<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:ffd="http://xbrl.sec.gov/ffd/2025q4"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <link:schemaRef
      xlink:href="https://xbrl.sec.gov/ffd/2025q4/ffd-2025q4.xsd"
      xlink:type="simple"/>
    <context id="rc">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_1">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>1</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_2">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>2</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_3">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>3</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_4">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>4</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_5">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>5</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_6">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>6</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_7">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>7</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_8">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>8</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_9">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>9</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>10</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <context id="offrl_11">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001513363</identifier>
            <segment>
                <xbrldi:typedMember dimension="ffd:OfferingAxis">
                    <dei:lineNo>11</dei:lineNo>
                </xbrldi:typedMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-27</startDate>
            <endDate>2026-02-27</endDate>
        </period>
    </context>
    <unit id="USD">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <ffd:FormTp contextRef="rc" id="ixv-509">N-2</ffd:FormTp>
    <ffd:SubmissnTp contextRef="rc" id="ixv-510">N-2ASR</ffd:SubmissnTp>
    <ffd:FeeExhibitTp contextRef="rc" id="ixv-511">EX-FILING FEES</ffd:FeeExhibitTp>
    <dei:EntityCentralIndexKey contextRef="rc" id="ixv-512">0001513363</dei:EntityCentralIndexKey>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-513">FIDUS INVESTMENT Corp</dei:EntityRegistrantName>
    <ffd:OfferingTableNa contextRef="rc" id="hiddenrcOfferingTableNa" xsi:nil="true"/>
    <ffd:OffsetTableNa contextRef="rc" id="hiddenrcOffsetTableNa">N/A</ffd:OffsetTableNa>
    <ffd:CombinedProspectusTableNa contextRef="rc" id="hiddenrcCombinedProspectusTableNa">N/A</ffd:CombinedProspectusTableNa>
    <ffd:FormTp contextRef="rc" id="ixv-631">N-2</ffd:FormTp>
    <dei:EntityRegistrantName contextRef="rc" id="ixv-632">FIDUS INVESTMENT Corp</dei:EntityRegistrantName>
    <ffd:PrevslyPdFlg contextRef="offrl_1" id="ixv-633">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_1" id="ixv-634">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_1" id="ixv-635">Common Stock, $0.001 par value</ffd:OfferingSctyTitl>
    <ffd:Rule457rFlg contextRef="offrl_1" id="ixv-636">true</ffd:Rule457rFlg>
    <ffd:FeeRate
      contextRef="offrl_1"
      decimals="7"
      id="ixv-637"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:PrevslyPdFlg contextRef="offrl_2" id="ixv-638">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_2" id="ixv-639">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_2" id="ixv-640">Preferred Stock, $0.001 par value</ffd:OfferingSctyTitl>
    <ffd:Rule457rFlg contextRef="offrl_2" id="ixv-641">true</ffd:Rule457rFlg>
    <ffd:FeeRate
      contextRef="offrl_2"
      decimals="7"
      id="ixv-642"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:PrevslyPdFlg contextRef="offrl_3" id="ixv-643">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_3" id="ixv-644">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_3" id="ixv-645">Subscription Rights</ffd:OfferingSctyTitl>
    <ffd:Rule457rFlg contextRef="offrl_3" id="ixv-646">true</ffd:Rule457rFlg>
    <ffd:FeeRate
      contextRef="offrl_3"
      decimals="7"
      id="ixv-647"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:PrevslyPdFlg contextRef="offrl_4" id="ixv-648">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_4" id="ixv-649">Debt</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_4" id="ixv-650">Debt Securities</ffd:OfferingSctyTitl>
    <ffd:Rule457rFlg contextRef="offrl_4" id="ixv-651">true</ffd:Rule457rFlg>
    <ffd:FeeRate
      contextRef="offrl_4"
      decimals="7"
      id="ixv-652"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:PrevslyPdFlg contextRef="offrl_5" id="ixv-653">false</ffd:PrevslyPdFlg>
    <ffd:OfferingSctyTp contextRef="offrl_5" id="ixv-654">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_5" id="ixv-655">Warrants</ffd:OfferingSctyTitl>
    <ffd:Rule457rFlg contextRef="offrl_5" id="ixv-656">true</ffd:Rule457rFlg>
    <ffd:FeeRate
      contextRef="offrl_5"
      decimals="7"
      id="ixv-657"
      unitRef="pure">0.0001381</ffd:FeeRate>
    <ffd:OfferingSctyTp contextRef="offrl_6" id="ixv-658">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_6" id="ixv-659">Common Stock, $0.001 par value</ffd:OfferingSctyTitl>
    <ffd:Rule415a6Flg contextRef="offrl_6" id="ixv-660">true</ffd:Rule415a6Flg>
    <ffd:CfwdFormTp contextRef="offrl_6" id="ixv-661">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_6" id="ixv-662">333-277540</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_6" id="ixv-663">2024-05-08</ffd:CfwdPrrFctvDt>
    <ffd:OfferingSctyTp contextRef="offrl_7" id="ixv-664">Equity</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_7" id="ixv-665">Preferred Stock, $0.001 par value</ffd:OfferingSctyTitl>
    <ffd:Rule415a6Flg contextRef="offrl_7" id="ixv-666">true</ffd:Rule415a6Flg>
    <ffd:CfwdFormTp contextRef="offrl_7" id="ixv-667">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_7" id="ixv-668">333-277540</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_7" id="ixv-669">2024-05-08</ffd:CfwdPrrFctvDt>
    <ffd:OfferingSctyTp contextRef="offrl_8" id="ixv-670">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_8" id="ixv-671">Subscription Rights</ffd:OfferingSctyTitl>
    <ffd:Rule415a6Flg contextRef="offrl_8" id="ixv-672">true</ffd:Rule415a6Flg>
    <ffd:CfwdFormTp contextRef="offrl_8" id="ixv-673">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_8" id="ixv-674">333-277540</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_8" id="ixv-675">2024-05-08</ffd:CfwdPrrFctvDt>
    <ffd:OfferingSctyTp contextRef="offrl_9" id="ixv-676">Debt</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_9" id="ixv-677">Debt Securities</ffd:OfferingSctyTitl>
    <ffd:Rule415a6Flg contextRef="offrl_9" id="ixv-678">true</ffd:Rule415a6Flg>
    <ffd:CfwdFormTp contextRef="offrl_9" id="ixv-679">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_9" id="ixv-680">333-277540</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_9" id="ixv-681">2024-05-08</ffd:CfwdPrrFctvDt>
    <ffd:OfferingSctyTp contextRef="offrl_10" id="ixv-682">Other</ffd:OfferingSctyTp>
    <ffd:OfferingSctyTitl contextRef="offrl_10" id="ixv-683">Warrants</ffd:OfferingSctyTitl>
    <ffd:Rule415a6Flg contextRef="offrl_10" id="ixv-684">true</ffd:Rule415a6Flg>
    <ffd:CfwdFormTp contextRef="offrl_10" id="ixv-685">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_10" id="ixv-686">333-277540</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_10" id="ixv-687">2024-05-08</ffd:CfwdPrrFctvDt>
    <ffd:OfferingSctyTp contextRef="offrl_11" id="ixv-688">Unallocated (Universal) Shelf</ffd:OfferingSctyTp>
    <ffd:Rule415a6Flg contextRef="offrl_11" id="ixv-689">true</ffd:Rule415a6Flg>
    <ffd:CfwdFormTp contextRef="offrl_11" id="ixv-690">N-2</ffd:CfwdFormTp>
    <ffd:CfwdPrrFileNb contextRef="offrl_11" id="ixv-691">333-277540</ffd:CfwdPrrFileNb>
    <ffd:CfwdPrrFctvDt contextRef="offrl_11" id="ixv-692">2024-05-08</ffd:CfwdPrrFctvDt>
    <ffd:CfwdPrevslyPdFee
      contextRef="offrl_11"
      decimals="2"
      id="ixv-693"
      unitRef="USD">14760.00</ffd:CfwdPrevslyPdFee>
    <ffd:TtlOfferingAmt contextRef="rc" decimals="2" id="ixv-694" unitRef="USD">0.00</ffd:TtlOfferingAmt>
    <ffd:TtlFeeAmt contextRef="rc" decimals="2" id="ixv-695" unitRef="USD">0.00</ffd:TtlFeeAmt>
    <ffd:TtlPrevslyPdAmt contextRef="rc" decimals="2" id="ixv-696" unitRef="USD">0.00</ffd:TtlPrevslyPdAmt>
    <ffd:TtlOffsetAmt contextRef="rc" decimals="2" id="ixv-697" unitRef="USD">0.00</ffd:TtlOffsetAmt>
    <ffd:NetFeeAmt contextRef="rc" decimals="2" id="ixv-698" unitRef="USD">0.00</ffd:NetFeeAmt>
    <ffd:OfferingNote contextRef="offrl_1" id="ixv-699">In accordance with Rule 456(b) and Rule 457(r) promulgated under the Securities Act of 1933, as amended (the "Securities Act"), Fidus Investment Corporation (the "Registrant") is deferring payment of all of the registration fees.</ffd:OfferingNote>
    <ffd:OfferingNote contextRef="offrl_2" id="ixv-700">In accordance with Rule 456(b) and Rule 457(r) promulgated under the Securities Act of 1933, as amended (the "Securities Act"), Fidus Investment Corporation (the "Registrant") is deferring payment of all of the registration fees.</ffd:OfferingNote>
    <ffd:OfferingNote contextRef="offrl_3" id="ixv-701">In accordance with Rule 456(b) and Rule 457(r) promulgated under the Securities Act of 1933, as amended (the "Securities Act"), Fidus Investment Corporation (the "Registrant") is deferring payment of all of the registration fees.</ffd:OfferingNote>
    <ffd:OfferingNote contextRef="offrl_4" id="ixv-702">In accordance with Rule 456(b) and Rule 457(r) promulgated under the Securities Act of 1933, as amended (the "Securities Act"), Fidus Investment Corporation (the "Registrant") is deferring payment of all of the registration fees.</ffd:OfferingNote>
    <ffd:OfferingNote contextRef="offrl_5" id="ixv-703">In accordance with Rule 456(b) and Rule 457(r) promulgated under the Securities Act of 1933, as amended (the "Securities Act"), Fidus Investment Corporation (the "Registrant") is deferring payment of all of the registration fees.</ffd:OfferingNote>
    <ffd:OfferingNote contextRef="offrl_11" id="ixv-704">Pursuant to Rule 415(a)(6) under the Securities Act, this Registration Statement includes $100,000,000 of unsold securities of the Registrant that were previously registered on the Registrant's Registration Statement on Form N-2 (File No. 333-277540) (the "Unsold Securities"), which was initially filed with the Securities and Exchange Commission (the "SEC") on February 29, 2024, as amended on May 8, 2024, and declared effective by the SEC on May 8, 2024 (the "Prior Registration Statement"). The Registrant previously paid a filing fee in the aggregate of $14,760 relating to the Unsold Securities. Pursuant to Rule 415(a)(6), the offering of the Unsold Securities registered under the Prior Registration Statement will be deemed terminated as of the effective date of this Registration Statement.</ffd:OfferingNote>
</xbrl>
