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Borrowings - 2031 Notes - Narrative (Details) - USD ($) $ in Thousands	May 27, 2026	Jun. 30, 2026	Sep. 30, 2025
Debt Instrument [Line Items]
Long-term debt		$ 4,537,552	$ 4,900,773
2031 Notes
Debt Instrument [Line Items]
Debt instrument, face amount	$ 500,000
Long-term debt		$ 500,000
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Debt instrument, redemption price, percent	100.00%
Debt instrument, basis spread on variable rate	0.35%
2031 Notes \| Interest Rate Swap
Debt Instrument [Line Items]
Debt instrument, face amount	$ 500,000
2031 Notes \| Tranche one \| Interest Rate Swap
Debt Instrument [Line Items]
Debt instrument, face amount	$ 350,000
Fixed interest rate	6.25%
Basis spread on variable rate	2.171%
2031 Notes \| Tranche two \| Interest Rate Swap
Debt Instrument [Line Items]
Debt instrument, face amount	$ 75,000
Fixed interest rate	6.25%
Basis spread on variable rate	2.203%
2031 Notes \| Tranche three \| Interest Rate Swap
Debt Instrument [Line Items]
Debt instrument, face amount	$ 75,000
Fixed interest rate	6.25%
Basis spread on variable rate	2.185%