Fair Value Measurements - Summary of Unrealized Gains (Losses) Recognized Related to Equity Securities (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Net losses recognized during the period on equity securities	$ 446,000	$ 1,228,000	$ 0
Less: net losses recognized during the period on equity securities sold during the period	0	0
Unrealized losses recognized during the reporting period on equity securities still held at the reporting date	$ 446,000	$ 1,228,000