Investments - Additional Information (Details) - USD ($)	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021
Schedule Of Available For Sale Securities [Line Items]
Realized losses from sale of short-term investments	$ 22,000	$ 4,000
Gain on investments, net	$ (22,000)	1,993,000
Debt Security
Schedule Of Available For Sale Securities [Line Items]
Gain on investments, net		$ 2,000,000.0

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27357-111563

Name:	us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration