Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized losses to marketable securities	$ 200,000	$ 400,000
Marketable Securities	19,818,000	31,901,000
Equity investments without readily determinable fair values	2,600,000	3,100,000
Impairment related to investments without readily determinable fair values	500,000	0	$ 0
Estimated Fair Value | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of notes	$ 257,400,000	$ 155,300,000