<?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="ck0001504619-20260304.xsd" xlink:type="simple"/>
    <context id="P03_04_2026To03_04_2026">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001504619</identifier>
        </entity>
        <period>
            <startDate>2026-03-04</startDate>
            <endDate>2026-03-04</endDate>
        </period>
    </context>
    <unit id="Unit_USD">
        <measure>iso4217:USD</measure>
    </unit>
    <dei:EntityCentralIndexKey contextRef="P03_04_2026To03_04_2026" id="ixv-325">0001504619</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag contextRef="P03_04_2026To03_04_2026" id="ixv-326">false</dei:AmendmentFlag>
    <dei:DocumentType contextRef="P03_04_2026To03_04_2026" id="ixv-338">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="P03_04_2026To03_04_2026" id="ixv-339">2026-03-04</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName contextRef="P03_04_2026To03_04_2026" id="ixv-340">PennantPark Floating Rate Capital Ltd.</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode contextRef="P03_04_2026To03_04_2026" id="ixv-341">MD</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber contextRef="P03_04_2026To03_04_2026" id="ixv-342">814-00891</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber contextRef="P03_04_2026To03_04_2026" id="ixv-343">27-3794690</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1 contextRef="P03_04_2026To03_04_2026" id="ixv-344">1691 Michigan Avenue</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown contextRef="P03_04_2026To03_04_2026" id="ixv-345">Miami Beach</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince contextRef="P03_04_2026To03_04_2026" id="ixv-346">FL</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode contextRef="P03_04_2026To03_04_2026" id="ixv-347">33139</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode contextRef="P03_04_2026To03_04_2026" id="ixv-348">786</dei:CityAreaCode>
    <dei:LocalPhoneNumber contextRef="P03_04_2026To03_04_2026" id="ixv-349">297-9500</dei:LocalPhoneNumber>
    <dei:WrittenCommunications contextRef="P03_04_2026To03_04_2026" id="ixv-350">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial contextRef="P03_04_2026To03_04_2026" id="ixv-351">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer contextRef="P03_04_2026To03_04_2026" id="ixv-352">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer contextRef="P03_04_2026To03_04_2026" id="ixv-353">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle contextRef="P03_04_2026To03_04_2026" id="ixv-354">Common Stock, par value $0.001 per share</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="P03_04_2026To03_04_2026" id="ixv-355">PFLT</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="P03_04_2026To03_04_2026" id="ixv-356">NYSE</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany contextRef="P03_04_2026To03_04_2026" id="ixv-357">false</dei:EntityEmergingGrowthCompany>
    <cef:LongTermDebtTableTextBlock contextRef="P03_04_2026To03_04_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 March&#160;4, 2026, PennantPark Floating Rate Capital Ltd. (the &#x201c;Company&#x201d;) and Equiniti Trust Company, LLC (the &#x201c;Trustee&#x201d;) entered into a Second Supplemental Indenture (the &#x201c;Second Supplemental Indenture&#x201d;) to the Indenture between the Company and the Trustee, dated March&#160;23, 2021 (the &#x201c;Base Indenture,&#x201d; and together with the Second Supplemental Indenture, the &#x201c;Indenture&#x201d;). The Second Supplemental Indenture relates to the Company&#x2019;s issuance of $200,000,000 aggregate principal amount of its 6.75% notes due 2029 (the &#x201c;Notes&#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 Notes will mature on March&#160;4, 2029 and may be redeemed in whole or in part at the Company&#x2019;s option at any time or from time to time at the redemption prices set forth in the Indenture. The Notes bear interest at a rate of 6.75% per year payable semi-annually on March&#160;4 and September&#160;4 of each year, commencing on September&#160;4, 2026. The Notes are general unsecured obligations of the Company that rank &lt;div style="font-style: normal; letter-spacing: 0px; top: 0px;display:inline;"&gt;&lt;div style="font-style:italic;display:inline;"&gt;pari passu&lt;/div&gt;&lt;/div&gt; in right of payment with any existing and future unsecured unsubordinated indebtedness of the Company; senior to any of future indebtedness of the Company that is expressly subordinated in right of payment to the Notes; senior to any series of preferred stock that the Company may issue in the future; effectively subordinated in right of payment to all of the existing and future secured indebtedness of the Company (including indebtedness that is initially unsecured, but to which the Company subsequently grants security), to the extent of the value of the assets securing such indebtedness; and structurally subordinated to all existing and future indebtedness and other obligations of any of the Company&#x2019;s subsidiaries, financing vehicles or similar facilities. &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 Indenture contains certain covenants, including covenants requiring the Company to comply with the asset coverage requirements of Section&#160;18(a)(1)(A) as modified by Section&#160;61(a)(1) and (2)&#160;of the Investment Company Act of 1940, as amended, giving effect to any exemptive relief granted to the Company by the U.S. Securities and Exchange Commission, and to provide financial information to the holders of the Notes and the Trustee if the Company is no longer subject to the reporting requirements under the Securities Exchange Act of 1934, as amended. These covenants are subject to important limitations and exceptions that are described in the Indenture. &lt;/div&gt;&lt;div style="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;In addition, on the occurrence of a &#x201c;change of control repurchase event,&#x201d; as defined in the Indenture, the Company will generally be required to make an offer to repurchase the outstanding Notes at a price equal to 100% of the principal amount of such Notes plus accrued and unpaid interest to, but not including, the repurchase date. &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 Notes were offered and sold in an offering registered under the Securities Act of 1933, as amended, pursuant to the Registration Statement on Form &lt;div style="white-space: nowrap; letter-spacing: 0px; top: 0px;display:inline;"&gt;N-2&lt;/div&gt; (File &lt;div style="white-space: nowrap; letter-spacing: 0px; top: 0px;display:inline;"&gt;No.&#160;333-279726)&lt;/div&gt; (the &#x201c;Registration Statement&#x201d;), the preliminary prospectus supplement dated February&#160;25, 2026 and a final prospectus supplement dated February&#160;25, 2026. The transaction closed on March&#160;4, 2026. The net proceeds to the Company were approximately $195.9&#160;million, after deducting the underwriting discounts and commissions and estimated offering expenses. The Company intends to use the net proceeds to repay outstanding indebtedness under the Company&#x2019;s multi-currency senior secured revolving credit facility, as amended from time to time, with Truist Bank and other lenders, initially into on August&#160;12, 2021, 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 foregoing descriptions of the Second Supplemental Indenture and the Notes do not purport to be complete and are qualified in their entirety by reference to the full text of the Second Supplemental Indenture and the Notes, respectively, each filed as exhibits hereto and incorporated by reference herein. &lt;/div&gt;</cef:LongTermDebtTableTextBlock>
    <cef:LongTermDebtPrincipal
      contextRef="P03_04_2026To03_04_2026"
      decimals="0"
      id="ixv-358"
      unitRef="Unit_USD">200000000</cef:LongTermDebtPrincipal>
    <cef:LongTermDebtDividendsAndCovenantsTextBlock contextRef="P03_04_2026To03_04_2026" id="ixv-166">&lt;div style="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"&gt;The Indenture contains certain covenants, including covenants requiring the Company to comply with the asset coverage requirements of Section&#160;18(a)(1)(A) as modified by Section&#160;61(a)(1) and (2)&#160;of the Investment Company Act of 1940, as amended, giving effect to any exemptive relief granted to the Company by the U.S. Securities and Exchange Commission, and to provide financial information to the holders of the Notes and the Trustee if the Company is no longer subject to the reporting requirements under the Securities Exchange Act of 1934, as amended. These covenants are subject to important limitations and exceptions that are described in the Indenture. &lt;/div&gt;</cef:LongTermDebtDividendsAndCovenantsTextBlock>
</xbrl>
