>Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995885 - Disclosure - Development Liability - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureDevelopmentLiabilityAdditionalInformationDetail</Role>
      <ShortName>Development Liability - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995895 - Disclosure - Development Liability - Summary of Development Liability (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureDevelopmentLiabilitySummaryOfDevelopmentLiabilityDetail</Role>
      <ShortName>Development Liability - Summary of Development Liability (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995925 - Disclosure - Accrued Expenses - Schedule of Accrued Expenses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureAccruedExpensesScheduleOfAccruedExpensesDetail</Role>
      <ShortName>Accrued Expenses - Schedule of Accrued Expenses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995935 - Disclosure - Long-term Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLongTermDebtAdditionalInformationDetail</Role>
      <ShortName>Long-term Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995945 - Disclosure - Long-term Debt - Financing Agreement and Credit Facility (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureLongtermDebtFinancingAgreementAndCreditFacilityAdditionalInformationDetails</Role>
      <ShortName>Long-term Debt - Financing Agreement and Credit Facility (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995955 - Disclosure - Long-term Debt - Schedule of Outstanding Balance of Convertible Notes (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureLongtermDebtScheduleOfOutstandingBalanceOfConvertibleNotesDetail</Role>
      <ShortName>Long-term Debt - Schedule of Outstanding Balance of Convertible Notes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995965 - Disclosure - Long-term Debt - Schedule of Interest Expense Recognized Related to Convertible Notes (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureLongtermDebtScheduleOfInterestExpenseRecognizedRelatedToConvertibleNotesDetail</Role>
      <ShortName>Long-term Debt - Schedule of Interest Expense Recognized Related to Convertible Notes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995975 - Disclosure - Long-term Debt - Summary of Credit Facility (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureLongtermDebtSummaryOfCreditFacilityDetail</Role>
      <ShortName>Long-term Debt - Summary of Credit Facility (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995985 - Disclosure - Long Term Debt - Summary of Interest Expense Recognized Related to Credit Facility (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureLongTermDebtSummaryOfInterestExpenseRecognizedRelatedToCreditFacilityDetail</Role>
      <ShortName>Long Term Debt - Summary of Interest Expense Recognized Related to Credit Facility (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995995 - Disclosure - Leases - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeasesAdditionalInformationDetail</Role>
      <ShortName>Leases - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>996005 - Disclosure - Leases - Schedule of Additional Information Related to Operating Lease Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeasesScheduleOfAdditionalInformationRelatedToOperatingLeaseAssetsAndLiabilitiesDetail</Role>
      <ShortName>Leases - Schedule of Additional Information Related to Operating Lease Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>996015 - Disclosure - Leases - Supplemental Cash Flow Information Related to Operating Leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeasesSupplementalCashFlowInformationRelatedToOperatingLeasesDetail</Role>
      <ShortName>Leases - Supplemental Cash Flow Information Related to Operating Leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>996025 - Disclosure - Leases - Maturities of Operating Lease Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLeasesMaturitiesOfOperatingLeaseLiabilitiesDetail</Role>
      <ShortName>Leases - Maturities of Operating Lease Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>996045 - Disclosure - Other Comprehensive Income and Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Other Comprehensive Income/(Loss), by Component (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeAndAccumulatedOtherComprehensiveIncomeSummaryOfChangesInAccumulatedOtherComprehensiveIncomeLossByComponentDetail</Role>
      <ShortName>Other Comprehensive Income and Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Other Comprehensive Income/(Loss), by Component (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>996055 - Disclosure - Fair Value Measurements - Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfFinancialInstrumentsAndRelatedFairValueHierarchyOfValuationTechniquesUtilizedDetail</Role>
      <ShortName>Fair Value Measurements - Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>996075 - Disclosure - Fair Value Measurements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureFairValueMeasurementsAdditionalInformationDetail</Role>
      <ShortName>Fair Value Measurements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>996085 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>996095 - Disclosure - License and Collaboration Agreements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail</Role>
      <ShortName>License and Collaboration Agreements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>996105 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="apls-20240930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>996115 - Disclosure - Net Loss per Share - Summary of Potential Common Shares that were Excluded from Calculation of Diluted Net Loss Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.apellis.com/20240930/taxonomy/role/DisclosureNetLossPerShareSummaryOfPotentialCommonSharesThatWereExcludedFromCalculationOfDilutedNetLossPerShareDetail</Role>
      <ShortName>Net Loss per Share - Summary of Potential Common Shares that were Excluded from Calculation of Diluted Net Loss Per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <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" isDefinitelyFs="true" isUsgaap="true" original="apls-20240930.htm">apls-20240930.htm</File>
    <File>apls-20240930.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="552">http://fasb.org/us-gaap/2024</BaseTaxonomy>
    <BaseTaxonomy items="29">http://xbrl.sec.gov/dei/2024</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2024</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
