Debt - Schedule of Carrying Value (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Sep. 30, 2025
Current maturities on debt:
Less: debt issuance costs	$ 0	$ (459)
Current maturities on debt	300,000	399,541
Long-term debt:
Less: debt issuance costs	(27,611)	(18,850)
Long-term debt	5,282,389	2,656,150
Total debt	5,582,389	3,055,691
Term loan \| Term loan \| Unsecured Debt
Current maturities on debt:
Current maturities on debt, gross	300,000	0
Long-term debt:
Long-term debt, gross	1,200,000	0
Senior Notes \| The 2018 Senior Notes
Current maturities on debt:
Current maturities on debt, gross	0	400,000
Senior Notes \| The 2019 Senior Notes and the 2021 Senior Notes
Long-term debt:
Long-term debt, gross	900,000	900,000
Senior Notes \| The 2025 Senior Notes
Long-term debt:
Long-term debt, gross	1,500,000	1,500,000
Senior Notes \| The 2026 Senior Notes
Long-term debt:
Long-term debt, gross	1,000,000	0
Revolving line of credit \| Revolving Credit Facility
Long-term debt:
Long-term debt, gross	$ 710,000	$ 275,000

Long-Term Debt Current Maturities, Gross

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after accumulated amortization, of debt issuance costs classified as current. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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