Borrowings - Adviser Revolver - Narrative (Details) - USD ($) |
3 Months Ended | 9 Months Ended | |||||
|---|---|---|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
Sep. 30, 2025 |
Jun. 13, 2025 |
Jun. 12, 2025 |
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| Debt Instrument [Line Items] | |||||||
| Long-term debt | $ 4,537,552,000 | $ 4,537,552,000 | $ 4,900,773,000 | ||||
| Average stated interest rate | 5.30% | 5.70% | 5.30% | 5.90% | |||
| Adviser Revolver | Line of Credit | |||||||
| Debt Instrument [Line Items] | |||||||
| Long-term debt | $ 33,200,000 | $ 33,200,000 | 39,200,000 | ||||
| Other Short-Term Borrowings | |||||||
| Debt Instrument [Line Items] | |||||||
| Short-term debt, average outstanding amount | 4,654,965,000 | $ 4,962,538,000 | 4,763,136,000 | $ 4,867,651,000 | |||
| Revolving Credit Facility | Adviser Revolver | Line of Credit | |||||||
| Debt Instrument [Line Items] | |||||||
| Line of credit facility, maximum borrowing capacity | $ 300,000,000 | $ 300,000,000 | $ 300,000,000 | $ 300,000,000 | $ 200,000,000 | ||
| Interest rate | 3.50% | 3.50% | |||||
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- Definition The average effective interest rate during the reporting period. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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