Investments - Consolidated Statements of Assets and Liabilities for PSSL (Details) - USD ($) $ in Thousands |
Mar. 31, 2026 |
Sep. 30, 2025 |
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| Assets | ||||||||||||||||||||||||||||
| Fair Value | $ 2,580,281 | [1],[2],[3],[4],[5] | $ 2,773,328 | [6],[7],[8],[9],[10] | ||||||||||||||||||||||||
| Cash and Cash Equivalent at Carrying Value | 121,900 | |||||||||||||||||||||||||||
| Cash | 90,444 | [3],[4],[5] | 81,959 | [8],[9],[10] | ||||||||||||||||||||||||
| Interest receivable | 12,611 | 13,832 | ||||||||||||||||||||||||||
| Receivable for investments sold | 37 | 838 | ||||||||||||||||||||||||||
| Prepaid expenses and other assets | 2,085 | 2,143 | ||||||||||||||||||||||||||
| Total assets | 2,747,936 | 2,913,681 | ||||||||||||||||||||||||||
| Liabilities | ||||||||||||||||||||||||||||
| Credit facility payable | 328,333 | 683,837 | ||||||||||||||||||||||||||
| Notes payable to members | 900 | 0 | ||||||||||||||||||||||||||
| Payable for investments purchased | 0 | 14,852 | ||||||||||||||||||||||||||
| Interest payable on notes to members | 15,407 | 19,172 | ||||||||||||||||||||||||||
| Distribution payable to members | 10,170 | 10,170 | ||||||||||||||||||||||||||
| Accrued expenses | 1,581 | 2,166 | ||||||||||||||||||||||||||
| Due to affiliate | 37 | 838 | ||||||||||||||||||||||||||
| Total liabilities | 1,709,279 | 1,839,165 | ||||||||||||||||||||||||||
| Commitments and contingencies | ||||||||||||||||||||||||||||
| Members' equity | 68,704 | [11] | 50,650 | |||||||||||||||||||||||||
| Total liabilities and net assets | 2,747,936 | 2,913,681 | ||||||||||||||||||||||||||
| PennantPark Senior Secured Loan Fund I LLC | ||||||||||||||||||||||||||||
| Assets | ||||||||||||||||||||||||||||
| Fair Value | 1,209,044 | 1,084,649 | ||||||||||||||||||||||||||
| Cash equivalents | 18,001 | 47,870 | ||||||||||||||||||||||||||
| Cash | 15,997 | 13,690 | ||||||||||||||||||||||||||
| Interest receivable | 3,782 | 4,138 | ||||||||||||||||||||||||||
| Receivable for investments sold | 262 | 50 | ||||||||||||||||||||||||||
| Due from affiliate | 25 | 208 | ||||||||||||||||||||||||||
| Prepaid expenses and other assets | 1,881 | 2,296 | ||||||||||||||||||||||||||
| Total assets | 1,248,767 | 1,153,689 | ||||||||||||||||||||||||||
| Liabilities | ||||||||||||||||||||||||||||
| Credit facility payable | 158,500 | 74,500 | ||||||||||||||||||||||||||
| Notes payable to members | 271,600 | 271,600 | ||||||||||||||||||||||||||
| Interest payable on credit facility and asset backed debt | 9,361 | 16,868 | ||||||||||||||||||||||||||
| Interest payable on notes to members | 6,251 | 6,788 | ||||||||||||||||||||||||||
| Accrued expenses | 1,314 | 997 | ||||||||||||||||||||||||||
| Due to affiliate | 262 | 50 | ||||||||||||||||||||||||||
| Total liabilities | 1,180,063 | 1,103,039 | ||||||||||||||||||||||||||
| Members' equity | 68,704 | 50,650 | ||||||||||||||||||||||||||
| Total liabilities and net assets | 1,248,767 | 1,153,689 | ||||||||||||||||||||||||||
| PennantPark Senior Secured Loan Fund I LLC | 2036 Asset-backed debt | ||||||||||||||||||||||||||||
| Liabilities | ||||||||||||||||||||||||||||
| Asset-Backed Debt, net | 244,803 | 244,659 | ||||||||||||||||||||||||||
| PennantPark Senior Secured Loan Fund I LLC | 2037 Asset-backed debt | ||||||||||||||||||||||||||||
| Liabilities | ||||||||||||||||||||||||||||
| Asset-Backed Debt, net | 244,268 | 244,096 | ||||||||||||||||||||||||||
| PennantPark Senior Secured Loan Fund I LLC | 2037 R Asset-backed debt | ||||||||||||||||||||||||||||
| Liabilities | ||||||||||||||||||||||||||||
| Asset-Backed Debt, net | 243,704 | $ 243,481 | ||||||||||||||||||||||||||
| Pennant Park Senior Secured Loan Fund II L L C [Member] | ||||||||||||||||||||||||||||
| Assets | ||||||||||||||||||||||||||||
| Fair Value | 339,929 | |||||||||||||||||||||||||||
| Cash equivalents | 5,320 | |||||||||||||||||||||||||||
| Cash | 9,169 | |||||||||||||||||||||||||||
| Interest receivable | 904 | |||||||||||||||||||||||||||
| Prepaid expenses and other assets | 2,169 | |||||||||||||||||||||||||||
| Due from affiliate | 18 | |||||||||||||||||||||||||||
| Total assets | 357,509 | |||||||||||||||||||||||||||
| Liabilities | ||||||||||||||||||||||||||||
| Credit facility payable | 226,000 | |||||||||||||||||||||||||||
| Notes payable to members | 87,500 | |||||||||||||||||||||||||||
| Interest payable on credit facility and asset backed debt | 3,247 | |||||||||||||||||||||||||||
| Interest payable on notes to members | 1,644 | |||||||||||||||||||||||||||
| Distribution payable to members | 1,200 | |||||||||||||||||||||||||||
| Accrued expenses | 746 | |||||||||||||||||||||||||||
| Total liabilities | 320,337 | |||||||||||||||||||||||||||
| Members' equity | [12] | 37,172 | ||||||||||||||||||||||||||
| Total liabilities and net assets | $ 357,509 | |||||||||||||||||||||||||||
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- Definition Asset backed debt net. No definition available.
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- Definition Cash Equivalents, Fair Value Disclosure No definition available.
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- Definition Due from affiliate No definition available.
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- Definition Due From Affiliate Noncurrent 1 No definition available.
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- Definition Interest payable on credit facility. No definition available.
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- Definition Payable for investments purchased. No definition available.
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- Definition Receivable for investments sold. No definition available.
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- Definition Amount of asset recognized for present right to economic benefit. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of cash and cash equivalent. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Represents the caption on the face of the balance sheet to indicate that the entity has entered into (1) purchase or supply arrangements that will require expending a portion of its resources to meet the terms thereof, and (2) is exposed to potential losses or, less frequently, gains, arising from (a) possible claims against a company's resources due to future performance under contract terms, and (b) possible losses or likely gains from uncertainties that will ultimately be resolved when one or more future events that are deemed likely to occur do occur or fail to occur. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of distribution payable to ownership interest holder from investment income and return of capital. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of interest payable on debt, including, but not limited to, trade payables. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in security owned. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of liability recognized for present obligation requiring transfer or otherwise providing economic benefit to others. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- References No definition available.
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- Definition Amount of liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of ownership interest in limited liability company (LLC), attributable to the parent entity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of expenses incurred but not yet paid classified as other. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets. No definition available.
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