Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Sep. 30, 2024
Income Tax Disclosure [Line Items]
Provision (benefit) for income taxes	$ 42,605	$ 31,300	$ 53,527	$ 50,512
Unrecognized tax benefits	42,500		42,500		$ 65,000
Income tax provision upon recognition of unrecognized tax benefit	42,500		42,500
Unrecognized tax benefits, increase in valuation allowance upon recognition	6,500		6,500
Potential decrease in unrecognized tax benefits	$ 1,000		1,000
Foreign Tax Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Provision (benefit) for income taxes			$ (10,400)	$ 3,600