Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gains (losses) to marketable securities	$ 300,000	$ 200,000	$ (400,000)
Equity investments without readily determinable fair values	2,600,000	2,600,000
Impairment related to investments without readily determinable fair values	0	500,000	$ 0
Estimated Fair Value | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of notes	$ 184,800,000	$ 257,400,000