Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Sep. 30, 2025
Income Tax Disclosure [Line Items]
Provision (benefit) for income taxes	$ 36,457	$ 10,922
Unrecognized tax benefits	48,600		$ 157,700
Income taxes payable	76,100		179,100
Accrued income taxes	39,400		28,700
Income tax provision upon recognition of unrecognized tax benefit	48,600
Unrecognized tax benefits, increase in valuation allowance upon recognition	5,800
Potential decrease in unrecognized tax benefits	1,000
Other Liabilities [Member]
Income Tax Disclosure [Line Items]
Accrued income taxes	36,700		$ 150,400
IRS [Member]
Income Tax Disclosure [Line Items]
Provision (benefit) for income taxes	$ (7,100)
Foreign Tax Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Provision (benefit) for income taxes		$ (5,400)