Insurance Liabilities - Weighted-Average Interest Rates (Details)	Sep. 30, 2024	Sep. 30, 2023
Insurance [Abstract]
Weighted-average interest rate, original discount rate	1.83%	1.84%
Weighted-average interest rate, current discount rate	3.30%	3.92%

Current weighted-average discount rate used to measure liability for future policy benefit.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(6)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-6

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-29E

Name:	us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant