<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:cef="http://xbrl.sec.gov/cef/2025"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="ck0001504619-20260527.xsd" xlink:type="simple"/>
    <context id="P05_27_2026To05_27_2026">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001504619</identifier>
        </entity>
        <period>
            <startDate>2026-05-27</startDate>
            <endDate>2026-05-27</endDate>
        </period>
    </context>
    <unit id="Unit_USD">
        <measure>iso4217:USD</measure>
    </unit>
    <dei:EntityCentralIndexKey contextRef="P05_27_2026To05_27_2026" id="ixv-263">0001504619</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag contextRef="P05_27_2026To05_27_2026" id="ixv-264">false</dei:AmendmentFlag>
    <dei:DocumentType contextRef="P05_27_2026To05_27_2026" id="ixv-276">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="P05_27_2026To05_27_2026" id="ixv-277">2026-05-27</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName contextRef="P05_27_2026To05_27_2026" id="ixv-278">PennantPark Floating Rate Capital Ltd.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode contextRef="P05_27_2026To05_27_2026" id="ixv-279">MD</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber contextRef="P05_27_2026To05_27_2026" id="ixv-280">814-00891</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber contextRef="P05_27_2026To05_27_2026" id="ixv-281">27-3794690</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1 contextRef="P05_27_2026To05_27_2026" id="ixv-282">1691 Michigan Avenue</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown contextRef="P05_27_2026To05_27_2026" id="ixv-283">Miami Beach</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince contextRef="P05_27_2026To05_27_2026" id="ixv-284">FL</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode contextRef="P05_27_2026To05_27_2026" id="ixv-285">33139</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode contextRef="P05_27_2026To05_27_2026" id="ixv-286">786</dei:CityAreaCode>
    <dei:LocalPhoneNumber contextRef="P05_27_2026To05_27_2026" id="ixv-287">297-9500</dei:LocalPhoneNumber>
    <dei:WrittenCommunications contextRef="P05_27_2026To05_27_2026" id="ixv-288">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial contextRef="P05_27_2026To05_27_2026" id="ixv-289">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer contextRef="P05_27_2026To05_27_2026" id="ixv-290">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer contextRef="P05_27_2026To05_27_2026" id="ixv-291">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle contextRef="P05_27_2026To05_27_2026" id="ixv-292">Common Stock, par value $0.001 per share</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="P05_27_2026To05_27_2026" id="ixv-293">PFLT</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="P05_27_2026To05_27_2026" id="ixv-294">NYSE</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany contextRef="P05_27_2026To05_27_2026" id="ixv-295">false</dei:EntityEmergingGrowthCompany>
    <cef:LongTermDebtTableTextBlock contextRef="P05_27_2026To05_27_2026" id="ixv-161">&lt;div style="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;On May&#160;27, 2026, PennantPark Floating Rate Capital Ltd. (the &#x201c;Company&#x201d;) entered into an underwriting agreement (the &#x201c;Underwriting Agreement&#x201d;) by and among the Company, PennantPark Investment Advisers, LLC (the &#x201c;Adviser&#x201d;) and Morgan Stanley&#160;&amp;amp; Co. LLC, Goldman Sachs&#160;&amp;amp; Co. LLC, Keefe, Bruyette&#160;&amp;amp; Woods, Inc., RBC Capital Markets, LLC, and UBS Securities LLC as representatives of the several underwriters (collectively, the &#x201c;Underwriters&#x201d;), in connection with the issuance and sale (the &#x201c;Offering&#x201d;) of $100&#160;million aggregate principal amount of the Company&#x2019;s 7.375% Notes due 2031 (the &#x201c;2031 Notes&#x201d;). The closing of the Offering is expected to occur on June&#160;1, 2026, subject to customary closing conditions. Pursuant to the Underwriting Agreement, the Company has also granted the Underwriters an option to purchase up to an additional $15&#160;million aggregate principal amount of the 2031 Notes within 30 days of May&#160;27, 2026. The Company intends to use the net proceeds from the Offering to repay its outstanding obligations under its revolving credit facility, to invest in new or existing portfolio companies and for general corporate or strategic purposes. &lt;/div&gt;&lt;div style="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;The Underwriting Agreement includes customary representations, warranties, and covenants by the Company and the Adviser. It also provides for customary indemnification by each of the Company, the Adviser, and the Underwriters against certain liabilities and customary contribution provisions in respect of those liabilities.&lt;/div&gt;&lt;div style="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;The 2031 Notes are expected to be listed on the New York Stock Exchange within 30 days of June&#160;1, 2026 and to trade under the trading symbol &#x201c;PFLA&#x201d;. &lt;/div&gt;&lt;div style="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;The Offering is being made pursuant to the Company&#x2019;s effective shelf registration statement on Form &lt;div style="white-space:nowrap;display:inline;"&gt;N-2&lt;/div&gt; (Registration &lt;div style="white-space:nowrap;display:inline;"&gt;No.&#160;333-279726)&lt;/div&gt; previously filed with the Securities and Exchange Commission, as supplemented by a preliminary prospectus supplement dated May&#160;27, 2026 and a final prospectus supplement to be dated May&#160;27, 2026. &lt;/div&gt;&lt;div style="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement filed with this report as Exhibit 1.1 and which is incorporated herein by reference. &lt;/div&gt;</cef:LongTermDebtTableTextBlock>
    <cef:LongTermDebtPrincipal
      contextRef="P05_27_2026To05_27_2026"
      decimals="-6"
      id="ixv-296"
      unitRef="Unit_USD">100000000</cef:LongTermDebtPrincipal>
    <cef:LongTermDebtDividendsAndCovenantsTextBlock contextRef="P05_27_2026To05_27_2026" id="ixv-297">The Underwriting Agreement includes customary representations, warranties, and covenants by the Company and the Adviser. It also provides for customary indemnification by each of the Company, the Adviser, and the Underwriters against certain liabilities and customary contribution provisions in respect of those liabilities.</cef:LongTermDebtDividendsAndCovenantsTextBlock>
</xbrl>
