Borrowings - 2026 Notes - Narrative (Details) - USD ($) $ in Thousands	Feb. 24, 2021	Mar. 31, 2026	Sep. 30, 2025	Oct. 13, 2021
Debt Instrument [Line Items]
Long-term debt		$ 4,702,478	$ 4,900,773
2026 Notes
Debt Instrument [Line Items]
Debt instrument, face amount	$ 400,000			$ 200,000
Long-term debt		$ 600,000	$ 600,000
Interest rate	2.50%
Debt instrument, redemption price, percent	100.00%
Debt instrument, basis spread on variable rate	0.30%