<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>93</ContextCount>
  <ElementCount>63</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>24</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>3</UnitCount>
  <MyReports>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fidelity.com/role/DocumentInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000002 - Disclosure - Risk/Return Detail Data - FidelityMagellanFund-RetailPRO</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fidelity.com/role/DisclosureDetailS000007112_FidelityMagellanFund-RetailPRO</Role>
      <ShortName>Risk/Return Detail Data - FidelityMagellanFund-RetailPRO</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>000004 - Disclosure - Risk/Return Detail Data - FidelityMagellanFund-KPRO</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fidelity.com/role/DisclosureDetailS000007112_FidelityMagellanFund-KPRO</Role>
      <ShortName>Risk/Return Detail Data - FidelityMagellanFund-KPRO</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>000006 - Disclosure - Risk/Return Detail Data - FidelityMagellanFund-AMCIZPRO</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fidelity.com/role/DisclosureDetailS000007112_FidelityMagellanFund-AMCIZPRO</Role>
      <ShortName>Risk/Return Detail Data - FidelityMagellanFund-AMCIZPRO</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>000008 - Disclosure - Risk/Return Detail Data - FidelityMagellanK6Fund-PRO</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fidelity.com/role/DisclosureDetailS000065695_FidelityMagellanK6Fund-PRO</Role>
      <ShortName>Risk/Return Detail Data - FidelityMagellanK6Fund-PRO</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>010001 - Disclosure - Investment Objectives and Goals</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/RiskReturn</Role>
      <ShortName>Investment Objectives and Goals</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>010002 - Disclosure - Fees and Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/FeesAndExpenses</Role>
      <ShortName>Fees and Expenses</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>010003 - Disclosure - Investment Strategy</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/InvestmentStrategy</Role>
      <ShortName>Investment Strategy</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>010004 - Disclosure - Investment Risks</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/InvestmentRisks</Role>
      <ShortName>Investment Risks</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>010005 - Disclosure - Performance Management</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/PerformanceManagement</Role>
      <ShortName>Performance Management</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>020010 - Disclosure - Shareholder Fees</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/ShareholderFeesData</Role>
      <ShortName>Shareholder Fees</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>020020 - Disclosure - Annual Fund Operating Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/OperatingExpensesData</Role>
      <ShortName>Annual Fund Operating Expenses</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>020030 - Disclosure - Expense Example</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/ExpenseExample</Role>
      <ShortName>Expense Example</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>020040 - Disclosure - Expense Example, No Redemption</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/ExpenseExampleNoRedemption</Role>
      <ShortName>Expense Example, No Redemption</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>020050 - Disclosure - Annual Total Returns</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/BarChartData</Role>
      <ShortName>Annual Total Returns</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="filing8718.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>020060 - Disclosure - Average Annual Total Returns</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/PerformanceTableData</Role>
      <ShortName>Average Annual Total Returns</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>16</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="485BPOS" isN1a="true" isOEF="true" isRRorOEF="true" isUsgaap="true" original="filing8718.htm">filing8718.htm</File>
    <File>fmr-20250530.xsd</File>
    <File>fmr-20250530_cal.xml</File>
    <File>fmr-20250530_def.xml</File>
    <File>fmr-20250530_lab.xml</File>
    <File>fmr-20250530_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>img108480_1.jpg</File>
    <File>img108481_1.jpg</File>
    <File>img108481_4.jpg</File>
    <File>img108482_1.jpg</File>
    <File>img108484_1.jpg</File>
    <File>img108484_4.jpg</File>
    <File>img108485_1.jpg</File>
    <File>img108486_1.jpg</File>
    <File>img108486_4.jpg</File>
    <File>img108532_1.jpg</File>
    <File>img108532_4.jpg</File>
    <File>img108533_1.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="6">http://xbrl.sec.gov/dei/2024</BaseTaxonomy>
    <BaseTaxonomy items="338">http://xbrl.sec.gov/oef/2024q3</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
